Brushing – scrubbing – and general cleaning – Implements – Brush or broom
Reexamination Certificate
1998-07-29
2001-12-18
Spisich, Mark (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Brush or broom
C015S105000, C116S212000
Reexamination Certificate
active
06330730
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a toothbrush, and in particular to a toothbrush which incorporates a device to indicate to the user that excessive force is being applied during brushing.
2. The Related Art
It is widely appreciated that people cause serious damage to their teeth and gums by brushing too hard, and there have been a number of designs of toothbrush aimed at overcoming this problem. Several studies have arrived at the conclusion that excessive pressure during brushing leads to recession on premolars, and also gingival recession, which exposes the underlying cementum, often leading to hypersensivity, loss of aesthetics, and may be a factor in root caries and root surface abrasion, leading to root fillings.
One solution is a brush which simply will not transmit excessive force, for example a design disclosed in DE 3 724 476 (Schliebs) where the neck of the toothbrush buckles if the user attempts to brush too hard. This, however, may result in a relatively flimsy product, which may be frustrating to use, as brushing may continually be interrupted. Another known solution is disclosed in U.S. Pat. No. 5,502,861 (Bioware) which provides a toothbrush with an indicator which signals to the user if excessive force is being applied. This has the advantage that the user is provided with a clear signal that brushing is too hard, and which can be used to learn to brush correctly. It is disclosed in U.S. Pat. No. 5,282,291 (Bioware) that it is thought preferable to make the indicator mechanism an integral part of the brush, rather than an attachment to it; the latter arrangement generally results in a brush which is awkwardly shaped and unnatural to use.
Known designs incorporating integral indicators generally use an electrical circuit of some kind. In the design disclosed in U.S. Pat. No. 5,282,291, components of the circuit are brought into contact as the brush flexes, completing the circuit and triggering the indicator. Often, the user must fit a battery to power the indicator, which battery must be small and will be difficult to fit. In designs where a battery is required, access to the circuitry must be available, for example through a removable cover. This arrangement is inevitably less hygienic; the cover is unlikely to fit exactly flush with the handle surface and so debris may collect in any gap between the cover and handle and possible also in the cavity itself. The device disclosed in DE 3 724 476 avoids the problem of powering the indicator circuit by relying instead on a piezoelectric component to act as a ‘mechanical-electrical convertor’ producing an electrical signal in response to the applied force. Obviously, these designs require a number of miniature components fitted into a small cavity in the-brush handle, which is likely to render them difficult and therefore expensive to manufacture. Also, it is not ideal to locate an electrical circuit in a persistently damp environment. These disadvantages can be overcome by the use of an indicator which does not require a separate power source or complex circuitry and can be incorporated easily into the body of the brush.
SUMMARY OF THE INVENTION
Thus, according to a first aspect of the invention there is provided a toothbrush incorporating an indicator comprising a pressure indicating material which provides an optical signal without the provision of a power supply, such as batteries or the electricity mains. Thus, the user can be provided with a visual indication when excessive brushing force is being used. Highly preferably, the pressure indicating material is one which provides an optical signal or response to indicate to the user when too much brushing pressure is being applied, but then may relax to its original state, e.g. colour, after a period of time. This may or may not be after the user has finished a normal brushing regime. As such, the relaxation time of the material providing the optical response may typically be in the region of 1 second to 24 hours, though it is preferably long enough for the user to register it, and is preferably less than 24 hours.
Preferably, the pressure indicating material is a piezochromic material.
The pressure indicating material according to the invention, which is preferably a piezochromic material, is a material susceptible to show an optical response upon the application of pressure.
The pressure indicating material may be a material, such as a molybdenum carbonyl, which is susceptible to changes in solvent polarity upon the application of pressure resulting in a change in colour.
In a preferred embodiment the pressure indicating material is a shear sensitive material, for example a liquid crystal or a liquid crystal blend.
The pressure indicating material may also be a material susceptible to conformational changes or structural re-arrangements upon the application of pressure, for example, crystals of toluene sulphonate diacetylene polymers; or co-polymers containing poly(diacetylenes) or poly(silylenes). Again, the pressure indicating material may be one susceptible to relative changes in refractive index upon the application of pressure, for example aromatic solvents containing poly(N-methyl acrylamide).
In another embodiment, the pressure indicating material may be one triggered to respond as a result of the pressure sensitivity of a material or materials. For example, the pressure indicating material may be a thermochromic material susceptible to a variation in temperature brought about by conduction from a further material whose temperatures varies in dependence upon the pressure applied thereto.
In yet another embodiment, the pressure indicating material may be one susceptible to a variation in electric current generated by a piezoelectric material. In this case, the pressure indicating material will display an optical response (for example a colour change) within the range of pressure generated by brushing, this pressure range being possibly amplified or reduced, and not being affected by the range of temperatures to which the brush will be routinely subjected.
In a preferred embodiment, the piezochromic material is a liquid crystal cholesterol ester. Such a material is commercially available from Hallcrest Liquid Crystal Technology Ltd, Unit 9, Stepnell Reach, 541 Blandford Road, Hamworthy, Poole, Dorset BH16 5BW. Many mixtures are available which differ in colour and physical characteristics. Examples include the CN series, e.g. CN/R1, CN/R2, CN/R3 and CN/G1 which comprise a mixture of cholesteric liquid crystals such as cholesteryl nonanoate, cholesteryl chloride, cholesteryl oleyl carbonate, cholesteryl 2,4 dichlorobenzoate.
It is envisaged that any suitable mixture of shear sensitive liquid crystal cholesteryl esters may be used in this invention.
This material displays an optical response (a colour change) within the range of pressure generated by brushing, and is not affected by the range of temperature to which a brush is normally subjected. A further advantage is that this material can relax to its original state reasonably quickly. An indicator substance which requires a period of days to recover would not be suitable for the present application. It has, however, been found useful to use a material for providing the optical response which demonstrates a degree of hysteresis.
Once the optical indicator has been triggered, the signal is preferably long enough so that the user can remove the brush from his mouth to inspect it. Typically, this period is in the range of from 1 second to 24 hours. This property allows the brush of the present invention to overcome another of the problems inherent in earlier designs, by ensuring that the indicator is easily visible to the user. When a brush is in use, it is partially inserted into the mouth and, generally, a significant proportion of the handle is covered by the user's hand. This means that a visual indicator integral with the brush is difficult to see during brushing, and that the user may have to rely on looking in the mirror. If, however, the indicator pe
Davies Richard Huw
Jones Paul
Savill Derek Guy
Chesebrough-Pond's USA Co. division of Conopco, Inc.
Honig Milton L.
Spisich Mark
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