Patent Publication Number: US-2023148743-A1

Title: Toothbrush

Description:
TECHNICAL FIELD 
     The present invention relates to a toothbrush for removing stains such as dental plaque attached to a tooth by using a brush section that is a handle end in which bristles are implanted. 
     BACKGROUND ART 
     Generally, a toothbrush is composed of a handle formed longitudinally so as to be grasped tightly and a brush section that is an end of the handle in which bristles are implanted. By grasping and moving the handle, a tip of the brush section formed on the end of the handle hits a tooth to remove stains such as dental plaque attached to the tooth. 
     In recent years, there has been a problem on how to efficiently remove stains not only on a surface of a tooth, but also between teeth (namely, in an interdental gap), on a boundary between a tooth and gums and in a dental groove. A type of toothbrush is available to address this problem. Namely, the configuration of the brush section thereof is devised so that the brush section efficiently enters between the teeth and into other parts. For example, the toothbrush disclosed in patent document 1 is configured so that the brush section is formed in a chevron shape in whole when viewed from the lateral side of the toothbrush. In other words, the brush section is cut so as to be gradually inclined upwardly toward the center of the brush section. Thus, compared to the case that the surface of the brush section is cut in a planar shape, a top part of the chevron-shaped brush section is easier to enter into an interdental gap and a gap between a tooth and gums (so-called “periodontal pocket”) and a dental groove. 
     However, even if the tip of the brush section formed in the chevron shape in whole such as the toothbrush disclosed in patent document 1, this type of toothbrush might not be able to effectively remove dental plaque on the surface of the tooth, in the interdental groove and in the gap between the tooth and the gums. 
     RELATED ART DOCUMENTS 
     Patent Documents 
     
         
         [Patent Document 1] Japanese Patent Application Publication No. 2012-075725 
       
    
     DISCLOSURE OF INVENTION 
     Problems to be Solved by the Invention 
     The present invention was made in view of an above-mentioned point, and the purpose is to provide a toothbrush that can more effectively clean an interdental gap, a gap between a tooth and gums, a dental groove and a surface of the tooth and the gums by brushing for a short time and with light force. 
     Means of Solving the Problems 
     The present invention to solve the above-mentioned problem has in one embodiment, a longitudinal handle ( 11 ), a bristle implanting section ( 12 ) having a bristle implanting surface ( 12   a ) formed at a tip of the handle ( 11 ) and a brush section ( 20 ) configured to include a plurality of bristle bundles ( 22 ,  23   a,    23   b ) composed of a large number of bristles implanted on the bristle implanting surface ( 12   a ). In a toothbrush ( 1 ) for cleaning teeth by using the brush section ( 20 ), the bristle implanting section ( 12 ) is formed in a shape of an ellipse having the major axis direction (P) and the minor axis direction (Q) when viewing the bristle implanting surface ( 12   a ) from a side of tip parts ( 22 T,  23   a T,  23   b T) of the bristle bundles ( 22 ,  23   a,    23   b ). The brush section ( 20 ) has the bristle bundles ( 22 ,  23   a,    23   b ) including a plurality of center bristle bundles ( 22 ) arranged along the major axis direction (P) at the center of the ellipse in the minor axis direction (Q) and side bristle bundles ( 23   a,    23   b ) arranged on both outer sides of the plurality of center bristle bundles ( 22 ) in the minor axis direction (Q). At least, the center bristle bundles ( 22 ) are characteristically formed in a chevron shape so as to be gradually inclined upwardly from both sides toward the center of the ellipse in the major axis direction (P). In addition, in this case, the bristle implanting section ( 12 ) may be formed in an elliptical shape of which the major axis direction (P) corresponds to the longitudinal direction of the handle ( 11 ). 
