Abstract:
A brush with flexible bristles in which each bristle includes a flexion integral with the bristle to provide innate resilience to the bristle for flexing along its longitudinal axis. The brush fitted with the bristles includes a perforated brushhead for passing the bristles so as to maintain the bristles on their axis. A trapezoidal bristle grid provides for bristle density in the brush comparable the standard brush density.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to brushes and particularly to brushes with flexible bristles, that is, bristles that flex along their longitudinal axis. 
     In conventional brush construction, bristles are anchored at their lower tips in a brush base. When scrubbing pressure is applied to the upper tips, the bristles tend to deflect off their axis with consequent loss of scrubbing effectiveness. To compensate, bristles are made stiffer for maintaining scrubbing effectiveness. Stiff bristles are suitable for flat surfaces and when the surface is convex only a portion of the bristles in the overall brush length make contact with the surface. In the case of a toothbrush, bristle contact occurs at the high points of teeth contour and the intermediate recesses or hollows remain unbrushed. 
     There is need for a brush with bristles that flex longitudinally, that is, undergo an effective or virtual decrease in the height of the bristle, so that the brush over its entire length of bristles remains in contact with curved surfaces such as a toothbrush for brushing teeth. 
     SUMMARY OF THE INVENTION 
     The present invention provides a brush with bristles or tufts of bristles that flex along the longitudinal axis of the bristle. 
     In a preferred embodiment of the invention, an elongate bristle has its lower tip embedded in a brush base, with an intermediate section of the bristle above the base being bent or flexed with respect to the longitudinal axis, and with the upper portion of the bristle lying along the axis normal to the base. The result is a bristle resilient to downward pressure applied at the upper tip, with the bristle compressing along its axis. A set of bristles compresses in conformity with a convex surface so that a toothbrush contacts both high and hollow surfaces of teeth. The innate resilience of the bristles permits design of a brush with tufts that can change in effective height thereby conforming to variations in the surface contour of the brushed object. 
     Several embodiments of compressible or flexible bristles and tufts of bristles are disclosed. 
     In another aspect of the invention, a brush with flexible bristles comprises a base for receiving a plurality of bristles and a perforated brushhead overlying the base and together with the base defining a cavity for enclosing the lower portion of the bristles including their flexed sections. The brushhead is perforated with apertures through which the bristles project and with the apertures maintaining the bristles normal to the base as the bristles flex along their longitudinal axis. 
     In another aspect of brush design, bristle tufts are distributed on the base in a trapezoidal pattern to provide the added space necessary for proper flexing of tufts when brushing. The trapezoidal pattern of tufts gives a tuft density comparable to that in standard brushes, toothbrushes for example. 
     A brush with bristles or tufts of bristles according to the invention follows a convex row (teeth) within the practical limits of bristle flexing. Along the brush length, conformity may be larger or smaller depending on the curvature of the teeth in a particular section of the row of teeth. Conformity also varies with the excursion of the bristles, i.e., the limits of longitudinal movement of bristle when pressure is applied to its upper tip. So, the greater the excursion, the greater is the conformity range along the length of the brush. In any case, conformity is significant for a single tooth or several teeth along a shorter range of the total length of the brush. 
     A brush according to the invention uses standard brush materials with little or no increase to the height of the brush measured from base to bristle tips. 
     OBJECTS OF THE INVENTION 
     An object of the invention is to provide a brush with bristles that readily conform to curved surfaces. 
     Another object of the invention is to provide a brush with bristles or tufts of bristles each having a flex section accommodating compression of the bristles along their long axis so that a section of bristles conforms to curved surfaces. 
     Another object of the invention is to provide a brush with flexible bristles and a brush head with apertures for maintaining bristles normal to the brush base as the bristles flex. 
     Another object of the invention is to provide a brush with flexible bristles arranged in a trapezoidal pattern in the brush base to allow for bristle flexing and a bristle density comparable to standard brush design. 
     Another object of the invention is to provide a toothbrush with flexible bristles for greater contact by the bristle tips with the irregular surface of a row of teeth. 
     Other and further objects of the invention will become apparent with an understanding of the following detailed description of the invention or upon employment of the invention in practice. 
    
    
     A preferred embodiment of the invention has been chosen for purposes of detailed description and is shown in the accompanying drawing in which: 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a flexible bristle embedded in a base according to the invention. 
