Patent Publication Number: US-2022233024-A1

Title: Blender

Description:
TECHNICAL FIELD 
     The present disclosure relates to a blender and, more particularly, to a blender including a blade that has a concave-convex portion or an inclined surface. 
     BACKGROUND 
     Generally, a blender is also referred to as a mixer. The blender is used primarily to chop food accommodated in a container body into small pieces or mix the food by rotating a blade by a rotational force of a motor. 
     In a normal blender, a main body into which the motor operating by electricity is located is positioned below, and a container body in which the food is accommodated is seated on the top of the main body. A blade for chopping the food into small pieces or mixing the food is provided inside the container body and is rotated by a rotational force generated by the motor. 
     After the food that needs to be chopped into small pieces is put into the container body, an operational button or a knob of the main body is used to drive the motor. The blade is rotated by the rotational force generated by the motor, and thus the food inside the container body is chopped into small pieces or mixed. 
     In recent years, various blenders of this type have been developed to satisfy the user&#39;s need for food intake in their busy everyday life. For example, small-sized hand-held blenders or large-sized high-volume blenders have been developed, and blenders capable of chopping food at a high speed have also been developed. 
     However, when a container body structure or a blade structure in the related art is employed, it takes a long time to chop the food into small pieces. Furthermore, the food is neither properly chopped into small pieces, nor properly mixed. 
     For example, a cutter for a mixer is disclosed in Korean Patent No.10-1219753. In the related art, two cutters (blades) are formed symmetrically in the leftward-rightward direction and are mounted horizontally. 
     Therefore, the cutters (blades) are rotated in a state of being in parallel with a bottom surface of a container body. Thus, only the food positioned in a lower portion of the container body is chopped into small pieces in a concentrated manner. Accordingly, the entire food is neither properly chopped into small pieces, nor properly mixed. Consequentially, it takes a long time to completely chop the food into small pieces. 
     In addition, Korean Patent No.10-1384979 discloses a blade that provides an improved performance over the cutter described above. That is, four blades are provided: two in the forward-backward direction and two in the leftward-rightward direction. The four blades are mounted in the downward direction, as well as in the horizontal direction. However, in this structure, a space where the blades chop the food into small pieces is also limited. Therefore, it takes a considerable amount of time to completely chop the food into small pieces and mix the food. 
     In order to solve these problems with the blender in the related art, a configuration where the blade of the blender extends in the upward-downward direction at a predetermined inclined angle is disclosed in US Patent Application Publication No.20160066748A1. A gusset is further provided to reinforce a portion at which the blade extends in the upward-downward direction at a predetermined inclined angle. 
     However, problems associated with the food-chopping capability of the blade and noise generated due to rotation of the blade have not yet been solved in the related art. That is, in the related art, a space where the blade that chops the food into pieces is expanded to some degree by the blade extending in the upward-downward direction at a predetermined inclined angle. However, a configuration is still employed where four blades are used in chopping the food into pieces. Thus, there is still a problem in that the food chopping capability is not improved. 
     The gusset formed on the blade only serves to reinforce the portion at which the blender extends in the upward-backward direction at a predetermined inclined angle. The gusset does not reduce the noise generated due to rotation of the blades and generates a vortex. Rather, the gusset serves as a source for generating noise. 
     Furthermore, US Patent Application Publication No.20190045976A1 also discloses a technology that chops the food into pieces using a plurality of blades extending in the upward-downward direction at a predetermined inclined angle. An increased number of blades are formed only to a shape of a flat plate having a predetermined thickness, and thus contribute to increasing noise. 
     SUMMARY 
     An objective of the present disclosure, which is made to solve the problems in the related art as described above, is to provide a blender including an auxiliary blade, as well as a main blade. 
     Another objective of the present disclosure is to provide a blender including an auxiliary blade of which a blade portion is positioned between each of the main blades. 
     Still another objective of the present disclosure is to provide a blender including a blade assembly that facilitates moving of food inside a container body. 
     Still another objective of the present disclosure is to provide a blade having a shape contributing to reducing noise generated due to rotation of a blade. 
     Still another objective of the present disclosure is to a blender including a plurality of blades, the blender capable of improving the efficiency of chopping food into small pieces and of reducing noise generated due to rotation of a blade. 
     Technical Solution 
     A feature of a blender according to the present disclosure that accomplishes the above-described objectives is that at least one end portion of a blade constituting a blade assembly is formed in such a manner as to have a smaller thickness than a center portion thereof. That is, at least one end portion of the blade has an inclined surface so that the thickness of the blade gradually decreases going toward an end of the one end portion. 
     Another feature of the blender according to the present disclosure is that a concave-convex portion is formed on a leading edge or a rear edge of the blade constituting the blade assembly. 
     Still another feature of the blender according to the present disclosure is that the concave-convex portion is formed on at least one portion of an upper surface or a lower surface of the blade constituting the blade assembly. 
     The concave-convex surface is formed in such a manner as to have a shape of owl wings or a sawtooth shape. The concave-convex surface in the shape of owl wings or in the sawtooth achieves the effect of reducing noise due to a flow of food and fluid. 
     Still another feature of the blender according to the present disclosure is that a main blade portion constituting the blade assembly is obliquely formed. Thus, a leading edge portion is positioned at a greater height than a rear edge portion. 
     Still another feature of the blender according to the present disclosure is that a plurality of main blade portions constituting the blade assembly is formed in such a manner as to make different angles with a main fixation portion. Accordingly, the effect of increasing a space where the blade chops the food into small pieces is achieved. 
     According to an aspect of the present disclosure, there is provided a blender including: a container body in which the food is accommodated; a main body provided underneath the container body and supporting the container body; a container lid detachably mounted on an upper surface of the container body and opening and closing the top of the container body; and a blade assembly of which a blade chops the food inside the container body into small pieces, wherein at least one end portion of the main blade is formed in such a manner as to have a smaller thickness than a center portion thereof. 
     In the blender, the at least one end portion of the blade may have an inclined surface so that the thickness of the blade gradually decreases going toward an end of the at least one end portion. 
     In the blender, an inclined surface may be formed at an upper surface and a lower surface of the blade so that the thickness of the main blade gradually decreases going toward an end of a leading edge or a rear edge. 
     In the blender, a concave-convex portion may be formed on the leading edge or the rear edge of the blade. 
     In the blender, the concave-convex portion may be formed on the inclined surface. 
     In the blender, the concave-convex portion may have a shape corresponding to a sawtooth shape. 
     In the blender, at least one portion of the upper surface and the lower surface of the blade may have a concave-convex shape. 
     In the blender, the concave-convex portion formed on the upper surface or the lower surface of the blade may have a shape corresponding to the shape of owl wings. 
     In the blender, the blade assembly may include a main blade on which a plurality of main blade portions is formed; and an auxiliary blade of which an auxiliary blade portion is positioned between each of the plurality of main blade portions, wherein the concave-convex portion or the inclined surface may be formed on or at at least one of the main blade portion and the auxiliary blade portion. 
     In the blender, the concave-convex portion to be formed on the main blade portion or the auxiliary blade portion may be formed on at least on one of the upper surface and the lower surface of the main blade portion or the auxiliary blade portion. 
     In the blender, the concave-convex portion formed on the upper surface or the lower surface of the main blade portion or the auxiliary blade portion may have a shape corresponds to the shape of owl wings. 
     In the blender, the concave-convex portion or the inclined surface formed on the main blade portion or the auxiliary blade portion may be formed on the leading edge or the rear edge of the main blade portion or the auxiliary blade portion. 
     In the blender, the concave-convex portion formed on the leading edge or the rear edge of the main blade portion or the auxiliary blade portion may have a shape corresponding to the sawtooth shape. 
     In the blender, the concave-convex portion formed on the leading edge of the main blade portion may be rounded with a radius of curvature. 
     In the blender, the concave-convex portion formed on the rear edge of the main blade portion may have the sawtooth shape. 
     In the blender, the blade assembly may include: a main blade including a main fixation portion combined with a blade shaft and a plurality of main blade portions formed on the main fixation portion in a manner that protrudes outward therefrom; and an auxiliary blade portion including an auxiliary fixation portion combined with the blade shaft and a plurality of auxiliary blade portions formed on the auxiliary fixation portion in a manner that protrudes outward therefrom, wherein the inclined surface may be formed at the main blade portion or the auxiliary blade portion. 
     In the blender, the main blade portion may be obliquely formed so that a leading edge portion is positioned at a greater height than the rear edge portion. 
     In the blender, the plurality of main blade portions may be formed in such a manner as to make different angles with the main fixation portion. 
     In the blender, at least one of the plurality of main blade portions may be formed on the main fixation portion in a manner that extends upward or downward at a predetermined inclination angle therefrom. 
     In the blender, four main blade portions may be formed on the main fixation portion in a manner that protrudes radially therefrom and may be symmetrically formed in such a manner as to be equiangular with respect to the center of the main fixation portion. 
     In the blender, among the four main blade portions, a pair of the main blade portions facing each other may extend upward at a predetermined inclined angle from the main fixation portion, and another pair of the main blade portions facing each other may extend downward at a predetermined inclined angle from the main fixation portion. 
     In the blender, the predetermined inclined angles at which the two main blade portions facing each other extend from the main fixation portion may be the same. 
     In the blender, the predetermined inclined angles at which the two main blade portions facing each other extend from the main fixation portion may be different from each other. 
     In the blender, the concave-convex portion may be formed on the upper surface or the lower surface of the main blade portion or the auxiliary blade portion, and the concave-convex portion may have the shape of owl wings. 
     The concave-convex portion may be formed on the leading edge or the rear edge of the main blade portion or the auxiliary blade portion, and the concave-convex portion may have the sawtooth shape. 
     In the blender, the concave-convex portion may be formed on the leading edge or the rear edge of the main blade portion or the auxiliary blade portion and on the upper surface or the lower surface of the main blade portion or the auxiliary blade portion in such a manner as to have the same convex part and the same concave part. Accordingly, it is possible that the wavelengths of the noise cancel each other out and that load on a motor assembly is reduced. 
     Advantageous Effects 
     A blender according to the present disclosure provides the following effects. 
     Firstly, according to the present disclosure, in addition to a main blade, an auxiliary blade is further provided on a blade assembly that chops food into small pieces. Therefore, the food is chopped twice into small pieces and is mixed: the first time by the auxiliary blade and the second time by the main blade. Thus, the advantage of improving the efficiency of chopping the food into small pieces is provided. 
     Secondly, according to the present disclosure, a blade portion of the auxiliary blade is positioned between each of the blade portions of the main blade. Therefore, the food inside a container body sequentially collides with the blade portion of the auxiliary blade and the blade portion of the main blade, and thus is chopped into small pieces. Thus, the advantage of reducing load on a motor assembly is provided. That is, the effect of chopping the food into small pieces and mixing the food under much less load than when the food is chopped one time into small pieces and is mixed is achieved. 
     Thirdly, according to the present disclosure, the auxiliary blade portion of the auxiliary blade is configured in such a manner as to have a smaller length than the main blade portion of the main blade. Therefore, food of a predetermined size is first positioned between each of the main blade portions, and some amount of the food is chopped into small pieces by the auxiliary blade portion. Then, the entire food is chopped into small pieces by the main blade portion, or much more amount of the food is chopped into pieces than when chopped into small pieces by the auxiliary blade portion. Thus, the advantage of preventing a malfunction or an error due to overload on the blade assembly is provided. 
     Fourthly, according to the present disclosure, the auxiliary blade portion of the auxiliary blade is configured in such a manner to extend upward at a greater inclined angle than the main blade portion of the main blade. That is, the auxiliary blade portion is positioned at a greater height and more toward a central position than the main blade portion. Therefore, the auxiliary blade portion that extends upward at a predetermined inclined angle prevents the food from gathering around the center of the container body or whirls the food around the center thereof by chopping the food gathering around the center into small pieces. Thus, the effect of mixing the food well is achieved. 
     Fifthly, according to the present disclosure, an even number of main blade portions are provided in a manner that is symmetrical about the main fixation portion. Structurally, a plurality of main blade portions extend upward and downward at a predetermined inclined angle from the main fixation portion. Structurally, the auxiliary blade portion extends upward at a greater inclined angle therefrom. Therefore, a space where the blade portion of the blade assembly by which the food is chopped into small pieces is expanded to a lower portion or a center portion of the container body. Thus, the advantage of increasing the efficiency of chopping the food into small pieces is provided. 
     Sixthly, according to the present disclosure, the blade that constitutes the blade assembly is formed in such a manner that at least one end portion thereof has a smaller thickness than a center portion thereof. That is, the blade has an inclined surface so that the thickness of the blade gradually decreases going toward an end of the leading edge or the rear edge. Therefore, the inclined surface of the leading edge facilitates the chopping of the food into small pieces, and the inclined surface of the rear edge reduces a vortex. Accordingly, the effect of reducing an amount of load on components and noise generated due to the rotation of the blade is achieved. 
     Seventhly, according to the present disclosure, a plurality of concave-convex portions, such as the ones in the shape of owl wings, is formed on an upper surface or a lower surface of the blade. Therefore, as is the case with the shape of owl wings, a phenomenon where the noise is trapped without being spread to the outside occurs, and wavelengths of the noise cancel each other out due to phase differences. Thus, the noise is reduced. Thus, the advantage of silently operating the blender, and thus satisfying a user&#39;s need for silent operation of the blender is provided. 
     Eighthly, the concave-convex portion is also formed on the leading edge of the blade. Therefore, the food introduced into a groove in the leading edge is chopped into small pieces without deviating outward. Thus, the advantage of improving the performance of chopping the food into small pieces is provided. 
     Ninthly, according to the present disclosure, the concave-convex portion is also formed on the leading edge of the blade. Therefore, the wavelengths of the noise generated in the rear edge of the blade cancel each other out. Thus, the effect of reducing the noise is achieved. 
     Tenthly, according to the present disclosure, the main blade portion of the main blade is obliquely formed so that a leading edge portion thereof is positioned at a greater height than a rear edge portion. Therefore, when the blade is rotated, the food inside the container body flows downward by the main blade portion, and thus the mixing of the food is facilitated. 
     Eleventhly, according to the present disclosure, the main blade portions constituting the blade assembly are in such a manner as to make different angles with a main fixation portion. Therefore, a space through which the blade passes during rotation is increased, and thus the effect of increasing the efficiency of chopping the food into small pieces is achieved. 
