Abstract:
A vacuum cleaner that includes: a suction part that is configured to receive dust; and a cleaner body that is coupled to the suction part, that is configured to collect dust from the suction part based on suction force, and that includes: a main body, a suction motor that is configured to generate suction force, a wheel that is coupled to a first surface of the main body and that is configured to rotate about an axis to move the main body, a driving unit that is configured to generate driving force to move the wheel, a display unit that is coupled to the wheel and that is configured to display operation state information of the vacuum cleaner, and a controller that is configured to control the driving unit and the display unit is disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. 119 and 365 to Korean Patent Application No. 10-2016-0024022, filed on Feb. 29, 2016 and Korean Patent Application No. 10-2016-0036257, filed on Mar. 25, 2016 in the Korean Intellectual Property Office, the entire contents of which is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a vacuum cleaner and a method of displaying the state thereof. 
       BACKGROUND 
       [0003]    In general, a vacuum cleaner refers to a device for sucking dust and foreign materials from a surface to be cleaned using a suction motor provided in a main body and filtering dust and foreign materials in the main body. 
         [0004]    The vacuum cleaner may be classified into an up-right type vacuum cleaner having a suction nozzle connected to a main body thereof and moving along with the main body and a canister type vacuum cleaner having a suction nozzle connected to a main body through an extension pipe, a handle, a hose, etc. 
         [0005]    As the related art, a canister type vacuum cleaner is disclosed in Korean Patent Laid-Open No. 10-2008-0017649. 
         [0006]    The vacuum cleaner of the related art includes a main body including a fan-motor assembly for providing vacuum suction force, a suction nozzle for sucking in various indoor foreign materials, an extension pipe extending from the suction nozzle, a suction hose connected to the main body to deliver vacuum suction force, a controller provided in the main body to control operation of various components such as the fan-motor assembly, and a panel provided in the main body to display various images and information under control of the controller. 
         [0007]    The vacuum cleaner of the related art generally displays the operation state thereof through a display unit provided in the main body. However, the method of displaying the state of the cleaner of the related art has low visibility and thus requires user&#39;s excessive concentration or efforts. Accordingly, the operation state of the cleaner or an error occurring during the operation of the cleaner may not be properly delivered to the user. In particular, if the user does not perceive the error occurring during the operation of the cleaner, the internal parts of the vacuum cleaner may be damaged or cleaning may not be properly performed. 
         [0008]    In addition, in the vacuum cleaner of the related art, since wheels are automatically driven by a driving device such as a motor, the user may not perceive the driving state of the wheels. 
         [0009]    As the related art, a vacuum cleaner is disclosed in Korean Patent Publication No. 10-1552437. 
         [0010]    The vacuum cleaner of the related art includes a cleaner body including a suction motor for generating suction force, a suction part communicating with the cleaner body to suck in air and dust, a connection part for connecting the suction part and the cleaner body, and a battery provided in the cleaner body to supply power to the suction motor. 
         [0011]    Meanwhile, in order to replace the battery or charge the battery using a charger, the battery should be detached from the cleaner body. However, in the related art, since a battery assembly is provided in the cleaner body, it is inconvenient to detach the battery assembly from the cleaner body. 
       SUMMARY 
       [0012]    In general, one innovative aspect of the subject matter described in this specification can be implemented in a vacuum cleaner comprising: a suction part that is configured to receive dust; and a cleaner body that is coupled to the suction part, that is configured to collect dust from the suction part based on suction force, and that includes: a main body, a suction motor that is configured to generate suction force, a wheel that is coupled to a first surface of the main body and that is configured to rotate about an axis to move the main body, a driving unit that is configured to generate driving force to move the wheel, a display unit that is coupled to the wheel and that is configured to display operation state information of the vacuum cleaner, and a controller that is configured to control the driving unit and the display unit. 
