EP1903907A1

EP1903907A1 - Wear indicator for a personal care device

Info

Publication number: EP1903907A1
Application number: EP06765816A
Authority: EP
Inventors: Ytsen Wielstra
Original assignee: Koninklijke Philips Electronics NV
Current assignee: Koninklijke Philips NV
Priority date: 2005-06-21
Filing date: 2006-06-21
Publication date: 2008-04-02
Also published as: CN101203157A; JP2008546466A; WO2006137028A1

Abstract

The present invention is directed to a wear indicator for a personal care device. The wear indicator includes a reflecting layer and a blocking layer. The blocking layer is disposed over the reflecting layer and is degradeable over time. The blocking layer prevents light from being reflected from the reflecting layer until the blocking layer has degraded.

Description

WEAR INDICATOR FOR A PERSONAL CARE DEVICE

The present invention relates generally to personal care devices, and more particularly, to a wear indicator for personal care devices. Many personal care devices are either disposable or have disposable elements. For example, manual toothbrushes and disposable wet shavers wear out and have to be replaced. Further, brush heads for electric toothbrushes and wet shaver cutting elements also wear out and have to be replaced.

A problem with these type of disposable devices is that it is not often evident to the user when to replace these devices. For examples, the bristles of a toothbrush may appear fully functional to the user. However, the bristles may still be worn enough where the toothbrush is not providing optimum cleaning for the user.

In view of the above, the present invention is directed to a wear indicator for a personal care device. The wear indicator includes a reflecting layer and a blocking layer. The blocking layer is disposed over the reflecting layer and is degradable over time. The blocking layer prevents light from being reflected from the reflecting layer until the blocking layer has degraded. In one example, the wear indicator also includes a contrast layer.

In another example, the reflecting layer is a reflective foil and the blocking layer is a non-transparent material. Further, the blocking layer is selected from a group consisting of a water soluble polymer or a water insoluble polymer.

In another example, the reflecting layer is a diffraction foil and the blocking layer is a water soluble polymer. Further, the water soluble polymer has an index of refraction approximately the same as the diffraction foil. Referring now to the drawings where like reference numbers represent corresponding parts throughout:

Figure 1 is one example of a personal care device according to the present invention;

Figure 2 is one example of a wear indicator according the present invention;

Figure 3 is another example of a wear indicator according to the present invention; Figure 4 is still another example of a wear indicator according to the present invention; and

Figure 5 is another example of a personal care device according to the present invention. One example of a personal care device according to the present invention is shown in Figure 1. In this example, the personal care device is a brush head 2 for an electric toothbrush. The brush head 2 will be made according to conventional methods except that it will include a wear indicator 6. The wear indicator 6 will preferably be disposed within the outer surface of the brush head 2. However, alternatively the wear indicator will be disposed on top of the outer surface.

The wear indicator 6 will consist of two layers including a reflecting layer and a blocking layer. The blocking layer will be disposed on top of the reflecting layer preventing any light from being reflected back to the user. Over time the blocking layer will degrade away to expose the reflecting layer enabling it to reflect light back to the user. This will indicate to the user that it is time to replace the brush head 2. The time it takes for the blocking layer to degrade away is due to the material selected and the thickness of the layer.

It is preferred that the material used and the thickness of the blocking layer be selected to provide a predetermined time to replace the brush head 2. One example of a wear indicator according to the present invention is shown in

Figure 2. In this example, the wear indicator 6 is disposed within an impression 4 of an outer surface of the personal care device. The wear indicator includes a reflecting layer 8 and a blocking layer 10. As can be seen, the blocking layer 10 is disposed over the reflecting layer 8. As previously described, the blocking layer 10 prevents any light from being reflected back to the user. Overtime the blocking layer 10 degrades away to expose the reflecting layer 8 enabling light to be reflected back to the user. This will indicate to the user that it is time to replace the brush head.

