Brush – broom – and mop making – Processes
Reexamination Certificate
2003-12-19
2004-09-07
Till, Terrence R. (Department: 1744)
Brush, broom, and mop making
Processes
Reexamination Certificate
active
06786558
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a brush head, particularly a toothbrush head, with a bristle carrier and bristles fixedly secured thereto, said bristle carrier having an elongated recess in which a multiplicity of bristles is received forming an elongated tuft with a closed, smooth outer contour corresponding essentially to the contour of the elongated recess.
This invention further relates to a method of manufacturing such a brush head, in which provision is made for a bristle carrier having a multiplicity of bristles fastened thereto.
BACKGROUND
Tufts can be fastened to bristle carriers of toothbrushes in various ways. A first method comprises arranging a tuft in a U-shaped configuration and, using a small metal anchor plate placed between the limbs of the U-shaped tuft, inserting it into a blind-end bore provided in the bristle carrier and fastening it there. The anchor plate lies over the U-shaped bend of the tuft and digs into opposing side walls of the blind-end bore. With this method referred to as anchor tufting it is mainly possible to fasten tufts of simple geometries, in particular those with a circular or square cross-section (cf. EP 0 700 259 B1).
A second method of fixedly securing the bristles to the bristle carrier comprises fastening the tufts by injection molding the material of the bristle carrier around the tufts (cf. EP 0 678 368 B1). With this method it is possible to fasten tufts of practically any cross-section and also any size to the bristle carrier.
A third method comprises the steps of inserting the tufts in a plastic perforated plate, welding together the bristle ends opposite the free end of the tufts by means of an embossing punch on the bottom side of the perforated plate, injection molding material onto the perforated plate with the tufts fastened thereto, and securing the perforated plate to a bristle carrier by adhesive bonding or alternatively, removably (cf. WO 99/55194). Tufts with variable cross-sectional geometries are obtainable with this embodiment, too, but the thermal welding of the bristles is, like the previously described injection molding operation, relatively complex and hence cost-intensive compared to the anchor tufting method.
A toothbrush head of the type initially referred to is known from U.S. Pat. No. 5,446,940, where the bristle carrier has several slot-type recesses, in each of which there is an elongated tuft with a closed, smooth outer contour. Because it is difficult to fill the slot-type recesses with bristles and align all the bristles in vertical direction it is proposed in U.S. Pat. No. 5,446,940 to replace the slot-type recess by several holes of circular or rectangular cross-section arranged in a row one behind the other and to fasten a separate tuft in each of these holes. The result, however, is not a single elongated tuft with a closed outer contour but a row of singular tufts arranged one behind the other. Furthermore, the size of the slot is limited by the anchor plates used.
The art also knows of an array of several circular tufts in a row one behind the other, in which the outer tufts can be inwardly inclined. To enable unhindered movement of the individual tufts it is proposed in said printed specification to space all the tufts a generous distance from one another. Mutual supporting of the individual tufts is to be prevented.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved brush head of the type initially referred to, as well as an improved method of the type initially referred to for its manufacture, which avoid the disadvantages known from the prior art and advance the prior art in advantageous manner. In particular it is intended to improve the manufacturability of a brush head having an elongated tuft of closed contour and to render the method of manufacturing more cost efficient.
This object is accomplished with a brush head of the type initially referred to in that, according to the invention, the elongated recess is divided by means of at least one transverse wall into several segments, a separate tuft is received in each of the segments, and the at least one transverse wall is constructed so that the separate tufts converge, forming in combination the elongated tuft with a closed, smooth outer contour.
Hence there are no completely separate individual tufts simply arranged in a row. At their fastening ends the tufts are separately joined and fastened, but at their free ends used to clean the teeth the bristles converge into a joint, elongated tuft and the division into separate tufts is no longer visible. This is important for the cleaning action and wear characteristics of the brushes.
To this effect the slot-type recess is constructed so that each segment has opposing side walls connected by the at least one transverse wall and extending symmetrically to the longitudinal axis of the slot-type recess, in particular parallel to each other. The side walls of contiguous segments lead continuously and steadily into each other and are interrupted solely by the transverse wall. The transverse walls lend stability to the bristle fixture to counter movement of the bristles in the longitudinal direction of the recess. They make it materially easier to fasten the bristles by the conventional anchor tufting method and, depending on the geometry of the recess, may even be a prerequisite for using this method.
In a further aspect of the invention the bristles of each separate tuft can be received in the respective segment in a U-shaped configuration and be held by a preferably plate-shaped anchor anchored in the respective segment. The anchor can extend between the limbs of the U-bent bristles over their connecting sections, holding them against the bottom of the slot-shaped recess. Hence there is no need for the bristles to be fixed in place by injection molding, adhesive bonding or welding. They can be anchored with a separate anchor to the bristle carrier by positive and frictional engagement. A brush head of such construction is far less costly to manufacture than conventional brush heads with elongated tufts.
The anchors provided in the individual segments to anchor the tufts can be arranged in various ways. According to a preferred embodiment of the invention the anchors extend in a direction essentially transverse to the longitudinal axis of the slot-type recess, meaning essentially or nearly parallel to the respectively neighboring transverse wall of the respective segment. The anchor preferably forms an angle of less than 30 degrees with the respectively neighboring transverse wall. The longitudinal axis of the slot-type recess is not necessarily straight in the context of the present invention, but rather the longitudinal alignment of the slot-type recess can be adapted to the conditions of the respective brush head, in particular can be curved or kinked, so that an angle can be formed between the anchor and the respectively neighboring transverse wall of the respective segment. Thanks to the alignment of the anchors in a direction essentially transverse to the longitudinal axis of the slot-type recess, the tufts in the respective segment are able to adapt to its contour to the best possible effect. The tufts anchored in the individual segments form, in particularly advantageous manner, the desired closed contour of the elongated tuft.
The at least one transverse wall in the slot-type recess can be constructed in various ways and forms. A preferred embodiment of the invention consists of providing a separately constructed transverse bar anchored to the bristle carrier to serve as the transverse wall. Provision can be made preferably for a thin metal bar which is anchored in opposing side walls of the slot-type recess. In particular it is possible to shoot an anchor wire or an anchor plate, of the type normally used to fasten the bristles, into the slot-type recess to serve as the transverse wall. However, to serve as the transverse wall the anchor plate or a comparable plate is inserted in advance without bristles in the slot-type recess
Driesen Georges
Fritsch Thomas
Schwarz-Hartmann Armin
Braun GmbH
Cole Laura C
Podszus Edward S.
Till Terrence R.
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