         [0013]    The foregoing and other implementations can each optionally include one or more of the following features, alone or in combination. In particular, one implementation includes all the following features in combination. The vacuum cleaner further includes: a first sensor that is configured to sense movement of the main body, wherein the controller is configured to control a rotation of the wheel based on the movement of the main body sensed by the first sensor. The controller is configured to: control the display unit to display power status of the first sensor. The controller is configured to: control the display unit to display a rotation direction of the wheel. The display unit includes: a light emitting unit that is configured to emit light, and wherein the controller is configured to: define a first region of the light emitting unit and control the first region of the light emitting unit to emit first light in a first color, and define a second region of the light emitting unit and control the second region of the light emitting unit to emit second light in a second color. The light emitting unit has a circular shape or a ring shape, and wherein the controller is configured to: define the first region to move along a perimeter of the light emitting unit based on a rotation of the wheel. The controller is configured to: determine whether the vacuum cleaner has an operation error, and based on a determination that the vacuum cleaner has an operation error, control the display unit to display the operation error. The vacuum cleaner further includes: a second sensor that is configured to sense an obstacle, wherein the controller is configured to control the display unit to display obstacle information indicating that an obstacle is present adjacent to the vacuum cleaner. The vacuum cleaner further includes: a battery that is configured to supply electric power to the main body, wherein the controller is configured to control the display unit to display battery level information including a remaining capacity of the battery. The battery is detachable to the main body. The cleaner body includes: a first portion located at a first side of the axis, and a second portion located at a second side of the axis, wherein the battery is detachable from the second portion of the cleaner body, and wherein, based on the battery being detached from the second portion, the second portion is heavier than the first portion. Based on the battery being detached from the second portion, the first portion is lifted from ground. At least a portion of the battery is closer to ground than the axis. The main body includes: a battery attachment part that is part of the second portion and to which the battery is attached, and wherein the battery is attached to the battery attachment part at a first angle relative to ground, the first angle being between 0 and 90 degrees. The vacuum cleaner further includes: a third sensor that is configured to sense movement of the cleaner body, wherein, based on movement of the cleaner body, the controller is configured to control the driving unit to move the wheel such that the cleaner body follows a user. The vacuum cleaner further includes: a supporter that is coupled to a surface of the main body, wherein the main body is configured to rotate about the axis based on the battery being detached from the second portion, and wherein the supporter is configured to block the main body from rotating beyond a second angle. The supporter includes: an auxiliary wheel that is configured to rotate with the wheel. The supporter includes: an extension that couples the auxiliary wheel to the main body. The supporter includes: an elastic member that is configured to provide elastic force to the extension. 
         [0014]    In general, another innovative aspect of the subject matter described in this specification can be implemented in a method of displaying operation state information of a vacuum cleaner that includes a main body, a wheel that is coupled to a first surface of the main body and that is configured to rotate to move the main body, a driving unit that is configured to generate driving force to move the wheel, a display unit that is coupled to the wheel and that is configured to display operation state information of the vacuum cleaner, a controller that is configured to control the driving unit and the display unit, and a sensor that is configured to sense movement of the main body, the method comprising: initiating, by the controller, an operation of the sensor; sensing, by the sensor, movement of the main body; controlling, by the controller, the driving unit to move the wheel to move the main body; and controlling, by the controller, the display unit to display a rotation direction of the wheel. 
         [0015]    The subject matter described in this specification can be implemented in particular examples so as to realize one or more of the following advantages. An advantage of the present invention is to provide a vacuum cleaner including a display unit for enabling a user to easily check the operation state of the vacuum cleaner. 
         [0016]    Another advantage of the present invention is to provide a vacuum cleaner capable of displaying the rotation direction of wheels to a user when the wheels of the vacuum cleaner are automatically driven. 
         [0017]    Another advantage of the present invention is to provide a vacuum cleaner capable of easily mounting a battery in a cleaner body thereof. 
         [0018]    Another advantage of the present invention is to provide a vacuum cleaner in which a cleaner body is two-point supported by wheels. 
