Brushing – scrubbing – and general cleaning – Implements – Brush or broom
Reexamination Certificate
2000-01-26
2002-05-21
Spisich, Mark (Department: 1744)
Brushing, scrubbing, and general cleaning
Implements
Brush or broom
C015S105000, C116S212000
Reexamination Certificate
active
06389636
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 a suitable 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 hypersensitivity, 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 due to the limited size of the brush must be small and is, therefore, tricky 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 debris may collect in any gap between the cover and handle and 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 a battery in a persistently damp environment, especially if it has to be replaced from time to time. 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.
Our co-pending application PCT/EP98/04998 discloses a brush comprising a piezochromic element which indicates when a safe brushing pressure has been exceeded.
There is, therefore, a need for a brush which positively indicates to the user that the correct brushing pressure is being used as opposed to informing him when too much pressure has been applied.
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 a signal without the provision of a power supply, such as a battery or the electricity mains, characterised in that the indicator is capable of providing the signal when a suitable brushing pressure is being or has been applied.
Thus, the user can be provided with a positive, indication when a suitable brushing force is being or has been used.
In a preferred embodiment the signal is provided when a suitable brushing pressure is being applied and is absent when brushing pressure is too high.
Preferably, the pressure signal is a signal, especially an optical signal, which indicates to the user when a suitable brushing pressure is being applied, but then may relax to its original state, e.g. colour or illumination, 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. More preferably, the relaxation time for the pressure indicating material is between 1 second and 10 minutes and especially between 1 second and 5 seconds.
Although the preferred signal is an optical signal it is also envisaged that the signal may be an audible or mechanical signal. For example, a suitable audible signal may be music or a buzzer, while a suitable mechanical signal may be a vibration.
Where the signal is an optical signal it is preferred that 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.
Such piezochromic materials include 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 rearrangements upon the application of pressure, for example, crystals of toluene sulphonate diacetylene polymers; or copolymers 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).
According to this invention the indicator is capable of providing a signal when brushing pressure is being or has been applied and is absent when brushing pressure is too high. Thus it is an essential feature of the invention that the pressure indicating material is so calibrated to be capable of providing such a signal. An example of such calibration for a brush comprising a piezochromic material may be the presence of only a certain amount of the active shear sensitive material or the inclusion of an additional material, such as a polymer, which may act as a signal modifier, e.g. by changing the viscosity of the crystals, which will prevent a signal being provided if the brushing pressure is too high.
It is also envisaged that the signal provided on application of a correct brushing pressure may be graduated to reflect changes in brushing pressure within the suitable range. For example, where the indicator provides an optical signal is possible that the optical signal may vary with dependence upon the changes of the brushing pressure, e.g. the signal may be green when brushing pressure is optimal; amber when pressure is sub-optimal but acceptable and red when pressure is approaching an unacceptable level. The signal would, of course, disappear when the correct pressure is no longer being applied. In a similar way the optical signal may involve the illumination of a single bulb and the degree of illumination may dim when the brushing pressure approaches levels which are not correct.
In another embodiment, the pressure indicating material may be one triggered to respond as a result of the pressure sensitivity of another material. For example, the pressure indicating material may be a thermochromic material susce
Spisich Mark
Unilever Home & Personal Care USA, Co, division of Conopco, Inc.
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