TOOTHBRUSH WITH NEEDLE-SHAPED BRISTLES HAVING IMPROVED CLEANING EFFECTS

Technical Field The present invention relates, in general, to toothbrushes with needle-shaped bristles and, more particularly, to a toothbrush with needle-shaped bristles having improved cleaning ability.

Background Art Generally, a toothbrush with needle-shaped bristles means a toothbrush in which bristles each having a needle- shaped end are set, as shown in FIG. 1. In this regard, several prior arts were proposed in Korean Patent Registration No. 130932, in Korean Utility Model Registration No. 114700, and in Korean Patent Registration No. 261658. In methods for manufacturing a needle-shaped bristle, there are a method of immersing a bristle in an acid or alkali chemical to dissolve its end, a method of mechanically grinding an end of a bristle, and a method of using both above-mentioned methods jointly. The method of immersing a bristle in the acid or alkali chemical is useful to achieve a greater reduction in diameter of an end of the bristle. Thus, typically, this method is mainly used. The conventional toothbrushes with needle-shaped bristles each have superior ability in penetration into gaps between teeth or between the teeth and the gingivae. As well, because ends of the needle-shaped bristles are soft, the gingivae of a user are prevented from being damaged. Therefore, recently, toothbrushes with needle- shaped bristles have become popular with consumers. However, the conventional toothbrushes with needle- shaped bristles are inferior in cleaning ability, compared with toothbrushes with typical bristles. The reason is that a contact area between the teeth and needle-shaped ends of the needle-shaped bristles is limited and, in addition, the needle-shaped ends lack stiffness. Furthermore, the conventional toothbrushes with needle-shaped bristles are problematic in that because the needle-shaped bristles' ends, having a narrow diameter, are easily worn or deformed, the life spans of the toothbrushes are reduced.

Description of Drawings FIG. 1 is a sectional view of a needle-shaped bristle; FIG. 2 is a plan view showing a conventional toothbrush; FIG. 3 is a plan view of a toothbrush body of a toothbrush, according to an embodiment of the present invention; FIG. 4 is a plan view of a toothbrush body of a toothbrush, according to another embodiment of the present invention; and FIG. 5 is a plan view of a toothbrush body of a toothbrush, according to a further embodiment of the present invention.

Disclosure

Technical Problem Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a toothbrush with needle-shaped bristles having improved cleaning ability. Another object of the present invention is to provide a toothbrush with needle-shaped bristles which has a long life span. A further object of the present invention is to provide a toothbrush with needle- shaped bristles in which the efficiency of setting bristles in the toothbrush is enhanced.

Technical Solution In order to accomplish the above object(s), the present invention provides a toothbrush with needle-shaped bristles, including: a plurality of rectangular setting grooves each having a minor axis from 1.5 to 2.5mm in length and a major axis from 2.5 to 4.0mm in length and spaced apart from each other at intervals from 1.0 to 3.0mm; and forty-five to eighty needle-shaped bristles set in each of the rectangular setting grooves at a depth of 4.0 to 5.0mm. The needle-shaped bristles each have an end point from 0.01 to 0.02mm in diameter and a tapered part from 4.0 to 10.0mm in length.

Advantageous Effects The toothbrush according to the present invention has cleaning ability superior to that of conventional toothbrushes, in spite of having similar penetration ability to the conventional toothbrushes. Furthermore, the life span of the needle-shaped bristles is markedly enhanced. In addition, because a high number of needle-shaped bristles is set in each setting groove, efficiency in setting the needle-shaped bristles in the setting grooves is markedly increased.

