US 20050177961 A1
In a first embodiment an electric toothbrush having a housing containing an electric motor, the motor being drivingly connected to a first brush head rotatably mounted on an end of the toothbrush remote from the motor and adjacent to at least one other rotatable brush head. In a second embodiment a packaged electric toothbrush including a “try me” facility for remotely testing the operation of the toothbrush, which “try me” feature comprises a two-sided metal strip such as aluminum foil, separated by a dielectric material, respective sides of the strip being connected at one end to respective parts used to operate the electric toothbrush and the other end of the strip being folded over and including a centrally disposed aperture onto which is a bendable metal connector such that upon bending or pressing of the connector the two sides of the strip are electrically connected together to temporarily operate the toothbrush whilst still in its packaging.
1. An electric toothbrush comprising, an electric motor, a first brush head and a second brush head; said first brush head is connected by a driving structure to said motor; and a drive member extends from said first brush head and is received in a guide slot within said second brush head.
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6. An electric toothbrush comprising an electric motor, a first brush head capable of movement, a second brush head capable of movement, a drive shaft operatively connected to and driven by said electric motor, said drive shaft being connected to said first brush head for movably driving said first brush head, a drive member provided at a first end of one of said first brush head and said second brush head and extending toward the other of said first brush head and said second brush head, said other of said brush head and said second brush head having a guide slot, said drive member having a second end remote from said first end, said second end of said drive member extending into said guide slot whereby said drive member spans said first and said second brush heads without the need for other supporting structure, said drive member being located at said first brush head at a location displaced from the location of the drive connection of said drive shaft to said first brush head, said drive member being separate and distinct from said drive shaft, and movement of said first brush head by being driven by said drive shaft being transmitted to said second brush head through said drive member for joint simultaneous movement of both said first brush head and said second brush head.
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This application is a division of application Ser. No. 09/969,632, filed Oct. 4, 2001.
This invention relates to electric toothbrushes including those powered by a rechargeable battery from a mains domestic electricity supply.
In U.S. Pat. No. 5,226,206, there is described an electric toothbrush having twin brush heads which are drivingly connected together by a rack and pinion assembly in which the rack is reciprocated via a drive shaft connected to a crank shaft mounted at one end for rotation on a gear driven by a motor. The twin brush heads are therefore able to oscillate about their respective axes either in the same direction or in opposite directions, depending upon the configuration of the rack, this being generally ‘U’ shaped so as to facilitate the use of gear teeth on the inside thereof for driving the respective heads via respective pinions in mesh therewith.
A potential problem with this arrangement is that it is relatively complex and is not easily cleanable with running water such that the moving parts may become clogged with toothpaste or debris. In addition, the complexity and number of the parts used to provide the oscillating motion for the twin heads adds to the cost and complexity of manufacture.
In U.S. Pat. No. 5,353,460 the use of a rack and pinion assembly is dispensed with in favour of a crank mechanism connecting the first brush head to the second brush head. The first brush head is directly driven by a mitre gear or crown wheel which then, in turn, drives the second brush head to oscillate in the opposite direction to that of the first brush head. This arrangement involves fewer moving parts but still depends on the presence of gears and the crank mechanism for its operation, leading to the possibility of these moving parts being difficult to clean and becoming clogged etc. In addition, because the crank arm necessarily has to connect the respective brush heads on the sides thereof remote from the bristles, it will be understood that additional space is required to provide for free movement of the crank arm when the brush is in use. This also has the disadvantage in that the working ends of the crank linkage can never be directly exposed to running water for rinsing and cleaning purposes.
In a first aspect the present invention is derived from the realization that it would be preferable to have an electric toothbrush having multiple, such as two, rotatable brush heads but which dispenses with the need for gears or crank mechanisms for transferring oscillating rotary motion from one brush to another, typically a first brush driven by a connection to an electric motor and the second brush driven by movement of the first brush.
According to a first aspect of the invention there is provided an electric toothbrush having a housing containing an electric motor, the motor being drivingly connected to a first brush head rotatably mounted on an end of the toothbrush remote from the motor adjacent to at least one other rotatable brush head, wherein the first brush head includes a drive pin extending therefrom substantially at right angles from the axis of rotation, the free end of the drive pin being received within a guide slot in a brush head to be driven thereby, the arrangement being such that the drive pin bears against respectively opposite sides of the guide slot to thereby drive a driven brush head clockwise and anti-clockwise about its axis of rotation as the first brush head is also being oscillated.
