Cutlery – Razors – With cooperating shearing blades
Reexamination Certificate
1998-12-01
2001-01-30
Rachuba, M. (Department: 3724)
Cutlery
Razors
With cooperating shearing blades
C030S346510
Reexamination Certificate
active
06178641
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an electrical hair-cutting apparatus having an external cutting member and an internal cutting apparatus which is drivable relative to the external cutting member, which external cutting member is formed by a first wall portion, which constitutes a cutting face, and at least a second wall portion, which is disposed at an angle with respect to the first wall portion, which first wall portion has lamellae between which elongate hair-entry apertures are situated, ends of the lamellae extending beyond the second wall portion in such a manner that the ends of the lamellae form a row of teeth for raising hairs before they are severed by cooperation between the cutting members.
BACKGROUND OF THE INVENTION
A hair-cutting apparatus of the type defined in the opening paragraph is known from JP-A-62/246396. The teeth at the ends of the lamellae serve to facilitate the entry of hairs to be severed into the hair-entry apertures between the lamellae. In practice, it appears that partly the hairs are not caught between the teeth but are flattened and, as result of this, do not enter into the hair-entry apertures.
SUMMARY OF THE INVENTION
It is an object of the invention to improve the hair-catching efficiency of the hair-cutting apparatus of the type defined in the opening paragraph. To this end, the hair-cutting apparatus in accordance with the invention is characterized in that the teeth have different projecting lengths with respect to the second wall portion. Surprisingly, it has been found that this results in more hairs being caught per cutting movement, i.e. during an average length of movement of the cutting apparatus over the skin. This can be explained from the fact that the distance between two teeth having a great projecting length (long teeth) is now larger, as a result of which hairs which lie flatter on the skin can be raised. Once such a hair has been lifted this hair can subsequently be raised further and guided into a hair-entry aperture (gap) by a tooth having a smaller projecting length (short tooth). If all the teeth would have the same length such a hair, which lies comparatively flat, could not be raised but would be flattened under the tooth. If in a situation that all the teeth have the same length the distance between the teeth would be made, for example, two or three times as large, this essentially leads to an increased chance of more flat-lying hairs being raised. However, to sever hairs the width of the hair-entry aperture (gap) between the lamellae should be within given limits. This width cannot be chosen to be, for example, twice as large in view of the protrusion of the skin in the hair-entry aperture. Increasing the distance between the teeth would then be possible only, for example, by leaving out every second tooth. In that case there are lamellae whose ends do not terminate in a tooth but which end near the second wall portion. As a result of this, a hair raised by a tooth is not guided properly into the hair-entry aperture because this hair strikes against the second wall portion near the lamella without a tooth and is subsequently flattened underneath the lamellae. It is therefore desirable that at least most lamellae, preferably all lamellae, end in a tooth. By using both long and short teeth, for example alternately, the likelihood of catching is increased and, as a result, the cutting performance is improved.
REFERENCES:
patent: 4003130 (1977-01-01), Rookus
patent: 4635360 (1987-01-01), Tanahashi et al.
patent: 5669138 (1997-09-01), Wetzel
patent: 5802721 (1998-09-01), Wain et al.
patent: 5802932 (1998-09-01), Vankov et al.
patent: 5893211 (1999-04-01), Hotani
patent: 62-246396 (1987-10-01), None
Bartlett Ernestine C.
Rachuba M.
U.S. Philips Corporation
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