Title of Invention	TOOTHBRUSH HAVING PRESSURE RELIEF UNIT AND METHOD OF PRODUCING THE SAME
Abstract	Disclosed are a toothbrush and a method of producing the same. The toothbrush of the present invention includes a pressure relief unit (r) which is installed in a head part of the toothbrush and has a plate shape and a predetermined size sufficient to cover bristles set in the head part. In the present invention, the head part is thin, and the bristles are set in the head part without using a wire. Furthermore, the present invention is easily adapted for mass production using inexpensive equipment. As well, the pressure relief unit (r), which is installed in the head part, serves as a reinforcing unit. Therefore, the head part is prevented from breaking during use despite having a reduced thickness.

Title of Invention

TOOTHBRUSH HAVING PRESSURE RELIEF UNIT AND METHOD OF PRODUCING THE SAME

Abstract

Disclosed are a toothbrush and a method of producing the same. The toothbrush of the present invention includes a pressure relief unit (r) which is installed in a head part of the toothbrush and has a plate shape and a predetermined size sufficient to cover bristles set in the head part. In the present invention, the head part is thin, and the bristles are set in the head part without using a wire. Furthermore, the present invention is easily adapted for mass production using inexpensive equipment. As well, the pressure relief unit (r), which is installed in the head part, serves as a reinforcing unit. Therefore, the head part is prevented from breaking during use despite having a reduced thickness.