     The concave-convex portion is formed on the leading edge or the rear edge of the main blade portion or the auxiliary blade portion and on the upper surface or the lower surface of the main blade portion or the auxiliary blade portion in such a manner as to have the same convex part and the same concave part. Therefore, a flow of fluid and food along the blade is facilitated, and the wavelengths of the noise cancel each other out at the same time. Thus, the advantage of significantly reducing the noise is provided. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a blender according to a desired embodiment of the present disclosure; 
         FIG. 2  is a longitudinal cross-sectional view illustrating an internal configuration of the blender according to the embodiment of the present disclosure; 
         FIG. 3  is an exploded perspective view illustrating a detailed configuration of a container body that constitutes the blender according to an embodiment of the present disclosure; 
         FIG. 4  is a perspective view illustrating the container body that constitutes the blender according to the embodiment of the present disclosure, when viewed from below; 
         FIG. 5  is a perspective view illustrating a main body that constitutes the blender according to an embodiment of the present disclosure; 
         FIG. 6  is an exploded perspective view illustrating components in an upper half of the main body that constitutes the blender according to the embodiment of the present disclosure; 
         FIG. 7  is a perspective view illustrating a state where a cover is removed from the main body that constitutes the blender according to the embodiment of the present disclosure; 
         FIG. 8  is a perspective view illustrating an example of a container lid that constitutes the blender according to an embodiment of the present disclosure; 
         FIG. 9  is a cross-sectional perspective view illustrating an internal configuration of the container lid in  FIG. 8 ; 
         FIG. 10  is an exploded perspective view illustrating a configuration of the container lid in  FIG. 8  when viewed from above; 
         FIG. 11  is an exploded perspective view illustrating a configuration of the container lid in  FIG. 8  when viewed from below ; 
         FIG. 12  is an exploded cross-sectional perspective view illustrating an internal configuration of the container lid in  FIG. 8 ; 
         FIG. 13  is an exploded perspective view illustrating a configuration of a container-lid body that constitutes the container lid in  FIG. 8 ; 
         FIG. 14  is a perspective view illustrating a configuration of a blade assembly that constitutes the blender according to an embodiment of the present disclosure; 
         FIG. 15  is an exploded perspective view illustrating a detailed configuration of the blade assembly that constitutes the blender according to the embodiment of the present disclosure; 
         FIG. 16  is a perspective view illustrating a configuration of a first implementation example of a main blade that constitutes the blender according to an embodiment of the present disclosure, when viewed from above; 
         FIG. 17  is a perspective view illustrating a configuration of the first implementation example of the main blade illustrated in  FIG. 16  when viewed from below; 
         FIG. 18  is a front view illustrating the first implementation example of the main blade illustrated in  FIG. 16 ; 
         FIG. 19  is a cross-sectional view taken along line A-A on  FIG. 16 ; 
         FIG. 20  is a plane view illustrating a configuration of a second implementation example of the main blade that constitutes the blender according to an embodiment of the present disclosure; 
         FIG. 21  is a perspective view illustrating a configuration of the second implementation example of the main blade illustrated in  FIG. 20 , when viewed from above; 
         FIG. 22  is a perspective view illustrating the second implementation example of the main blade illustrated in  FIG. 21 , when viewed from below; 
         FIG. 23  is a front view illustrating the second implementation example of the main blade illustrated in  FIG. 21 ; 
         FIG. 24  is a perspective view illustrating a configuration of a third implementation example of the main blade that constitutes the blender according to an embodiment of the present disclosure, when viewed above; 
         FIG. 25  is a perspective view illustrating the third implementation example of the main blade illustrated in  FIG. 24 , when viewed from below; 
         FIG. 26  is a front view illustrating the third implementation example of the main blade illustrated in  FIG. 24 ; 
         FIG. 27  is a perspective view illustrating a configuration of a fourth implementation example of the main blade that constitutes the blender according to an embodiment of the present disclosure, when viewed above; 
         FIG. 28  is a perspective view illustrating the fourth implementation example of the main blade illustrated in  FIG. 27 , when viewed from below; 
         FIG. 29  is a front view illustrating the fourth implementation example of the main blade illustrated in  FIG. 27 ; 
         FIG. 30  is a perspective view illustrating the configuration of the fourth implementation example of the main blade illustrated in  FIG. 27  when viewed from above; 
         FIG. 31  is a perspective view illustrating a configuration of a fifth implementation example of the main blade that constitutes the blender according to an embodiment of the present disclosure, when viewed above; 
         FIG. 32  is a perspective view illustrating the fifth implementation example of the main blade illustrated in  FIG. 31 , when viewed from below; 
         FIG. 33  is a front view illustrating the fifth second implementation example of the main blade illustrated in  FIG. 31 ; and 
         FIG. 34  is a perspective view illustrating the fifth implementation example of the main blade illustrated in  FIG. 31  when viewed from above. 
     
    
    
     DETAILED DESCRIPTION 
     A blender according to the present disclosure will be described in detail below with reference to the accompanying drawings. 
       FIG. 1  is a perspective view illustrating a blender according to an embodiment of the present disclosure.  FIG. 2  is a longitudinal cross-sectional view illustrating the blender to the embodiment of the present disclosure. 
     As illustrated in  FIGS. 1 and 2 , the blender according to the present disclosure is configured to include a container body  100 , a main body  500 , and the like. The container body  100  is positioned at a relatively great height and accommodates food. The main body  500  is provided underneath the container body  100  and supports the container body  100 . 
     The food is accommodated to the container body  100  and is chopped into pieces or mixed there. The main body  500  supports the container body  100 . A plurality of components that control food chopping and mixing in the container body  100 , supply electric power, and perform other functions are provided inside the main body  500 . 
     It is desirable that the entire container body  100  has the shape of a cylinder when viewed as a whole. The container body  100  is configured to be open at the top. Thus, the food may be inserted into and taken out of the container body  100 . 
     It is desirable that the container body  100  is made of a transparent material in such a manner that the inside thereof may be viewed from the outside. That is, the container body  100  is made of glass or transparent plastic in such a manner that a user may visually check a state of the food inside the container body  100  from the outside. 
     A blade assembly  200  is mounted on the inside bottom of the container body  100 . A plurality of blades are rotatably mounted in the blade assembly  200  and chop the food accommodated in the container body  100  into small pieces or mix the food. 
     The blade assembly  200  is configured in such a manner as to be connected to the motor assembly  600  described below and to be rotatable by a rotational force generated by the motor assembly  600 . 
     It is desirable that the wall and the bottom of the container body  100  are formed in a double-layered manner. That is, the container body  100  is configured to include an outer container body  110  that provides an exterior appearance of the container body  100  and an inner container body  120  that is positioned inward from the outer container body  110 . In a case where the outer container body  110  and the inner container body  120  are configured in such a manner as to be brought into contact with each other or in such a manner as to be spaced apart from each other, it is also possible that the outer container body  110  and the inner container body  120  are mounted in such a manner as to be partly brought into contact with each other. 
     One or more inner guides  122  that have a predetermined length in an upward-downward direction are provided inside the container body  100 . The inner guide  122  serves to guide rotating of the food inside the container body  100 . It is desirable that the inner guides  122  are symmetrically arranged in each pair in the forward-backward direction or in the leftward-rightward direction. 
     A handle  300  that is to be gripped with the user&#39;s hand is formed on a right-side surface of the container body  100  in a manner that protrudes rightward. It is desirable that the handle  300  is formed in such a manner that the user holds the handle  300  with their hand. According to the present disclosure, an example is illustrated where an upper end portion of the handle  300  is formed integrally with and is configured in such a manner as to be integrally combined with an upper end portion of an external surface of the container body  100 . 
     A projection lip  102  is further formed on the upper portion of the external surface of the container body  100  in a manner that is opposite to the handle  300 . 
     The projection lip  102 , as illustrated, is formed on an upper portion of a left-side surface of the container body  100  and serves to guide discharging of the small pieces of the food inside the container body  100  in an easy manner to the outside. Therefore, it is desirable that the projection lip  102  is formed in a manner that the nearer an upper end of the projection lip  210  is to the upper surface of the container body  100 , the more the upper end thereof protrudes in the leftward direction. 
     The top of the container body  100  is covered by a container lid  400 . That is, the container lid  400  is detachably mounted on the upper surface of the container body  100 , and thus closes or opens the top of the container body  100 . 
     The container lid  400  covers the top of the container body  100  in such a manner that the food does not get out of the container body  100  to the outside, and blocks an outside foreign material from being introduced into the container body  100 . 
     The container lid  400  is configured in such a manner as to be attached on the upper surface of the container body  100  by the user pressing or rotating the container lid  400 . A gasket  402  is further provided on an outer circumferential surface of the container lid  400  and bridges a gap between the container lid  400  and the container body  100 . Of course, the gasket  402  also serves to press the container lid  400  against the upper surface of the container body  100 , and thus hold the container lid  400  firmly in place. 
     A cap  450  is further provided on the container lid  400 . That is, a cover hole  401  that is a circular hole of a predetermined size is formed in a center portion of the container lid  400  in a manner that passes through the center portion thereof from top to bottom. The cap  450  is inserted into the cover hole  401  and plugs the cover hole  401 . 
     The cap  450 , as illustrated, is mounted on the center portion of the container lid  400 . The cap  450  is formed in such a manner as to have a smaller diameter than the container lid  400  when viewed as a whole. It is desirable that the cap  450  is detachably mounted on the container lid  400  by forcefully inserting the cap  450  thereinto or by rotating the cap  450 . 
     According to the present disclosure, an example is illustrated where the cap  450  is detachably mounted on the container lid  400  by rotating the cap  450 . A detailed configuration of the cap  450  is described as follows. 
     The cap  450  is detachably mounted on the container lid  400 . Thus, the user may observe the food inside the container body  100  without the need to detach the container lid  400  in a state where only the cap  450  is detached from the container lid  400 . After the cap  450  is detached, it is also possible that the food is inserted into the container body  100  or that the food inside the container body  100  is mixed using a rod or the like. 
     An upper end portion of the cap  450  is formed in such a manner as to protrude more upward than an upper end portion of the container lid  400 . Thus, the upper end portion thereof may also serve as a container lid handle that is to be gripped by the user&#39;s hand when attaching or detaching the container lid  400 . 
     As illustrated, the main body  500  is formed in such a manner as to have the shape of a parallelepiped when viewed as a whole. The main body  500  is provided underneath the container body  100  and supports the container body  100 . A plurality of components including electronic components, such as the motor assembly  600  and a printed circuit board (PCB), is mounted inside the main body  500 . Of course, the main body  500  may have an exterior appearance that can vary widely whenever necessary. 
     The motor assembly  600  is positioned inside a center portion of the main body  500 . The motor assembly  600  is supplied with electric power from the outside, and thus generates a rotational force. The blades constituting the blade assembly  200  are rotated by the generated rotational force. 
     Therefore, it is desirable that a lower end of the blade assembly  200  is connected to an upper end portion of the motor assembly  600 . 
     A knob  502  is formed on a front surface of the main body  500  in a manner that protrudes forward. The knob  502  serves to set the blender according to the present disclosure in operation. It is desirable that the knob  502  is rotatably mounted on the main body  500 . 
     The knob  502  may also be configured in such a manner as to control a rotational speed of the motor assembly  600 . That is, the knob  502  may be configured in such a manner that clockwise or counterclockwise rotation thereof changes the rotational speed of the motor assembly  600  from high to low or from low to high. 
     A touch operation unit  504  is provided on an upper surface of the main body  500 . 
     The touch operation unit  504  serves to operate the blender according to the present disclosure via contact. It is desirable that the touch operation unit  504  is configured in such a manner as to perform operations, such as starting the blender and stopping the blender. 
     Of course, the knob  502  and the touch operation unit  504  may be configured in such a manner as to selectively perform a function of setting the blender and a function of operating the blender or in such a manner as to perform these two functions individually. That is, for convenience, according to the user&#39;s selection, one of the knob  502  and the touch operation unit  504  may be configured in such a manner as to perform the function of operating the blender or the function of setting the blender. 
     A display unit  506  is further provided adjacent to the touch operation unit  504  (to the left side of the touch operation unit  504  in  FIG. 1 ). That is, the display unit  506  is further provided on the upper surface of the main body  500 . The display unit  506  serves to display an operating state of the blender in such a manner as to be viewed by the user from the outside. Therefore, it is desirable that the display unit  506  is configured as a seven-segment display. 
     A cooling fan  610  is further provided below the motor assembly  600 . 
     The cooling fan  610  is connected to a lower end portion of the motor assembly  600 , and thus is rotated by the rotational force generated by the motor assembly  600 . Accordingly, outside air is forced to be introduced into the main body  500 . In this manner, the cooling fan  610  introduces air into the main body  500  from the outside. Thus, the cooling fan  610  serves to cool components, such as a PCB, that are provided inside the main body  500 . 
     A base support  510  is further provided on a lower surface of the main body  500 . 
     The base support  510  is formed in such a manner as to protrude downward from a bottom surface of the main body  500 . A space of a predetermined size is formed inside the base support  510 . A wireless electric power module  520  is accommodated in this space. The wireless electric power module  520  is supplied with electric power from the outside in a wireless manner that uses an induced electromotive force and serves to supply the electric power to the motor assembly  600  inside the main body  500 . 
     A detection system is further provided in the main body  500 , the container body  100 , and the like. The detection system detects whether or not the container lid  400  is attached on the upper surface of the container body  100 . 
     An electric circuit (not illustrated) capable of being turned on and off is provided on the container body  100 . The electric circuit forms a closed circuit. Thus, it is desirable that the detection system is configured in such a manner as to detect whether electric current flows through the closed circuit by a voltage supplied from the main body  500 . 
     More specifically, the detection system is configured to include an electric power transmission unit  700 , an electric power reception unit  220 , an opening and closing unit  230 , a transparent electrode film  240 , a detection unit  800 , and the like. The electric power transmission unit  700  is provided in the main body  500  and supplies electric power to the container body  100 . The electric power reception unit  220  is provided in the container body  100  and receives the electric power supplied from the electric power transmission unit  700 . The opening and closing unit  230  is provided on an upper end portion of the container body  100  and opens and closes an electric circuit formed in the container body  100  according to whether or not the lid  400  covers the top of the container body  100 . The transparent electrode film  240  is made of a transparent material and is provided on one surface of the container body  100 . The transparent electrode film  240  is connected to the electric power reception unit  220  and the opening and closing unit  230  in a manner that allows electricity to flow therebetween. The detection unit  800  is provided on one side of the main body  500  or the container body  100  and detects whether or not electric current flows through a closed circuit formed by the electric circuit connected to the electric power reception unit  220  and the opening and closing unit  230 . 
     The electric power transmission unit  700  serves to transfer the electric power supplied to the main body  500  from the outside of the main body  500  or the electric power pre-stored in the main body  500  itself to the container body  100 . It is desirable that an induction coil or the like where an induced electromotive force can occur is used as the electric power transmission unit  700 . 