     In another embodiment, the present invention has the longitudinal handle ( 11 ), the bristle implanting section ( 12 ) having the bristle implanting surface ( 12   a ) formed at the tip of the handle ( 11 ) and the brush section ( 20 ) configured to include the plurality of bristle bundles ( 21 ,  22 ,  23   a,    23   b ) composed of a large number of bristles implanted on the bristle implanting surface ( 12   a ). In a toothbrush ( 1 - 2 ) for cleaning teeth by using the brush section ( 20 ), the bristle implanting section ( 12 ) is formed in the shape of the ellipse having the major axis direction (P) and the minor axis direction (Q) when viewing the bristle implanting surface ( 12   a ) from the side of the tip parts ( 21 T,  22 T,  23   a T,  23   b T) of the bristle bundles ( 21 ,  22 ,  23   a,    23   b ). The brush section ( 20 ) has the bristle bundles ( 21 ,  22 ,  23   a,    23   b ) including a top bristle bundle ( 21 ) that is positioned at the center of the ellipse in the major axis direction (P) and in the minor axis direction (Q) and the highest of a plurality of the bristle bundles ( 21 ,  22 ,  23   a,    23   b ), a plurality of center bristle bundles ( 22 ) arranged on both sides of the top bristle bundle ( 21 ) along the major axis direction (P), and a plurality of side bristle bundles ( 23   a,    23   b ) arranged on both sides of the plurality of the center bristle bundles ( 22 ) in the minor axis direction (Q). At least, the plurality of the center bristle bundles ( 22 ) are characteristically formed in the chevron shape so as to be gradually inclined upwardly from both ends toward the top bristle bundle ( 21 ) in the major axis direction (P). A tip part ( 21 T) of the top bristle bundle ( 21 ) is characteristically at a position that is higher than an intersecting point (X) of ridgelines (R) formed by connecting tip parts ( 22 T) of the plurality of the center bristle bundles ( 22 ). In addition, in this case also, the bristle implanting section ( 12 ) may be formed in an elliptical shape of which the major axis direction (P) corresponds to the longitudinal direction of the handle ( 11 ). 
     In the toothbrush of the above-described configuration in accordance with the present invention, as the bristle implanting surface of the bristle implanting section is formed in the shape of the ellipse having the major and minor axis directions when viewed from the tip part side of the bristle bundles, the bristles of the brush section (namely, bristle bundles) are arranged in a curved line along the outer periphery of the ellipse. Accordingly, compared to a bristle implanting section formed into a rectangle shape, the bristle implanting section of the present invention can prevent an edge part of the bristle implanting section (namely, the tip of the handle) and the bristle bundles on the outer peripheral side of the brush section from interfering parts in the mouth (such as teeth, gums and an inner surface of a cheek) needlessly. Therefore, a move of the brush section only with light force enables smooth and efficient brushing. Moreover, as the bristles (bristle bundles) of the brush section are arranged in the curved shape along the outer periphery of the ellipse, a stroke of the toothbrush enables the tip of the bristles (bristle bundles) to effectively touch (namely, slide to) an upper surface and a side surface of the tooth having a complex uneven shape and an interdental gap. Consequently, stains can be removed more efficiently from the dental groove and the interdental gap. Furthermore, compared to a bristle implanting section formed in a circular shape (perfect circular shape), the bristle implanting section of the present invention can secure a longer distance (linear dimension) of the brush section along the longitudinal direction of the handle, namely, the stroke direction of the toothbrush. Accordingly, a proportionally larger area contacting with the tooth can be secured in the brush section. This enables more effective removal of dental stains. The toothbrush of the present invention having the bristle implanting section formed in the above-described elliptical shape can thus provide the above-described multiple effects in combination and remove stains in the dental groove and the interdental gap efficiently. 
     In addition, in the toothbrush in accordance with the present invention, at least a part of the bristle bundles of the brush section are formed in the chevron shape so as to be gradually inclined upwardly toward the center of the above-described ellipse in the major axis direction. This enables the tip of the center bristle bundle at the highest position of the brush section to enter deeply into the gap between the tooth and the gums and the interdental gap without being interfered by the neighboring bristle bundles, and stains at a deeper position to be scraped securely as the plurality of the side bristle bundles support the center bristle bundles that have entered in the deeper position. 
     Moreover, as the bristle implanting section is formed in the elliptical shape and the side bristle bundles are arranged on both sides of the center bristle bundles (in the minor axis direction), the plurality of the side bristle bundles uniformly contact with the surface of the tooth and gums around the part that the center bristle bundle enters into. Furthermore, as far as the side bristle bundles are also formed in the chevron shape so as to be gradually inclined upwardly toward the center of the side bristle bundles, when lower ones of the bristle bundles on the further outer peripheral side abut to a tooth, higher ones of the side bundles on the center side can abut to a further inner tooth without interfering between the side bristle bundles. This enables the side bristle bundles to clean the surfaces of the teeth and the gums around the gaps and the grooves effectively. 
