Power toothbrushes generally comprise a power source, a motor and a powered element that is driven by the motor. In one type of power toothbrush, a power toothbrush head is provided with movable cleaning elements that are usually driven laterally, rotationally or in an oscillating manner by a motor located in the handle. The motor generates a vibration that is absorbed directly by the hands of the user. However, such vibration is effectively a byproduct of the motor operation and is usually not intended to enhance the effectiveness of the movable cleaning elements. Instead, the vibration provides a tactile sensation to the user and generally creates a perceived feeling of increased cleaning effectiveness.
Another type of power toothbrush relies primarily on vibrations to produce a cleaning operation. These are normally referred to as “sonic”-type brushes because the vibrations generated to achieve a high cleaning efficacy are generally of a frequency of 20-20,000 Hz that can be perceived by the human ear as a “buzz.” However, the combination of this sonic noise and the high-frequency vibration felt on one's teeth create a tactile sensation of highly increased effectiveness. To achieve the greatest cleaning, it is preferable to situate the vibration-generation device as close to the toothbrush head as possible so as to focus the vibratory energy near the site of greatest cleaning, and not along the handle.
In some prior art sonic-type brushes, elastomeric regions are provided between the motor and the handle to dampen the vibrations felt in the handle. However, such regions tend to decrease the structural strength of the neck and create localized weaknesses in the neck material that could subject the toothbrush to breakage or cause the toothbrush to fail cyclic fatigue tests. Dampening regions are also noticed in other vibrating-type toothbrushes near the junction of the neck and the handle, usually in the form of an elastomeric section or sections of varying configurations. However, again, such sections create structural weaknesses at a location that usually receives a significant amount of stress during use.
There is a need, therefore, to provide a vibration-powered toothbrush having cleaning vibrations that are directed toward or isolated in the head region and reduced in the handle region, and that do not create weakened areas that subject the toothbrush to breakage and cyclic fatigue.