In this example, the reflecting layer 8 is a reflective foil. Reflective foils are thin pliable laminated films that have reflective properties. Reflective foils consist of two different layers of material that are laminated together and then folded over a number of times. Examples of the two different materials used for reflective foils are polymethylmethacrylate (PMMA) and polyethyleneterephtalate (PET). Reflective foils are capable of reflecting a wide range of colors depending on the layer thickness and the number of layers. One example of a reflective foil is manufactured by Engelhard under the trademark AURORA. When a metallic reflection is desired aluminum plated foils can be used. In the present example, the reflective foil 8 may be applied in the impression 4 by gluing or insert molding. In this example, the blocking layer 10 can be any non-transparent material that is capable of degrading over time. Suitable materials include a water-soluble polymer or a water insoluble polymer. Water-soluble polymers degrade over time by being exposed to water and are well suited to be used in tooth brushes and wet shavers. Examples of water soluble polymers include Polyethyleneglycol (PEG), Polyvinylalcohol (PVA), starches and poly caprolacton, polycaprolactam, polyhydroxy (meth)acrylates, copolymers of vinylmethylether and maleic anhydride, etc. These water soluble polymers can be applied over the reflecting layer 8 by macro/micro dosing, pad printing, hot melt or other suitable applicable technique known in the art. Since water soluble polymers can be transparent, in this example, a filler is included in the material of the blocking layer to make the water soluble polymer non-transparent.

Water insoluble polymers degrade over time due to wear and are well suited to be used in applications where the personal care device is not necessarily exposed to water such as an dry electric shaver. Examples of water insoluble polymers include amongst others cellulose esters, one component polyacrylates or two component polyurethanes. Many more can be found in Dieter Stoye and Werner Freitag, Resins for Coatings ISBN 3-446-18489-9. In this example, the water insoluble polymer may also be applied over the reflecting layer 8 by macro/micro dosing pad printing, hot melt or other suitable applicable technique known in the art. In another example, the reflective layer 8 is a hologram that provides a holographic image. In this example, the blocking layer 10 may also be a water soluble polymer or a water insoluble polymer, as previously described.

Another example of a wear indicator according to the present invention is shown in Figure 3. In this example, the wear indicator 6 is also disposed within an impression 4 of an outer surface of the personal care device. The wear indicator 6 also includes a reflecting layer 12 and a blocking layer 10. However, in this example, the reflecting layer 12 is a diffraction foil.

Diffraction foils are thin pliable films that include a plurality of reflective slits forming a diffraction grating. Light is reflected from the grating in unique patterns of light due to constructive and destructive interference. The light patterns will differ due to wavelength being reflected and the size of the slits in the grating. Diffraction foils consist of a carrier layer (e.g PET) and an embossed diffraction layer (e.g. nitrocellulose). In the present example, the diffractive foil 12 may be applied in a number of different ways including embossing, photo replication techniques using ultra violet curable polymers or injection molding. The technique used will depend on the material used. For example, polymeric materials such as nitrocellulose work well with embossing.

It should be noted that some materials used for diffraction foils do not have a very high reflectivity. Thus, it may be desirable to coat such materials with another material to increase the reflectivity in order to provide a better visual effect. For example, a diffraction foil of nitrocellulose material could be coated with aluminum to increase its reflectivity. The aluminum may be applied by an evaporation technique.

As described above, if a coated diffraction foil is used as the reflecting layer 12, it may be disposed in the impression 4 so that diffraction layer is on top, as shown in Figure 3. Alternatively, the coated diffraction layer may be disposed within the impression 4 upside down so that the diffraction layer is on the bottom. This would be desirable to protect the coating from wearing away depending on the application. In this example, the blocking layer will disposed over the carrier layer of the diffraction foil. As can be further seen, this example also includes a blocking layer 10 disposed over the diffraction foil 12. As previously described, the blocking layer 10 is degradable over time. Further, in this example, the blocking layer 10 is capable of inhibiting the light pattern generated from the diffraction foil. In the case where the diffraction foil 12 is coated, the blocking layer may be any non-transparent material such as a water soluble polymer or a water insoluble polymer, as mentioned above.