     Moreover, in the toothbrush ( 1 ,  1 - 2 ) of the above-described configuration in accordance with the present invention, the side bristle bundles ( 23 ) may include first side bristle bundles ( 23   a ) arranged on a side closer to the center bristle bundle ( 22 ) and second side bristle bundles ( 23   b ) arranged on a side farther from the center bristle bundle ( 22 ) in the minor axis direction (Q). Furthermore, in this case, it is desirable that the first side bristle bundles ( 23   a ) are higher than the neighboring second side bristle bundles ( 23   b ). According to this configuration, the shape of the brush section is formed so that the bristles (bristle bundles) gradually lower toward both sides of the ellipse from the center of the bristle implanting section in the minor axis direction. Therefore, as the tip of the first side bristle bundle ( 23   a ) at the higher position can enter into a deeper position in the gap (MG) between the tooth (T) and the gums (M) and the dental groove (TU) without being interfered by the neighboring bristle bundles, the stains at the deeper position can be scraped off. 
     Moreover, in the toothbrush including the above-described top bristle bundle ( 21 ) in accordance with the present invention, this top bristle bundle ( 21 ) should be configured to be higher than the center bristle bundles ( 22 ) and the side bristle bundles ( 23 ) that are arranged around the top bristle bundle ( 21 ). Thus, while the center bristle bundles ( 22 ) and the side bristle bundles ( 23 ), which are inclined in the chevron shape (pyramid shape), are cleaning the interdental gap and the surface of tooth (T) adjacent to the gap between the tooth and the gums, the tip part ( 21 T) of the top bristle bundle ( 21 ) enters deeply into the groove (TU) on the surface of the tooth (T), the interdental gap (TG) and the gap (MG) between the tooth (T) and the gums (M). Accordingly, the dental groove, the dental gap and the gap between the tooth and the gums can be cleaned more effectively by brushing for a short time and with light force. 
     Moreover, in the toothbrush in accordance with the present invention, the center bristle bundles ( 22 ) excluding the top bristle bundle ( 21 ) and the side bristle bundles ( 23 ) are formed to be inclined in the chevron shape (pyramid shape). Thus, compared to a toothbrush with a normal (conventional) planar tip, the center bristle bundles ( 22 ) and the side bristle bundles ( 23 ) can cleanse the surface of the tooth, the interdental gap and the dental groove more effectively. Further, if the tip part ( 21 T) of the top bristle bundle ( 21 ) is at a position that is higher than the intersecting point (X) of the ridgelines (R) formed by connecting the tip parts ( 22 T) of the plurality of the center bristle bundles ( 22 ), stains deeper in the dental groove, the interdental gap and the gap between the teeth and the gums can be scraped by the tip part ( 21 T) of the top bristle bundle ( 21 ). Therefore, these effects enable the toothbrush of the present invention to effectively remove stains in the whole oral cavity including the interdental gap and the gap between the tooth and the gums by brushing for a short time and with light force. It should be noted that the bracketed reference numerals are examples of the elements of the embodiment described later. 
     Effects of the Invention 
     The toothbrush in accordance with the present invention can provide the above-described effects as the bristle implanting section is formed so that the bristle implanting surface thereof is in the elliptical shape having the major and minor axis directions when viewed from the tip side of the bristle bundles. Therefore, the toothbrush can more effectively clean the interdental gap, the gap between the tooth and the gums and the dental groove, and the surface of the tooth and the gums by brushing for a short time and with light force. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a view illustrating a whole toothbrush in accordance with a first embodiment of the present invention; 
         FIG.  2    are enlarged views of a brush section of the toothbrush of the first embodiment, of which  FIG.  2 A  is a plan view,  FIG.  2 B  is a side view and  FIG.  2 C  is a front view; 
         FIG.  3    is a view illustrating a state of cleaning an interdental gap when viewing teeth from the above; 
         FIG.  4    is a view illustrating a state of cleaning a gap between a tooth and gums when viewing the tooth and the gums from sideways; and 
         FIG.  5    are enlarged views of a brush section of a toothbrush in accordance with a second embodiment, of which  FIG.  5 A  is a plan view,  FIG.  5 B  is a side view, and  FIG.  5 C  is a front view. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
     First Embodiment 
       FIG.  1    is a view illustrating a whole toothbrush in accordance with one embodiment of the present invention. The toothbrush has a main body including a longitudinal handle  11  ( 11 A,  11 B) and a bristle implanting section  12  having a bristle implanting surface  12   a  formed at a tip of the handle  11 , and a brush section  20  configured to include bristle bundles (namely, center bristle bundles  22  and side bristle bundles  23   a,    23   b ), which will be described later, composed of a number of bristles implanted on the bristle implanting surface  12   a.    