         [0019]    Another advantage of the present invention is to provide a vacuum cleaner capable of improving driving stability of a cleaner body thereof. 
         [0020]    Another advantage of the present invention is to provide a vacuum cleaner for preventing a cleaner body thereof from being overturned backward. 
         [0021]    The details of one or more examples of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other potential features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claim. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a perspective view of a vacuum cleaner according to an embodiment of the present invention. 
           [0023]      FIG. 2  is a perspective view of a cleaner body of  FIG. 1 . 
           [0024]      FIG. 3  is a block diagram of a vacuum cleaner according to an embodiment of the present invention. 
           [0025]      FIG. 4  is a view showing a state of turning a display unit off. 
           [0026]      FIG. 5  is a view showing a state in which a display unit emits light. 
           [0027]      FIG. 6  is a view showing a state in which only a portion of a display unit emits light. 
           [0028]      FIG. 7  is a view showing a state in which a main body of  FIG. 1  is inclined forward. 
           [0029]      FIG. 8  is a view showing a state in which the main body of  FIG. 1  is inclined backward. 
           [0030]      FIG. 9  is a view showing the configuration of a supporter of  FIG. 8 . 
           [0031]      FIG. 10  is a view sequentially showing a state of attaching a battery to the main body of the cleaner. 
           [0032]      FIG. 11  is a view sequentially showing a state of detaching a battery from the main body of the cleaner. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which the same or similar portions are denoted by the same reference numerals. In describing the present invention, a detailed description of known functions and configurations will be omitted when it may obscure the subject matter of the present invention. 
         [0034]    It will be understood that, although the terms first, second, A, B, (a), (b), etc. may be used herein to describe various elements of the present invention, these terms are only used to distinguish one element from another element and essential, order, or sequence of corresponding elements are not limited by these terms. It will be understood that when one element is referred to as being “connected to”, “coupled to”, or “accessing” another element, one element may be “connected to”, “coupled to”, or “access” another element via a further element although one element may be directly connected to or directly access another element. 
         [0035]      FIG. 1  is a perspective view of a vacuum cleaner according to an embodiment of the present invention,  FIG. 2  is a perspective view of a cleaner body of  FIG. 1 , and  FIG. 3  is a block diagram of a vacuum cleaner according to an embodiment of the present invention. 
         [0036]    Referring to  FIGS. 1 to 3 , the vacuum cleaner  1  according to the embodiment of the present invention includes a cleaner body  10  and a suction device  20 . The cleaner body  10  includes a suction motor for generating suction force. When the suction motor is driven to generate suction force, the suction device  20  may guide air including dust to the cleaner body  10 . 
         [0037]    The suction device  20  may include a suction part  21  for sucking dust from a surface to be cleaned, e.g., a floor, and connection parts  22 ,  23  and  24  for connecting the suction part  21  to the cleaner body  10 . The connection parts  22 ,  23  and  24  may include an extension pipe  24  connected to the suction part  21 , a handle  22  connected to the extension pipe  24  and a suction hose  23  for connecting the handle  22  to the cleaner body  10 . 
         [0038]    The cleaner body  10  includes a main body  110  and wheels  120 . 
         [0039]    The main body  110  may include the suction motor and various parts and electronic parts for driving the vacuum cleaner  1 . 
         [0040]    The cleaner body  10  may include a connector  103  connected to the suction hose  23 . Dust received through the suction hose  23  may flow into the main body  110  through the connector  103 . 
         [0041]    The main body  110  includes a dust canister  105  in which dust sucked through the suction device  20  is stored. The dust canister  105  may be detachably mounted in the main body  110 . In addition, the dust canister  105  may be provided in front of the main body  110  and may be made of a transparent material to enable a user to view the inside of the dust canister. 
         [0042]    The vacuum cleaner  1  may include a dust separator (not shown) for separating air and dust sucked by the suction device  20 . The dust separator may be provided separately from or integrally with the dust canister  105 . 