     The electric power reception unit  220  serves to receive the electric power transmitted from the main body  500  and has a structure corresponding to that of the electric power transmission unit  700 . That is, it is desirable that the electric power reception unit  220  is configured as a coil in such a manner that, by the induced electromotive force, the electric power is transferred between the electric power transmission unit  700  and the electric power reception unit  220 . 
     It is desirable that the electric power transmission unit  700  and the electric power reception unit  220  are positioned adjacent to each other in such a manner as to generate the induced electromotive force. Therefore, according to the present disclosure, a case is illustrated where the electric power transmission unit  700  is mounted on an upper right end portion of the main body  500  and where the electric power reception unit  220  is mounted on a lower right end portion of the container body  100 . 
     The turning-on and -off unit  230  serves to turn on and turn off the electric circuit (not illustrated) formed in the container body  100  according to whether or not the container lid  400  covers the top of the container body  100 . 
     The turning-on and -off unit  230  is configured to include a permanent magnet  232 , and a reed switch  234  that are provided in the container lid  400  and the container body  100 , respectively, and the like. 
     As illustrated in  FIG. 2 , according to the present disclosure, a case is illustrated where the permanent magnet  232  is mounted on a right edge of the container lid  400  and where the reed switch  234  is mounted on the upper end portion (a portion of the handle  300 ) of the container body  100 . 
     More specifically, it is desirable that the reed switch  234  is mounted in such a manner as to be accommodated in a switch groove  236  formed in the upper end portion of the handle  300 . 
     The reed switch consists of a pair of ferromagnetic flexible metal contacts in a hermetically sealed glass envelope. The contacts are open when a magnetic field is applied. The configuration of the reed switch is well known in the related art. Therefore, a further detailed description of the configuration and principle of the reed switch is omitted. 
     Of course, instead of the permanent magnet  232  and the reed switch  234 , it is also possible that a different electric turning-on and -off unit or a mechanical structure is used, as the turning-on and -off unit  230 , to turn on and off the electric circuit. It is also possible that the permanent magnet  232  and the reed switch  234  are mounted on the container lid  400  and the container body  100 , respectively. 
     Various types of electric devices, various types of structures, or the like, if they have a function of being able to detect whether or not electric current flows by the turning-on and -off unit  230  through the electric circuit formed in the container body  100 , may be used as the detection unit  800 . According to the present disclosure, the detection unit  800  is described by taking, as an example, detection of light that uses a photosensor or photodetector. 
     Therefore the detection unit  800  is configured to include an optical transmission module  810 , an optical reception module  820 , and the like. The optical transmission module  810  is provided in the container body  100  and generates light. The optical reception module  820  is provided in the main body  500  and receives the light transmitted by the optical transmission module  810 . 
     It is desirable that the optical transmission module  810  and the optical reception module  820  are positioned adjacent to each other. According to the present disclosure, as illustrated, the optical transmission module  810  is positioned on a lower left end portion of the container body  100 , and the optical reception module  820  is positioned on an upper left end portion of the main body  500 . 
     It is desirable that a light emitting diode (LED) or the like that generates light using electricity is used as the optical transmission module  810 . It is desirable that a photosensor, a photodetector, or the like that receives light and converts the received light into an electric signal is used as the optical reception module  820 . 
     Then, the transparent electrode film  240  is provided between the outer container body  110  and the inner container body  120 . More specifically, it is desirable that the transparent electrode film  240  is mounted on an internal surface of the outer container body  110 . 
     The transparent electrode film  240  is made of a transparent material, such as indium-tin oxide (ITO), and is attached on a surface of the container body  100 . The turning-on and -off unit  230  provided on the upper end portion of the container body  100  is also connected to the electric power reception unit  220  and the optical transmission module  810 , which are provided on a lower end portion of the container body  100 , thereby constituting the electric circuit. 
     In this manner, the transparent electrode film  240  is attached on the surface of the container body  100  made of a transparent material in a manner that extends longitudinally in the upward-downward direction. Thus, the transparent electrode film  240  serves to guide transfer of an electric signal between upper and lower end portions of the container body  100 . 
     When the container body  100  and the transparent electrode film  240  are both made of a transparent material, the transparent electrode film  240  is not visually exposed to the outside. Thus, the transparent electrode film  240  does not spoil the exterior appearance of the container body  100 , and a design of the container body  100  is maintained as is. 
     Then, in a case where the transparent electrode film  240  is attached on the surface of the container body  100 , a hole may be formed in the transparent electrode film  240 . The hole serves to remove a bubble occurring between the transparent electrode film  240  and the surface of the container body  100  on which the transparent electrode film  240  is attached. That is, in order to prevent the bubble from occurring, it is desirable that a hole is drilled through a center portion of the transparent electrode film  240  made of ITO in such a manner that the bubble escapes therethrough. 
     A seating support  900  is formed on the upper surface of the main body  500  in such a manner as to protrude upward therefrom. 
     The seating support  900  is formed to a circular shape that corresponds to a shape of the lower end portion of the container body  100 . The lower end portion of the container body  100  is seated in the upward-downward direction on the seating support  900  in a manner that is removable therefrom. 
     The container body  100  is formed in a double-layered layer. That is, the container body  100  is configured to include the outer container body  110  and the inner container body  120 . It is desirable that the inner guide  122  is formed in such a manner as to protrude inward from an internal surface of the inner container body  120 . 
     A configuration of the container body  100  will be described in detail below. 
       FIG. 3  is an exploded perspective view illustrating a container body  100 .  FIG. 4  is a perspective view illustrating the container body  100 , when viewed from below. 
     As illustrated in  FIGS. 3 and 4 , the container body  100  is formed to a cylindrical shape when viewed as a whole and is formed in a double-layered manner. That is, the container body  100  is configured to include the outer container body  110  that provides the exterior appearance of the container body  100  and the inner container body  120  that is positioned inward from the outer container body  110 . 
     It is desirable that the container body  100 , that is, the outer container body  110  and the inner container body  120  are made of a transparent material. That is, it is desirable that the outer container body  110  and the inner container body  120  are made of a transparent material, such as glass, polycyclohexylenedimethylene terephthalate (PCT), transparent plastic in such a manner that the user may visually check the state of the food inside the container body  100  from the outside. 
     The outer container body  110  provides the exterior appearance of the container body  100 . It is desirable that the external container body  110  is formed to a cylindrical shape that has upper and lower portions of the same size. A main handle  302  is formed in such a manner as to protrude rightward from a right-side external surface of the outer container body  110 . The main handle is to be gripped with the user&#39;s hand. 
     The main handle  302  is formed to the shape of “┐”. An upper end portion of the main handle  302  is connected to an upper right end portion of the outer container body  110 . It is desirable that the main handle  302  is formed by injection molding in such a manner as to be integrally combined with the outer container body  110 . In this manner, the main handle  302  has relatively more improved strength and durability in terms of an advantage when formed by injection molding in such a manner as to be integrally combined with the outer container body  110  than when jointed or fixed, as a separate single component, to the outer container body  110 . 
     The switch groove  236  in which the reed switch  234  is accommodated is formed in a portion of the main handle  302  that is connected to the container body  100 . That is, the switch groove  236  is formed in the upper end portion of the main handle  302  and provides a space in which the reed switch  234  is mounted. The switch groove  236  is open at the left side. 
     An exterior handle  304  and an internal handle  306  are further provided in such a manner as to extend outward from the main handle  302 . That is, as illustrated, the exterior handle  304  is provided to the right side of the main handle  302 , and the internal handle  306  is provided to the left side thereof. 
     More specifically, like the main handle  302 , the exterior handle  304  is also formed to the shape of “┐” when viewed as a whole. The exterior handle  304  is formed in such a manner as to enclose an upper surface, a right-side surface, and front and rear surfaces of the main handle  302 . It is desirable that the exterior handle  304  is made of a less-unbreakable antirust material having a smooth surface, such as a stainless steel material. This formation of the exterior handle  304  provides a visually aesthetic impression to a consumer. 
     The internal handle  306  encloses a left-side surface and a bottom surface of the main handle  302 . The internal handle  306  is formed to the shape of “┐” that corresponds to a shape of the bottom surface of the main handle  302 . It is desirable that at least one portion of the internal handle  306  is made of an elastic material. 
     Specifically, the internal handle  306  is configured to include a connection portion  306   a,  a grip portion  306   b,  and the like. The connection portion  306   a  encloses a lower part of the upper end portion of the main handle  302 . The grip portion  306   b  is formed in such a manner as to extend downward from the connection portion  306   a  and encloses the left-side surface of the main handle  302 . 
     It is desirable that, like the external handle  304 , the connection portion  306   a  is made of a less-breakable material having a smooth surface. The grip portion  306   b  is covered by the user&#39;s fingers. Thus, it is desirable that the grip portion  306   b  is made of an elastic material. That is, it is desirable that the connection portion  306   a  is made of a stainless material. The grip portion  306   b  is covered by the user&#39;s four fingers (other than the thumb). Thus, it is desirable that grip portion  306   b  is made of an elastic material, such as rubber, that provides a sense of smooth touch to the user. 
     The inner container body  120  is formed in such a manner as to have a smaller size (diameter) than the outer container body  110  and is seated inside the outer container body  110 . 
     The inner container body  120  is formed to a cylindrical shape that is open at the top. More specifically, as illustrated, the nearer a cross section of the inner container body  120  is to the bottom, the more decreased a diameter thereof. That is, the inner container body  120  is formed in such a manner as to be tapered to the bottom. 
     A plurality of inner guides  122  as described above is formed in the upward-downward direction in an external surface of the inner container body  120 . The blade assembly  200  and the like are mounted on a lower end portion of the inner container body  120 . 
     The projection lip  102  is formed on an upper left end portion of the inner container body  120  in a manner that protrudes leftward. A covering container lid  124  is formed on an upper right end portion of the inner container body  120  in a manner that extends rightward. 
     The covering container lid  124  serves to cover the top of the switch groove  236  in the outer container body  110 . The covering container lid  124  is formed to a plate that has a predetermined thickness. In order to correspond to a size of an upper end portion of the switch groove  236 , the covering container lid  124  is formed in such a manner that the more a right end thereof protrudes rightward, the smaller a width thereof. 
     The blade assembly  200  is mounted on the lower end portion of the inner container body  120 . 
     The blade assembly  200  serves to chop food into small pieces or mix food using the blades. The blade assembly  200  is configured in such a manner as to be rotated by the rotational force generated by the motor assembly  600 . The blades and the like that chop the food into small pieces are mounted on a bottom surface of the inner container body  120  in a manner that protrudes upward therefrom. 
     A magnet holder  404  is further provided on the outer circumferential surface of the container lid  400 . That is, as illustrated, the magnet holder  404  is formed in the outer circumferential surface of the container lid  400  in a manner that protrudes outward. The permanent magnet  232  is inserted into the magnet holder  404 . 
     When the container lid  400  is attached on the upper surface of the container body  100  or detached therefrom, the permanent magnet  232  serves to perform control to turn on and off the reed switch  234 . 
     A coil holder assembly is further provided between the outer container body  110  and the inner container body  120 . 
     The coil holder assembly is configured to include a coil holder  130 , an upper cover  140 , a lower cover  150 , and the like. An induction coil is provided on the coil holder  130 . The upper cover  140  and the lower cover  150  enclose upper and lower portions, respectively, of the coil holder  130 . 
     Specifically, the coil holder  130  is provided between a bottom surface of the outer container body  110  and a bottom surface of the inner container body  120 . The electric power reception unit  220  and the optical transmission module  810  are mounted on the coil holder  130 . 
     The coil holder  130  has the shape of a circular ring of a predetermined width when viewed as a whole. The electric power reception unit  220  is provided on a right end portion of the coil holder  130  in the shape of the circular ring. That is, although not illustrated in detail, the induction coil receiving electric power is provided on the right end portion of the coil holder  130  and constitutes the electric power reception unit  220 . 
     The electric power reception unit  220  provided on the coil holder  130  is realized as a reception induction coil patterned in the same plane on a PCB. That is, in an implementation example of the electric power reception unit  220 , the reception induction coil is wound a number of times in helical form on a reception core on the PCB on the bottom surface of the coil holder  130 . 
     The optical transmission module  810  is provided on the bottom surface of the coil holder  130 . 
     The optical transmission module  810  emits light by electricity supplied from the electric power reception unit  220  and constitutes the detection unit  800 . As described above, it is desirable that an LED or the like is used as the optical transmission module  810 . 
     The electric power reception unit  220  and the optical transmission module  810  are electrically connected to each other. That is, the electric power reception unit  220  and the optical transmission module  810  are formed in such a manner as to form a closed circuit along with the turning-on and -off unit  230  and the like. Therefore, it is desirable that the electric power reception unit  220 , the optical transmission module  810 , and the like are configured in such a manner as to be electrically connected to each other by a printed circuit board or the like on the coil holder  130 . 
     Although not illustrated, a conversion module that converts alternating current (AC) into direct current (DC) may be further provided on the coil holder  130 . 
     A holder terminal  132  is provided on an upper surface of a right end portion of the coil holder  130 . 
     A lower end portion of the transparent electrode film  240  is inserted into the holder terminal  132  for being connected thereto. 
     As illustrated, the coil holder  130  is formed to the shape of a ring when viewed as a whole. As illustrated, it is desirable that the coil holder  130  is formed in such a manner that the right end portion thereof has a relatively wide width so that the electric power reception unit  220  and the like are formed on the right end portion thereof. 
     A hole may be formed in outer and inner circumferential surfaces of the coil holder  130 . A hook for fixing a plurality of components passes through the hole. 
     The coil holder  130  is protected by the upper and lower covers  140  and  150 . The upper cover  140  and the lower cover  150  that correspond to upper and lower surfaces, respectively, of the coil holder  130  are provided over and under the coil holder  130 , respectively, and enclose upper and lower portions, respectively, of the coil holder  130 . 
     A terminal holder  142  is formed on a right end portion of the upper cover  140  in a manner that protrudes upward. The holder terminal  132  of the coil holder  130  is accommodated in the terminal holder  142 . Therefore, the holder terminal  132  is inserted, from below, into the terminal holder  142  for being accommodated therein. An upper portion of the terminal holder  142  is formed in such a manner as to be open at the part thereof. The lower end portion of the transparent electrode film  240  passes through the opening. 
     A hook may be formed on the upper cover  140 . With the hook, the upper cover  140  is combined with the lower cover  150 . 
     As described above, the transparent electrode film  240  is made of a transparent material, such as indium-tin oxide (ITO). The transparent electrode film  240  is configured in such a manner as to have a size corresponding to a length in the upward-downward direction of the container body  100 . 
