Bristle unit used for toothbrush and implanting method thereof

A bristle unit mounted on a brush head of the top of a handle of a toothbrush in a freely rotatable manner, said bristle unit comprising:

• a reel having spiral grooves on its circumference;
• a plurality of strands made of synthetic resin filament such as nylon;
• and
• a lead wire for winding the strands,
• said plurality of strands are bent into two in a U-shape so that the lead wire for winding which is common to the bent center part is fixed by welding or adhering thereto while the lead wire is plunged in such a manner to be wound around a spiral groove arranged around the circumference of the reel at a spiral pith along the spiral groove,
• Wherein a free end of the set of strands extended above the waist of the reel in a predetermined length, wherein the edges of the ejecting part are trimmed so as to form the bristle unit in a reel shape as a whole,
• said brush head comprises an axis member supporting the reel wherein the axis member is inserted into a penetrating hole provided at the center of the reel body so as to support the bristle unit in a freely rotatable manner.

An implanting method of a bristle unit for a toothbrush comprising the following steps [A] to [C]:

• [A] preparing a set of strands of bristles formed by bending a plurality of strands, made of synthetic resin filament such as nylon, into two in a U-shape and by aggregating the strands as a bunch, wherein a lead wire for winding common to the center of the strands is fixed by welding or adhering thereto;
• [B] preparing a reel for bristles by providing a spiral groove on its circumference so that one or more rows of said set of strands of bristles are plunged into the groove;
• and
• [C] plunging said set of strands of bristles into the spiral groove in such a manner to be wound spirally around the groove on the circumference of the reel with a spiral pitch along it from one end of the lead wire while the center of the strands is fixed by the lead wire, wherein a free end of the set of the stands extends above the reel while a clearance is provided between the strands plunged into the grooves adjacent to each other.