Full Text	DESCRIPTION □Invention Title TOOTHBRUSH HAVING PRESSURE RELIEF UNIT AND METHOD OF PRODUCING THE SAME Technical Field The present invention relates, in general, to toothbrushes and methods of producing the same and, more particularly, to a toothbrush in which a pressure relief unit is installed in a head part of the toothbrush, and a method of producing the same. Background Art Generally, to produce a toothbrush, first, a toothbrush body having holes in a head part thereof is manufactured. Subsequently, bristles, folded in half, are set in the holes of the head part. The bristles are fastened to the toothbrush body by inserting wires, which are made of elastic metal and have a length greater than the diameter of the hole, into the holes. However, such a toothbrush production method has disadvantages in that, because bristles are not reliably fixed to the toothbrush body, the bristles are easily removed from the toothbrush body, and impurities are easily held in the holes formed in the head part of the 1 toothbrush. As well, this toothbrush producing method is problematic in that bristles cannot be set in various patterns. As an example of techniques to overcome the above- mentioned problems, in Korean Patent No. 360977, bristles are set in a mold of an injection molding machine having a bristle setting device. Thereafter, portions of the bristles protruding into the mold are thermally welded through a heat treatment process. Subsequently, a toothbrush body is injection-molded along with the bristles so that the bristles are integrated with the toothbrush body. In this technique, the bristles are reliably fixed to the toothbrush body. Furthermore, because it is not necessary to form holes in a head part of the toothbrush, the problems of the prior art are solved. However, the above-mentioned conventional technique has disadvantages as follow. First, because toothbrushes are manufactured using a mold having a constant shape, it is very difficult to change the shape of the toothbrush body. The toothbrush body is frequently subject to changes due to trends. Therefore, the difficulty in changing the shape of the toothbrush body is a serious problem. Of course, toothbrush bodies having different shapes may be simultaneously manufactured by mounting several different molds to a single injection molding machine. However, in this case, 2 there is a problem in that the same number of different toothbrushes must be manufactured and marketed. Second, there is a problem in that if an error occurs even in one process of a series of manufacturing processes, all other processes must also be stopped. That is, the conventional technique consists of processes as follow: (1) a process of setting bristles in the mold, (2) a process of thermally welding parts of the bristles which protrude into the mold, and (3) a process of injection-molding a toothbrush. If an error occurs in even one among the above- mentioned processes, the production must be stopped. Third, the injection molding machine is not operated during the setting and thermal welding processes. Accordingly, in consideration of the expensive injection molding machine having the bristle setting device, productivity per hour is markedly reduced. To solve the above-mentioned problems, another technique was proposed in Korean Patent Application No. 10- 2003-0036887. In this technique, bristles are set in through holes formed through a head insert 10, which is made of plastic and has a thickness ranging from 1.5 to 3.0 mm, such that parts of the bristles protrude from a back surface of the head insert 10 by 1 to 3 mm. Thereafter, the protruded parts of the bristles are thermally welded, thus separately manufacturing the head insert 10 which has the bristles and 3 is a partial-product. Subsequently, the head insert 10 having the bristles is placed in a cavity of the mold such that the bristles are placed outside the cavity of the mold. Thereafter, a toothbrush body is injection-molded by injecting resin into the mold using a normal injection molding machine, thus producing a toothbrush. In this technique, a process of setting the bristles in the head insert 10, a process of thermally welding parts of the bristles which protrude from the back surface of the head insert 10, and a process of placing the head insert 10 having the bristles in the mold and injection-molding a toothbrush body are separately conducted. Therefore, even if an error occurs in one process, other processes can be conducted. Therefore, the rate of operation of equipment is markedly enhanced. Furthermore, the shape of the toothbrush can be easily changed merely by manufacturing an additional mold for the injection molding machine, which is relatively inexpensive. However, in this technique, when injection-molding the toothbrush body after the head insert 10 having the bristles is placed in the mold, a phenomenon, in which resin may flow out along the bristles due to injection pressure, frequently arises. As such, if resin flows out along the bristles, the bristles become bonded to each other, so the value of the product is deteriorated. Meanwhile, another toothbrush manufacturing method, 4 in which a head insert 10 having bristles is separately manufactured and is then bonded to a toothbrush body, manufactured through a separate process, using ultrasonic waves, was proposed. In this technique, because a process of manufacturing the head insert 10 and a process of manufacturing the toothbrush body are separately conducted, the problem of deterioration of workability is solved. However, in this technique, because the head insert 10 is inserted into a head part of the toothbrush body and integrated with the toothbrush body using an ultrasonic bonding method, the head insert 10 must be precisely aligned with the toothbrush body. Therefore, an accurate mold is required, thus the price of equipment is excessively increased. Furthermore, there is a problem in that the head part of the toothbrush becomes too thick. Generally, a head part of a toothbrush that is thin and narrow is more convenient for a user and increases tooth brushing efficiency. However, in the above-mentioned technique, because the head insert is bonded to the head part of the toothbrush along a bonding line (b) defined on a sidewall of the head part, the head part of the toothbrush becomes relatively thick (see, FIG. 1) . To reduce the thickness of the head part of the toothbrush, the bonding operation may be conducted on the front surface of the head part. However, this bonding method requires an increase in the area of the head part and may cause damage 5 to the bristles. Therefore, this bonding method should not be conducted. 