ROTARY TOOTHBRUSH

Abstract: A rotative toothbrush comprising a brushhead (1) having an eccentric center (p), which may have one or more projections (5) on the back-edge side of said round brushhead (1), a grip (2) and a shaft (4), which connects rotatively the eccentric center (p) of said brushhead (1) with the end of said grip (2).

Description: Description Title of the Invention ROTARY TOOTHBRUSH The present invention relates to an improvement in a rotative toothbrush which can brush the teeth vertically up and down as well as horizontally right and left. The effective way of brushing the teeth is to brush the teeth vertically up and down as well as horizontally right and left. This invention is concerned with the improvement of a rotative toothbrush which automatically moves up and down, when the users brush their teeth horizontally right and left in a conventional way. Prior Arts A toothbrush which has the most generally used is the one illustrated in Fig. 8. A human mouth is opened hori¬ zontally and it is the most convenient to brush the teeth horizontally right and left. For a long time, human being has brushed the teeth hori¬ zontally right and left with the conventional toothbrush shown in Fig. 8. However, because such a brushing of the teeth is carried out horizontally right and left, food dirts and plaques existing between the teeth are not removed well. A nd, moreover, the teeth themselves are weared out horizon¬ tally by the conventional brushing of the teeth and there¬ fore one or more grooves near the teethridge are formed by a conventional long brushing of the teeth. Therefore, dentists advise that the user brushes the teeth vertically up and down. However, such a vertical brushing of the teeth is not familiar with common users and according¬ ly, the vertical brushing of teeth up and down by a conven¬ tional toothbrush is very inconvenient. In order to solve these problems, US Paent No. 4,783,869 described a tooth¬ brush shown in Fig. 9. However, the toothbrush shown in the said US Patent No. 4,783,869 is, in fact, not rotative and even though the rotative movement is done as described in the said US Patent, the brushing effect is not sufficient because as shown in Fig. 11, only a small part of the brush- hairs of the brushhead are contacted with the teeth, when the user uses the toothbrush. The present inventor invented a rotative toothbrush as shown in Fig. 10 in which the center of a round brushhead is connected with the grip by the shaft, and filed a Korean utility model application as No. 87-19458 (Unexamined Utili¬ ty Model Publication No. 89-10102) . However, as the rotati¬ ve shaft is located at the center of the brushhead and the friction powers between the brushhairs of the brushhead and the teeth are the same in all directions, the brushhead does not rotate well. Accordingly, the effect of vertical brushing of the teeth up and down is not, in fact, obtained. The present inventor invented the present invention as a result of an intensive study. Object of the Invention One object of the present invention is to provide a novel toothbrush which can be moved vertically up and down as well as horizontally right and left when user moves the toothbrush right and left in a conventional way. The toothbrush is composed of a round brushhead having an eccentric center, a grip and a shaft and the end of the grip is rotatively connected with said brushhead by the shaft. Another object of the present invention is to provide a novel toothbrush which can be moved vertically up and down as well as horizontally right and left when user moves the toothbrush right and left in a conventional way. The tooth¬ brush is composed of a round brushhead having an * ,eccentric center in which one or more projections are formed on the back-edge side of the long eccentricity radius and a shaft. Brief Description of the Drawings Fig. 1 is an external view of an embodiment of the toothbrush of the present invention; Fig. 2 is a rear view showing the toothbrush of Fig. 1 9121 of the present invention; Fig. 3 is an external view of another embodiment of the present invention; Fig. 4 is a diagram illustrating the brushhead of the present invention; (A) is a round brushhead having no projection; (B) is a round brushhead having one projection; and (C) is a round brushhead having three projections; Fig. 5 is a rear view showing the ratio of eccentricity of the brushhead of the present invention; Fig. 6A is a sectional view showing an embodiment of rotative parts of the toothbrush of the present invention; Fig. 6B is a sectional view showing another embodiment of the rotative parts of the rotative toothbrush of the present invention. Fig. 7 is an explanatory view of use of the toothbrush of the present invention; Fig. 8 is an external view of a conventional toothbrush; Fig. 9 is an external view of the toothbrush of US Patent No. 4,783,869; Fig. 10 is an external view of the toothbrush of Korean