EP3863464B1

EP3863464B1 - Eyelash curler

Info

Publication number: EP3863464B1
Application number: EP19790574.8A
Authority: EP
Inventors: Viola Ardin
Original assignee: Sidereus Oy
Current assignee: Sidereus Oy
Priority date: 2018-10-09
Filing date: 2019-10-08
Publication date: 2022-08-17
Anticipated expiration: 2039-10-08
Also published as: KR20210059780A; FI20185843A1; AU2019358527A1; FI128414B; WO2020074774A1; EP3863464A1; SG11202103510QA; US20210337949A1; JP2022511615A; CN112804909A; CA3115418A1

Description

FIELD OF THE INVENTION

The invention concerns the technology of cosmetic eye care. In particular the invention concerns an apparatus for curling eyelashes in an easy and safe way with long-lasting effects.

BACKGROUND OF THE INVENTION

Most mechanical eyelash curlers on the consumer market follow the commonly used scissors-like structural principle, in which a simple lever joint between two arms transforms the swinging movement of the loop-formed handles into a reciprocal movement of the proximal edges of a pair of curved blades. A band of silicone rubber or the like on one of the edges forms a groove, into which the other edge presses, causing eyelashes therebetween to assume a curved shape. While the structural solution is relatively simple and the devices consequently robust and inexpensive to manufacture, these known eyelash curlers involve a number of drawbacks. For example, each eyelash is only bent at one point, or at most at a very short length around the point that gets pressed between the blades. This may damage the delicate structure of the eyelash, and does not lead to an optimal result in all cases. Also, the result may not be very long-lasting.
It is known to apply heat to the eyelashes while curling them, in order to obtain more permanent results, as disclosed in US6230715 B1 .
A patent publication JP4569993 and the corresponding published application JP2001340128 disclose an eyelash curler in which a resistive wire has been embedded in the elastic material that constitutes one of the pressing surfaces. A battery inside the handle of the device acts as a source of electric energy, so that an electric current can be made to flow through said resistive wire, causing it to warm up and deliver heat to that point of the eyelash that was caught between the pressing surfaces. However, the suggested structure involves a number of drawbacks, including difficult cleaning and relatively complicated mechanics for producing the movement of the pressing surfaces.
Another prior art document GB 2516622 A suggests a different mechanical approach, in which the eyelash curler is brought to the eye horizontally from the front direction and not from below. The user pinches the distal ends of two arms together with her thumb and forefinger against a spring, forcing the pressing surfaces at the proximal end of the device apart. Closer to the eye the user releases her grab, so that the spring causes the pressing surfaces press against each other, catching the eyelashes therebetween and making them bend. Also here a battery-powered heating resistor can be used to enhance the curling effect. Also this structural approach involves drawbacks, at least some of which are related to the position of use. In order to bring the device into the correct operating position the user must push her elbow forwards, which makes the position unstable and tiring. Keeping the device hygienic during prolonged use may also prove problematic.

