Patent Application
20210268674
The present application is concerned with a personal care device having a treatment head arranged for pivoting around a pivot axis with respect to a body of the personal care device.
Document EP 1 372 428 A1 generally describes an epilator having a head and a housing, where the head is mounted at the housing so that it can pivot around a rest position. A spring is mounted between head and housing so that the head is forced back into the rest position once it is pivoted out of the rest position.
It is an object of the present description to provide a personal care device having a head arranged for swiveling around a swivel axis with respect to a body of the device comprising an improved or at least alternate provision of a return force providing arrangement.
In accordance with one aspect, a personal care device with a treatment head being pivot-mounted around a pivot axis with respect to a body of the personal care device, the personal care device having a pin having a pin head, the pin being provided at one of the treatment head or body, a cam element having a cam surface being provided at the other one of the treatment head or body, a spring element biasing the pin head and the cam surface against each other, wherein the pin head is in contact with the cam surface and the cam surface is shaped such that it defines a rest position at which the biasing spring force provided by the spring element with which the pin head and the cam surface are pushed against each other has a non-zero minimum value, and wherein a pivoting of the head around the pivot axis causes the pin head to move along the cam surface and the cam surface is further shaped such that the spring force pushing the pin head and the cam surface against each other increases with increasing pivoting angle.
The present disclosure is further elucidated by a detailed description of example embodiments and with reference to figures. In the figures
In the context of the present description “personal care” shall mean the nurture (or care) of the skin and of its adnexa (i.e. hairs and nails) and of the teeth and the oral cavity (including the tongue, the gums etc.), where the aim is on the one hand the prevention of illnesses and the maintenance and strengthening of health (“care”) and on the other hand the cosmetic treatment and improvement of the appearance of the skin and its adnexa. It shall include the maintenance and strengthening of wellbeing. This includes skin care, hair care, and oral care as well as nail care. This further includes other grooming activities such as beard care, shaving, and depilation. A “personal care device” thus means any device for performing such nurturing or grooming activity, e.g. (cosmetic) skin treatment devices such as skin massage devices or skin brushes; wet razors; electric shavers or trimmers; electric epilators; and oral care devices such as manual or electric toothbrushes, (electric) flossers, (electric) irrigators, (electric) tongue cleaners, or (electric) gum massagers. This shall not exclude that the proposed personal care system may have a more pronounced benefit in one or several of these nurturing or device areas than in one or several other of these areas. In the below description with reference to the figures, an epilation device was chosen to present details of the proposed personal care device. To the extent in which the details are not particular to an epilation device, the proposed technology can be used in any other personal care device.
The present disclosure is concerned with a personal care device that has a treatment head and a handle, where the treatment head can be swiveled or pivoted with respect to the handle around a swivel or pivot axis. The treatment head has a rest position (which may also be called a center position in case the rest position is about centric with respect to two swivel directions) out of which the head can be swiveled or pivoted into a least one angular direction against a return spring force provided by a spring element. The treatment head and the body are biased against each other in the rest position by a biasing force that needs to be overcome to swivel the head out of the rest position. The biasing force and the return spring force are provided by a spring element acting between a pin and a cam element, where the pin has a pin head that is in contact with a cam surface of the cam element. The spring element biases the pin head and the cam surface against each other with a certain non-zero minimal value (e.g. 2 N). While it is here mentioned that the personal care device has one spring element, this only means that one spring element is needed, but this shall not exclude that further spring elements are used to provide the total spring return force. In order to pivot the treatment head around the pivot axis, first the biasing force needs to be overcome and then the pin head glides over the cam surface if the applied force increases further. The biasing force thus provides a good feedback to the user as first the biasing force needs to be overcome before the head indeed pivots. In case of a spring just providing a return force, but no biasing force, the pivoting starts once a force is applied. Without intended limitation, the biasing force may generally be in a range of between 0.5 N and 8 N, in particular in a range of between 1.0 N and 5.0 N, further in particular in a range of between 1.5 N and 4.0 N, and even further in particular in a range of between 2.0 N and 3.0 N. Without intended limitation, the spring constant of the spring element may be in a range of between 0.05 N/mm and 1.0 N/mm, in particular in a range of between 0.1 N/mm and 0.4 N/mm, and further in particular in a range of between 0.15 N/mm and 0.25 N/mm. While in the discussed embodiments, the biasing force pushes the pin head against the cam surface, this shall not exclude that the cam surface is biased against the pin head, i.e. where the cam element can move, and the pin head can only pivot.