Utility Model Appln. No. 87-19458; and Fig. 11 is an explanatory view of use of the toothbrush of the present invention. Detailed Description of the Invention Fig. 1 shows the external form of the rotative tooth- 121 brush of the present invention. The rotative eccentric center(p) of the round brushhead(1) is connected with the end of the grip(2) by the shaft(4). The rotative center(p) is eccentrically and rotatively located from the center of the round brushhead(1) . The present rotative toothbrush is well rotative, even though all the brushhairs of the brushhead are contacted with the teeth. As long as the ratio of the eccentricity [the ratio of the short radius (a): the long radius(b) ] is large, the round brushhead will be well rotative, when the user uses the rotative toothbrush of the present invention. However, it is inconvenient for the user to use the toothbrush of which the ratio of the eccentricity is large. And as long as the ratio is small, it is convenient for the user to use it. However, the rotating power will be weak. The preferable ratio of a:b is about 2:3 to about 1:3. The brushhead(1) , the grip(2) and brushhairs (3) can be made of the conventional plastic materials used in a conven¬ tional toothbrush. Fig. 6A shows an embodiment of the structure of the rotative parts of the tobthbrush. The shaft(4) which has the rounded end(4') and a sill (4") is loosely set in the hole(6) formed in the end of the grip(2). The upper end(4"') of the shaft(4) is covered with the cap(7 having a hole(6') through the hole(6') and then the upper end(4'") is firmly fitted in the hole(8) of the .brushhead(1) The cap(7) is sealed with the end of the grip(2) by a conve tional way, e.g. by a supersonic sealing or by adhesives which is not melted in water or by heat-sealing method. Fig. 6B shows another embodiment of the rotative parts of the toothbrush. The base plate(41') of the shaft(41) is vertically molded into the upper end of the grip(2). Then, the shaft(41) is set into the housing(71) having the hole (71') and the groove(71") in the way that the shaft(41) having projection(41") is loosely fitted into the hole(71') of the housing (71) having the groove(71"). And then the housing(71) is fixed into the hole(81) of the brushhead(1) . The shaft(4) or (41) becomes freely rotative in the set state. There will be another various conventional structures of the rotative parts, which also come under the scope of the present invention. As long as the thin shaft(4) is used, the thin shaft(4) becomes well rotative. However, it is desirable that the shaft(4) of which diameter is from 0.5mm to 2.0mm is used. The shaft(4) can be made of metal or plastic. However, metal is more desirable than the plastic material because metal is usually more strong than the plastic material. When the user moves the grip of the toothbrush right or left in a conventional way, the brushhead(1) is rotated each by 180 degrees at its maximum owing to the difference of the friction powers between the brushhairs of short radius and the brushhairs of long radius contacted with the teeth. Therefore, the effect of brushing the teeth verti- cally up and down is obtained. Fig. 3 shows another embodiment of the rotative tooth¬ brush of the present invention. In this case, one or more round projection(s) (5) are formed on the back-edge side of the long eccentricity radius of the brushhead(1) (See Fig. 4(B) and (C).). When the user uses the toothbrush having one or more round projection(s) (5) on the back-edge side of the long eccentricity radius of the brushhead(1) , the round projection(s) (5) which are contacted with the inside muscles of the user's mouth produce friction and therefore a couple power between the rotative center(p) and the round projec- tion(s) (5) is generated. So, the brushhead(l) is more rotative. One three round projections are desirable.

Claims: What we c laim is : 1. A rotative toothbrush comprising: a round brushhead member; a grip member; and a shaft member, said shaft member rotatively connects the eccentric center of said round brushhead member and the end of the grip member. 2. A rotative toothbrush comprising: a round brushhead member having one or more projections on the back-edge side of the long eccentricity radius of said round brushhead member; a grip member; and a shaft member, said shaft member rotatively connects the eccentric center of said round brushhead member and the end of the grip member. 3. A rotative toothbrush according to claim 1 or 2, wherein the eccentricity between the short radius and long radius of the eccentric center is about 2:3 to about 1:3. 4. A rotative toothbrush according to claim 2, in which one to three round projections are formed on the back- edge side of the long eccentricity radius of the round brushhead member.

Inventors: PARK SA RYONG, PARK, SA, RYONG
Applicants: PARK SA RYONG, PARK, SA, RYONG
Application year: 1990
Main classification: A46B9
IPC codes: A46B7, A46B9