SUMMARY

It is an objective of the invention to present an eyelash curler that is easy and safe to use, produces long-lasting effects, and has a pleasing outer appearance.
The objectives of the invention are achieved with an eyelash curler that combines a linear movement, advantageously designed pressing surfaces, and heating.
According to an aspect, an eyelash curler is provided. The eyelash curler comprises a palm part having a first end and a second end, a direction from said first end towards said second end defining a longitudinal direction. The eyelash curler comprises a movable part having a first end and a second end, attached to said palm part with a sliding joint that enables movement of the movable part with respect to said palm part in said longitudinal direction. There is a first curling surface at said first end of the palm part, and a second curling surface at said first end of the movable part, configured to engage at least part of said first curling surface upon said movement of the movable part. The eyelash curler comprises an electric heating element configured to heat said second curling surface, a battery compartment for receiving a battery, and a control circuit configured to control the flow of electric current between a battery received in said battery compartment and said electric heating element. Said electric heating element, said battery compartment, and said control circuit are all located in said movable part.
In an embodiment of the eyelash curler said palm part and said movable part together constitute an elongated entity that is thicker towards said second end than said first end of the palm part, so that towards said second end said elongated entity constitutes a handle, a diameter of which is between 15 and 40 mm and a length of which is between 60 and 160 mm, to fit in a hand of a human user. This involves the advantage that the overall outer appearance of the eyelash curler automatically prompts the user to take a convenient and ergonomic grip of the device and hold it in an effective operating position.
In an embodiment of the eyelash curler said first curling surface is a part of a first plate, directed transversally with respect to said longitudinal direction and supported by a first support arm as a part of said palm part. Said first support arm may attach to a middle part of said first plate, and a transverse thickness of said first support arm may be less than 10 mm at a location below said first plate in said longitudinal direction. This involves the advantage that the user gets a good and unobstructed view of her face if a mirror is placed in front of her.
In an embodiment of the eyelash curler said second curling surface is a part of a second plate, directed transversally with respect to said longitudinal direction and supported by a second support arm as a part of said movable part. This involves the advantage that making the curling surfaces at least partly engage upon said longitudinal movement is mechanically simple.
In an embodiment of the eyelash curler said palm part comprises, towards said second end, a tubular section so that said movement of the movable part with respect to said palm part in said longitudinal direction involves moving a portion of said movable part inside said tubular section. This involves the advantage that the sliding movement can be mechanically robust, and a nice and convenient grip can be offered to the user.
In an embodiment of the eyelash curler each of said first and second curling surfaces is limited on one side by a concave eyelid-side edge, and at least said first curling surface extends for more than 8 millimetres from the respective eyelid-side edge towards a respective distal edge. This involves the advantage that the eyelashes of the user can be treated for their whole length.
In an embodiment of the eyelash curler at least one of said first and second curling surfaces comprises one or more ridges or grooves directed parallel to the respective eyelid-side edge. This involves the advantage that the desired curled form of the eyelashes can be achieved.
In an embodiment of the eyelash curler at least one ridge in one of the first and second curling surfaces is met by a corresponding groove in the other. This involves the advantage that very exact control of the resulting curled form of the eyelashes can be obtained.
In an embodiment of the eyelash curler said first curling surface comprises a protruding ridge parallel to the eyelid-side edge of said first curling surface and displaced from said eyelid-side edge by less than 3 mm. This involves the advantage of producing a bend near the base of each eyelash, which helps to achieve the desired curled form.
In an embodiment of the eyelash curler said electric heating element is located under at least one surface layer of said second curling surface. This involves the advantage that the electric heating element may remain well protected, while one or more surface layers of the second curling surface can be made easily replaceable.
In an embodiment of the eyelash curler said second curling surface comprises a piece of elastic material detachably attached to a support located at said first end of said movable part. This involves the advantage that smooth and careful curling of the eyelashes can be combined with a high level of hygiene and easy cleaning of the eyelash curler.
In an embodiment of the eyelash curler said support is a support box with a bottom and edges, so that said electric heating element is located in said support box and separated from said bottom by an array of protrusions in said bottom. This involves the advantage that the heat generated by the electric heating element can be effectively directed to just those areas where it is needed, without wasting energy.
In an embodiment of the eyelash curler said movable part comprises a flex circuit that extends from said battery compartment to said electric heating element and carries all electric connections between discrete electric parts of the eyelash curler. This involves the advantage that reliable and safe electric operation can be combined with advantages in manufacturing and assembling.
In an embodiment of the eyelash curler said electric heating element consists of resistors attached to that end of the flex circuit that extends to the first end of the movable part. This involves the advantage that the electric heating element can be made structurally simple, while having accurate control about its electrical properties.
In an embodiment of the eyelash curler said movable part comprises a push pad formed of a surface oriented at least partially obliquely or transversally with respect to said longitudinal direction for enabling a human user to push said movable part in said longitudinal direction. This involves the advantage that it is easy and intuitive for the user to take the most appropriate grab of the eyelash curler and to effect the appropriate longitudinal movement.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illustrate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Figure 1 is a side view of an eyelash curler,
Figure 2 is a front view of the eyelash curler of fig. 1,
Figure 3 is a side view of the eyelash curler of fig. 1 with the curling surfaces pressed together,
Figure 4 is a front view of the eyelash curler of fig. 3,
Figure 5 is a side view of a palm part of an eyelash curler,
Figure 6 is a front view of the palm part of fig 5,
Figure 7 is a side view of a movable part of an eyelash curler,
Figure 8 is a front view of the movable part of fig. 7,
Figure 9 is a side view of a detail of an eyelash curler,
Figure 10 is a front view of the detail of fig. 9,
Figure 11 is an exploded view of a detail of an eyelash curler,
Figure 12 is a front view of the exploded view of fig. 11,
Figure 13 is a cut-out view of two engaging curling surfaces,
Figure 14 is a cut-out view of two engaging curling surfaces in another embodiment,
Figure 15 is a cut-out view of a first curling surface in another embodiment,
Figure 16 is a side view of an eyelash curler with the curling surfaces open,
Figure 17 is a side view of the eyelash curler of fig. 16 with the curling surfaces pressed together, and
Figure 18 is a circuit diagram of the electric parts of an eyelash curler.

