Patent Application
20050278877
This invention relates generally to powered skin cleansing brushes and more specifically to bristle arrangements for use in such a skin cleansing brush.
In a skin cleansing brush, particularly a powered brush which is constructed such that a portion of the brushhead and the bristles thereon remain stationary while another portion thereof oscillates, a number of factors are important for good cleansing action. The ability of the powered skin cleansing brush to effectively and safely function, including in addition to cleansing, exfoliation and increasing the absorption of various skin formulations, is significantly affected by the bristle morphology and bristle arrangement of the brush.
In some existing arrangements, the skin will be ineffectively cleansed, with little or no sense of cleansing by the user, while in other cases, the skin may be overly cleansed with a mild sensation of abrasion, which is undesirable.
Many design considerations contribute to overall effectiveness of a skin cleansing brush, including bristle length and diameter, and bristle material, as well as the overall bristle arrangement, including the number of bristle tufts in a given area and the number of bristles per tuft. It is important to select and arrange these various bristle considerations to provide the desired result of effective cleansing, accompanied by an actual sensation or feeling of cleanliness, but without discomfort. In certain applications, this will also include an increased ability of the skin to absorb selected skin formulations; while in another application, the effectiveness of shaving cream is enhanced.
Accordingly, the present invention is a bristle arrangement for a powered skin cleaning brush, comprising: a first brush portion which includes a first set of bristles with the first brush portion remaining stationary in operation; a second brush portion which includes a second set of bristles, the second brush portion oscillating when the device is in operation, wherein the first and second sets of bristles are within the range of 3 to 5 mils in diameter and 0.3 to 0.5 inches in length, and wherein the first brush portion includes approximately 40 to 100 bristle tufts and the second set of bristles includes 40 to 120 bristle tufts, spaced over the area of the brushhead.
The structure of such a brushhead, apart from the bristles, is shown and described in co-pending application titled “Oscillating Brushhead Attachment System for Personal Care Appliance”. An example of an appliance, including a drive system for such a brushhead, is shown and described in co-pending application titled “Motor Providing Oscillating Action for a Personal Care Appliance”. Both of the above applications are owned by the same assignee as the present invention, and are hereby incorporated by reference.
The brushhead bristle arrangement shown and described herein, used in the appliance/brushhead disclosed in the above applications is effective for skin cleaning applications, particularly facial skin. The present brushhead bristle arrangement can also be used in other skin care applications, however, as discussed in the above applications, including acne and black head treatment, athlete's foot treatment, callused skin and psoriasis, razor bumps and related skin applications, wound cleansing and treatment of slow or non-healing wounds, scalp cleaning, chemical peel procedures and shaving cream applications. Preferred bristle configurations and arrangements will differ somewhat depending upon the particular application.
The following description concerns a brushhead/bristle arrangement for facial skin cleansing. It includes desired ranges of selected bristle characteristics and tufting, including the diameter of the bristles, the length of the bristles and the bristle material. The brushhead/bristle arrangement also takes into account the necessary time for the brush to dry, which must be fast enough to reduce microbial growth. The rate of drying is dependent upon both the number of bristles per tuft and the number of tufts in a given area. A brush may dry efficiently, but not have the ability to cleanse effectively, as well as cleanse effectively but not dry fast enough.
The optimum ranges for the important bristle characteristics and tufting requirements in order to provide the best performance and cleansing feel/impression depend to an extent upon the energy generated by the appliance which depends in turn upon both frequency and amplitude of bristle movement. In the embodiment shown, the frequency of brushhead movement will be within the range of 120-220 Hz. For a facial brush, the length of the bristles using a Tynex (DuPont) type bristle will be between 0.3 inches and 0.425 inches with a desired diameter of approximately 3 mils. For applications other than facial cleansing, such as those mentioned above, the diameter of the nylon bristles can be increased up to 5 mils, with the length remaining the same or slightly longer.
It has been discovered that generally, bristles with diameters less than 3 mils are difficult to connect reliably into a bristle base element. Further, bristles with a diameter greater than 5 mils produced discomfort in most users, although in some applications, a bristle diameter of greater than 5 mils, for particular applications such as aggressive foot cleansing, are appropriate.
With SuperSoft (DuPont) bristles, the ranges are slightly different, with the length of the bristles again being approximately 0.3 to 0.425 inches, while the diameter of the bristles can vary between 3 and 4 mils. For brush applications other than a facial cleansing application, the length of the bristles is approximately the same, in some cases slightly shorter for more aggressive applications and slightly longer for gentler applications, while the diameter of the bristles can be between 3 and 5 mils.
Relative to effective drying, the general range for the number of tufts is 40-100 in the outer brushhead portion and 40-120 in the inner brushhead portion. The preferred range is 60-90 for the outer brushhead portion and 70-110 for the inner brushhead portion, with 80 and 96 being optimal. The tufts should be evenly spaced.
Hence, particular characteristics of bristles are important (diameter and length) relative to effective skin cleansing, such as facial cleansing. Further, by maintaining the number of bristles in a particular tuft and the number of tufts in the movable brushhead portion within selected ranges, the overall brush can dry sufficiently fast to reduce microbial growth while at the same time cleansing effectively without harm or discomfort to the user.
Although a preferred embodiment of the invention has been disclosed here for purposes of illustration, it should be understood that various changes, modifications and substitutions may be incorporated in the embodiment without departing from the spirit of the invention, which is defined by the claims which follow.