         [0043]    The main body  110  may include a grip part  106  gripped by the user. The user may grip the grip part  106  in order to lift up or incline the main body  110 . 
         [0044]    The battery  130  may be detachably coupled to the main body  110 . The battery  130  may be responsible for supplying power necessary to drive the vacuum cleaner  1 . The battery  130  may be a secondary battery which may be charged or discharged. The battery  130  may be connected with a power cord (not shown) for supplying commercial power. 
         [0045]    The wheels  120  may be rotatably coupled to the main body  110 . 
         [0046]    The wheels  120  may form a pair and the wheels  120  may be coupled to both sides of the main body  110 . 
         [0047]    The wheels  120  may rotate by a driving unit  50 . The driving unit  50  may include a motor, etc. When a voltage is applied to the driving unit  50 , power may be generated in the driving unit  50  and delivered to the wheels  120 . 
         [0048]    The wheels  120  may cover over half the side surface of the main body  110  as shown in the figure. As the size of the wheels  120  increases, the cleaner body can more easily pass an obstacle. 
         [0049]    The vacuum cleaner  1  may include a controller  30 . The controller  30  may control overall driving of the vacuum cleaner  1  including the driving unit  50 . 
         [0050]    The cleaner body  10  may further include a first sensor  40  for sensing motion of the cleaner body  10 . 
         [0051]    As the first sensor  40 , a gyro sensor for sensing a current angle and a current speed of the cleaner body  10  upon operating the cleaner body  10  may be used. 
         [0052]    The gyro sensor senses angular velocity from the Coriolis force applied in a direction perpendicular to a direction in which a moving object rotates and may measure not only the angle of the moving object but also change in position of the moving object from a first reference point. 
         [0053]    The controller  30  may control the driving unit  50  such that the main body  110  automatically follows motion of the user based on the sensed information of the first sensor  40 . 
         [0054]    When the first sensor  40  is turned on, the controller  30  may control the driving unit  50  such that the center of gravity of the main body  110  is located on the vertical line passing the rotation center of the wheels  120 . That is, the main body  110  is subjected to inverted pendulum control, which is referred to as self-balancing control in this specification. For self-balancing control, the first sensor  40  may sense the speed of the rotation center of the main body  110 . 
         [0055]    Upon self-balancing control, the controller  30  may perform control to move the wheels  120  such that the main body  110  falls. At this time, the bottom of the main body  110  may be spaced apart from the floor. 
         [0056]    When the first sensor  40  is in OFF state, self-balancing control may be finished. That is, self-balancing control may start when the first sensor  40  is turned on and may finish when the first sensor  40  is turned off 
         [0057]    The vacuum cleaner  1  may further include a second sensor  60  for sensing an obstacle. 
         [0058]    The second sensor  60  senses an obstacle located near the moving route of the main body  110 . For example, the second sensor  60  may include an ultrasonic sensor, a laser sensor, an infrared sensor, etc. Information sensed by the second sensor  60  may be delivered to the controller  30 . The second sensor  60  may be referred to as an obstacle sensor. 
         [0059]    The vacuum cleaner  1  may further include a display unit  180  for displaying the state of the vacuum cleaner  1 . The display unit  180  may be provided on the wheel  120 . Thus, the display unit  180  may rotate along with the wheel  120 . If a pair of wheels  120  is provided, the display unit  180  may be provided in each wheel  120 . 
         [0060]    Hereinafter, a method of displaying the state of the vacuum cleaner  1  through the display unit  180  will be described in detail. 
         [0061]      FIG. 4  is a view showing a state of turning a display unit off, and  FIG. 5  is a view showing a state in which a display unit emits light. 
         [0062]    Referring to  FIGS. 4 and 5 , the display unit  180  may include a light emitting unit for emitting light. The light emitting unit of the display unit  180  may be turned on/off, flickered or dimmed. In addition, the color of light emitted from the display unit  180  may be changed. The state of the vacuum cleaner  1  may be displayed using a pattern of light emitted from the display unit  180 . Light emitted from the display unit  180  may be controlled by the controller  30 . 