The cam surface is in particular shaped such that the spring force applied by the spring element increases with increasing pivot angle. Here, the shape of the cam surface is such that the distance between the pivot axis and the cam surface decreases and thus the pin is forced to move towards the pivot axis (or the cam element is forced to move away from the pivot axis) and by this motion the spring element is deformed in a manner that the spring force with which the pin head is pushed against the cam surface is increased. In case the cam surface would follow a circular function with respect to the pivot axis (i.e. the cam surface would be a portion of circle with the pivot axis being in the center of the circle), neither the pin nor the cam element would move, and the spring force would not change. The cam surface may follow any arbitrary function in dependence from the pivot angle as long as the distance between cam surface and pivot axis is essentially monotonously increased. The increasing spring force acts against the deflection of the treatment head and tries to return the treatment head into the rest position. The spring element may be a coil spring that is compressed when the pin moves towards the swivel axis to increase the spring force. But the spring element may also be a leaf spring that is bent, a torsion spring that is twisted etc. As already said, instead of one spring element, two or more spring elements may be used. The cam surface may be shaped such that the distance between cam surface and pivot axis decreases linearly with the pivot angle. The cam surface may also be shaped so that any other distance decreasing function is achieved. This shall not exclude that the cam surface provides for one or several lock positions at lock pivot angles, where the pivot angle would be maintained without applied external force.
While in some embodiments, the treatment head can only be pivoted out of the rest position into one pivot direction, i.e. a clockwise direction or a counter-clockwise direction with respect to the rest position, the treatment head can in some embodiments be pivoted in a plane into a clockwise and into a counter-clockwise direction out of the rest position. The maximum pivot angle in clockwise direction may have the same value as the maximum pivot angle in counter-clockwise direction (e.g. 13 degrees). Alternately, the maximum pivot angle may have different values in clockwise and counter-clockwise direction (e.g. 6 degrees and 20 degrees). The personal care device may comprise at least one stopper element to mechanically limit the deflection of the treatment head out of the rest position so that a maximum pivot angle cannot be exceeded. Two stopper elements may be present in case the treatment head can be pivoted in clockwise and counter-clockwise direction.
The pin head may have a contact surface for contacting the cam surface. The contact surface may be shaped to provide an essentially point-like or line-like contact region between the contact surface of the pin head and the cam surface. The contact surface of the pin head may be shaped as a portion of a sphere or a portion of a cylinder. In some embodiments, the pin head is a cylinder or a sphere that is in particular pivotably mounted at the pin. Such a design may help to reduce friction between the contact surface of the pin head and the cam surface. The cam surface may have a depression to define the rest position. The depression may be smaller in diameter than the diameter of the pin head and in particular smaller than the size of the contact surface so that the contact surface of the pin head has two point-like or line-like contact regions with the cam surface in the rest position. In particular, the depression may start and end at the contact pints or contact lines of the contact surface of the pin head with the cam surface. This leads to a better-defined rest position and balances out tolerances.
As the pin shall in some embodiments move in linear direction towards (and away) from the pivot axis depending on the pivot direction, the pin may be guided by any suitable linear bearing that in particular pivots together with the pin. In some embodiments, the pin is guided in a hollow of a pin mount, the pin mount providing a slide bearing. The materials of pin and pin mount may be chosen to allow for self-lubrication. While it may be possible to manufacture pin and pin mount by machining a metal block, a plastic block or a ceramic block to achieve very low tolerance so that the inner hollow of the pin mount can precisely receive the pin, it may be less costly to realize at least the hollow pin mount from a thermoplastic material so that the hollow pin mount can be made by plastic injection molding, where many pin mounts can be made in parallel and with a low cycle time. The hollow in such an injected pin mount may then be differently shaped than the pin. E.g. the pin may have a circular cross section and the hollow of the pin mount may have a polygonal, e.g. a hexagonal cross section. In some embodiments, the pin mount has at least two in particular oppositely arranged guiding surfaces that guide the pin. Additionally, the pin mount may have at least four guiding surfaces where two guiding surfaces are disposed at a first longitudinal position and two guiding surfaces are arranged at a second longitudinal position, respectively. By such an arrangement, the pin is guided at two positions along its length extension, leading to a precise linear guidance and a relief for the design of the pin mount as the pin mount does not need to guide the pin along its complete length inside of the pin mount. The hollow in the pin mount may be realized as a blind hole. Instead of a pure blind hole, the hollow may continue as a smaller diameter bore, which bore may be used in the step of mounting the spring element.
The spring element may at least partially be arranged in a hollow of the pin where the hollow in the pin may be concentric with the longitudinal axis of the pin. The spring element may generally be realized as a coil spring. One end of the spring element may abut an abutting surface of the hollow in the pin and a second end of the spring element may abut an abutting surface in the hollow of the pin mount. The abutting surface in the pin mount may be precisely dimensioned to tightly receive the second end of the spring element so that the second end of the spring element cannot move with respect to the pin mount. The abutting surface in the pin mount may be provided by a recess in the pin mount. As was already indicated, the hollow may continue as a smaller diameter bore. A metal pin may be slid through the smaller diameter bore, on which pin the spring element (e.g. the coil spring) may be mounted until the pin that compresses the spring element is mounted in the hollow. The metal pin may be retracted from the smaller diameter bore once the mounting of pin and spring element has happened.