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 production method which solves problems of the conventional arts when holes are formed in a head part of a toothbrush body and wires are used, and which increases the productivity and permits the shape of a toothbrush body to be easily changed. Another object of the present invention is to provide a toothbrush production method in which even if an error occurs in one production process, other production processes are not affected. A further object of the present invention is to provide a toothbrush producing method which prevents resin from flowing out along set bristles during an injection molding process. Yet another object of the present invention is to provide a toothbrush which has a thin head part. Technical Solution In order to accomplish the above objects, the present invention provides a method of producing a toothbrush, including: setting bristles in a plurality of through holes 6 formed through a head insert, which is made of plastic and has a thickness ranging from 1.5 to 3.0 mm, such that parts of the bristles protrude from a back surface of the head insert by 1 to 3 mm; fastening the bristles to the head insert by thermally welding the protruded parts of the bristles to the head insert, thus manufacturing the head insert with bristles; placing the head insert having the bristles in a cavity of a mold for manufacturing a toothbrush body such that the bristles are placed outside the cavity of the mold; and injecting resin and forming a toothbrush body. The method of the present invention further includes the step of placing a pressure relief unit having a plate shape on the back surface of the head insert before the step of injecting resin into the mold. Advantageous Effects In the present invention, bristles can be set in a toothbrush body without wires. The work efficiency of an expensive injection molding machine is maximized. Furthermore, because a normal mold, which is manufactured in a desired shape, can be mounted to the injection molding machine, the shape of the toothbrush body is easily changed. As well, even if an error occurs in one production process, because other production processes are not affected, the productivity is maximized. Particularly, the present invention can prevent a 7 problem of resin flowing out along set bristles, experienced in Korean Patent Application No. 10-2003-0036887, which was filed by the inventor of the present invention. Furthermore, in the case that an appropriate pressure relief unit is used, a functional toothbrush such as an antibacterial toothbrush can be provided. Moreover, the present invention can produce a high grade toothbrush having reduced thickness. In addition, because the present invention uses the pressure relief unit (r) serving as a core material, the present invention solves a problem of the head part breaking during use due to its reduced thickness. Description of Drawings FIG. 1 is a side view showing a toothbrush manufactured by a conventional ultrasonic bonding method; FIG. 2 is a perspective view of a head insert used in the present invention; FIG. 3 is a side view of a first receiving unit used in the present invention; FIG. 4 is a side view of a second receiving unit used in the present invention; FIG. 5 is a sectional view showing a pushing plate inserted into the first receiving unit according to the present invention; FIG. 6 is a sectional view showing a process of setting bristles into a head insert, according to the 8 present invention; FIG. 7 is a sectional view showing the bristles fastened to the head insert by thermally welding parts of the bristles protruding from a back surface of the head insert, according to the present invention; FIG. 8 is a perspective view showing the head insert in which bristles are set; FIG. 9 is a plan view showing a pressure relief unit layered on the head insert according to the present invention; FIG. 10 is a view showing a hole formed in a head part of a toothbrush according to the present invention; FIG. 11 is a view showing the head insert placed in a cavity of a mold for manufacturing a toothbrush body through an injection molding process, according to the present invention; FIG. 12 is a perspective view showing a holding unit to be used in the present invention; and FIG. 13 is a perspective view of a toothbrush produced by a toothbrush producing method according to the present invention. * Description of the elements in the drawings 10: head insert 11: through hole 20: first receiving unit 30: second receiving unit 40: pushing plate 41: insert rod h: bristle p: support pin 9 s: automatic movable insertion device r: pressure relief unit b: bonding line k: hole q: holding unit Best Mode A toothbrush of the present invention includes a pressure relief unit (r) which has a plate shape and a size that is sufficient to cover bristles set in a head part of the toothbrush. Hereinafter, the present invention will be described in detail with reference to the attached drawings. FIG. 2 is a perspective view of a head insert 10 which is used in the present invention. The head insert 10 is made of plastic and has a thickness ranging from 1. 5mm to 3.0mm. If the thickness of the head insert 10 is less than the above-mentioned range, the head insert 10 may undesirably bend during a thermal welding process. If the thickness of the head insert 10 is greater than the above- mentioned range, the head part of a toothbrush is excessively thick. The head insert 10 has through holes 11 therein so that bristles are set in the through holes 11. The through holes 11 may have different sizes, unlike conventional arts using wires. In other words, in consideration of the setting pattern of bristles, the size and shape of the through holes 11 may be appropriately adjusted. 10 To set bristles in the through hole 11 of the head insert 10, first, bristles are cut to predetermined lengths and are held by a first receiving unit 20 having the shape shown in FIG. 3. Thereafter, the bristles set in the head insert 10 are transferred to a second receiving unit 30 shown in FIG. 4 and, then, are transferred to the head insert 10. Here, the first receiving unit 20, the second receiving unit 30 and the head insert 10 have through holes corresponding to each other. Furthermore, because the first receiving unit 20 and the second receiving unit 30 serve to repeatedly transfer bristles (h) to head inserts 10, they must be made of metal having superior durability. A process of receiving bristles (h) into the first receiving unit 20 is as follows. The bristles (h) are received into the first receiving unit 20 by pushing the bristles (h) into the through holes 11 of the first receiving unit 20 using a pushing plate 40 (see, FIG. 5) provided with insert rods 41 having shapes corresponding to shapes of the through holes 11 of the first receiving unit 20. A process of setting the bristles (h) in the head insert 10 is as follows. The first and second receiving units 20 and 30 and the head insert 10 come into contact with each other such that their through holes 11 are aligned with each other. Thereafter, the pushing plate 40 11 pushes the bristles (h) , which are received in the first receiving unit 20, in the direction of the head insert 10 through the second receiving unit 30 (see, FIG. 6). At this time, the bristles (h) are set in the head insert 10 such that parts of the bristles (h) protrude from a back surface of the head insert 10 by 1 to 3 mm. If the protruding length of the bristles is less than the above-mentioned range, there is difficulty in closing the through holes 11 through a thermal welding process which will be explained later herein. If the protruding length of the bristles is greater than the above-mentioned range, there is a problem