         [0063]    The display unit  180  may have a circular, concentric or ring shape around the rotation center of the wheel  120 . That is, the outer circumference of the display unit  180  forms a circle around the rotation center of the wheel  120 . 
         [0064]    The center of the display unit  180  matches the rotation center of the wheel  120 , the shape of the display unit  180  when the wheel  120  is stationary and the afterimage of the display unit  180  formed when the wheel  120  rotates are similarly perceived. 
         [0065]    Unlike the figure, the display unit  180  may have various shapes. For example, the display unit  180  may have an elliptical, rectangular or triangular shape. 
         [0066]    A plurality of LEDs may be provided according to the shape of the display unit  180 . 
         [0067]    The color of light emitted from the display unit  180  may include white, red, green, blue, etc. as shown in the figure and the color of light may be divided into a first color, a second color and a third color. 
         [0068]    The display unit  180  may display whether the self-balancing control function of the vacuum cleaner  1  is performed. 
         [0069]    More specifically, while the self-balancing control function is performed, the display unit  180  may continuously emit light of the first color. Meanwhile, when the self-balancing control function starts, the display unit  180  may control flickering of light of the first color in order to notify the user that the self-balancing control function starts. 
         [0070]    As described above, self-balancing control may be performed according to ON/OFF of the first sensor  40 . Accordingly, the controller  30  may perform control such that the display unit  180  emits light of the first color when the first sensor  40  is turned on and the display unit  180  is turned off when the first sensor  40  is turned off. 
         [0071]    In addition, the display unit  180  may perform display to notify the user of an obstacle when the obstacle is sensed near the moving route of the main body  110 . 
         [0072]    More specifically, when the second sensor  60  senses the obstacle near the moving route of the main body  110 , the controller  30  may perform control such that light of the second color emitted from the display unit  180  flickers once. 
         [0073]    The display unit  180  may display lack of the remaining capacity of battery  130  or an error occurring upon operating the vacuum cleaner  1 . 
         [0074]    More specifically, when lack of the remaining capacity of the battery  130  is sensed, the controller  30  may perform control such that light of the second color emitted from the display unit  180  flickers twice. In addition, when an error occurring upon operating the vacuum cleaner  1  is sensed, the controller  30  may perform control such that light of the third color emitted from the display unit  180  flickers. 
         [0075]      FIG. 6  is a view showing a state in which only a portion of a display unit emits light. Referring to  FIG. 6 , the display unit  180  may perform control to emit light in a second region  182  and not to emit light in a first region  181 . 
         [0076]    The display unit  180  may include a plurality of LEDs arranged in a circular shape. Only some of the plurality of LEDs may be turned on to form the second region  182  and the other LEDs are turned off to form the first region  181 . 
         [0077]    The second region  182  has an arc shape having a central angle θ with respect to the center O of a circle formed by the display unit  180 , that is, the rotation center of the wheel  120 . If the display unit  180  has a circular shape, the second region  182  has a fan shape having a central angle θ with respect to the rotation center of the wheel  120 . 
         [0078]    The angle θ of the second region  182  may be controlled by the controller  30 . A portion other than a portion occupied by the second region  182  in the display unit  180  corresponds to the first region  181  and the first region  181  may have an arc shape like the second region  182 . The angle θ of the second region  182  may be less than that of the first region  181  without being limited thereto. 
         [0079]    When the wheel  120  rotates, the display unit  180  rotates and thus the second region  182  rotates while drawing a circle. Therefore, the user may perceive the rotation direction of the second region  182  and, as a result, check the rotation direction of the wheel  120 . 
         [0080]    Accordingly, upon self-balancing control, the user may perceive the rotation direction of the wheel  120  through rotation of the second region  182 . 