However, in the case where the diffractive foil 10 is not coated with another material, the blocking material 12 may be transparent when the index of refraction of the blocking layer 10 is the same as the diffractive foil 12. This is because diffraction patterns are only visible when there is a difference of index of refraction between two materials. For example, nitrocellulose material has an index of refraction of approximately 1.5, while air has a refractive index of about 1. Thus, a suitable material for the blocking layer 10 would be a water soluble polymer such as Polyvinylalcohol and Polyvinylpyrrolidone, which both have approximately an index of refraction of approximately 1.5.

Another example of a wear indicator according to the present invention is shown in Figure 4. This example is the same as the example of Figure 3 except that it includes one more layer 14. As can be seen, a contrast layer 14 is disposed below the diffraction foil 10. The contrast layer 14 is of a material darker than the diffraction foil 10 so that it absorbs more of the light that is not diffracted. This will provide a brighter light pattern to be reflected from the diffraction foil 12. The contrast layer 14 can be the carrier layer of the diffractive foil itself or may be of an additional laminated foil, but it also can be a part of the brush using 2 K injection molding techniques.

In the examples of Figures 2-4, the thickness of the blocking layer 10 may also be selected to provide a predetermined time to indicate to the user when to replace the brush head. For example, the typical thickness is around a few tenths of a millimeter depending on the material used.

Another example of a personal care device according to the present invention is shown in Figure 5. In this example, the personal care device is a wet shaver 16. The wet shaver will be made according to conventional methods except that it will include a wear indicator 6. The wear indicator 6 will again also consist of two layers including a reflecting layer and a blocking layer. Any of the examples of the wear indicators shown in Figures 2- 4 may be used depending on the desired application.

While the present invention has been described above in terms of specific examples, it is to be understood that the invention is not intended to be confined or limited to the examples disclosed herein. Therefore, the present invention is intended to cover various structures and modifications thereof included within the spirit and scope of the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A wear indicator, comprising: a reflecting layer; a blocking layer disposed over the reflecting layer and being degradable over time, the blocking layer preventing light from being reflected from the reflecting layer until the blocking layer has degraded.

2. The wear indicator of claim 1, wherein the blocking layer is of a material and thickness that enables the blocking layer to degrade over predetermined time period.

3. The wear indicator of claim 1, which further includes a contrast layer.

4. The wear indicator of claim 1, wherein the reflecting layer is a reflective foil.

5. The wear indicator of claim 4, wherein the blocking layer is a non- transparent material.

6. The wear indicator of claim 4, wherein the blocking layer is selected from a group consisting of a water soluble polymer or a water insoluble polymer.

7. The wear indicator of claim 1, wherein the reflecting layer is a diffraction foil.

8. The wear indicator of claim 7, wherein the blocking layer is a water soluble polymer.

9. The wear indicator of claim 8, wherein the water soluble polymer has an index of refraction approximately the same as the diffraction foil.

10. The wear indicator of claim 7, wherein the blocking layer is a water insoluble polymer.

11. A personal care device, comprising: an outer surface; a wear indicator on the outer surface including a reflecting layer and a blocking layer disposed over the reflecting layer and being degradable over time, the blocking layer preventing light from being reflected from the reflecting layer until the blocking layer has degraded.

12. The device of claim 11 , wherein the blocking layer is of a material and a thickness that enables the blocking layer to degrade over predetermined time period.

13. The device of claim 11, which further includes a contrast layer.

14. The device of claim 11, wherein the reflecting layer is a reflective foil.

15. The device of claim 14, wherein the blocking layer is a non-transparent material.

16. The device of claim 14, wherein the blocking layer is selected from a group consisting of a water soluble polymer or a water insoluble polymer.

17. The device of claim 11, wherein the reflecting layer is a diffraction foil.

18. The device of claim 17, wherein the blocking layer is a water soluble polymer.

19. The device of claim 18, wherein the water soluble polymer has an index of refraction approximately the same as the diffraction foil.

20. The device of claim 17, wherein the blocking layer is a water insoluble polymer.