in that the head part of a toothbrush becomes excessively thick. After the bristles (h) are set in the head insert 10, the parts of the bristles (h) which protrude from the back surface of the head insert 10 are melted by heating and thus are fastened to the head insert 10 by partially closing the through holes 11 (see, FIG. 7) . The head insert 10 which has the bristles (h) and is a semi-finished product is shown in FIG. 8. Prior to an injection molding process, a pressure relief unit (r) is layered on the back surface of the head insert 10 (which is the surface opposite to a side on which the bristles are placed) to which the bristles are fastened by thermal welding. The pressure relief unit (r) prevents resin from flowing out along the set bristles during the 12 injection molding process. As shown in FIG. 9, the pressure relief unit (r) has a size smaller than the size of the head insert, but has a predetermined size that can cover all through holes 11, which are formed through the head insert. If the size of the pressure relief unit (r) is greater than the above- mentioned range, there is a problem in that the head insert 10 cannot be integrated with a toothbrush body. If the size of the pressure relief unit (r) is less than the above- mentioned range, resin may undesirably flow outside through the set bristles. The pressure relief unit (r) is made of metal or synthetic resin having a melting point higher than that of bristles. Preferably, a silver plate or silvered plate is used as the material for the pressure relief unit (r). The pressure relief unit (r) made of such a silver or silvered plate prevents resin from flowing out along the bristles and, as well, has an antibacterial effect and a dental calculus prevention effect thanks to the emission of silver ions. To ensure the above-mentioned effects, it is required to form a hole (k) , which extends from the back surface of the head part to the pressure relief unit (r) (see, FIG. 10). Preferably, the pressure relief unit (r) has a thickness ranging from 0.05 to 0.3mm. If the thickness of the pressure relief unit (r) is less than the above- 13 mentioned range, a pressure relief effect becomes insufficient. If the thickness of the pressure relief unit (r) is greater than the above-mentioned range, the head part of the toothbrush becomes excessively thick, thus reducing tooth brushing efficiency. After the pressure relief unit (r) is layered on the back surface of the head insert 10 in which the bristles (h) are set, as shown in FIG. 11, the head insert 10 is placed in a cavity of a toothbrush forming mold using an automatic movable insertion device (s) such that the bristles (h) are placed outside the cavity of the mold. Thereafter, resin is injected into the mold, thus completing the manufacture of the toothbrush. Here, to prevent the head insert 10 having the bristles (h) from being pushed out by the injection pressure of resin, it is necessary to support the head insert 10 using a support pin (P). More preferably, as shown in FIG. 12, a holding unit (q) , which has through holes formed in the same pattern as the setting pattern of the bristles, is used in place of the support pin (p) . In this case, every bristle passes through the through holes of the holding unit (q) , and a front surface of the head insert 10 comes into close contact with the holding unit (q) . The holding unit (q) prevents the head insert 10 from being pushed out by the injection pressure and, as well, solves a problem of the 14 use of the support pin (p) in that the imprint of the support pin (p) remains on the front surface of the head insert 10. Furthermore, even in the case that the holding unit (q) is integrally mounted in the lower mold, the same effect is ensured. As such, the bristles (h) , the head insert 10 and the toothbrush body are integrated together through the above- mentioned production process. Furthermore, the present invention reliably prevents resin from flowing out along the bristles (h) . The toothbrush produced according to the present invention is shown in FIG. 13. 15 CLAIMS Claim 1 A method of producing a toothbrush, comprising: setting bristles (h) in a plurality of through holes (11) formed through a head insert (10), which is made of plastic and has a thickness ranging from 1.5 to 3.0 mm, such that parts of the bristles (h) protrude from a back surface of the head insert (10) by 1 to 3 mm; fastening the bristles (h) to the head insert (10) by thermally welding the protruded parts of the bristles (h) to the head insert (10), thus manufacturing the head insert (10) with bristles (h) ; placing the head insert (10) having the bristles (h) in a cavity of a mold for manufacturing a toothbrush body such that the bristles (h) are placed outside the cavity of the mold; placing a pressure relief unit (r) having a plate shape on the back surface of the head insert (10); and injecting resin and forming a toothbrush body. Claim 2 The method according to claim 1, wherein the process of manufacturing the head insert (10) having the bristles and the process of forming the toothbrush body through injection molding are separately conducted using different equipment. Claim 3 16 The method according to claim 1, wherein the pressure relief unit (r) is made of metal or synthetic resin having a melting point higher than a melting point of the bristles. Claim 4 The method according to claim 1, wherein the pressure relief unit (r) has a thickness ranging from 0.05 to 0.3mm. Claim 5 The method according to claim 1, wherein the pressure relief unit (r) has a predetermined size that covers the through holes, formed through the head insert, but smaller than a surface area of the head insert. Claim 6 A toothbrush, comprising: a pressure relief unit (r) installed in a head part of the toothbrush and having a plate shape and a predetermined size sufficient to cover bristles set in the head part. Claim 7 The toothbrush according to claim 6, wherein the pressure relief unit (r) is made of metal or synthetic resin having a melting point higher than a melting point of the bristles. 17 Claim 8 The toothbrush according to claim 6, wherein the pressure relief unit (r) comprises a silver plate or a silvered plate. Claim 9 The toothbrush according to claim 6, wherein the pressure relief unit (r) has a thickness ranging from 0.05 to 0.3mm. Claim 10 The toothbrush according to claim 6, further comprising: 18 a hole (k) formed in the head part and communicating from a back surface of the head part to the pressure relief unit (r). Disclosed are a toothbrush and a method of producing the same. The toothbrush of the present invention includes a pressure relief unit (r) which is installed in a head part of the toothbrush and has a plate shape and a predetermined size sufficient to cover bristles set in the head part. In the present invention, the head part is thin, and the bristles are set in the head part without using a wire. Furthermore, the present invention is easily adapted for mass production using inexpensive equipment. As well, the pressure relief unit (r), which is installed in the head part, serves as a reinforcing unit. Therefore, the head part is prevented from breaking during use despite having a reduced thickness.