This arrangement has the advantage in that the connection between two or more brush heads is extremely simple and since there are no moving parts other than the free end of the or each drive pin as it rocks back and forth within the or a respective guide slot, such can be easily cleaned under running water. A further advantage is that the mechanical motion of the brush head driven by the first brush head is necessarily magnified slightly due to its displacement from the first brush head and this overcomes any backlash that may be inherent in the system. Although a preferred embodiment of the invention uses only two brush heads, one driven directly via the drive link between the electric motor and the brush itself and the other being driven by a drive pin extending from the periphery of the first brush head, nevertheless it will be apparent that the same principle can be used to drive more than a second brush head and, in turn, the second brush head may itself drive a third brush head, and so on. Additionally, one or more of the brush heads may be of different diameter to the first brush head, although it will be appreciated that where there are differences in diameter a consideration of equivalent gear ratios then becomes necessary to determine whether the difference is too great to allow for the required movement.
The means by which the first brush head is driven back and forth about its axis may comprise a bell crank arrangement in which an elbowed end of a crankshaft, drivingly connected at its other end to the motor, is received within an elongated slot extending into the periphery of the first brush head diametrically opposite the drive pin (for a twin brush head toothbrush), the length of the slot being at least as great as the range of movement available to the elbow when the crankshaft is rotated through 360°.
The use of a drive pin for driving a second brush head has a still further advantage to the linkages referred to in the preamble hereto in that the second head may have a plane of rotation which is angled relative to the plane of rotation of the first brush head, such as being angled inwardly slightly, although it will be understood that there are practical limits to the amount that a second or even more such brush heads can be angled with respect to the plane of rotation of the first brush head.
Preferably, the end of the elbowed end of the crankshaft and the or each drive pin is partly spherical and takes the form of a ball joint, each being receivable within a respective slot of substantially the same diameter so as to minimize rattle and wear. A convenient arrangement has been found to be a ball joint made of nylon where the bristle holding part of the brush heads are made of e.g. PVC or some other suitable plastics material. Preferably, the slot for receiving each ball joint is partly arcuate so as to maximize the surface area in contact between the ball joint to thereby decrease the load forces on the slot and therefore reduce wear.
According to a second embodiment of the invention, the toothbrush is packaged in e.g. a blister pack and includes a “try me” facility for remotely testing the operation of the toothbrush, such as by a prospective purchaser of the toothbrush, whilst the toothbrush is still in its protective sales packaging, which “try me” feature comprises a two-sided metal foil or strip (such as aluminum foil), separated by a di-electric material such as paper or plastics, respective sides of the foil or strip being connected at one end to respective conductors of an electric circuit used to operate the electric toothbrush and, in particular, to energize the electric motor thereof, the other end of the foil or strip being folded over and including a centrally disposed aperture onto or over which is disposed a bendable metal connector such that upon bending or pressing of the connector the two sides of the strip or foil are electrically connected together to temporarily operate the toothbrush whilst still in its packaging.
Preferably, the “try me” feature may be permanently disconnected from the toothbrush after being purchased by simply being pulled away from the electrical connectors to which it is attached.
The invention will now be described, by way of example only, with reference to the accompanying drawings in which:
Referring firstly to
Reciprocating clockwise and anti-clockwise rotation of the first brush head 4 is facilitated by means of a bell crank mechanism which includes a stainless steel crankshaft 14 secured for rotation about its major axis in a journal 15 extending from a spigot 16 on the inside of the brush head holder 3 as shown more clearly in
Brush head 5 is driven in a different manner by means of a drive pin 19 which extends diametrically outwardly from the bristle holder 8 of the brush 4, to which it is fixed for rotation therewith, and is received in a slotted region 20 of the bristle holder 10 of the brush head 5. In this case, the slotted region 20 is wide enough to permit the drive pin 19 to move in an arc dictated by the movement of the elbow 17 within the slotted region 18 about the major axis of the crankshaft 14 but in an opposite sense so that clockwise movement of the brush head 4 causes anticlockwise movement of the brush head 5, and vice versa.
As will be understood by those skilled in the art, the absence of any gears in this part of the electric toothbrush 1 enables it to be easily cleaned in running water and because there arc few moving parts as compared to toothbrushes which include gears or crank arms for driving the or each brush head it will be appreciated that manufacture of the toothbrush according to the first embodiment of the invention can be easily facilitated.
The free end of the strip 23 has a folded over region in the form of a ring 28 onto which can be fitted a metal disc 29 which includes a domed central region 30 which may be pressed to temporarily connect both sides of the strip 3 to complete the circuit between the connectors 25 and 26 and thereby temporarily activate the toothbrush 1. As will be appreciated, because the “try me” feature 7 includes a strip 23 by which it allows a prospective purchaser of the toothbrush to determine if and how it works prior to purchase following pressing of the metal disc 29, after purchase the “try me” feature 7 can be effectively deactivated by simply pulling the strip 23 away from the printed circuit board 24 and hence out of engagement with the connectors 25, 26 thereon, whereafter an end cap 31 can be refitted onto the housing 2 of the toothbrush 1 in order to commence normal operation via pressing of the button 6.