         [0081]    In addition, in order for the display unit  180  to display the remaining capacity of the battery  130 , a ratio of the second region  182  to the first region  181  may be controlled according to the remaining capacity of the battery  130 . For example, the central angle θ of the second region  182  may be 180° if the remaining capacity of the battery  130  is 50% and may be 120° if the remaining capacity of the battery  130  is 30%. 
         [0082]    In addition, in order to display the rotation direction of the wheel  120 , the position of the second region  182  may be controlled to rotate around the rotation center of the wheel  120 . 
         [0083]    At this time, the controller  30  may perform control such that LEDs for emitting light among the plurality of LEDs provided on the display unit  180  are continuously changed. 
         [0084]    Meanwhile, a plurality of second regions  182  may be provided. That is, the first region  181  may be provided between the plurality of second regions  182 . Even in this case, the user may perceive the rotation direction of the second region  182  and thus check the rotation direction of the wheel  110 . 
         [0085]    The vacuum cleaner  1  according to the present invention include the above-described wheel  120  to display the operation state information of the vacuum cleaner  1 . The user may check the rotation direction of the wheel  120  through rotation of the display unit  180 . 
         [0086]      FIG. 7  is a view showing a state in which a cleaner body of  FIG. 1  is inclined forward,  FIG. 8  is a view showing a state in which the cleaner body of  FIG. 1  is inclined backward, and  FIG. 9  is a view showing the configuration of a supporter of  FIG. 8 . 
         [0087]    Referring to  FIGS. 7 to 9 , at least a part of the bottom of the main body  110  is separated from a floor. Thus, the main body  110  may rotate to the front side or the back side of the wheels  120 . 
         [0088]    A part, in which the connector  103  is provided, of the cleaner body  10  with respect to a vertical line passing through a rotation center of the wheels  120  may be defined as a front side and a part, in which the battery  130  is provided, may be defined as a back side. In addition, the main body  110  rotating forward means that the main body  110  rotates in a counter-clockwise direction (see  FIG. 7 ) in the figure and the main body  110  rotating backward means that the main body  110  rotates in a clockwise direction (see  FIG. 8 ). 
         [0089]    Referring to  FIG. 3 , the cleaner body  10  may further include a driving unit  50  for driving the wheels  120 . 
         [0090]    The driving unit  50  may be automatically controlled by a controller  30 , such that the wheels  120  may be automatically driven along a direction desired by the user. That is, the controller  30  may perform control such that the cleaner body  10  automatically follows motion of the user. 
         [0091]    The cleaner body  10  may further include a sensor  40  for sensing motion of the cleaner body  10 . The controller  30  may control driving of the wheels  120  by information sensed by the sensor  40 . 
         [0092]    As the sensor  40 , a gyro sensor for sensing a current angle and a current speed of the cleaner body upon operating the cleaner body  10  may be used. 
         [0093]    The gyro sensor senses angular velocity from the Coriolis force applied in a direction perpendicular to a direction in which a moving object rotates and may measure not only the angle of the moving object but also change in position of the moving object from a first reference point. 
         [0094]    The controller  30  may control the driving unit  50  such that the main body  110  automatically follows motion of the user based on the sensed information of the sensor  40 . 
         [0095]    If the sensor  40  is turned off, the wheels  120  may not be driven. In this case, the cleaner body  10  is inclined according to the position of the center of gravity thereof. For example, when the center of gravity of the cleaner body  10  is located at the front side of the vertical line V passing through the rotation center  122  of the wheels  120 , the cleaner body  10  is inclined forward as shown in  FIG. 7  and, when the center of gravity of the cleaner body  10  is located at the back side of the vertical line V, the cleaner body  10  is inclined backward as shown in  FIG. 8 . 
         [0096]    The cleaner body  10  may include a first bottom B and a second bottom C. The second bottom C extends at a predetermined angle with respect to the first bottom B. 