Full Text

DESCRIPTION
□Invention Title
TOOTHBRUSH HAVING PRESSURE RELIEF UNIT AND METHOD OF
PRODUCING THE SAME
Technical Field
The present invention relates, in general, to
toothbrushes and methods of producing the same and, more
particularly, to a toothbrush in which a pressure relief
unit is installed in a head part of the toothbrush, and a
method of producing the same.
Background Art
Generally, to produce a toothbrush, first, a
toothbrush body having holes in a head part thereof is
manufactured. Subsequently, bristles, folded in half, are
set in the holes of the head part. The bristles are
fastened to the toothbrush body by inserting wires, which
are made of elastic metal and have a length greater than
the diameter of the hole, into the holes.
However, such a toothbrush production method has
disadvantages in that, because bristles are not reliably
fixed to the toothbrush body, the bristles are easily
removed from the toothbrush body, and impurities are easily
held in the holes formed in the head part of the
1

toothbrush. As well, this toothbrush producing method is
problematic in that bristles cannot be set in various
patterns.
As an example of techniques to overcome the above-
mentioned problems, in Korean Patent No. 360977, bristles
are set in a mold of an injection molding machine having a
bristle setting device. Thereafter, portions of the
bristles protruding into the mold are thermally welded
through a heat treatment process. Subsequently, a
toothbrush body is injection-molded along with the bristles
so that the bristles are integrated with the toothbrush
body. In this technique, the bristles are reliably fixed to
the toothbrush body. Furthermore, because it is not
necessary to form holes in a head part of the toothbrush,
the problems of the prior art are solved.
However, the above-mentioned conventional technique
has disadvantages as follow.
First, because toothbrushes are manufactured using a
mold having a constant shape, it is very difficult to
change the shape of the toothbrush body. The toothbrush
body is frequently subject to changes due to trends.
Therefore, the difficulty in changing the shape of the
toothbrush body is a serious problem. Of course, toothbrush
bodies having different shapes may be simultaneously
manufactured by mounting several different molds to a
single injection molding machine. However, in this case,
2

there is a problem in that the same number of different
toothbrushes must be manufactured and marketed.
Second, there is a problem in that if an error occurs
even in one process of a series of manufacturing processes,
all other processes must also be stopped. That is, the
conventional technique consists of processes as follow: (1)
a process of setting bristles in the mold, (2) a process of
thermally welding parts of the bristles which protrude into
the mold, and (3) a process of injection-molding a
toothbrush. If an error occurs in even one among the above-
mentioned processes, the production must be stopped.
Third, the injection molding machine is not operated
during the setting and thermal welding processes.
Accordingly, in consideration of the expensive injection
molding machine having the bristle setting device,
productivity per hour is markedly reduced.
To solve the above-mentioned problems, another
technique was proposed in Korean Patent Application No. 10-
2003-0036887.
In this technique, bristles are set in through holes
formed through a head insert 10, which is made of plastic
and has a thickness ranging from 1.5 to 3.0 mm, such that
parts of the bristles protrude from a back surface of the
head insert 10 by 1 to 3 mm. Thereafter, the protruded
parts of the bristles are thermally welded, thus separately
manufacturing the head insert 10 which has the bristles and
3

is a partial-product. Subsequently, the head insert 10
having the bristles is placed in a cavity of the mold such
that the bristles are placed outside the cavity of the
mold. Thereafter, a toothbrush body is injection-molded by
injecting resin into the mold using a normal injection
molding machine, thus producing a toothbrush.
In this technique, a process of setting the bristles
in the head insert 10, a process of thermally welding parts
of the bristles which protrude from the back surface of the
head insert 10, and a process of placing the head insert 10
having the bristles in the mold and injection-molding a
toothbrush body are separately conducted. Therefore, even
if an error occurs in one process, other processes can be
conducted. Therefore, the rate of operation of equipment is
markedly enhanced. Furthermore, the shape of the toothbrush
can be easily changed merely by manufacturing an additional
mold for the injection molding machine, which is relatively
inexpensive.
However, in this technique, when injection-molding
the toothbrush body after the head insert 10 having the
bristles is placed in the mold, a phenomenon, in which
resin may flow out along the bristles due to injection
pressure, frequently arises. As such, if resin flows out
along the bristles, the bristles become bonded to each
other, so the value of the product is deteriorated.
Meanwhile, another toothbrush manufacturing method,
4

in which a head insert 10 having bristles is separately
manufactured and is then bonded to a toothbrush body,
manufactured through a separate process, using ultrasonic
waves, was proposed. In this technique, because a process
of manufacturing the head insert 10 and a process of
manufacturing the toothbrush body are separately conducted,
the problem of deterioration of workability is solved.
However, in this technique, because the head insert 10 is
inserted into a head part of the toothbrush body and
integrated with the toothbrush body using an ultrasonic
bonding method, the head insert 10 must be precisely
aligned with the toothbrush body. Therefore, an accurate
mold is required, thus the price of equipment is
excessively increased. Furthermore, there is a problem in
that the head part of the toothbrush becomes too thick.
Generally, a head part of a toothbrush that is thin
and narrow is more convenient for a user and increases
tooth brushing efficiency. However, in the above-mentioned
technique, because the head insert is bonded to the head
part of the toothbrush along a bonding line (b) defined on
a sidewall of the head part, the head part of the
toothbrush becomes relatively thick (see, FIG. 1) . To
reduce the thickness of the head part of the toothbrush,
the bonding operation may be conducted on the front surface
of the head part. However, this bonding method requires an
increase in the area of the head part and may cause damage
5