Best Mode Hereafter, a toothbrush of the present invention will be described in detail. In a conventional toothbrush with needle-shaped bristles, the needle-shaped bristles shown in FIG. 1 are set in a toothbrush body shown in FIG. 2. In the conventional toothbrush, each of the circular setting grooves shown in FIG. 2 has a diameter from 1.5 to 1.6mm. From fifteen to twenty five needle-shaped bristles are set in each circular setting groove at a depth of 3.0mm. FIG. 3 is a plan view of a toothbrush body, according to an embodiment of the present invention. Referring to FIG. 3, each of rectangular setting grooves has a minor axis of 1.5-2.5mm in length and a major axis of 2.5-4.Omm in length. Each interval between the rectangular setting grooves ranges from 1.0 to 3.0mm. An area of each of the rectangular setting grooves is 2.5 times wider than that of each of the conventional circular setting grooves. Due to the wide area of the rectangular setting groove, a high number of bristles can be set in each of the rectangular setting grooves. Therefore, the present invention solves a problem of the conventional toothbrush in which needle- shaped bristles are excessively bent while brushing teeth, thus deteriorating cleaning ability. If the area of each of the rectangular setting grooves is less than the above- mentioned range, desired cleaning ability cannot be 'achieved. Otherwise, if the area of each of the rectangular setting grooves is greater than the above-mentioned range, the workability of the toothbrush is decreased. FIG. 4 is a plan view of a toothbrush body of a toothbrush, according to another embodiment of the present invention. As shown in FIG. 4, setting grooves are not rectangular, but are rounded in each corner. Due to this feature, difficulty occurring in setting bristles into grooves is markedly reduced. In a detailed description, because each rectangular setting groove formed on the toothbrush body of the present invention is relatively large, an extended support pin having a shape similar to that of the rectangular setting groove must be used to fasten the needle-shaped bristles into the rectangular setting groove. Therefore, in the case in which a high number of needle-shaped bristles is fastened in the rectangular setting groove by using the extended support pin, lengths of exposed parts of the needle-shaped bristles set in the toothbrush body are different from each other, unlike the conventional toothbrush having small circular setting grooves. As such, in the case that the exposed parts of the set needle-shaped bristles are uneven, a separate after-treatment, such as a cutting process, must be executed. However, if corners of the rectangular setting grooves are rounded, the problem of the needle-shaped bristles being unevenly set is markedly reduced. FIG. 5 is a plan view of a toothbrush body of a toothbrush, according to a further embodiment of the present invention. Referring to FIG. 5, setting grooves are not rectangular, but are elliptical. The elliptical setting grooves provide the same effect as those of the setting grooves shown in FIG. 4. Each interval between the elliptical setting grooves ranges from 1.0 to 3.Oram. If the intervals are less than the above-mentioned range, because the available space between the elliptical setting grooves is not enough, the set needle-shaped bristles become excessively hard. If the intervals are greater than the above-mentioned range, the set needle-shaped bristles become excessively soft, thus reducing cleaning ability. A diameter of an end point of each of the needle- shaped bristles used for the present invention ranges from 0.01 to 0.02mm. A length of a tapered part of each of-the needle-shaped bristles used for the present invention ranges from 4.0 to 10.0mm. If the diameter of the end point of the needle-shaped bristle is less than the above- mentioned range, difficulty in the manufacture of the needle-shaped bristle exists and, in addition, the desired cleaning ability is not obtained. If the diameter of the end point is greater than the above-mentioned range, the penetration ability of the needle-shaped bristles is reduced. If the length of the tapered part of each of the needle-shaped bristles is less than the above-mentioned range, the hardness of the needle-shaped bristle increases excessively. Thus, the gingivae of the user may be damaged by the needle-shaped bristles while brushing the teeth. If the length of the tapered part is greater than the above- mentioned range, the desired cleaning ability is not obtained. In the present invention, because the needle-shaped bristles are set in the relatively wide setting grooves, an appropriate range of a depth of setting the needle-shaped bristles in each setting groove is from 4.0 to 5.0mm. If the depth of setting the needle-shaped bristles in the setting groove is less than the above-mentioned range, the needle-shaped bristles may be undesirably missing. If the depth of setting the needle-shaped bristles in the setting groove is greater than the above-mentioned range, the thickness of the toothbrush body must be excessively increased. The appropriate