     The transparent electrode film  240  is provided between the outer container body  110  and the inner container body  120 . In this manner, the presence of the transparent electrode film  240  between the outer container body  110  and the inner container body  120  prevents a contact with the food inside the inner container body  120  and blocks an outside foreign material from coming into contact with the outer container body  110  as well. 
     The transparent electrode film  240  may be attached on a surface of the outer container body  110  or may be attached on a surface of the inner container body  120 . That is, the transparent electrode film  240  may be attached on the internal surface of the outer container body  110  or may be attached on an external surface (outer circumferential surface) of the inner container body  120 . 
     A case where the transparent electrode film  240  is attached on the internal surface of the outer container body  110  in a manner that extends longitudinally in the upward-downward direction is described hereinafter as an example. 
     The transparent electrode film  240 , as illustrated, is bent one or more times. A lower end portion thereof passes through the terminal holder  142  of the upper cover  140  and is connected to the holder terminal  132  of the coil holder  130 , and an upper end portion thereof is connected to the reed switch  234 . 
     That is, a film guide on which the transparent electrode film  240  is attached is formed on the internal surface of the outer container body  110  in a manner that extends longitudinally in the upward-downward direction. That is, the film guide is formed on an internal right-side surface of the outer container body  110  in a manner that extends longitudinally in the upward-downward direction, and thus guides attaching of the transparent electrode film  240 . 
     A magnet groove  126  is formed in an upper end portion of the inner container body  120  in a manner that is cut outward. The permanent magnet  232  is accommodated in the magnet groove  126 . That is, an end portion on the right side of the inner container body  120  is partly cut off rightward in such a manner as to be stepped, and thus the magnet groove  126  is formed. The permanent magnet  232  and the like are positioned in the magnet groove  126 . 
     The container body  100  is formed in such a manner that a bottom surface thereof has a shape corresponding to a shape of the upper surface of the main body  500 . With this configuration, the container body  100  is easily attached and detached on and from the upper surface of the main body  500 . 
     More specifically, the container body  100  is seated on the seating support  900  of the main body  500  described below. 
     The container body  100  is formed in such a manner that the bottom surface thereof has a shape corresponding to a shape of an upper end portion of the main body  500 . Thus, the container body  100  is seated on the main body  500  and is easily removed therefrom. 
     An edge rim  170  of a predetermined width is formed on the bottom surface of the container body  100  in a manner that protrudes downward. The edge rim  170  is brought into contact with an upper surface of a lower rim  910  of the seating support  900  on the main body  500 . The edge rim  170  is formed to a shape corresponding to a shape of an upper surface of the lower rim  910 . The lower rim  910  will be described below. 
     One part of a center portion of the bottom surface of the container body  100  is recessed in the upward direction, and thus an upper-rim accommodation groove  172  is formed. That is, the one part of the center portion of the bottom surface of the container body  100  is recessed in the upward direction inward from the edge rim  170  of the container body  100 , and thus the upper-rim accommodation groove  172  is formed. When the container body  100  is seated on the main body  500 , an upper rim  920  of the seating support  900  on the main body  500  is accommodated in the upper-rim accommodation groove  172 . The upper rim  920  will be described below. 
     The edge rim  170  is formed to a shape of a circular ring that has an opening at one portion thereof. A coil seating part  940  described below is accommodated in this opening. That is, the edge rim  170  is open at the right ends, and thus a coil seating groove  170   a  is formed. The coil seating part  940  described below is accommodated in the coil seating groove  170   a.    
     One part of the center portion of the bottom surface of the container body  100  protrudes downward, and thus a circular rim  174  is formed. That is, the center portion of the upper-rim accommodation groove  172  includes the circular rim  174  protruding downward. 
     As illustrated, the circular rim  174  has the shape of a circular ring. The circular rim  174  is open at the center. The circular rim  174  provides a path along which the blade assembly  200  and the motor assembly  600  may be connected to each other. 
     The circular rim  174  is accommodated in a circular-rim accommodation groove  980  formed in the main body  500 . The circular-rim accommodation groove  980  will be described below. 
     A plurality of mounting protrusions  174   a  that protrude radially is further provided on an outer circumferential surface of the circular rim  174 . The mounting protrusion  174   a  serves to hold the container body  100  firmly at its home position on the main body  500  and to keep the container body  100  stationary without being rotated. One or more mounting protrusions  174   a  are provided. 
     According to the present disclosure, a case is illustrated where four mounting protrusions  174   a  are provided. It is desirable that the mounting protrusion  174   a  is formed in such a manner that the farther an end thereof extends outward from the outer circumferential surface of the circular rim  174 , the more decreased a diameter thereof. For the reason for this is to easily accommodate the mounting protrusion  174   a  in the protrusion groove  982  described below. 
       FIGS. 5 to 7  are views each illustrating in detail components in an upper half of the main body  500 .  FIG. 5  is a perspective view illustrating the main body  500 .  FIG. 6  is an exploded perspective view illustrating the components in the upper half of the main body  500 .  FIG. 7  is a perspective view illustrating a state where a cover is removed from the main body  500 . 
     As illustrated in  FIGS. 5 to 7 , the seating support  900  is provided on the upper surface of the main body  500  in a manner that protrudes upward to be stepped. The bottom of the container body  100  is seated on the seating support  900 . 
     The lower end portion of the container body  100  is seated on the seating support  900  and is supported thereon. Therefore, it is desirable that the seating support  900  is formed in such a manner as to have a shape corresponding to a shape of the lower end portion of the container body  100 . 
     Specifically, the seating support  900  is configured to include the lower rim  910 , the upper rim  920 , and the like. The lower rim  910  is formed in such a manner as to be stepped and has a diameter corresponding to a diameter of the lower end portion of the container body  100 . The upper rim  920  is formed in such a manner as to protrude upward from the lower rim  910  and has a smaller diameter than the lower rim  910 . 
     As illustrated, the lower rim  910  is formed in such a manner as to have a circular shape and a predetermined height. The upper rim  920  having a smaller diameter than the lower rim  910  is formed on the upper surface of the lower rim  910  in such a manner as to protrude upward therefrom to a predetermined height. Therefore, it is desirable that a step surface  902 , like the upper surface of the main body  500 , is in the horizontal plane formed between the lower rim  910  having a relatively great diameter and the upper rim  920  having a relatively small diameter. 
     An exterior ring  912  and an upper end ring  914  are provided on external surfaces, respectively, of the lower rim  910  and the upper rim  920 . The exterior ring  912  and an upper end ring  914  have shapes corresponding to shapes, respectively, of the external surfaces of the lower rim  910  and the upper rim  920 . The exterior ring  912  and the upper end ring  914  are provided on outer circumferential surfaces, respectively, of the lower rim  910  and the upper rim  920  that have a circular external surface, and thus enclose external surfaces (flank surfaces), respectively, of the lower rim  910  and the upper rim  920 . 
     The exterior ring  912  and the upper end ring  914  serve to protect components inside and serve as an exterior material. Therefore, it is desirable that like the exterior handle  304 , the exterior ring  912  and the upper end ring  914  are made of an antirust material having a smooth surface, such as a stainless steel material. 
     An elastic member  930  made of an elastic material is further provided on the step surface  902  between the upper rim  920  and the lower rim  910 . It is desirable that as illustrated, the elastic member  930  is formed in such a manner as to cover the step surface  902  formed on the upper surface of the lower rim  910  and to enclose a lower portion of the upper rim  920 . 
     The elastic member  930  is made of an elastic material, and thus serves as a cushion that absorbs shock when the container body  100  is placed on the main body  500 . That is, when the bottom surface of the container body  100  is brought into contact with the upper rim  920 , the elastic member  930  also serves to prevent the upper rim  920  and the lower rim  910  on the main body  500 , which are made of a solid material, and the bottom surface of the container body  100  from being damaged or from generating noise due to collision with each other. 
     In this manner, the elastic member  930 , made of a material, such as rubber, is used to smoothly seat the container body  100  on the main body  500  without any shock. In addition, conductivity rubber may be used whenever necessary. In this case, conductivity rubber may also be provided on the bottom of the container body  100 . 
     The electric power transmission unit  700  and the optical reception module  820  are mounted on an upper surface of the upper rim  920 . 
     More specifically, a right-side surface of the upper rim  920  further protrudes rightward, and the coil seating part  940  is formed on the right-side surface thereof. The electric power transmission unit  700  is mounted on an upper surface of the coil seating part  940 . 
     The electric power transmission unit  700  is positioned adjacent to the electric power reception unit  220  provided on the container body  100  and serves to supply electric power to the electric power reception unit  220 . Therefore, it is desirable that the electric power transmission unit  700  is configured as an induction coil. That is, like the electric power reception unit  220 , the electric power transmission unit  700  may be configured as an induction coil wound a number of times in helical form on a core (not illustrated) on the same surface and may be mounted on a PCB. 
     In addition, although not illustrated in detail, an oscillation circuit unit may be provided inside the main body  500 . The oscillation circuit unit may generate electric power and may apply electric current to the electric power transmission unit  700 . A magnetic field may be produced by the electric current applied to the electric power transmission unit  700 . Then, the oscillation circuit unit may change strength of the electric current that is applied to the electric power transmission unit  700 , and the change in the strength of the electric current changes the magnetic field in the electric power transmission unit  700 . 
     Therefore, according to the present disclosure, when the electric power reception unit  220  and the electric power transmission unit  700  are mounted in such a manner as to correspond to each other in the upward-downward direction, the strength of the electric current that is applied to the electric power transmission unit  700  is changed, and the magnetic field in the electric power transmission unit  700  is accordingly changed. Thus, inductive coupling between the electric power transmission unit  700  and the electric power reception unit  220  changes magnetic flux passing through the electric power reception unit  220 . Consequently, an induced electromotive force develops in the electric power reception unit  220 . This induced electromotive force may also be supplied to the optical transmission module  810 . 
     The optical reception module  820  is provided in a direction opposite to a direction of the electric power transmission unit  700 . That is, it is desirable that the optical reception module  820  is provided in a reception groove  822  formed in an upper surface of a left end portion of the upper rim  920 . The reception groove  822  is positioned in a manner that corresponds in the upward-downward direction to the optical transmission module  810  mounted on the container body  100 . 
     More specifically, the reception groove  822  of a predetermined size is formed in the upper surface of the left end portion of the upper rim  920  in a manner that is cut downward. The optical reception module  820  is fixedly mounted in the reception groove  822 . 
     It is desirable that the optical reception module  820 , as described above, includes a photosensor or photodetector. The optical reception module  820  may receive light transmitted by the optical transmission module  810  and may transmit this received optical signal. 
     A Hall sensor  950  and a container body detection switch  960  may be further provided on the upper surface of the upper rim  920 . That is, a container body switch groove  962  and a sensor groove  952  are formed in upper surfaces, respectively, of leading and rear edge portions of the upper rim  920  in a manner that is cut downward. The container body detection switch  960  and the Hall sensor  950  are fixedly mounted in the container body switch groove  962  and the sensor groove  952 , respectively. 
     The container body detection switch  960  is configured as a reed switch and serves to detect whether or not the container body  100  is seated on the upper surface of the main body  500 . In a case where the container body detection switch  960  is mounted, a magnet (not illustrated) corresponding to the container body detection switch  960  is also further provided on the lower end portion of the container body  100 . 
     The Hall sensor  950  serves to determine a type of the container body  100  seated on the main body  500 . In this case, a signal transfer unit that corresponds to the bottom surface of the container body  100  may also be necessary. 
     The upper end ring  914  is mounted an edge of the upper rim  920 . It is desirable that the upper end ring  914  is configured in such a manner as to be separated into two pieces. That is, as illustrated, the right-side surface of the upper rim  920  protrudes rightward, and thus the coil seating part  940  is formed. Therefore, the upper end ring  914  is configured to include a protrusion piece  916  and a curvature piece  918 . The protrusion piece  916  encloses an external surface of the coil seating part  940 . The curvature piece  918  encloses portions other than the external surface thereof. 
     An upper portion of the upper rim  920  is covered by a cover  970 . Therefore, the electric power transmission unit  700 , the optical reception module  820 , the container body detection switch  960 , the Hall sensor  950 , and the like that are mounted on the upper rim  920  are covered by the cover  970  for being protected. 
     A center portion of the seating support  900  is open at the top and bottom. Thus, the blade assembly  200  of the container body  100  and the motor assembly  600  built into the main body  500  are connected to each other. 
     More specifically, the circular-rim accommodation groove  980  is formed in a center portion of the upper rim  920  in a manner that is cut downward. The above-described circular rim  174  on a lower end of the container body  100  is accommodated in the circular-rim accommodation groove  980 . That is, the upper rim  920  has the shape of a circular ring when viewed as a whole. The circular-rim accommodation groove  980  in the shape of a circle is formed in the center portion of the upper rim  920 . 
     One or more protrusion grooves  982  are formed in an internal surface of the upper rim  920 . One or more portions of the protrusion groove  982  are recessed outward, and thus one or more circular-rim accommodation grooves  980  are radially formed. The mounting protrusion  174   a  of the container body  100  is seated in the circular-rim accommodation groove  982 . 
     Therefore, it is desirable that the protrusion grooves  982  are formed in such a manner that the number or sizes thereof correspond to the number or sizes of the mounting protrusions  174   a  and that the protrusion groove  982  is formed in such a manner that a size thereof corresponds to a size of the mounting protrusion  174   a.  It is desirable that the protrusion groove  982  is formed in such a manner as to have the same width as or a greater width than the mounting protrusions  174   a.    
       FIGS. 8 to 13  each illustrate a detailed configuration of the container lid  400 .  FIG. 8  is a perspective view illustrating the container lid  400 .  FIG. 9  is a cross-sectional perspective view illustrating the container lid  400 .  FIG. 10  is an exploded perspective view illustrating the container lid  400  when viewed from above. 
       FIG. 11  is an exploded perspective view illustrating the container lid  400  when viewed from below.  FIG. 12  is an exploded cross-sectional perspective view illustrating the container lid  400 .  FIG. 13  is an exploded perspective view illustrating a container-lid body  410  of the container lid  400 . 
     As illustrated in  FIGS. 8 to 13 , the container lid  400  is configured to include the container-lid body  410 , the cap  450 , a fastening portion  440 , and the like. The cover hole  401  is formed in the container-lid body  410  in a manner that passes through the container-lid body  410  from top to bottom. The cap  450  opens and closes the cover hole  401 . With the fastening portion  440 , the cap  450  is detachably mounted on the container-lid body  410 . 
     Specifically, the container-lid body  410  is formed in such a manner as to have the shape of a circular ring. The cover hole  401  is formed in a center portion of the container-lid body  410  in a manner that passes through the center portion thereof from top to bottom. The cap  450  is detachably mounted in the cover hole  401  and closes and opens the cover hole  401 . 