to the bristles. Therefore, this bonding method should not
be conducted.
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 production method which solves problems of the
conventional arts when holes are formed in a head part of a
toothbrush body and wires are used, and which increases the
productivity and permits the shape of a toothbrush body to be
easily changed. Another object of the present invention is
to provide a toothbrush production method in which even if
an error occurs in one production process, other production
processes are not affected. A further object of the present
invention is to provide a toothbrush producing method which
prevents resin from flowing out along set bristles during an
injection molding process. Yet another object of the present
invention is to provide a toothbrush which has a thin head
part.
Technical Solution
In order to accomplish the above objects, the present
invention provides a method of producing a toothbrush,
including: setting bristles in a plurality of through holes
6

formed through a head insert, which is made of plastic and
has a thickness ranging from 1.5 to 3.0 mm, such that parts
of the bristles protrude from a back surface of the head
insert by 1 to 3 mm; fastening the bristles to the head
insert by thermally welding the protruded parts of the
bristles to the head insert, thus manufacturing the head
insert with bristles; placing the head insert having the
bristles in a cavity of a mold for manufacturing a
toothbrush body such that the bristles are placed outside
the cavity of the mold; and injecting resin and forming a
toothbrush body. The method of the present invention
further includes the step of placing a pressure relief unit
having a plate shape on the back surface of the head insert
before the step of injecting resin into the mold.
Advantageous Effects
In the present invention, bristles can be set in a
toothbrush body without wires. The work efficiency of an
expensive injection molding machine is maximized.
Furthermore, because a normal mold, which is manufactured
in a desired shape, can be mounted to the injection molding
machine, the shape of the toothbrush body is easily
changed. As well, even if an error occurs in one production
process, because other production processes are not affected,
the productivity is maximized.
Particularly, the present invention can prevent a
7

problem of resin flowing out along set bristles, experienced
in Korean Patent Application No. 10-2003-0036887, which was
filed by the inventor of the present invention. Furthermore,
in the case that an appropriate pressure relief unit is used,
a functional toothbrush such as an antibacterial toothbrush
can be provided. Moreover, the present invention can produce
a high grade toothbrush having reduced thickness. In
addition, because the present invention uses the pressure
relief unit (r) serving as a core material, the present
invention solves a problem of the head part breaking during
use due to its reduced thickness.
Description of Drawings
FIG. 1 is a side view showing a toothbrush
manufactured by a conventional ultrasonic bonding method;
FIG. 2 is a perspective view of a head insert used in
the present invention;
FIG. 3 is a side view of a first receiving unit used
in the present invention;
FIG. 4 is a side view of a second receiving unit used
in the present invention;
FIG. 5 is a sectional view showing a pushing plate
inserted into the first receiving unit according to the
present invention;
FIG. 6 is a sectional view showing a process of
setting bristles into a head insert, according to the
8

present invention;
FIG. 7 is a sectional view showing the bristles
fastened to the head insert by thermally welding parts of
the bristles protruding from a back surface of the head
insert, according to the present invention;
FIG. 8 is a perspective view showing the head insert
in which bristles are set;
FIG. 9 is a plan view showing a pressure relief unit
layered on the head insert according to the present
invention;
FIG. 10 is a view showing a hole formed in a head
part of a toothbrush according to the present invention;
FIG. 11 is a view showing the head insert placed in a
cavity of a mold for manufacturing a toothbrush body
through an injection molding process, according to the
present invention;
FIG. 12 is a perspective view showing a holding unit
to be used in the present invention; and
FIG. 13 is a perspective view of a toothbrush
produced by a toothbrush producing method according to the
present invention.
* Description of the elements in the drawings
10: head insert 11: through hole
20: first receiving unit 30: second receiving unit
40: pushing plate 41: insert rod
h: bristle p: support pin
9

s: automatic movable insertion device
r: pressure relief unit b: bonding line
k: hole q: holding unit
Best Mode
A toothbrush of the present invention includes a
pressure relief unit (r) which has a plate shape and a size
that is sufficient to cover bristles set in a head part of
the toothbrush.
Hereinafter, the present invention will be described
in detail with reference to the attached drawings.
FIG. 2 is a perspective view of a head insert 10
which is used in the present invention. The head insert 10
is made of plastic and has a thickness ranging from 1. 5mm
to 3.0mm. If the thickness of the head insert 10 is less
than the above-mentioned range, the head insert 10 may
undesirably bend during a thermal welding process. If the
thickness of the head insert 10 is greater than the above-
mentioned range, the head part of a toothbrush is
excessively thick.
The head insert 10 has through holes 11 therein so
that bristles are set in the through holes 11. The through
holes 11 may have different sizes, unlike conventional arts
using wires. In other words, in consideration of the
setting pattern of bristles, the size and shape of the
through holes 11 may be appropriately adjusted.
10