The hollow in the pin mount may be defined by a precisely machined core in the plastic injection molding of the pin mount. In particular the guiding surfaces (i.e. the distance between the guiding surfaces) of the hollow may then be realized with high quality, e.g. a tolerance of ±0.03 mm may be applied for the guiding surfaces. The same or a similar low tolerance may be applied for the respective cooperating outer surface portions of the pin itself, so that the pin is finally guided with high precision and with neglectable play or gaps.
The pin head or the cam element may be made at least in the area of the contact surface of the pin or the cam surface from one of the following materials: a plastic material, in particular a hard plastic material having a Shore D hardness of at least 40, further in particular a reinforced plastic material; a lightweight metal or a metal alloy having a specific density in the range of between 2 g/cm3 and 5 g/cm3 such as titanium or aluminum; a heavy metal or a metal alloy having a specific density in the range of between 5 g/cm3 and 20 g/cm3 such as steel, brass, or bronze; or a ceramic material such as silicon carbide or tungsten carbide.
The handle 200 has a handle housing 201 that may house a battery or a rechargeable accumulator and a drive unit for driving the treatment unit 120. In some embodiments, the treatment unit is not driven and may only be supplied with electric energy. In some embodiments, the treatment unit is driven and is supplied with energy. In some embodiments, the treatment unit is neither actively driven nor supplied with energy. The handle 200 may comprise one or several switches 210 such as an ON/OFF switch or a mode switch etc. The handle may comprise any other feature that a skilled person would provide at a handle, e.g. a light source 220 for illuminating the area to be treated.
The pin head 166A has an outer contact surface 1661A that is in frictional contact with a cam surface 151A. The cam surface 151A of the cam element 150A defines a rest position of the pin unit 160A. In order to pivot the pin unit 160A out of the rest position, the pin head 166A must move along the cam surface 151A, which is shaped such that the pin 165A will be moved towards a pivot axis R with increasing pivot angle as shown in
In the shown realization, the cam element 150A and the cam surface 151A are symmetric with respect to the rest position so that the rest position is also a center position. To avoid that the pin head 166A is pivoted over an end of the cam element 150A, the personal care device may comprise stopper elements that inhibit any pivoting beyond a maximum pivot angle. The personal care device may comprise two such stopper elements, where one stopper element is limiting the pivot range in clockwise direction and the other stopper element is limiting the pivot range in counter-clockwise direction, where clockwise and counter-clockwise is defined with respect to the paper plane. While the cam element 150A is here symmetric, the stopper elements may provide for non-symmetric pivot ranges in clockwise and counter-clockwise direction.
The pin 165A may comprise an extension that is arranged in a groove or cutout of the pin mount 161A (or vice versa) so that the pin 165A is secured at the pin mount 161A during the assembly process.
In
As was said, the cam surface is shaped in a manner that results in a monotonous decrease of the distance D(α) between the contact point CP3 and the pivot axis R with increasing pivot angle α. In some embodiments, the mathematical relation can be expressed by a linear equation:
D(α)=D0−k·α,
where D0 is the distance in the rest position and k is a slope factor that defines how fast the distances decreases per pivot angle, i.e. k=ΔD/Δα. This shall of course not exclude that the cam surface can take other shapes, i.e. a shape where the distance decreases in a potential manner or a shape supporting an intermediate locking position at a lock angle.
The materials from which the pin head 166A are made at least in the area of the contact surface 1661A and the cam element 150A at least in the area of the cam surface 151A may be chosen such that the friction between the two parts does not lead to self-locking. In particular, the friction coefficient between both materials may be chosen to be below 0.4, in particular below 0.35 such as 0.3 or 0.25 or 0.2. As was said in a previous paragraph, the pin head may be realized as a cylinder or a sphere that is pivotably mounted at the pin and thus self-locking issues may be overcome.
Generally, it shall not be excluded that the pin fits smoothly into the pin mount. E.g. the pin and the pin mount may be precisely shaped aluminum parts or the like and they may be lubricated with a suitable lubricant. With reference to
The pin unit 160A comprises the pin mount 161A, the pin 165A and the spring element 169A. With respect to the spring element 169A it is referred to the previous paragraphs. The pin 165A is guided by the pin mount 161A. The pin mount 161A has a hollow 162A realized as a bore having a blind hole end 164A. As can be seen from
The pin 165A is also generally tapering from a front region 1653A to a back-end region 1654A. But as was described for the hollow 162A of the pin mount 161A, the pin 165A has low tolerance areas at the front and at the back that coincide in the mounted state with the longitudinal locations of the guiding surfaces in the hollow 162A. As can best be seen in
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”
Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