     The container-lid body  410  is configured to include a cover casing  420 , a cover exterior material  430 , and the like. The cover hole  401  is formed in a center portion of the cover casing  420  in a manner that passes through the center portion thereof from top to bottom. The cover exterior material  430  encloses a flank surface of the cover casing  420 . 
     A plurality of slit ribs  420   a  are formed in the flank surface of the cover casing  420  in a manner that protrudes outward therefrom. With the plurality of slit ribs  420 , the cover exterior material  430  and the cover casing  420  are combinable with each other. 
     The slit ribs  420   a  are provided in pairs. A slit that is a gap of a predetermined size is formed between a pair of slit ribs  420   a.  An adhesive, such as silicone, or an elastic material is dispensed on the slit or is provided to fill the slit. It is desirable that the cover exterior material  430  and the cover casing  420  are configured in such a manner as to be combined with each other using the adhesive or the elastic material. 
     Of course, the slit rib  420   a  protrudes outward from the flank surface of the cover casing  420 . Therefore, it is also possible that the cover case  420  is forced to be inserted into the cover exterior material  430  for being combined therewith. 
     The cover casing  420  provides an exterior appearance of the container-lid body  410  and an overall frame thereof. The cover hole  401  is formed in the center portion of the cover casing  420  in a manner that has a predetermined diameter and passes through the center portion thereof from top to bottom. 
     Then, the cover casing  420  is inserted into the cover exterior material  430  for being combined therewith. The exterior material  430  provides a good-quality and aesthetically pleasing exterior appearance to a user. That is, the cover casing  420  may be made of a plastic material or the like by injection molding or the like. It is desirable that the cover exterior material  430  is made of a stainless material or the like. 
     That is, it is desirable that the cover exterior material  430  is made of an antirust material having a smooth surface, such as a stainless steel material. 
     The cover exterior material  430  may be attached on an outer circumferential surface (flank surface) of the cover casing  420  using an adhesive or the like. The cover casing  420  is forced to be inserted into the cover exterior material  430  for being combined therewith. Therefore, as illustrated, it is desirable that the slit ribs  420   a  are formed in an equally spaced manner on the outer circumferential surface (flank surface) of the cover casing  420  in such a manner as to protrude outward from the outer circumferential surface thereof. 
     The cover casing  420  is configured to include an outer wall  422 , an inner wall  424 , an upper circular plate  426 , and the like. The outer wall  422  is formed in such a manner as to have the shape of a circular ring and provides an exterior appearance of the cover casing  420 . The inner wall  424  is formed in such a manner as to have a smaller diameter than the outer wall  422  and to have the cover hole  401  in the center thereof. The upper circular plate  426  connects respective upper ends of the outer wall  422  and the inner wall  424  to each other. 
     Specifically, the cover casing  420  is formed to a shape of a circular ring of a predetermined width that is closed at the top, when viewed as a whole. That is, the cover casing  420  is formed in the cover hole  401  in a manner that passes through the center portion thereof from top to bottom. The cover casing  420  is closed at the top, and thus has a circular-ring structure that has a longitudinal cross-sectional area in the shape of “∩”. 
     The container lid  400  serves to cover the top of the container body  100 . The cover hole  401  is formed in the center portion of the container lid  400  in a manner that passes through the center portion thereof from top to bottom. 
     The cap  450  is detachably mounted in the cover hole  401 . That is, as illustrated, the cover hole  401  is formed in the center portion of the container lid  400  in a manner that passes through the center portion thereof from top to bottom. The cover hole  401  is opened and closed by the cap  450 . 
     The gasket  402  and a support ring  412  are further provided on a lateral side of the container-lid body  410 . The gasket  402  bridges the gap between the container lid  400  and the container body  100 . The support ring  412  fixedly supports the gasket  402 . 
     In this manner, the support ring  412  and the gasket  402  that have the shape of a circular ring are provided on a lower portion of the container-lid body  410 . The support ring  412  may be fixed to the lower portion of the container-lid body  410  using an adhesive or the like. The gasket  402  is brought into contact with an external surface of the support ring  412  for being fixed thereto. 
     More specifically, the support ring  412  is fixedly combined with a lower portion of the outer wall  422 , and the gasket  402  is brought into contact with the external surface of the support ring  412  for being mounted thereon. 
     A support groove  412   a  is formed in the external surface of the support ring  412  in a manner that is cut inward. The gasket  402  is accommodated in the support groove  412   a  for being fastened thereto. 
     The gasket  402  serves to bridge the gap between the container lid  400  and the container body  100  and, at the same time, serves to prevent the container lid  400  attached to the container body  100  from being of itself separated from the container body  100 . 
     Therefore, the gasket  402  may be made of an elastic material. As illustrated, a plurality of concave-convex portions may be formed on an outer circumferential surface of the gasket  402 . 
     The cap  450  is configured to include an upper surface plate  452 , a cap body  454 , and the like. The upper surface plate  452  is exposed to the outside at the upper surface of the container-lid body  410 . At least one portion of the cap body  454  is accommodated in the cover hole  401 . 
     The cap body  454 , as illustrated, is formed to a shape of a truncated cone or a cylinder that has an empty space inside when viewed as a whole. That is, it is desirable that the cap body  454  is formed to a shape of a truncated cone that is tapered to the top, or to a shape of a cylinder that has the same diameter at the top and bottom. 
     The upper surface plate  452  opens and closes the tip of the cap body  454 . As illustrated, the upper surface plate  452  is formed in such a manner as to have a greater diameter than an end portion of the cap body  454 . 
     An intermediate ring  456  is further formed on the cap body  454  in such a manner as to protrude outward therefrom. The intermediate ring  456  is brought into contact with an internal surface of an upper end portion of the cover hole  401 . 
     Specifically, the intermediate ring  456  may be formed in such a manner as to protrude outward from a center portion or an upper portion of the cap body  454 . When the cap  450  is mounted on the container-lid body  410 , the intermediate ring  456  lies in the same plane with the upper circular plate  426 . Therefore, an upper surface of the intermediate ring  456  is exposed to the outside at the top of the container-lid body  410 . 
     A ventilation groove  456   a  is further formed in an outer circumferential surface of the intermediate ring  456  in a manner that is cut inward. Thus, it is possible that air flows through the intermediate ring  456  in the upward-downward direction. That is, the ventilation groove  456   a  serves to allow air to flow through the intermediate ring  456  on the cap  450  in the upward-downward direction. As illustrated, the ventilation groove  456   a  is formed in a manner that is cut inward from the outer circumferential surface of the intermediate ring  456 . 
     A seating groove  424   a  is formed on an upper end portion of the inner wall  424 . An edge of the intermediate ring  456  is seated in the seating groove  424   a.  That is, as illustrated, the seating groove  424   a  is formed in an upper end portion of an internal surface of the inner wall  424  in such a manner as to be stepped. The seating groove  424   a  is formed in a manner that is cut outward. 
     It is desirable that an inner circumferential surface of the seating groove  424   a  is formed in such a manner as to correspond to an outer circumferential surface of the intermediate ring  456  or to have a larger size than the outer circumferential surface thereof. An internal diameter of the upper end portion of the inner wall  424  is smaller than an external diameter of the intermediate ring  456 . Therefore, the intermediate ring  456  is seated in the seating groove  424   a,  and thus is supported on the seating groove  424   a  without falling below the inner wall  424 . 
     As illustrated, the outer wall  422  may be formed in such a manner as to have a height corresponding to a height of the inner wall  424  or may be formed in such a manner as to have a greater or smaller height than the inner wall  424 . 
     The fastening unit  440  is configured to include a fastening protrusion  442 , a fastening passage  444 , and the like. The fastening protrusion  442  is formed on the container-lid body  410  in a manner that protrudes therefrom in one direction. The fastening passage  444  is formed in the cap  450 . The fastening protrusion  442  is accommodated in the fastening passage  444 . That is, the fastening unit  440  is configured to include the fastening protrusion  442  that protrudes inward from an inner circumferential surface of the container-lid body  410 , the fastening passage  444  that is formed in a manner that is cut inward from an outer circumferential surface of the cap  450 , and the like. The fastening protrusion  442  is moved or accommodated in the fastening passage  444 . 
     Respective structures of and respective formation positions of the fastening protrusion  442  and the fastening passage  444  will be described in more detail below. 
     The fastening protrusion  442  is formed on the inner wall  424  in a manner that protrudes inward therefrom. That is, it is desirable that the fastening protrusion  442  is formed in such a manner as to be arranged a predetermined distance upward from a lower end portion of the inner wall  424 . 
     More specifically, a close-contact plate  424   b  is further formed on the internal surface of the inner wall  424  in a manner that protrudes inward from the internal surface thereof. The close-contact plate  424   b  is brought into contact with an external surface of the cap body  454 . That is, a lower end portion of the cap body  454  is formed in a manner that protrudes partly more inward, and thus the close-contact plate  424   b  is formed. A plurality of close-contact plates  424   b  may be formed on the cap body  454 . According to the present disclosure, a case is illustrated where two close-contact plates  424   b  is formed on the cap body  454  symmetrically in the forward-backward direction or in the leftward-rightward direction. 
     The fastening protrusion  442  is formed on the close-contact plate  424   b  in a manner that protrudes inward therefrom. That is, as illustrated, the fastening protrusion  442  is formed on the close-contact plate  424   b  in a manner that protrudes inward (toward the center of the container lid  400 ) therefrom. The fastening protrusion  442  is formed in such a manner as to be positioned a predetermined distance upward from a lower end portion of the close-contact plate  424   b.    
     It is desirable that a distance that the fastening protrusion  442  is arranged upward from the lower end portion of the cap body  454  or the close-contact plate  424   b  corresponds to a length in the upward-downward direction of an access groove  444   a  in the cap  450  described below. 
     Of course, it is also possible that the fastening protrusion  442  is formed, for example, on the internal surface of the inner wall  424  instead of on the close-contact plate  424   b.  Since the close-contact plate  424   b  further protrudes inward from the inner wall  424 , the protruding fastening protrusion  442  has a greater thickness when formed on the internal surface of the inner wall  424  other than the close-contact plate  424   b  than when formed on the close-contact plate  424   b.    
     The fastening protrusions  442  are formed at positions, respectively, that correspond to positions of the fastening passages  444 . Therefore, one or more the fastening protrusions  442  may be formed on the inner wall  424  or the close-contact plate  424   b.  According to an embodiment of the present disclosure, a case is illustrated where two fastening protrusions  442  are formed on the inner wall  424  or the close-contact plate  424   b  in such a manner as to face each other at symmetrical positions. 
     A return groove  424   c  is further provided in the close-contact plate  424   b.  The return groove  424   c  is formed in a manner that is cut more outward than the close-contact plate  424   b  and serves as a path along which food on the close-contact plate  424   b  falls under. That is, two close-contact plates  424   b  are formed separately at symmetrical positions, respectively, on a lower portion of the inner wall  424 . The return groove  424   c  is formed between these two close-contact plates  424   b.    
     The return groove  424   c  is formed in a manner that is cut more outward than the close-contact plate  424   b.  Thus, the return groove  424   c  is open at the top and bottom. Therefore, in a state where the cap  450  is fastened to the container-lid body  410 , in a case where the food in the container body  100  spills onto the close-contact plate  424   b,  the food falls under through the return groove  424   c  back into the container body  100 . 
     A return guide  424   d  is further provided on one end portion of the close-contact plate  424   b.  The return guide  424   d  is formed in such a manner that, the more the return guide  424   d  protrudes in one direction, the more decreased a height of an upper end thereof. The return guide  424   d  serves to guide moving of the food on the close-contact plate  424   b  toward the return groove  424   c.    
     Specifically, the return guide  424   d  is formed on opposite end portions of the close-contact plate  424   b  or any one of the right or left end portions thereof in such a manner that, the more the return guide  424   d  protrudes leftward or rightward, the more the return guide  424   d  is inclined downward and the more decreased the height of the upper end thereof. Therefore, the food positioned on the close-contact plate  424   b  slides into the return groove  424   c  along the return guide  424   d.  Then, the food falls into the container body  100  below through the return groove  424   c.    
     The fastening passage  444  is formed in the outer circumferential surface of the cap  450 . The fastening passage  444  not only provides a path along which the fastening protrusion  442  moves, but also keeps the fastening protrusion  442  accommodated. Thus, the cap  450  is combined with the container-lid body  410 . 
     The fastening passage  444  is configured to include the access groove  444   a,  a fastening groove  444   b,  and the like. The access groove  444   a  is formed in a manner that is cut inward from the outer circumferential surface of the cap  450 . The access groove  444   a  guides moving of the fastening protrusion  442  in the upward-downward direction. The fastening groove  444   b  is formed in such a manner as to horizontally extend from one end portion of the access groove  444   a.  The fastening grooves  444   b  provides a space in which the fastening protrusion  442  is accommodated. 
     Specifically, when a pair of fastening passages  444  are formed in an outer circumferential surface of the lower end portion of the cap body  454 , it is desirable that the same number of the fastening passages  444  are formed as the fastening protrusions  442 . 
     As illustrated, the access groove  444   a  is formed in such a manner as to extend upward from the lower end portion of the cap body  454 . The access groove  444   a  is formed in such a manner as to extend a predetermined distance upward from an internal surface of the lower end portion of the cap body  454 . That is, it is desirable that a length in the upward-downward direction of the access groove  444   a  corresponds to a distance from a lower end of the internal wall  424  to the fastening protrusion  442 . 
     The fastening groove  444   b  is formed in such a manner as to vertically extend leftward or leftward from an upper end portion of the access groove  444   a.  That is, the access groove  444   a  is formed in such a manner as to vertically extend in the upward-downward direction, and the fastening groove  444   b  is formed in such a manner as to horizontally extend in the leftward-rightward direction. Therefore, an upper end portion of the access groove  444   a  and a left end portion or a right end portion of the fastening groove  444   b  are connected to each other, and thus the fastening protrusion  442  is able to move in a state of being accommodated in the access groove  444   a  and the fastening groove  444   b.    
     A prevention protrusion  446  is formed on the fastening groove  444   b  in a manner that protrudes outward therefrom. The prevention protrusion  446  prevents separation of the fastening protrusion  442  accommodated in the fastening groove  444   b.  That is, as illustrated, the prevention protrusion  446  of a predetermined size is formed on the fastening groove  444   b  in a manner that protrudes outward therefrom. 
     It is desirable that the prevention protrusion  446  is formed in a manner that intersects the fastening groove  444   b  in the upward-downward direction. It is desirable that the prevention protrusion  446  is formed in such a manner that a length of the protruding prevention protrusion  446  is smaller than a depth of the fastening groove  444   b.    
     It is desirable that the prevention protrusion  446  is formed adjacent to the end portion of the fastening groove  444   b.    FIG. 11  illustrates a case where the prevention protrusion  446  is formed adjacent to the right end portion of the fastening groove  444   b.    