To set bristles in the through hole 11 of the head
insert 10, first, bristles are cut to predetermined lengths
and are held by a first receiving unit 20 having the shape
shown in FIG. 3. Thereafter, the bristles set in the head
insert 10 are transferred to a second receiving unit 30
shown in FIG. 4 and, then, are transferred to the head
insert 10. Here, the first receiving unit 20, the second
receiving unit 30 and the head insert 10 have through holes
corresponding to each other.
Furthermore, because the first receiving unit 20 and
the second receiving unit 30 serve to repeatedly transfer
bristles (h) to head inserts 10, they must be made of metal
having superior durability.
A process of receiving bristles (h) into the first
receiving unit 20 is as follows. The bristles (h) are
received into the first receiving unit 20 by pushing the
bristles (h) into the through holes 11 of the first
receiving unit 20 using a pushing plate 40 (see, FIG. 5)
provided with insert rods 41 having shapes corresponding to
shapes of the through holes 11 of the first receiving unit
20.
A process of setting the bristles (h) in the head
insert 10 is as follows. The first and second receiving
units 20 and 30 and the head insert 10 come into contact
with each other such that their through holes 11 are
aligned with each other. Thereafter, the pushing plate 40
11

pushes the bristles (h) , which are received in the first
receiving unit 20, in the direction of the head insert 10
through the second receiving unit 30 (see, FIG. 6). At this
time, the bristles (h) are set in the head insert 10 such
that parts of the bristles (h) protrude from a back surface
of the head insert 10 by 1 to 3 mm. If the protruding
length of the bristles is less than the above-mentioned
range, there is difficulty in closing the through holes 11
through a thermal welding process which will be explained
later herein. If the protruding length of the bristles is
greater than the above-mentioned range, there is a problem
in that the head part of a toothbrush becomes excessively
thick.
After the bristles (h) are set in the head insert 10,
the parts of the bristles (h) which protrude from the back
surface of the head insert 10 are melted by heating and
thus are fastened to the head insert 10 by partially
closing the through holes 11 (see, FIG. 7) . The head insert
10 which has the bristles (h) and is a semi-finished
product is shown in FIG. 8.
Prior to an injection molding process, a pressure
relief unit (r) is layered on the back surface of the head
insert 10 (which is the surface opposite to a side on which
the bristles are placed) to which the bristles are fastened
by thermal welding. The pressure relief unit (r) prevents
resin from flowing out along the set bristles during the
12

injection molding process.
As shown in FIG. 9, the pressure relief unit (r) has
a size smaller than the size of the head insert, but has a
predetermined size that can cover all through holes 11,
which are formed through the head insert. If the size of
the pressure relief unit (r) is greater than the above-
mentioned range, there is a problem in that the head insert
10 cannot be integrated with a toothbrush body. If the size
of the pressure relief unit (r) is less than the above-
mentioned range, resin may undesirably flow outside through
the set bristles.
The pressure relief unit (r) is made of metal or
synthetic resin having a melting point higher than that of
bristles. Preferably, a silver plate or silvered plate is
used as the material for the pressure relief unit (r). The
pressure relief unit (r) made of such a silver or silvered
plate prevents resin from flowing out along the bristles
and, as well, has an antibacterial effect and a dental
calculus prevention effect thanks to the emission of silver
ions. To ensure the above-mentioned effects, it is required
to form a hole (k) , which extends from the back surface of
the head part to the pressure relief unit (r) (see, FIG.
10).
Preferably, the pressure relief unit (r) has a
thickness ranging from 0.05 to 0.3mm. If the thickness of
the pressure relief unit (r) is less than the above-
13

mentioned range, a pressure relief effect becomes
insufficient. If the thickness of the pressure relief unit
(r) is greater than the above-mentioned range, the head
part of the toothbrush becomes excessively thick, thus
reducing tooth brushing efficiency.
After the pressure relief unit (r) is layered on the
back surface of the head insert 10 in which the bristles
(h) are set, as shown in FIG. 11, the head insert 10 is
placed in a cavity of a toothbrush forming mold using an
automatic movable insertion device (s) such that the
bristles (h) are placed outside the cavity of the mold.
Thereafter, resin is injected into the mold, thus
completing the manufacture of the toothbrush. Here, to
prevent the head insert 10 having the bristles (h) from
being pushed out by the injection pressure of resin, it is
necessary to support the head insert 10 using a support pin
(P).
More preferably, as shown in FIG. 12, a holding unit
(q) , which has through holes formed in the same pattern as
the setting pattern of the bristles, is used in place of
the support pin (p) . In this case, every bristle passes
through the through holes of the holding unit (q) , and a
front surface of the head insert 10 comes into close
contact with the holding unit (q) . The holding unit (q)
prevents the head insert 10 from being pushed out by the
injection pressure and, as well, solves a problem of the
14