     The handle  11  has a gripper  11 A that a user grasps, a neck section  11 B with resilience due to a configuration thereof narrower in width than the gripper  11 A. According to this configuration, the user cleans a tooth T (illustrated in  FIGS.  3  and  4   ) by holding the gripper  11 A and then moving the brush section  20  at the tip of the handle  11 . It should be noted that the handle  11  of the toothbrush  1  is made of relatively hard synthetic resinous materials such as polypropylene, and the bristles of the bristle bundles of the brush section  20  (namely, the center bristle bundles  22 , first side bristle bundles  23   a  and second side bristle bundles  23   b,  which will be described below) are made of relatively soft synthetic resinous materials such as nylon. 
     The bristle implanting section  12  of the toothbrush  1  is formed so that the bristle implanting surface  12   a  (upper surface) thereof is in an elliptical shape of which the major axis direction P corresponds to the longitudinal direction of the handle  11  when viewed from a tip part (upper end)  22 T,  23   a T,  23   b T side (namely, from the front side of the paper, on which  FIG.  1    is printed) of the bristle bundles  22 ,  23   a,    23   b.  Moreover, the elliptical shape of the bristle implanting section  12  and the brush section  20  of the toothbrush  1  should be preferably, for example, approximately 2 cm in length in the major axis direction so as to easily enter an oral cavity and then turn in a small radius. 
     The brush section  20  of the toothbrush  1  will be described in detail.  FIG.  2    are enlarged views of the brush section  20 , of which  FIG.  2 A  is a plan view,  FIG.  2 B  is a side view and  FIG.  2 C  is a front view. As shown in  FIGS.  2   , the bristles forming the brush section  20  are classified into the center bristle bundles  22 , the side bristle bundles  23   a,    23   b  (namely, the first bristle bundles  23   a  and the second bristle bundles  23   b ) according to where in the bristle implanting section  12  (specifically, where on the bristle implanting surface  12   a ) the bristles are implanted. In other words, the brush section  20  is composed of a plurality of the center bristle bundles  22  arranged (in sequence) along the major axis direction P of the bristle implanting section  12  in a center area AC in the minor axis direction Q and a plurality of side bristle bundles  23   a,    23   b  arranged in areas AS 1 , AS 2  adjacent to the center bristle bundles  22  in the minor axis direction Q. Next, configurations of the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  will be described in detail. 
     As shown in  FIG.  2 A , the center bristle bundles  22  are composed of a plurality of the bristle bundles and arranged (in line) in the area AC along the major axis direction P. In this embodiment, eight disposed bundles of the center bristle bundles  22  are illustrated as one example. The plurality of the center bristle bundles  22  are formed in a chevron shape (pyramid shape) so as to be gradually inclined upwardly toward the center in the major axis direction P. Specifically, as shown in  FIG.  2 B , the plurality of the center bristle bundles  22  are formed to be inclined so that four bundles thereof on the handle  11  side are gradually elevated linearly toward an end part of the handle  11  and the other four bundles on the end part side are gradually lowered linearly toward the end part of the handle  11 . In addition, as shown in  FIGS.  2 B and  2 C , the center bristle bundles  22  are configured to be higher than the neighboring side bristle bundles  23   a,    23   b.    
     As shown in  FIG.  2 A , the plurality of the side bristle bundles  23   a,    23   b  are arranged adjacent to the center bristle bundles  22  in the areas AS 1 , AS 2  on both outer sides of the center bristle bundles  22 . Furthermore, the plurality of the side bristle bundles  23   a,    23   b  include the first side bristle bundles  23   a  arranged in the area AS 1  on a side closer to the center bristle bundles  22  (namely, on an inner side of the bristle implanting surface  12   a ) in the minor axis direction Q and the second side bristle bundles  23   b  arranged in the area AS 2  on a side farther from the center bristle bundles  22  (namely, an outer side of the bristle implanting surface  12   a ) in the minor axis direction Q. 
     In this embodiment, as one example, seven bundles of the first side bristle bundles  23   a  are arranged each on both sides of the center bristle bundles  22 , and four bundles of the second side bristle bundles  23   b  are arranged each on outer sides of the first side bristle bundles  23   a.  Specifically, as shown in  FIG.  2 B , the first side bristle bundles  23   a  are formed to be inclined so that the center one in the major axis direction P is highest while the other three ones on the handle  11  side are gradually elevated linearly toward the end part of the handle  11  and the other three ones on the end part side of the handle  11  are gradually lowered linearly toward to the end part of the handle  11 . Further, the second side bristle bundles  23   b  are formed to be inclined so that two ones on the handle  11  side are gradually elevated linearly toward the end part of the handle  11  and the other two ones on the end part side of the handle  11  are gradually lowered linearly toward to the end part of the handle  11 . 