     One portion of an inner circumferential surface of the cap body  454  may further protrude inward. Thus, a reinforcement portion  454   a  may be formed. That is, in a case where an opposite side (internal surface) of the cap body  454 , in which the fastening passage  444  is formed, further protrudes inward and where the fastening passage  444  is formed in an outer circumferential surface of the cap body  454 , it is also desirable that the cap body  454  maintain a predetermined thickness. 
       FIGS. 14 and 15  each illustrate a configuration of the blade assembly  200 . That is,  FIG. 14  is a perspective view illustrating the blade assembly  200 , and  FIG. 15  is an exploded perspective view illustrating the blade assembly  200 . 
     As illustrated in  FIGS. 14 and 15 , the blade assembly  200  is configured to include a main blade  250 , an auxiliary blade  252 , a blade shaft  260 , a body  270 , a fixation cap  280 , and the like. The main blade  250  includes a plurality of main blade portions  250   b.  The auxiliary blade  252  includes auxiliary blade portions  252   b,  each being positioned between each of the plurality of main blade portions  250   b.  The main blade  250  and the auxiliary blade  252  rotate about the blade shaft  260 . The body  270  is mounted on the lower end portion of the container body  100  and rotatably supports the blade shaft  260 . The fixation cap  280  is fastened to the blade shaft  260  and serves to fix the main blade  250  and the auxiliary blade  252  to the blade shaft  260 . 
     The blade assembly  200  serves to chop food into small pieces or to mix the food using the blades. These blades that chop the food into small pieces include the main blade  250 , the auxiliary blade  252 , and the like. 
     The main blade  250  primarily serves to chop the food into small pieces. The auxiliary blade  252  serves to assist the main blade  250  in easily chopping the food into smaller pieces and mixing the food. 
     The main blade  250  is configured to include a main fixation portion  250   a,  the plurality of blade portions  250   b,  and the like. The main fixation portion  250   a  is combined with the blade shaft  260 . The plurality of blade portions  250   b  are formed in a manner that protrudes outward from the main fixation portion  250   a.    
     As illustrated, the main fixation portion  250   a  is formed in such a manner as to constitute a center portion of the main blade  250 . The main fixation portion  250   a  is combined with the blade shaft  260  and supports the plurality of main blade portions  250   b  that are formed integrally into one piece in a manner that protrudes outward from the main fixation portion  250   a.    
     Four main blade portions  250   b  are formed in a manner that protrudes radially from the main fixation portion  250   a.  The four main blade portions  250   b  are symmetrically formed in such a manner as to be equiangular with respect to the center of the main fixation portion  250   a.    
     Specifically, as illustrated, the main fixation portion  250   a  of a predetermined size having the shape of a flat plate is formed on a center portion of the main blade  250 . The four main blade portions  250   b  are formed integrally into one piece in a manner that protrudes outward from the main fixation portion  250   a.    
     It is desirable that an even number of main blade portions  250   b  are provided. It is desirable that the main blade portions  250   b  are formed in such a manner as to be symmetrical about the blade shaft  260  in the forward-backward direction or the leftward-rightward direction. 
     According to the present disclosure, a case is illustrated where four main blade portions  250   b  are provided. Of course, it is also possible that three or five main blade portions  250   b  are formed in such a manner as to be equiangular with respect to the center of the main fixation portion  250   a.  That is, it is also possible that an even number of main blade portions  250   b  are provided. 
     The main blade portion  250   b  is formed in such a manner as to be in parallel with the main fixation portion  250   a  or in such a manner as to make a predetermined angle with the main fixation portion  250   a.    
     Specifically, the main blade portion  250   b  is formed in a manner that extends horizontally outward from an end of the main fixation portion  250   a  or in a manner that extends upward or downward at a predetermined inclined angle from the end of the main fixation portion  250   a.    
     According to the present disclosure, as illustrated in  FIGS. 14 and 15 , among the total four main blade portions  250   b,  two main blade portions  250   b  in the leftward-rightward direction are formed in such a manner as to be horizontal with the main fixation portion  250   a,  and two main blade portions  250   b  in the forward-backward direction extend upward at a predetermined inclined angle from front and rear ends, respectively, of the main fixation portion  250   a.    
     In addition to this configuration, the main blade portion  250   b  may extend downward at a predetermined inclined angle from the main fixation portion  250   a  (refer to  FIG. 17 ). 
     In addition, in  FIGS. 14 and 15 , the main blade portions  250   b  are configured in such a manner as to be symmetrical in the forward-backward direction or the leftward-rightward direction about the main fixation portion  250   a.  However, it is also possible that the main blade portions  250   b  are configured in such a manner as not to be symmetrical in the forward-backward direction or the leftward-rightward direction about the main fixation portion  250   a.    
     For example, it is possible that two main blade portions  250   b  are formed on the left and right sides, respectively, of the main fixation portion  250   a  in such a manner as to extend horizontally or to extend upward or downward at a predetermined inclined angle. In addition, it is also possible that two main blade portions  250   b  are formed on the left and right sides, respectively, of the main fixation portion  250   a  in such a manner as to extend in opposite directions at a predetermined inclined angle. That is, it is possible that one main blade portion  250   b  of a pair of main blade portions  250   b  is formed on the left side of the main fixation portion  250   a  in such a manner as to extend downward at a predetermined inclined angle and that the other main blade portion  250   b  is formed on the right side of the main fixation portion  250   a  in such a manner as to extend upward at a predetermined inclined angle (refer to  FIG. 17 ). 
     The auxiliary blade  252  is configured to include an auxiliary fixation portion  252   a,  a plurality of auxiliary blade portions  252   b,  and the like. The auxiliary fixation portion  252   a  is combined with the blade shaft  260 , and the plurality of auxiliary blade portions  252   b  is formed in such a manner as to protrude outside from the auxiliary fixation portion  252   a.    
     As illustrated, the auxiliary fixation portion  252   a  constitutes a center portion of the auxiliary blade  252  and is combined with the blade shaft  260 . The auxiliary fixation portion  252   a  supports one or more auxiliary blade portions  252   b  that are formed integrally into one piece in a manner that protrudes outward from the auxiliary fixation portion  252   a.    
     It is desirable that a smaller number of the auxiliary blade portions  252   b  are provided than the main blade portions  250   b.  It is desirable that the auxiliary blade portions  252   b  has a smaller length than the main blade portion  250   b.    
     Of course, it is also possible that the number of the provided auxiliary blade portions  252   b  is the same as the number of the provided main blade portions  250   b  or that the auxiliary blade portion  252   b  has the same size as the main blade portion  250   b.  According to the present disclosure, the auxiliary blade portion  252   b  is formed in such a manner as to be smaller in number than the main blade portion  250   b  or in such a manner as to have a smaller size than the main blade portion  250   b.  For this reason, the auxiliary blade portion  252   b  will be described taking as an example a function of assisting the main blade portion  250   b  in chopping the food into smaller spaces. 
     It is also desirable that an even number of the auxiliary blade portions  252   b  are provided. That is, as illustrated, it is desirable that two auxiliary blade portions  252   b  are provided in such a manner as to extend upward at a predetermined inclined angle from both ends, respectively, of the auxiliary fixation portion  252   a.  As is the case with the main blade portion  250   b,  four auxiliary blade portions  252   b  may be provided depending on the situation. 
     According to the present disclosure, as illustrated, a case is illustrated where two auxiliary blade portions  252   b  are formed in such a manner as to protrude symmetrically outward from the auxiliary fixation portion  252   a.    
     The auxiliary blade portion  252   b  is formed in such a manner as to extend upward at a predetermined inclined angle from an end of the auxiliary fixation portion  252   a.  Thus, the auxiliary blade portion  252   b  makes the predetermined angle with the auxiliary fixation portion  252   a.    
     Then, it is desirable that an angle that the auxiliary blade portion  252   b  and the auxiliary fixation portion  252   a  make with each other is smaller than an angle that the main blade portion  250   b  and the main fixation portion  250   a  make with each other. 
     Specifically, the auxiliary blade portion  252   b  extends upward at a greater inclined angle than the main blade portion  250   b.  That is, it is desirable that an angle that the auxiliary blade portion  252   b  and an upper surface of the auxiliary fixation portion  252   a  make with each other is smaller than the angle that the main blade portion  250   b  and the main fixation portion  250   a  make with each other. 
     Accordingly, the auxiliary blade  252  serves to assist the main blade  250  in chopping the food into smaller pieces and at the same time to control moving of the food inside a center portion of the container body  100 . That is, the auxiliary blade portion  252   b  of the auxiliary blade  252  is positioned in the center portion of the container body  100 , and thus this positioning is also effective in mixing the food inside the container body  100  by rotation. 
     Specifically, the auxiliary blade portion  252   b  partially chops the food lying on a center portion other than a space in which the main blade portion  250   b  operates. At the same time, the auxiliary blade portion  252   b  also serves to push the food lying on the center portion upward or outward or to rotate the food lying thereon, thereby moving the food toward the main blade portion  250   b,  upward, or in other directions. 
     In this manner, the main blade  250  primarily serves to move the food accommodated in the container body  100  and at the same time to chop the food into small pieces, and the auxiliary blade  252  serves to assist the main blade  250  in chopping the food on the center portion of the container body  100  into smaller pieces and at the same time to move the food thereon. 
     The auxiliary blade portion  252   b  is mounted in such a manner as to be positioned between each of the plurality of main blade portions  250   b.  That is, the plurality of main blade portions  250   b  is mounted in such a manner that an angle that the main blade portion makes with respect to the center of the main fixation portion  250   a  is 90° and in such a manner as to be equally spaced. The auxiliary blade portion  250   b  is positioned between each of the main blade portions  250   b.    
     Accordingly, when the main blade portion  250   b  cannot touch the food, the auxiliary blade portion  252   b  may touch the food. Thus, the efficiency of chopping the food into small pieces and mixing the food can be increased. 
     A fastening hole  254  is formed in respective center portions of the main blade  250  and the auxiliary blade  252  in a manner that passes through the respective center portions thereof from top to bottom. A fastening plate  264  described below is accommodated in the fastening hole  254 . That is, the fastening hole  254  is formed in each of the center portions of the main fixation portion  250   a  of the main blade  250  and the center portion of the auxiliary fixation portion  252   a  of the auxiliary blade  252  in a manner that passes through from top to bottom. 
     The fastening hole  254  is formed in such a manner as to have a shape corresponding to a shape of an external surface of the fastening plate  264  described below. Thus, with this configuration, rotation of the blade shaft  260  rotates the main blade  250  and the auxiliary blade  252 . 
     Therefore, as illustrated, it is desirable that the fastening hole  254  is formed in such a manner as to have a four-square cross-section. 
     The body  270  is configured to include a seating portion  272 , a protrusion portion  274 , and the like. The seating portion  272  is fixedly mounted on the bottom surface of the container body  100 . The protrusion portion  274  is formed on an upper surface of the seating portion  272  and is exposed in a manner that protrudes upward from the bottom surface of the container body  100 . 
     As illustrated, the seating portion  272  is formed in such a manner as to have the shape of a cylinder when viewed as a whole, and thus is mounted on the bottom surface of the container body  100 . Therefore, it is desirable that a key pocket  272   a  is further formed in at least one surface of the seating portion  272 . A portion of the bottom surface of the container body  100  is inserted into the key pocket  272   a  from bottom to top, and thus the body  270  is prevented from being rotated. That is, the key pocket  272   a  is further formed in the seating portion  272 , and a portion of the bottom surface of the container body  100  is inserted into the key pocket  272   a,  thereby holding the body  270  in place. 
     Specifically, the body  270  needs to be stationary without being rotated in a state of being mounted in the container body  100  when the blade shaft  260  is rotated. For this reason, the key pocket  272   a  into which a portion of the bottom surface of the container body  100  is to be inserted is formed. 
     The key pocket  272   a  is cut inward from an external surface of the seating portion  272  in such a manner as to have a flat bottom. The key pocket  272   a  is brought into contact with a corresponding surface (not illustrated) of the container body  100 , thereby preventing the rotation of the body  270 . 
     As illustrated, the key pocket  272   a  is formed to a shape of a flat groove that is open at the bottom. It is desirable that key pockets  272   a  are formed in a pair in such a manner as to be symmetrical in the leftward-rightward direction. Therefore, the body  270  is held in place in a state where a portion of the bottom surface of the container body  100  is inserted into the key pocket  272   a  from bottom to top. 
     As illustrated, a protrusion portion  274  is formed on the upper surface of the seating portion  272 . Then, the protrusion portion  274  is formed in such a manner that a lower end portion thereof has a greater external diameter than the seating portion  272 . 
     Therefore, when the body  270  is mounted on the bottom surface of the container body  100 , the external diameter of the lower end portion of the protrusion portion  274  is greater than an internal diameter of a body insertion hole (not illustrated) that is formed on the bottom surface of the container body  100  in a manner that passes through the bottom surface thereof from top to bottom. The protrusion portion  274  is exposed in a manner that protrudes upward from a bottom surface of in the inner container body  100 . 
     As illustrated, it is desirable that the protrusion portion  274  is tapered to the top, and thus an external diameter thereof gradually decreases in the upward direction. 
     The blade shaft  260  is formed in such a manner as to have a predetermined length in the upward-downward direction and is mounted in such a manner as to pass through an internal center portion of the body  270 . 
     Then, the blade shaft  260  is rotatably mounted inside the body  270 . Therefore, although not illustrated, it is desirable that a bearing is mounted inside the body  270 . The bearing allows the blade shaft  260  to be rotated in a state of being inserted. 
     A connection portion  262  is provided on a lower end portion of the blade shaft  260 . The connection portion  262  moves in conjunction with the motor assembly  600 , and thus serves to transfer the rotational force generated by the motor assembly  600 . 
     As illustrated, it is desirable that the connection portion  262  is configured as a spline shaft having a cross section in a concave-convex shape. Therefore, although not illustrated, it is desirable that a corresponding spline boss is provided on an upper-end connection portion of the motor assembly  600  that is combined with the connection portion  262 . 
     The fastening plate  264  and a fastening shank  266  are provided on an upper end of the blade shaft  260 . The main blade  250  and the auxiliary blade  252  are mounted on the fastening plate  264 . The fixation cap  280  is fastened to the fastening shank  266 . 
     Specifically, the fastening shank  266  with which the fixation cap  280  is to be combined is formed on the upper end of the blade shaft  260 . The fastening plate  264  is provided underneath the fastening shank  266 . 
     As illustrated, it is desirable that the fastening plate  264  is formed in such a manner as to have a smaller external diameter than the blade shaft  260  accommodated in body  270 . 