number of needle-shaped bristles 'set in each setting groove ranges from forty-five to eighty. If the number of the needle-shaped bristles is less than the above-mentioned range, the desired cleaning ability cannot be attained. If the number of the needle-shaped bristles is greater than the above-mentioned range, the efficiency in setting the needle-shaped bristles into the setting grooves is decreased and, as well, the set needle-shaped bristles are excessively hard. In the meantime, in the case that each of the needle- shaped bristles is not tapered at both ends, but is tapered at one end as are the needle-shaped bristles in Korean Patent Application No. 2002-0076349, the needle-shaped bristles cannot be fastened in the setting groove by the support pin. Therefore, in the case of the needle-shaped bristles tapered at one end, ends opposite to the tapered ends are attached to a head part of the toothbrush through an ultrasonic process after being heat-welded. Alternatively, the ends opposite to the tapered ends may be attached to the head part by a bonding agent. Several examples of methods of manufacturing toothbrushes are as follows. (Example 1) A toothbrush body having the same structure as that of the toothbrush body of FIG. 3 is prepared. Sixty needle- shaped bristles, each of which is made of a PBT material and has an end point of 0.015mm diameter and a 7mm tapered part, are set at a depth of 4.5mm in each of the setting grooves each of which has a minor axis of 2.0mm and a major axis of 4.0mm and which are spaced 2.5mm apart. At this time, if the needle-shaped bristles are unevenly set in each setting groove, ends of excessively long needle-shaped bristles are cut off through the cutting process. The product manufactured through the above-mentioned process is called "toothbrush number one" (Example 2) A toothbrush called "toothbrush number two" is manufactured in the same manner as that described for the toothbrush number one of the first manufacturing example, but a toothbrush body having the same structure as that of the toothbrush body of FIG. 4 is used, unlike toothbrush number one. In this case, needle-shaped bristles are relatively evenly set, so that a separate cutting process is not required. (Comparative Example 1) A toothbrush called "toothbrush number three" is manufactured in the same manner as that described for toothbrush number two of the second manufacturing example, but each interval between setting grooves is 1.5mm, unlike toothbrush number two. (Comparative Example 2) A toothbrush called "toothbrush number four" is manufactured in the same manner as that described for toothbrush number two of the second manufacturing example, but forty needle-shaped bristles are set in each setting groove, unlike toothbrush number two. (Comparative Example 3) A toothbrush called "toothbrush number fifth" is manufactured in the same manner as that described for toothbrush number two of the second manufacturing example, but eighty-five needle-shaped bristles are set in each setting groove, unlike toothbrush number two. (Comparative Example 4) A toothbrush called "toothbrush number six" is manufactured in the same manner as that described for toothbrush number two of the second manufacturing example, but a length of a tapered part of each needle-shaped bristle is 3mm, unlike toothbrush number two. (Comparative Example 5) A toothbrush called "toothbrush number seven" is manufactured in the same manner as that described for toothbrush number two of the second manufacturing example, but a toothbrush body has the same structure as that of the toothbrush body of FIG. 2 and a diameter of 1.5mm, and each interval between setting grooves is 1.2mm, unlike toothbrush number two. (Experiment 1) Fifty adult men and women used the toothbrushes, manufactured by the methods explained in the above- mentioned manufacturing examples, for fifteen days. Thereafter, preferences according to predetermined items were researched. The results are described in the following Table 1. [Table 1] Sample Cleaning ability Penetration ability Total Toothbrush number one 4.3 4.0 8.3 Toothbrush number two 4.2 4.3 8.5 Toothbrush number three 4.3 3.5 7.8 Toothbrush number four 3.5 4.1 7.6 Toothbrush number five 4.3 3.2 7.5 Toothbrush number six 3.2 4.2 7.4

* estimation standard: very excellent;5, excellent;4, normal;3, poor;2, very poor;l (Experiment 2) Each of toothbrush number two and toothbrush number six was mounted on a ceramic mold shaped like a teeth. Thereafter, automatic reciprocation of the toothbrushes was executed three thousand times after a solution, in which toothpaste and water were mixed into a ratio of 1:1, was applied to the ceramic mold. The results that relate to the gap between needle-shaped bristles are described in the following Table 2. [Table 2] Sample Gap between needle-shaped bristles (%) Toothbrush number two 4.7±0.2 Toothbrush number six 12.7+0.3

* gap between needle-shaped bristles (%) = {(width of the set of needle-shaped bristles after the test)-(width of the set of needle-shaped bristles before the test)}/(width of the set of needle-shaped bristles before the test)