     As shown in  FIG.  2 B , an inclination angle θ 1  of a line connecting tips  22 T of the center bristle bundles  22  inclined in the chevron shape, an inclination angle θ 2  of a line connecting tips  23   a T of the first side bristle bundles  23   a  and an inclination angle θ 3  of tips  23   b T of the second side bristle bundles  23   b  are all the same. In addition, the center bristle bundles  22  are configured to be harder in material than the side bristle bundles  23   a,    23   b.  In this connection, the center bristle bundles  22  may be larger in quantity than the side bristle bundles  23   a,    23   b.  This can maintain high hardness of the brush section  20 . It should be noted that while the center bristle bundles  22  are arranged in line along the major axis direction P in this embodiment, but not necessarily limited thereto. The center bristle bundles  22  may be arranged in a plurality of rows. Further, the number of the side bristle bundles  23   a,    23   b  (the first and second side bristle bundles  23   a,    23   b ) are also not limited to number in this embodiment. 
       FIGS.  3  and  4    are views illustrating use states of the toothbrush  1  cleaning a gap TG between a tooth T and a tooth T (namely, interdental gap) and a gap MG between a tooth T and gums M, of which  FIG.  3    is a view when viewing a plurality of the teeth T from the above and  FIG.  4    is a view when viewing the tooth T and the gums M from sideways. As shown in  FIGS.  3  and  4   , the toothbrush  1  of this embodiment is used by applying the brush section  20  to a surface TS of the tooth T and between the tooth T and the gums and then moving the brush section  20  little by little, thereby cleaning the tooth T and the gap MG between the tooth T and the gums M. 
     At this time, as the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  are disposed on the elliptical bristle implanting surface  12   a,  strokes of the toothbrush  1  enable the tips  22 T,  23   a T,  23   b T of the bundles (namely, bristle bundles  22 ,  23   a,    23   b ) of the brush section  20  to effectively touch (slide to) an upper surface and a side surface of the tooth having a complex uneven shape and a gap TG between the teeth T. This enables more effective clearance of stains in a groove TU of the tooth T and the interdental gap TG. In addition, as the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  are inclined in the chevron shape (pyramid shape), the tip of the chevron shape easily enters into the groove TU of the tooth T, the interdental gap TG and the gap MG between the tooth T and the gums M. This can scrape stains at a deep position in the groove TU of the tooth T, the interdental gap TG and the gap MG between the tooth T and the gums M. Moreover, as the bristle implanting surface  12   a  is in the elliptical shape and the center bristle bundles  22  and the side bristle bundles  23   a ,  23   b  are in the chevron shape, not only the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  positioned at the tip of the chevron shape, but also the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  adjacent to this tip can easily enter into the groove TU of the tooth T, the interdental gap TG and the gap MG between the tooth T and the gums M. Therefore, these synergistic effects can effectively scrape stains in the overall oral cavity including the interdental gap TG and the gap MG between the tooth T and the gums M by brushing for a short time and with light force. 
     In addition, as the bristle implanting surface  12   a  of the toothbrush  1  are in the elliptical shape and the center bristle bundles  22  are configured to be higher than the side bristle bundles  23   a,    23   b  on both sides, a tip part  21 T of the center bristle bundles  22  and a tip part  22   a T,  22   b T of the side bristle bundles  23   a,    23   b  inclined in the chevron shape (pyramid shape) enter deep into the groove TU of the tooth T, the interdental gap TG and the gap MG between the tooth T and the gums M. This can scrape the stains that have entered into the groove TU of the tooth, the interdental gap TG and the gap between the tooth M and the gums M by brushing for a short time and with light force. 
     Further, as described above, the inclination angle θ 1  of the center bristle bundles  22  inclined in the chevron shape and the inclination angles θ 2 , θ 3  of the side bristle bundles  23   a,    23   b  similarly inclined in the chevron shape are all the same. Thus, when the tip part  21 T of the center bristle bundles  22  enters deeply into the gap MG between the tooth T and the gums M and the dental groove TU, the side bristle bundles  23   a,    23   b  adjacent to the center bristle bundles  22  in the minor axis direction Q enter into and thus abut to, at the same inclination angle with the center bristle bundles  22 , the tooth T and the gums M adjacent to where the tip part  21 T of the center bristle bundles  22  enters deeply. In this manner, the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  effectively clean the gap MG between the tooth T and the gums M, the dental groove TU and the neighboring parts of the tooth T and the gums M. Thus, the toothbrush of the present invention can scrape the stains in the overall oral cavity including the interdental gap and the gap between the tooth and the gums by brushing for a short time and with light force. 