     Therefore, the main blade  250  and the auxiliary blade  252  no longer moves down in a state of being mounted on the fastening plate  264 . Thus, the main blade  250  and the auxiliary blade may be rotated without respective bottom surfaces thereof interfering with an upper surface of the body  270 . 
     The main blade  250  and the auxiliary blade  252 , along with the blade shaft  260 , are rotated in a state of being mounted on the fastening plate  264 . 
     Therefore, it is desirable that an external surface of the fastening plate  264  has a shape corresponding to an internal diameter of the fastening hole  254 . That is, the fastening hole  254  formed in the main blade  250  and the auxiliary blade  252  has a four-square cross section. Thus, when the external surface of the fastening plate  264  has a size and a shape corresponding to a size and a shape of the fastening hole  254 , the main blade  250  and the auxiliary blade  252 , along with the blade shaft  260 , are rotatable in a state of being mounted on the fastening plate  264  without a separate fixation mechanism. 
     In this manner, it is desirable that a flat cross-section of the fastening plate  264  has a four-square shape corresponding to a shape of the fastening hole  254 . The fastening plate  264  needs to have an external surface that is smaller than an internal surface of the fastening hole  254  in such a manner that the fastening plate  264  is accommodated in the fastening hole  254 . The fastening plate  264  needs to be formed in such a manner that a length of a diagonal of the flat cross-section thereof is greater than a distance between surfaces facing each other in the fastening hole  254 . Thus, the main blade  250  and the auxiliary blade  252  are not allowed to be rotated in a state of being fastened to the fastening plate  264 . 
     The fixation cap  280  is fastened to the upper end of the blade shaft  260 . The main blade  250  and the auxiliary blade  252  are mounted on the blade shaft  260 , and thus are kept held in place without deviating upward. 
     The fixation cap  280  is configured to include a nut portion  282 , a cap portion  284 , and the like. The nut portion  282  is combined with the fastening shank  266 . The cap portion  284  protrudes upward from an upper surface of the nut portion  282  in a manner that has the shape of a dome. 
     It is desirable that the fixation cap  280  is fastened by a bolt-nut mechanism to the fastening shank  266 . The nut portion  282  is tapped, and the fastening shank  266  is threaded. 
     The cap portion  284  is formed to a shape of a dome that is a hemispherical roof. The cap portion  284  is formed integrally with the nut portion  282 . The cap portion  284  may serve to prevent the food or foreign material from permeating into a hole underneath the cap portion  284  that is formed on the center portion of the nut portion  282  and may serve to guide sliding of the food without coming into contact with an upper surface thereof and being fixed to the upper surface. 
       FIGS. 16 to 34  are views each illustrating a configuration of the blade that constitutes the blade assembly  200 .  FIGS. 16 to 19  each illustrate a configuration of a first implementation example of the main blade  250  that constitutes the blade assembly  200 .  FIGS. 20 to 23  illustrate a configuration of a second implementation example thereof.  FIGS. 24 to 26  illustrate a configuration of a third implementation example thereof.  FIGS. 27 to 30  illustrate a configuration of a fourth implementation example thereof.  FIGS. 31 to 34  illustrate a configuration of a fifth implementation example thereof. The configurations of the five implementation examples of the main blade  250  described below may also be applied to the auxiliary blade  252 . 
     First, a configuration of a first implementation example of the blade that constitutes the blade assembly  200  is described with reference to  FIGS. 16 to 19 .  FIG. 16  is a perspective view illustrating the configuration of the first implementation example of the blade that constitutes the blade assembly  200 , when viewed from above.  FIG. 17  is a perspective view illustrating the configuration of the first implementation example of the blade that constitutes the blade assembly  200 , when viewed from below.  FIG. 18  is a front view illustrating the first implementation example of the blade.  FIG. 19  is a cross-sectional view taken along line A-A on  FIG. 16 . 
       FIGS. 16 to 34  each illustrate the implementation example of the main blade  250  of the main and auxiliary blades  250  and  252 . Therefore, a description will be described below, taking as an example a configuration of the main blade  250 . The auxiliary blade  252  may have the same configuration as the main blade  250 , or may have a different configuration than the main blade  250 . 
     A component of the main blade  250  that is the same as described above, when performing the same function, is given the same reference character as assigned above, and detailed descriptions of a configuration and a function of the component are omitted for convenience of description. 
     As described above, the main blade  250  is configured to include the main fixation portion  250   a,  the plurality of blade portions  250   b,  and the like. The main fixation portion  250   a  is combined with the blade shaft  260 . The plurality of blade portions  250   b  are formed in a manner that protrudes outward from the main fixation portion  250   a.    
     Four main blade portions  250   b  are formed in a manner that protrude radially from the main fixation portion  250   a.  The four main blade portions  250   b are symmetrically formed in such a manner as to be equiangular with respect to the center of the main fixation portion  250   a.  That is, the four main blade portions  250   b  are formed integrally into one piece in a manner that protrudes outward from the main fixation portion  250   a.    
     According to the present disclosure, a case is illustrated where the four main blade portions  250   b  are provided. The main blade portion  250   b  may be formed in such a manner as to lie in the same plane with the main fixation portion  250   a  or to have a predetermined angle. 
     As a specific example, as illustrated, among the total four main blade portions  25   b,  two main blade portions  250   b  in the leftward-rightward direction are formed in such a manner as to extend upward at predetermined inclined angles α and β, respectively, with respect to the main fixation portion  250   a,  and two main blade portions  250   b  in the forward-backward direction extend downward at predetermined inclined angles from the front and rear ends, respectively, of the main fixation portion  250   a.    
     In addition to this configuration, one or more of the main blade portions  250   b  may be formed in such a manner as to extend sideways in the same plane in order to be in parallel with the main fixation portion  250   a.    
     In addition, the main blade portion  250   b  may be configured in such a manner as to be symmetrical in the forward-backward direction or the leftward-rightward direction about the main fixation portion  250   a.  However, it is also possible that the main blade portion  250   b  is configured in such a manner as not to be symmetrical in the forward-backward direction or the leftward-rightward direction about the main fixation portion  250   a.    
     For example, it is possible that two main blade portions  250   b  are all formed on the left and right sides, respectively, of the main fixation portion  250   a  in such a manner as to extend horizontally or to extend at predetermined inclined angles in the upward-downward direction. In addition, it is also possible that two main blade portions  250   b  are formed on the left and right sides, respectively, of the main fixation portion  250   a  in such a manner as to extend in opposite directions at predetermined inclined angles. That is, it is also possible that one main blade portion  250   b  of a pair of main blade portions  250   b  is formed on the left side of the main fixation portion  250   a  in a manner as to extend downward at a predetermined inclined angle and that the other main blade portion  250   b  is formed on the right side of the main fixation portion  250   a  in a manner as to extend upward at a predetermined inclined angle. 
     In a case where the pair of main blade portions  250   b  that are formed on the left and right sides, respectively, of the main fixation portions  250   a  both extend upward or downward at a predetermined inclined angle, it is also possible that the pair of main blade portions  250   b  are formed in such a manner as to expend upward or downward at different inclined angles. That is, with reference to  FIG. 18 , as an example, an angle α that a main blade portion  250   b ′ formed on the left side of the main fixation portion  250   a  and the main fixation portion  250   a  make with each other may be set to be different from an angle β that a main blade portion  250   b ″ formed on the right side of the main fixation portion  250   a and the main fixation portion  250   a  make with each other. 
     Furthermore, it is also possible that the two main blade portions  250   b  formed on the left side of the main fixation portion  250   a  and the two main blade portions  250   b  formed on the right side of the main fixation portion  250   a  are all formed in such a manner as to expand horizontally or in such a manner as to expand at four different inclined angles or in four different directions. 
     In this manner, when the main blade portion  250   b  is configured to expand at various inclined angles in this manner, this configuration is effective in expanding an area where food is chopped into small pieces by the main blade portion  250   b,  and thus the efficiency of chopping the food into small pieces can be improved. 
     It is desirable that at least one end portion of the main blade  250  is formed in such a manner as to have a smaller thickness than a center portion thereof. That is, the main blade  250  or the auxiliary blade  252  is formed in such a manner that the thickness of the blade  250  gradually decreases going toward one end thereof. 
     As illustrated in the drawings, a leading edge and a rear edge of the main blade  250  are formed in such a manner that the thickness of the main blade  250  gradually decreases going toward respective ends (in the forward direction and the backward direction) of the leading edge and the rear edge. 
     For convenience of description, the leading edge of the main blade  250  is hereinafter referred to as an edge (leading edge) that serves as a blade edge. The rear edge of the main blade  250  is defined as meaning an edge on the other side of the main blade  250  from the blade edge. That is, in  FIG. 16 , when the main blade  250  is rotated clockwise (when viewed from above) as indicated by an arrow, a blade edge that chops food into small pieces is referred to as a leading edge, and an edge on the opposite side of the main blade  250  from the blade edge, the edge not in use for chopping the food into small pieces, is referred to as a rear edge. In this case, in  FIG. 19 , a left end portion is the leading edge of the main blade  250 , and a right end portion thereof is the rear edge of the main blade  250 . 
     In this manner, in the present implementation example, at least one surface of each of the main and auxiliary blades  250  and  252  is an inclined surface  250   c  or  250   c ′ so that the thickness of the main blade  250  gradually decreases going toward an end of the inclined surface  250   c  or  250   c ′. That is, it is desirable that the inclined surface  250   c  or  250   c ′ is formed at at least one of the leading edge and the rear edge of the main blade portion  250   b  of the main blade  250 . 
     More specifically, the inclined surface  250   c  or  250   c ′ is formed at an upper surface or a lower surface of the main blade portion  250   b  of the main blade so that the thickness of the main blade  250  gradually decreases going toward an end of the leading edge or the rear edge. That is, the inclined surface  250   c  or  250 ′ is formed at an upper-surface or lower-surface end portion of the main blade portion  250   b  of the main blade  250  so that the thickness of the main blade  250  gradually decreases going toward an end of the upper-surface or lower-surface end portion. 
     In the present implementation example, in the drawings, a case is illustrated where the inclined surfaces  250   c  and  250 ′ are formed at the leading edge and the rear edge, respectively, of the main blade  250 . That is, the downward inclined surface  250   c  is formed at a rear edge of the upper surface of the main blade portion  250   b  of the main blade  250  in a manner that the height of the main blade  250  gradually decreases going toward an end (end of the rear edge) of the upper surface. The upward inclined surface  250   c ′ is formed at a leading edge of a lower surface of the main blade portion  250   b  of the main blade  250  in such a manner that the height of the main blade  250  is gradually increased going toward an end (end of the leading edge) of the lower surface. 
     The inclined surfaces  250   c  and  250   c ′ serve to facilitate chopping of the food and also serve to reduce a vortex generated by the food and fluid. That is, when the leading edge of the main blade portion  250   b  of the main blade  250  has the inclined surface  250   c,  the blade edge is sharp, and thus easily chops the food into small pieces. The vortex is much more prevented or reduced when the rear edge of the main blade portion  250   b  has the inclined surface  250   c ′ than when the rear edge of the main blade portion  250   b  has a vertical surface. Accordingly, resistance is reduced, and thus, the load on the motor assembly  600  is reduced. 
     In addition, the main blade portion  250   b  of the main blade  250  is obliquely formed so that a leading edge portion is formed in such a manner as to have a greater height than a rear edge portion. That is, as illustrated in  FIG. 19 , the main blade portion  250   b  of the main blade  250  is formed in such a manner that a height of the leading edge (left end portion in  FIG. 19 ) thereof is greater by a predetermined angle γ than a height of the rear edge (right end portion in  FIG. 19 ) thereof. 
     In this manner, when the main blade portion  250   b  of the main blade  250  is formed in such a manner that the height of the leading edge thereof is greater by the predetermined angle γ than the height of the rear end portion thereof, this structure is effective in the downward pushing of the food by the main blade portion  250   b.  Thus, chopping and moving of the food occur at the same time, and thus the mixing of the food is facilitated. 
       FIGS. 20 to 23  each illustrate a configuration of a second implementation example of the main blade  250 .  FIG. 20  is a plane view illustrating the configuration of the second implementation example of the main blade  250 .  FIG. 21  is a perspective view illustrating the configuration of the second implementation example of the main blade  250  when viewed from above.  FIG. 22  is a perspective view illustrating the second implementation example of the main blade  250  when viewed from below.  FIG. 23  is a front view illustrating the second implementation example of the main blade  250 . 
     As illustrated in  FIGS. 20 to 23 , a concave-convex portion is formed on the leading edge or the rear edge of the main blade  250 . The concave-convex portion is formed on the leading edge or the rear edge of the main blade portion  250   b  of the main blade  250 . The concave-convex portion may be formed on the inclined surfaces  250   c  and  250   c′.    
     In the present implementation example, a case is illustrated where the concave-convex portion is formed on the leading edge of the main blade portion  250   b  of the main blade  250 . 
     In this manner, when the concave-convex portion is formed on the leading edge of the main blade portion  250   b  of the main blade  250 , an area of the blade edge with which the food comes into contact is increased, and thus, the efficiency of chopping the food into small pieces is improved. 
     The concave-convex portion may be formed on the leading edge of the main blade portion  250   b  of the main blade  250  in such a manner as to be rounded with a radius of curvature. That is, as illustrated, the concave-convex portion is formed on the main blade portion  250   b  of the main blade  250  in such a manner as to have a convex part and a concave groove that are both semi-circular (when viewed from above). 
     Therefore, when the main blade portion  250   b  of the main blade  250  is rotated, this structure is effective in temporarily trapping the food inside the container body  100  in the concave groove of the concave-convex shape and chopping the trapped food into small pieces. Thus, the efficiency of chopping the food into small pieces is improved. 
     The concave-convex portion may be formed on the rear edge of the main blade portion  250   b  of the main blade  250 . This structure is effective in reducing noise that is generated when the main blade portion  250   b  of the main blade  250  is rotated. That is, the noise is trapped in troughs (concave grooves) in the plurality of concave-convex portions without being spread out to the outside. Furthermore, the wavelengths of the noise generated in the troughs (concave grooves) cancel each other out due to phase differences. Thus, the effect of reducing the noise is achieved. 
       FIGS. 24 to 26  each illustrate a configuration of a third implementation example of the main blade  250 .  FIG. 24  is a perspective view illustrating the third implementation example of the main blade  250  when viewed above.  FIG. 25  is a perspective view illustrating the third implementation example of the main blade  250  when viewed below.  FIG. 26  is a front view illustrating the third implementation example of the main blade  250 . 
     As illustrated in  FIGS. 24 to 26 , the concave-convex portion may be formed on both the leading edge and the rear edge of the main blade  250 . The concave-convex portion is formed on each of the leading edge and the rear edge of the main blade portion  250   b  of the main blade  250 . The concave-convex surface may be formed on the inclined surfaces  250   c  and  250   c′.    