     FIG. 2 is a schematic view of a brush with flexible bristles according to the invention. 
     FIGS. 3a-d are schematic views of flexible bristles with particular types of flexions. 
     FIGS. 4a-c are schematic detail views of bristle tuft spacing on a trapezoidal pattern. 
     FIG. 5 is an enlarged perspective view of a flexible tuft of bristle according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawing, FIG. 1 illustrates a segment of a brush 10 according to the invention including a base 12, and an elongate bristle 14 anchored at its lower tip 14a in the base. The bristle projects upwardly from the base along a longitudinal axis x--x&#39; normal to the base. The bristle includes a flexion 16 in the form of a bent or oblique section that yields or flexes like a knee,18 when pressure is applied to the upper tip 14b of the bristle. 
     A brush 10 fitted with bristles 14 according to the invention is shown in FIG. 2 and includes a base 12 for anchoring bristles or tufts of bristles projecting upwardly. A modified bristle includes a perpendicular flexion or knee 20 lying generally horizontally between upper 20a and lower 20b portions of the bristle. A brushhead 22 overlies the base and together with the base defines a cavity 24 enclosing the flexion portion of the bristle. Each bristle passes through an aperture 26 in the brushhead so that the brushhead keeps the bristle aligned along its axis enabling the bristle to move vertically to the limits of its design excursion. 
     If desired, one or more drain ports 27 (FIG. 1) may be located in the brush as for example in base 12 to provide for draining and drying of the cavity. 
     Several modified embodiments of bristle are shown in FIGS. 3a-d. 
     In Figure, 3a, a brush as described in FIG. 2 is fitted with a bristle 14 having an arcuate flexion 28 in the form of a segment of a circle. The flexion acts as a spring and flexes when pressure is applied at tip 14b. 
     FIG. 3b illustrates a bristle 14 with one form of concentric flexion. The flexion 30 comprises a plurality of legs 30a bent at an acute angle interconnecting the bottom 14c of the bristle and the base 12 of the brush 10. The legs 30a are positioned radially of the bristle body as seen in FIG. 3b&#39;. The legs provide flex for the bristle when pressure is applied to its tip 14b. It is also to be observed in FIG. 3b&#39; that the interlocking of legs reduces intertuft distance for achieving greater bristle density. 
     Another type of concentric flexion is shown in FIG. 3c and includes a pair of oblique flexions or knees 32 opening outwardly form each other to provide flex. 
     An offset flexion 34 is illustrated in FIG. 3d wherein the base 12 includes integral posts 12a with horizontally opening bores 12b receiving the lower bristle tips 14a. The canted flexion 34 carries an upwardly extending bristle 14 projecting through one of the brushhead apertures 26. The offset flexion accommodates vertical excursion of the bristle when pressure is applied to the tip 14b. 
     In a brush according to the invention, bristles are arranged in a trapezoidal grid to achieve to space required for flexing and to provide a bristle density comparable to standard brush design. As shown in FIG. 4a-c, a bristle 14 with perpendicular flexion 20 has a width of 3.8 mm (FIG. 4a). The trapezoidal pattern P for spacing of the bristles in a base appears in FIG. 4b with horizontal center-to-center spacing of 2.8 mm; vertical center spacing of 1.8 mm; and diagonal spacing of 1.8 mm. This arrangement gives a distribution or density of bristles as shown in FIG. 4c. 
     A tuft of bristles 36 is illustrated in FIG. 5 comprising an upper section 36a of a bundle, of individual, discrete strands or bristles 14 free at their upper ends and joined as by fusing at an intermediate section 36b. A lower, shorter section 36c of the tuft includes a bundle of bristles including a fused section 36d and discrete bristles 36e. If desired discrete bristles 36e may be fused. The upper and lower bundles of strands are joined by a helical compression spring 38 serving as a flexion to accommodate vertical movement of the tuft of bristles when pressure is applied to the tip 36f. The ends 38a-b of the spring are affixed or fused to the fused sections. A flat or arcuate spring may be used in place of the helical spring. 
     A brush with flexible bristles according to the invention has many applications and is particularly suited for toothbrushes. Reference in the specification to toothbrushes is intended in an illustrative sense. 
     Various changes may be made to the structure embodying the principles of the invention. The foregoing embodiments are set forth in an illustrative and not in a limiting sense. The scope of the invention is defined by the claims appended hereto.