         [0097]    In the state shown in  FIG. 7 , the first bottom B is substantially aligned with the floor G. In contrast, the second bottom C is separated from the floor G and is inclined at a predetermined angle with respect to the floor G. 
         [0098]    When the sensor  40  is turned on, the controller  30  may control driving of the wheels  120  such that the center of gravity of the cleaner body  10  is located on the vertical line V passing through the rotation center  122  of the wheels  120 . 
         [0099]    In this case, as shown in  FIG. 8 , the first bottom B of the cleaner body  10  may be separated from the floor G. 
         [0100]    The cleaner body  10  may further include a supporter  140 . The supporter  140  may extend from the second bottom C of the cleaner body  10 . The supporter  140  may perform a function for restricting the angle of the cleaner body  10  inclined backward. 
         [0101]    The supporter  140  may include an auxiliary wheel  142 . The auxiliary wheel  142  may rotate by friction with the floor G. Therefore, the cleaner body  10  may be smoothly driven. 
         [0102]    The supporter  140  may further include an extension  144 . The auxiliary wheel  142  may be rotatably connected to one side of the extension  144 . 
         [0103]    The supporter  140  may further include a rotation shaft  146 . The other side of the extension  144  may be rotatably connected to the main body  110  by the rotation shaft  146 . 
         [0104]    The extension  144  may rotate within a predetermined range. More specifically, the extension  144  may rotate upward or downward within a range of a to a′. The main body  110  may include a stopper (not shown) for restricting the rotation range of the extension  144 . 
         [0105]    The supporter  140  may further include an elastic member  150 . For example, the elastic member  150  may be a torsion spring. 
         [0106]    One end  152  of the elastic member  150  may be supported by the main body  110  and the other end  153  of the elastic member  150  may be supported by the extension  144 . The elastic member  150  may apply elastic force such that the extension  144  rotates in a clockwise direction in the figure. 
         [0107]    When the main body  110  is inclined forward to the maximum extent, the front part of the bottom B of the main body  110  may contact the floor G. Thus, the maximum angle of the main body  110  rotated forward may be restricted. 
         [0108]    In contrast, when the main body  110  is inclined backward, the supporter  140  may contact the floor G. Thus, the maximum angle of the main body  110  rotated backward may be restricted. Therefore, it is possible to prevent the main body  110  from being overturned forward or backward. 
         [0109]    Since elastic force of the elastic member  150  is applied to the extension  140  in a clockwise direction (see  FIG. 9 ) in the figure, when the main body  110  is excessively inclined backward, forward rotation force may be applied to the main body  110  by the supporter  140 . 
         [0110]    When the main body  110  rotates backward to the maximum extent, the bottom B of the main body  110  forms a predetermined angle  0  with respect to the floor G. At this time, the angle θ between the bottom B of the main body  110  and the floor G may be about 17° to 20°. 
         [0111]    The battery  130  may include a cover  131 . In a state in which the battery  130  is mounted in the main body  110 , the cover  131  may be exposed. Thus, the cover  131  may form at least a part of the appearance of the main body  110 . In addition, the user may detach the battery  130  from the main body  110  or attach the battery to the main body  110  without disassembling the main body  110 . The cover  131  may include a grip part (not shown) facilitating attachment and detachment of the battery  130  to and from the main body  110 . 
         [0112]    Hereinafter, a process of attaching and detaching the battery  130  to and from the main body  110  will be described in detail. Hereinafter, assume that the center of gravity of the main body  110  is located at the front side of the main body  110  when the battery  130  is detached from the main body  110  and is located at the back side of the main body  110  when the battery  130  is attached to the main body  110 . 
         [0113]      FIG. 10  is a view sequentially showing a state of attaching a battery to the cleaner body of the cleaner. 
         [0114]    (a) of  FIG. 10  shows a state in which the battery  130  is detached from the main body  110 , (b) of  FIG. 10  shows a state in which the battery  130  is attached to the main body  110 , and (c) of  FIG. 10  shows a state in which the main body  110  is inclined backward. 