     As described above, the concave-convex portion may be formed on the main blade portion  250   b  of the main blade  250  in manner as to be rounded with a radius of curvature or to have a sawtooth shape. 
     Specifically, as illustrated, the concave-convex portion is formed on the leading edge of the main blade portion  250   b  of the main blade  250  in such a manner as to be rounded with a radius of curvature, and the concave-convex portion is formed on the rear edge of the main blade portion  250   b  of the main blade  250  in such a manner as to have the sawtooth shape. 
     Therefore, as described above, in this case, the concave-convex portion on the leading edge of the main blade portion  250   b  of the main blade  250  also achieves the effect of increasing the area of the blade edge that comes into contact with the food, thereby improving the efficiency of chopping the food into small pieces. Furthermore, the concave-convex portion in the sawtooth shape that is formed on the rear edge of the main blade portion  250   b  of the main blade  250  achieves the effect of reducing the noise because the wavelengths of the noise generated when the main blade portion  250   b  is rotated cancel each other out due to the phase differences. 
     In addition, as described, although a pair of the main blade portions  250   b  are both formed on the left and right sides, respectively, of the main fixation portion  250   a  in such a manner as to extend upward or downward at predetermined inclined angles, the predetermined inclined angles may be set to be the same or to be different from each other. As illustrated in  FIG. 26 , an angle α that the main blade portion  250   b ′ formed on the left side of the main fixation portion  250   a  and the main fixation portion  250   a  make with each other may be set to be the same as or different from an angle β that the main blade portion  250   b ″ formed on the right side of the main fixation portion  250   a  and the main fixation portion  250   a  make with each other. 
       FIGS. 27 to 30  each illustrate a configuration of a fourth implementation example of the main blade  250 .  FIG. 27  is a perspective view illustrating the configuration of the fourth implementation example of the main blade  250  when viewed from above.  FIG. 28  is a perspective view illustrating the configuration of the fourth implementation example of the main blade  250  when viewed from below.  FIG. 29  is a front view illustrating the fourth implementation example of the main blade  250 .  FIG. 30  is a perspective view illustrating the fourth implementation example of the main blade  250  when viewed from above at an angle different from an angle from which the fourth implementation example is viewed in  FIG. 27 . 
     As illustrated in  FIGS. 27 to 30 , the main blade  250  is formed in such a manner that at least one portion of the upper surface or the lower surface thereof has the concave-convex shape. That is, the concave-convex portion may also be formed on the upper surface or the lower surface of the main blade portion  250   b  of the main blade  250 . 
     In the present implementation example, a case is illustrated where the concave-convex portion is formed on the upper surface of the main blade portion  250   b  of the main blade  250 . Of course, in a case where the concave-convex portion is formed on the upper surface or the lower surface of the main blade portion  250   b  of the main blade  250 , the concave-convex portion may also be formed on the leading edge and the rear edge of the main blade portion  250   b.    
     It is desirable that the concave-convex portion formed on the main and auxiliary blades  250  and  252  has a shape corresponding to the shape of owl wings. That is, it is desirable that the concave-convex portion formed on the upper surface or the lower surface of the main blade portion  250   b  of the main blade  250  has the shape of owl wings. 
     As illustrated, in the present implementation example, a peak that protrudes upward and a trough that is cut downward are alternately formed on the upper surface of the main blade portion  250   b  of the main blade  250 . It is desirable that the peak and the trough are rounded with a radius of curvature. 
     In a case where, in this manner, the concave-convex portion in the shape of owl wings is formed on the upper surface of the main blade portion  250   b  of the main blade  250 , as described above, the inclined surfaces  250   c ′ and  250   c  may also be further formed at the leading edge and the rear edge, respectively, of the main blade portion  250   b,  and the concave-convex portion may also be further formed on the leading edge and the rear edge thereof. 
     In addition, the concave-convex portion may be formed on both the upper surface of the main blade portion  250   b  and the lower surface of the main blade portion  250   b.  As described above, the concave-convex portion may be formed on an upper surface or a lower surface of the auxiliary blade portion  252   b  of the auxiliary blade  252 . 
     In this manner, when the concave-convex portion, such as one in the shape of owl wings, is formed on the upper surface or the lower surface of the main blade  250  or the auxiliary blade  252 , the effect of considerably reducing the noise can be achieved. That is, when a plurality of concave-convex portions, such as ones in the shape of owl wings, is formed on the main blade portion  250   b  of the main blade  250  or on the auxiliary blade portion  252   b  of the auxiliary blade  252  in such a manner as to be equally spaced, the plurality of concave-convex portions serve as common rotational vortex generators. Thus, the flow of fluid along the upper surface and the lower surface is stabilized, and the flow separation is prevented. 
     In this manner, the concave-convex portions, such as ones in the shape of owl wings, that are formed on the upper surface of the main blade portion  250   b  of the main blade  250  in such a manner as to be equally spaced generate vortexes in common flows. Thus, the flow is stabilized, and this stabilized flow continues until reaching the rear edge of the main blade portion  250   b.  Accordingly, the noise due to the vortex occurring at the rear edge thereof is reduced. That is, the vortex layers are connected to each other due to the vortex in common flows, and at the same time, a thickness of the layers is decreased. Thus, the effect of reducing the noise occurring at the rear edge is achieved. 
     When the concave-convex portions in the shape of owl wings are formed on the upper surface or the lower surface of the main blade portion  250   b  of the main blade  250  in such a manner as to be equally spaced, the noise generated between the troughs is trapped without being transmitted to the outside, and, at the same time, the wavelengths of the noise generated in each of the troughs cancel each other out due to the phase differences. Accordingly, the effect of reducing the noise is achieved. 
     Actually, an owl flies silently with its wings being spread out because an overall elliptical shape of owl wings causes wavelengths of noise generated in flight to cancel each other out. Contribution of the shape of owl wings to silent flight is technically explained in the related research paper and the like. Thus, more detailed theoretical description thereof is omitted. 
     In a case where the concave-convex portion is formed on the upper surface or the lower surface of the main blade portion  250   b  of the main blade  250  or on the auxiliary blade portion  252   b  of the auxiliary blade  252 , as described above, it is also possible that the concave-convex portion is formed on the leading edge or the rear edge of the main blade portion  250   b  or of the auxiliary blade portion  252   b.    
     In this case, it is desirable that the same concave-convex portions are formed on the upper and lower surfaces or the leading and rear edges of the main blade portion  250   b  or the auxiliary blade portion  252   b  in such a manner as to be connected to each other. That is, it is desirable that convex parts of the concave-convex portions formed on the upper and lower surfaces of the main blade portion  250   b  or the auxiliary blade portion  252   b  are formed in such a manner as to be the same as convex parts of the concave-convex portions formed on the leading and rear edges of the main blade portion  250   b  or the auxiliary blade portion  252   b.  Furthermore, it is desirable that the concave parts of the concave-convex portions formed on the upper and lower surfaces of the main blade portion  250   b  or the auxiliary blade portion  252   b  are formed in such a manner as to be the same as concave parts of the concave-convex portions formed on the leading and rear edges of the main blade portion  250   b  or the auxiliary blade portion  252   b.    
     When in this manner, the concave-convex portions on the upper and lower surfaces of the main blade portion  250   b  or the auxiliary blade portion  252   b  are the same as the concave-convex portions on the leading and rear edges thereof, and thus, the flow of the fluid or the food as a whole is stabilized, and the resistance to the main and auxiliary blades  250  and  252  is reduced. Accordingly, the effect of reducing an amount of load on the motor assembly  600  and the like can also be expected. 
       FIGS. 31 to 34  each illustrate a configuration of a fifth implementation example of the main blade  250 .  FIG. 31  is a perspective view illustrating the configuration of the fifth implementation example of the main blade  250  when viewed from above.  FIG. 32  is a perspective view illustrating the configuration of the fifth implementation example of the main blade  250  when viewed from below. FIG. is a front view illustrating the fifth implementation example of the main blade  250 .  FIG. 34  is a perspective view illustrating the fifth implementation example of the main blade  250  when viewed from above at an angle different from an angle from which the fifth implementation example is viewed in  FIG. 31 . 
     In the present implementation example, a case is illustrated where, in addition to being formed on the upper surface or the lower surface of each of the main and auxiliary blades  250  and  252 , the concave-convex portion is formed on both the leading edge and the rear edge of each of the main and auxiliary blades  250  and  252 . 
     In the case where in this manner, the concave-convex portion is formed on the upper surface or the lower surface of the main blade portion  250   b  of the main blade  250  or the auxiliary blade portion  252   b  of the auxiliary blade  252 , the concave-convex portion may also be formed on both the leading edge and the rear edge of the main blade portion  250   b  or the auxiliary blade portion  252   b.    
     More specifically, in the present implementation example, the following case is illustrated. The concave-convex portion, such as one in the shape of owl wings, is formed on the upper surface of the main blade portion  250   b  of the main blade  250 , and the concave-convex portion rounded with a radius of curvature corresponding to the shape of owl wings is formed on the leading edge of the main blade portion  250   b  of the main blade  250 . In addition, the concave-convex portion, such as one in the sawtooth shape, is formed on the rear edge of the main blade portion  250   b  of the main blade  250 . 
     In this case, it is desirable that concave-convex portions are formed on the upper surface, the leading edge, and the rear edge, respectively, of the main blade portion  250   b  in such a manner as to have the same concave part and the same convex part. That is, it is desirable that the concave-convex portion in the shape of owl wings formed on the upper surface of the main blade portion  250   b,  the concave-convex portion on the leading edge of the main blade portion  250   b,  and the concave-convex portion in the sawtooth shape formed on the rear edge of the main blade portion  250   b  have the same pitch. 
     Accordingly, the flow of the food and the fluid through the concave part and the convex part is much more facilitated, and all the wavelengths of the noise cancel each other out at the same time. Thus, the effect of reducing the noise is achieved. 
     When in this manner, the concave-convex portion is formed on each of the upper surface, the leading edge, and the rear edge of the main blade portion  250   b,  it is possible that all the effects described above are achieved. That is, the effect of reducing the noise and other effects can be achieved by the concave-convex portions on the upper surface and the rear edge of the main blade portion  250   b.  The effect of improving the performance of chopping the food into small pieces and other effects can be achieved by the concave-convex portion on the leading edge of the main blade portion  250   b.    
     In addition, as described above, the inclination and the like of the main blade portion  250   b  can enable the food to flow. 
     Operation of the blender according to the present disclosure that has the configuration as described above will be described below with reference to the accompanying drawings. 
     The container body  100  is seated on the main body  500  as illustrated in  FIG. 1 . In this state, the blender according to the present disclosure is ready for use. 
     First, electric power needs to be supplied from the outside in order to use the blender. It is also possible that the wireless electric power module  520  supplies the electric power in a wireless manner. That is, it is possible that the electric power is supplied from the outside using an induced electromotive force. Of course, it is also possible that the electric power is supplied in a wired manner. 
     The wireless electric power module  520  supplies the electric power to components, such as the motor assembly  600 , the touch operation unit  504 , and the electric power transmission unit  700 , that need the electric power for operating. The user may operate the blender or may stop the blender by operating the touch operation unit  504  or the knob  502 . 
     For example, when the user operates the touch operation unit  504  or the knob  502 , the motor assembly  600  operates, the blades of the blade assembly  200  are rotated, and then food is chopped into small pieces. 
     At this time, the detection system determines whether or not the container lid  400  is attached. In a case where the container lid  400  is not attached, the motor assembly  600  and the blade assembly  200  do not operate. 
     Specifically, the reed switch  234  is turned off when the blender is not in use. Therefore, the electric power reception unit  220 , the reed switch  234 , the optical transmission module  810 , and the like do not form a closed circuit within the container body  100 , and thus light reception does not occur in the optical reception module  820 . 
     In this manner, when the light reception does not occur in the optical reception module  820 , with no signal representing the non-occurrence of the light reception, the motor assembly  600  is blocked from receiving electric power. 
     When the container lid  400  is attached in this state, the permanent magnet  232  of the container lid  400  is positioned in proximity to the reed switch  234 , and thus the reed switch  234  is turned on. In return, the electric power reception unit  220 , the reed switch  234 , the optical transmission module  810 , and the like form the closed circuit. Accordingly, the optical reception module  820  receives light that occurs in the optical transmission module  810 . 
     Thus, when it is detected that the container lid  400  is attached, the motor assembly  600  starts to operate according to the user&#39;s operation. The food inside the container body  100  is chopped into small pieces. Of course, at this time, it is desirable that the container body detection switch  960  or the like also detects whether or not the container body  100  is mounted on the main body  500  and thus that the motor assembly  600  starts to operate. 
     At this time, an operating state of the blender according to the present disclosure is displayed on the display unit  506  or the like for being viewed from the outside. Thus, the user may visually recognize the operating state, operation time, and the like of the blender. 
     When attaching or detaching the container lid  400  on and from the container body  100 , the user attaches or detaches the container lid  400  while holding an upper portion of the cap  450  with their hand. The user presses the container lid  400  in a direction of motion from upward to downward, and thus the container lid  400  is brought into contact with the upper surface of the container body  100  and thus is fixed thereto. At this time, the gasket  402  provided on an external surface of the container lid  400  bridges a gap between the container lid  400  and the container body  100 . 
     When with the operation of each of the motor assembly  600  and the blade assembly  200 , an operation of chopping food inside the container body  100  into small pieces or an operation of mixing food inside the container body  100  is finished according to the user&#39;s intention, the user may lift the container body  100  upward from the main body  500  for being separated therefrom and then may detach the container lid  400  to take the food out of the container body  100 . 
     In addition, the user may separate the cap  450  mounted on the center portion of the container lid  400  from the center portion thereof. The user may perform this separation operation by rotating the cap  450  and thus moving the cap  450  upward while holding the upper end portion thereof with their hand. 
     When the cap  450  is separated from the container lid body  410 , the user may place food into the container body  100  through the cover hole  401  or may stir food inside the container body  100  using a tamper or the like. 
     The blade edge of the blade assembly  200  is configured to include the main blade  250  and the auxiliary blade  252 . With this configuration, it is easier to chop food into small pieces and to mix the food. 
     As described above,  FIGS. 16 to 34  illustrate various configurations of the main blade  250 . As described above, with the shape of each of the main and auxiliary blades  250  and  252 , the performance of chopping the food into small pieces is improved, and the effect of reducing the noise is achieved. 
     The present disclosure is not limited to the embodiments described above. It would be apparent to a person of ordinary skill in the art that various modifications will be made to the embodiments of the present disclosure without departing the scope of the present disclosure.