     Further, as shown in  FIG.  3   , the toothbrush  1  of this embodiment, the linear dimension L 1  of the bristle implanting section  12  in the major axis direction P is set in a width dimension L 2  of two teeth T. Accordingly, as the teeth T can be easily cleaned two by two, the interdental gap TG and the gap MG between the tooth T and the gums M can be easily brushed one by one, which enables effective cleaning for a shorter time. 
     As described above, the toothbrush  1  of this embodiment has the longitudinal handle  11  and the bristle implanting section  12  having the bristle implanting surface  12   a  formed at the end part of the handle  11  and the brush section  20  configured to include the plurality of the bristle bundles configured by a number of bristle bundles  22 ,  23   a,    23   b  implanted on the bristle implanting surface  12   a.  And, in the toothbrush  1  that cleans the teeth by using the brush section  20 , the bristle implanting section  12  is formed so that the bristle implanting surface  12   a  thereof is in the elliptical shape of which the major axis direction P corresponds to the longitudinal direction of the handle  11  when viewed from the tip part  22 T,  23   a T,  23   b T side of the bristle bundles  22 ,  23   a,    23   b.  Further, the brush section  20  includes as the bristle bundles  22 ,  23   a,    23   b,  the plurality of the center bristle bundles  22  arranged along the major axis direction P in the center area AC of the ellipse in the minor axis direction Q and the plurality of the side bristle bundles  23   a,    23   b  arranged in the areas AS 1 , AS 2  on both outer sides of the plurality of the center bristle bundles  22 . And, the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  are formed so as to be gradually inclined upwardly from both sides toward the center of the ellipse in the major axis direction P. 
     In the toothbrush of this embodiment, as the bristle implanting surface  12   a  is formed in the shape of the ellipse of which the major axis direction P corresponds to the longitudinal direction of the handle  11  when viewed from the tip part  22 T,  23   a T,  23   b T side of the bristle bundles  22 ,  23   a,    23   b,  the bristles (bristle bundles) of the brush section  20  are arranged in the shape of a curved line along the outer periphery  12   b  of the ellipse. Accordingly, compared to a bristle implanting section formed into a rectangle shape, when brushing the teeth by using the brush section  20 , the toothbrush of the present invention can prevent an edge part of the bristle implanting section  12  (namely, the end part of the handle  11 ) and the bristle bundles on the outer peripheral side of the brush section  20  from interfering parts in the mouth (such as teeth, gums and an inner surface of a cheek) needlessly. Therefore, a move of the brush section  20  only with light force enables smooth and efficient brushing. 
     Moreover, as the bristles (bristle bundles) of the brush section  20  are arranged in the curved shape along the outer periphery of the ellipse, the strokes of the toothbrush  1  enable the tip of the bristles (bristle bundles) to effectively touch (namely, slide to) the upper surface and the side surface of the tooth having a complex uneven shape and interdental gap. Consequently, the stains can be removed more efficiently from the dental groove and the interdental gap. 
     Furthermore, compared to an outer periphery of a bristle implanting section formed in a circular shape (perfect circular shape), the bristle implanting section  12  of the present invention can secure a longer distance (linear dimension) of the brush section  20  along the longitudinal direction of the handle  11 , namely, the stroke direction of the toothbrush  1 . Consequently, a larger contact area of the brush section can be secured by that amount. This enables more effective removal of dental stains. Thus, in the toothbrush  1  of this embodiment, the outer periphery  12   b  of the bristle implanting section  12  formed into the above-described elliptical shape can provide the above-described multiple effects in combination. 
     In addition, as the tips (upper ends) of the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  are configured to be inclined in the chevron shape (pyramid shape), the tip of the center bristle bundles  22 , which is the highest of the plurality of the center bristle bundles  22  and the plurality of the side bristle bundles  23   a,    23   b,  can enter, without being interfered by the neighboring bristle bundles, into a deep position of the gap MG between the tooth T and the gums M and the dental groove TU. Thus, the stains in the deep position can be scraped off. Furthermore, as the plurality of the center bristle bundles  22  are formed in the chevron shape, the second highest center bristle bundle  22  adjacent to the highest center bristle bundles  22  also easily enters into the interdental gap MG and the dental groove TU following the highest center bristle bundle  22 . The same applies to the plurality of the side bristle bundles  23   a,    23   b  similarly formed in the chevron shape. 
     Further, as the center bristle bundles  22  are configured to be higher than the side bristle bundles  23   a,    23   b  on both sides, when the center bristle bundles  22  enter into the deepest part of the gap MG between the tooth T and the gums M and the dental groove TU, the side bristle bundles  23   a,    23   b  lower than the center bristle bundles  22  easily enter into the tooth T and the gums M adjacent to the deepest part following the center bristle bundles  22 . 