         [0115]    A battery attachment part  107  coupled with the battery  130  is formed in the main body  110 . The battery attachment part  107  may be a recess formed in the main body  110 . In addition, an attachment guide (not shown) for guiding attachment of the battery  130  may be formed in the battery attachment part  107 . 
         [0116]    The battery attachment part  107  is formed at the lower side of the main body  110  and thus the battery  130  is attached to the lower side of the main body  110 . The center of gravity of the battery  130  may be located at the lower side of the rotation center of the wheels  120  in a state in which the battery  130  is mounted in the main body  110 . 
         [0117]    Accordingly, when the battery  130  is attached to the main body  110 , the center of gravity of the main body  110  may be moved downward, it is possible to improve driving stability of the cleaner body  10 . 
         [0118]    When the battery  130  is attached to the lower side of the main body  110 , it is possible to improve driving stability. However, since the battery  130  is attached to the lower side of the main body  110 , user inconvenience may be caused upon attaching the battery  130 . 
         [0119]    However, in a state in which the battery  130  is detached from the main body  110 , the center of gravity of the main body  110  may be located at the front side of the vertical line passing through the center of the wheels  120 . Therefore, when the battery  130  is detached from the main body  110 , the main body  110  may be inclined to the front side of the wheels  120 . 
         [0120]    As the main body  110  is inclined forward, the front side of the bottom of the main body  110  contacts the floor. At this time, the battery attachment part  107  is inclined upward. Therefore, the user may easily attach the battery  130 . 
         [0121]    The battery  130  may be obliquely attached to the main body  110  by the attachment guide provided in the battery attachment part  107 . More specifically, the insertion direction S of the battery  130  may form an acute angle with respect to the vertical direction V and the floor. Accordingly, when the front side of the bottom of the main body  110  contacts the floor, the insertion direction S of the battery  130  forms an acute angle with respect to the floor. 
         [0122]    When the battery  130  is attached to the main body  110 , the center of gravity of the main body  110  may move backward. That is, in a state in which the battery  130  is attached to the main body  110 , the center of gravity of the main body  110  may be located at the back side of the vertical direction passing through the center of the wheels  120 . 
         [0123]    That is, when the battery  130  is attached to the main body  110 , the main body  110  may be inclined to the back side of the wheels  120 . At this time, the supporter  140  may selectively contact the floor. At this time, the bottom B of the main body  110  forms a predetermined angle θ with respect to the floor G. 
         [0124]      FIG. 11  is a view sequentially showing a state of detaching a battery from the cleaner body of the cleaner. 
         [0125]    More specifically, (a) of  FIG. 11  shows a state before the battery  130  is detached from the main body and (b) of  FIG. 11  is a state after the battery  130  is detached from the main body  110 . 
         [0126]    In order to detach the battery  130  from the main body  110 , the user may directly apply force to the main body  110  to incline the main body  110  forward. Next, the user may detach the battery  130  in a direction opposite to the insertion direction S. The user may grip the grip part  106  and then apply force forward in order to incline the main body  110  forward. 
         [0127]    When the battery  130  is detached from the main body  110 , the center of gravity of the main body  110  moves forward. Therefore, the main body  110  may be maintained in a forward inclined state. 
         [0128]    In the vacuum cleaner  1  of the present invention, in the state in which the battery  130  is mounted in the main body  110 , the main body  110  rotates backward such that the bottom of the main body  110  is separated from the floor. That is, the main body  110  may be two-point supported by the wheels  120 . In this case, since the cleaner body  10  easily passes an obstacle and friction applied to the wheels  120  is reduced, it is possible to reduce user labor required to move the main body  10 . 
         [0129]    When the battery  130  is detached from the main body  110 , the center of gravity of the main body  110  moves forward to rotate forward and thus the battery attachment part  107  provided at the lower back side of the main body  110  is raised. Therefore, the user can easily attach the battery  130  to the battery attachment part  107 .