Copyright © Françoise Herrmann
What kind of toothbrush do you use? If it is an Oral-B® indicator toothbrush then it will have a few rows or other configuration of blue bristle tuffs that fade with use. This is patented technology designed to inform you that it is time to change your toothbrush!
US4802255 titled Novel brush filaments is the patent corresponding to this indicator technology, originally filed by The Gillette Company in 1989. The principle of the invention resides in dying the filaments with food grade dyes in such a manner that the degree of fastness and penetration of the dye into the filament correspond to the wear characteristics of the filament. Thus, change in the intensity of filament color becomes “a reliable indicator of the filament deterioration due to wear.”
Embodying the invention thus consisted in calculating the correct degree of dye fastness and depth of penetration into the filament, according to such variables as the width of the filament cross section , the material used for the filament (e.g., nylon), the use of solvents and/or surfactants to enhance or control penetration of the dye into the filament.
In general it is assumed that a visual indicator of bristle wear will serve to remind users to change their toothbrushes. The recommended length of toothbrush use is on average three months, although, according to consumer data quoted in the patent, users tended (in 1989) to change toothbrushes only once a year!
Embodying the invention thus consisted in calculating the correct degree of dye fastness and depth of penetration into the filament, according to such variables as the width of the filament cross section , the material used for the filament (e.g., nylon), the use of solvents and/or surfactants to enhance or control penetration of the dye into the filament.
In general it is assumed that a visual indicator of bristle wear will serve to remind users to change their toothbrushes. The recommended length of toothbrush use is on average three months, although, according to consumer data quoted in the patent, users tended (in 1989) to change toothbrushes only once a year!
The abstract for US4802255 titled Novel brush filaments is included below with a patent figure of the filament showing the dyed portions of the filament. A commercial picture of the indicator bristle tuffs for an Oral-B® toothbrush is included above.*
*Oral-B® used to belong to the Gillette Company before it was purchased by Proctor & Gamble.
"Novel, improved filaments (20) for brushes. The filaments (20) include a colored region (26) provided by a dye colorant and the colored region (26) is adapted to provide a color intensity which can change in response to increased use of the filament to provide a signal indicative of filament wear. The filaments (20) are particularly useful in toothbrushes."
The "B"in Oral-B® stands for "Brush".