     Moreover, as the inclination angle θ 1  of the center bristle bundles  22  inclined in the chevron shape and the inclination angles θ 2 , θ 3  of the side bristle bundles  23   a,    23   b  similarly inclined in the chevron shape are all the same, when the center bristle bundles  22  enters deeply into a deep part of the gap MG between the tooth T and the gums M and the dental groove TU, the side bristle bundles  23   a,    23   b  adjacent to the center bristle bundles  22  in the minor axis direction Q enter into and thus abut to, at the same inclination angle with the center bristle bundles  22 , the tooth T and the gums M adjacent to where the center bristle bundles  22  enters deeply. In this manner, as the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  effectively clean the gap MG between the tooth and the gums M and the dental groove TU, and the neighboring part of the tooth T and the gums M by brushing for a short time and with light force, whereby the toothbrush  1  of the present invention can scrape the stains in the overall oral cavity including the interdental gap and the gap between the tooth and the gums. 
     In addition, in the toothbrush  1  of the above-described configuration, the center bristle bundles  22  may be configured to be harder in material than the side bristle bundles  23   a ,  23   b.  In this manner, if the bristle bundles  21 ,  22  that are elevated gradually towards the center of bristle implanting section  12  are hardened gradually towards the center of the bristle implanting section  12 , the brush section  20  can maintain high hardness. Consequently, cleaning performance of the center bristle bundles  22  when entering deeply into the interdental gap TG, the gap MG between the tooth T and the gums M and the dental groove TU can be maintained at a high level. 
     Furthermore, in the toothbrush  1  of the above-described configuration, the center bristle bundles  22  may have a larger amount of bristles than the side bristle bundles  23   a,    23   b . A larger amount of the bristles of the center bristle bundles  22  can improve the hardness of the center bristle bundles  22  that are longer than the side bristle bundles  23   a,    23   b.  Thus, cleaning performance of the center bristle bundles  22  when entering deeply into the interdental gap TG, the gap MG between the tooth and the gums M and the dental groove TU can be maintained at a high level. 
     Second Embodiment 
     Next, a second embodiment of the present invention will be described below. In the description of the second embodiment and the corresponding figures, like reference characters refer to components corresponding or equivalent to those of the first embodiment, and a detailed description thereof is dispensed with.  FIGS.  5    are enlarged views of a brush section  20  of a toothbrush  1 - 2  of the second embodiment, of which  FIG.  5 A  is a plan view,  FIG.  5 B  is a front vies and  FIG.  5 C  is a side view. 
     A bristle implanting section  12  (bristle implanting surface  12   a ) of the toothbrush  1 - 2  of this embodiment is formed in the elliptical shape similar to the bristle implanting section  12  of the toothbrush  1  of the first embodiment. And, as shown in  FIGS.  5   , the bristles forming the brush section  20  of the toothbrush  1 - 2  are classified into a top bristle bundle  21 , center bristle bundles  22  and side bristle bundles  23   a,    23   b  (namely, first bristle bundles  23   a  and second bristle bundles  23   b ) according to where in the bristle implanting section  12  (bristle implanting surface  12   a ) the bristles are implanted. In other words, the brush section  20  is composed of the top bristle bundle  21  at the center of the bristle implanting section  12 , a plurality of the center bristle bundles  22  arranged in line with the top bristle bundle in the major axis direction P and a plurality of the side bristle bundles  23   a,    23   b  arranged adjacent to the center bristle bundles  22  in the minor axis direction Q. Each of these bristle bundles  21 ,  22 ,  23  will be described in detail below. 
     First, a configuration of the top bristle bundle  21  will be described. The top bristle bundle  21  is positioned at the center of the bristle implanting section  12  (bristle implanting surface  12   a ). Here, the center of bristle implanting section  12  refers to the center of the elliptical bristle implanting section  12  in the major axis direction P and in the center of the minor axis direction Q in the plan view of the bristle implanting section  12  (bristle implanting surface  12   a ) as shown in  FIG.  5 A . The top bristle bundle  21  is formed so that a tip part  21 T thereof is the highest of tip parts of the bristle bundles  21 ,  22 ,  23 . Specifically, the tip part  21 T of the top bristle bundle  21  is at a higher position than an intersecting point X of ridgelines R formed by connecting the tip parts  22 T of the center bristle bundles  22  (See  FIG.  5 B ). Therefore, the tip part  21 T of the top bristle bundle  21  is projected from the center bristle bundles  22  and the side bristle bundles  23   a,    23   b.    