use of the support pin (p) in that the imprint of the
support pin (p) remains on the front surface of the head
insert 10. Furthermore, even in the case that the holding
unit (q) is integrally mounted in the lower mold, the same
effect is ensured.
As such, the bristles (h) , the head insert 10 and the
toothbrush body are integrated together through the above-
mentioned production process. Furthermore, the present
invention reliably prevents resin from flowing out along
the bristles (h) . The toothbrush produced according to the
present invention is shown in FIG. 13.
15

CLAIMS
Claim 1
A method of producing a toothbrush, comprising:
setting bristles (h) in a plurality of through holes (11)
formed through a head insert (10), which is made of plastic
and has a thickness ranging from 1.5 to 3.0 mm, such that
parts of the bristles (h) protrude from a back surface of
the head insert (10) by 1 to 3 mm; fastening the bristles
(h) to the head insert (10) by thermally welding the
protruded parts of the bristles (h) to the head insert
(10), thus manufacturing the head insert (10) with bristles
(h) ; placing the head insert (10) having the bristles (h)
in a cavity of a mold for manufacturing a toothbrush body
such that the bristles (h) are placed outside the cavity of
the mold; placing a pressure relief unit (r) having a plate
shape on the back surface of the head insert (10); and
injecting resin and forming a toothbrush body.
Claim 2
The method according to claim 1, wherein the process
of manufacturing the head insert (10) having the bristles
and the process of forming the toothbrush body through
injection molding are separately conducted using different
equipment.
Claim 3
16

The method according to claim 1, wherein the pressure
relief unit (r) is made of metal or synthetic resin having
a melting point higher than a melting point of the
bristles.
Claim 4
The method according to claim 1, wherein the pressure
relief unit (r) has a thickness ranging from 0.05 to 0.3mm.
Claim 5
The method according to claim 1, wherein the pressure
relief unit (r) has a predetermined size that covers the
through holes, formed through the head insert, but smaller
than a surface area of the head insert.
Claim 6
A toothbrush, comprising: a pressure relief unit (r)
installed in a head part of the toothbrush and having a
plate shape and a predetermined size sufficient to cover
bristles set in the head part.
Claim 7
The toothbrush according to claim 6, wherein the
pressure relief unit (r) is made of metal or synthetic
resin having a melting point higher than a melting point of
the bristles.
17

Claim 8
The toothbrush according to claim 6, wherein the
pressure relief unit (r) comprises a silver plate or a
silvered plate.
Claim 9
The toothbrush according to claim 6, wherein the
pressure relief unit (r) has a thickness ranging from 0.05
to 0.3mm.
Claim 10
The toothbrush according to claim 6, further
comprising:
18
a hole (k) formed in the head part and communicating
from a back surface of the head part to the pressure relief
unit (r).

Disclosed are a toothbrush and a method of producing
the same. The toothbrush of the present invention includes
a pressure relief unit (r) which is installed in a head
part of the toothbrush and has a plate shape and a
predetermined size sufficient to cover bristles set in the
head part. In the present invention, the head part is thin,
and the bristles are set in the head part without using a
wire. Furthermore, the present invention is easily adapted
for mass production using inexpensive equipment. As well,
the pressure relief unit (r), which is installed in the
head part, serves as a reinforcing unit. Therefore, the
head part is prevented from breaking during use despite
having a reduced thickness.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=GELVW9vUMTS8w0b2JKzWOA==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

279658

Indian Patent Application Number

3050/KOLNP/2007

PG Journal Number

05/2017

Publication Date

03-Feb-2017

Grant Date

27-Jan-2017

Date of Filing

20-Aug-2007

Name of Patentee

KWON, SUNG-WOOK

Applicant Address

201-7 HEUKSEOK-1 DONG, DONGJAK-GU, 156-861 SEOUL

Inventors:

#	Inventor's Name	Inventor's Address
1	KWON, SUNG-WOOK	201-7 HEUKSEOK-1 DONG, DONGJAK-GU, 156-861 SEOUL
2	KWON, YONG-JUN	4-7 YADANG-RI, GYOHA-MYUN, 413-835 PAJU, GYUNGGI-DO
3	KWON, SUNG-HWAN	201-7 HEUKSEOK-1 DONG, DONGJAK-GU, 156-861 SEOUL

PCT International Classification Number

A46D 3/05

PCT International Application Number

PCT/KR2005/000903

PCT International Filing date

2005-03-28

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10-2005-0020507	2005-03-11	Republic of Korea