     Further, as shown in  FIGS.  5 B and  5 C , the tip part  21 T of the top bristle bundle  21  is formed in a sharp conical shape. In addition, the top bristle bundle  21  should be preferably configured to be harder than the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  to achieve high hardness. Specifically, materials of the top bristle bundle  21  should be hardened more than materials of the center bristle bundles  22  and the side bristle bundles  23   a ,  23   b,  and the brush bristle constituting the top bristle bundle  21  should be thickened more than the center bristle bundles  22  and the side bristle bundles  23   a,    23   b.  Moreover, the amount of the top bristle bundle  21  (namely, thickness of the bristle bundle) should be preferably larger than the amount of the center bristle bundles  22  or the side bristle bundles  23   a,    23   b  to achieve higher hardness of the bristle bundle. 
     Next, the center bristle bundles  22  and the side bristle bundles  23   a,    23   b  will be described. As shown in  FIG.  5 A , the center bristle bundles  22  are composed of a plurality of the bristle bundles and arranged in a center area AC of the bristle implanting section  12  in the minor axis direction Q. In addition, the side bristle bundles  23   a,    23   b  are composed of a plurality of the bristle bundles and arranged in side areas AS 1 , AS 2  on both sides of the center area AC of the bristle implanting section  12  in the minor axis direction Q. Furthermore, the side bristle bundles  23   a,    23   b  include first side bristle bundles  23   a  arranged in the area AS 1  on a side closer to the center bristle bundles  22  (namely, on the inner side) in the minor axis direction Q, and second side bristle bundles  23   b  arranged in the area AS 2  on a side farther from the center bristle bundles  22  (namely, on the outer side) in the minor axis direction Q. 
     The center bristle bundles  22  are arranged in line on both sides in the major axis direction P so as to sandwich the top bristle bundle  21 . In addition, the first side bristle bundles  23   a  are arranged in line in the major axis direction P in the first side area AS 1  outside of the center area AC, and the second side bristle bundles  23   b  are arranged in line in the major axis direction P in the second side area AS 2  outside of the first side area AS 1 . It should be noted that in this embodiment, each of the center bristle bundles  22 , the first side bristle bundles  23   a  and the second side bristle bundles  23   b  is arranged in line along the major axis direction P, but not limited thereto. In other words, each of the center bristle bundles  22 , the first side bristle bundles  23   a  and the second side bristle bundles  23   b  may be arranged in two lines or more. 
     As shown in  FIG.  5 B , the center bristle bundles  22 , the first side bristle bundles  23   a  and the second side bristle bundles  23   b  are formed in the chevron shape (pyramid shape) to be gradually inclined upwardly toward the center (in the major axis direction P) of the bristle implanting section  12  when viewed from the side of the brush section  20 . Furthermore, as shown in  FIG.  5 C , the center bristle bundles  22  are formed to be higher than the first side bristle bundles  23   a  adjacent in the minor axis direction Q of the bristle implanting section  12 , and the first side bristle bundles  23   a  are formed to be higher than the second side bristle bundles  23   b  similarly adjacent in the minor axis direction Q. 
     In the toothbrush  1 - 2  of this embodiment, as the top bristle bundle  21  is configured to be higher than the neighboring center bristle bundles  22  and the side bristle bundles  23   a,    23   b , the tip part  21 T of the top bristle bundle  21  enters deeply into the groove of the tooth T, the interdental gap TG and the gap MG between the tooth T and the gums M while the center bristle bundles  22  and the side bristle bundles  23   a,    23   b,  of which the tip parts are inclined in the chevron shape (pyramid shape), are cleaning the surface TS of the tooth T adjacent to the interdental gap TG and the gap MG between the tooth T and the gums M. This can scrape the stains that have entered into the groove TU of the tooth T, the interdental gap TG and the gap MG between the tooth T and the gums M for a short time and with light force. 
     While one embodiment of the present invention has been described above, the invention is not limited to the above-mentioned embodiment, but various modifications are possible within the scope of the technical idea as defined in the claims, the specification, and the drawings. For example, in the toothbrush  1  ( 1 - 2 ) of the above-described embodiment, the bristle implanting section  12  is formed in the elliptical shape, of which the major axis direction P corresponds to the longitudinal direction of the handle  11 , but not limited thereto. In other words, the elliptical shape of the bristle implanting section of the toothbrush of the present invention may be formed so that the major axis direction thereof is different from the longitudinal direction of the handle.