DETAILED DESCRIPTION

Fig. 1 is a side view of an eyelash curler that comprises two basic structural parts: a palm part 101 and a movable part 102. Fig. 2 is a front view of the same eyelash curler. The palm part 101 is so called because it is meant to rest in the user's palm in the normal operating position. The palm part 101 is generally elongated in form, having a first end (the upper end in figs. 1 and 2) and a second end (the lower end in figs. 1 and 2). The direction from said first end towards said second end, i.e. the vertical direction in figs. 1 and 2, can be said to define a longitudinal direction 103. Also the movable part 102 has a first end and a second end, and these are directed similarly: the first end of the movable part 102 is its upper end, and the second end of the movable part 102 is its lower end in figs. 1 and 2.
The movable part 102 is attached to the palm part 101 with a sliding joint that enables movement of the movable part 102 with respect to the palm part 101 in the longitudinal direction 103. Figs. 3 and 4 are side and front views, respectively, of the same eyelash curler when the movable part 102 has been moved upwards (with respect to the directions shown in the drawings) by a distance of several millimetres, like 10 to 20 millimetres. The significance of the distance will be considered in more detail later.
The exact way in which the sliding joint between the palm part 101 and the movable part 102 is implemented is outside the scope of this description. Sliding joints between two structural parts are known as such, and any suitable mechanical means can be used, including but not being limited to mating pairs of rails and grooves; mutually engaging slider surfaces; or the like.
A first curling surface 104 is provided at the first end of the palm part 101, and a second curling surface 105 is provided at the first end of the movable part 102. The first and second curling surfaces face each other, so that the second curling surface 105 is configured to engage at least part of the first curling surface 104 upon a suitable longitudinal movement of the movable part 102 with respect to the palm part 101. This happens in figs. 3 and 4: the movable part 102 has been moved upwards (with respect to the directions shown in the drawings) far enough to make the first and second curling surfaces engage. In order to make this possible, the mechanical means that implement the sliding joint between the palm part 101 and the movable part 102 must be designed so that the sliding, longitudinal movement of the movable part 102 takes place in exactly that direction in which the first curling surface 104 is located, seen from the second curling surface 105, before the longitudinal movement. Likewise, the first and second curling surfaces must be sufficiently parallel to each other (or the sliding, longitudinal movement of the movable part 102 must bring them sufficiently parallel to each other) so that at the end of the movement they press against each other across the whole surface area that is to act as a curling surface.
Above it was pointed out that in the normal operating position the eyelash curler should be placed so that the palm part 101 rests in the palm of the user. The operating position of the eyelash curler is generally upright: when doing it right, the user should see the eyelash curler approaching her face in the position shown in fig. 2. In order to offer a comfortable grab to the user, the palm part 101 and the movable part 102 together constitute an elongated entity that is generally thicker towards the second end than the first end. In the drawings the second end points downwards, and it is seen how towards the second end said elongated entity constitutes a handle for the user to grab. Taken the dimensions of a normal human hand, the diameter 106 of the handle should be between 15 and 40 mm, and the length 107 of the handle should be between 60 and 160 mm, to comfortably fit in a hand of a human user.
The upright operating position of the eyelash curler is advantageous, because the user will experience it as ergonomic and intuitive. Lifting the eyelash curler in the correct operating position close to the face does not require pushing the elbow forward, but the whole arm can be kept close to the body, which helps to avoid tiring. The same upright operating position can be used regardless of which hand the user keeps the eyelash curler in, which is advantageous because right-handed and left-handed users of the eyelash curler will notice no difference in its comfort of use.
The first curling surface 104 is a part of a first plate-like part, or a first plate 108 for short. The first plate 108 is directed transversally with respect to the longitudinal direction 103, and supported by a first support arm 109 as a part of the palm part 101. The first support arm 109 has generally the shape of an inverted J or inverted L, and attaches to the middle part of the first plate 108, so that the whole arrangement of the first plate 108 and first support arm 109 is essentially symmetrical in the front view of figs. 2 and 4. This kind of symmetricity is another factor of ergonomics in use: the user can treat both eyes just as easily, without having to change the operating position. The symmetricity is also a factor in making the eyelash curler just as easy to use for both right-handed and left-handed users.
A transverse thickness 110 of the first support arm 109 is less than 10 mm at a location below the first plate 108 (considered in the longitudinal direction 103). This is another factor of additional ergonomics, because this is the part where the user is looking through, typically at her image in a mirror, when bringing the eyelash curler close to her eye for use. A narrow transverse thickness 110 of the first support arm 109 means very little obstruction in the field of view of the user. The "inverted-J" or "inverted-L" shape of the first support arm 109 serves the same function, because it enables supporting the first plate 108 from above the eye of the user, even if the main body of the eyelash curler is well below the eye, on the level of the user's cheek.
The second curling surface 105 is a part of a second plate-like part, or a second plate 111 for short. Like the first plate 108, the second plate 111 is directed transversally with respect to the longitudinal direction 103. It is supported by a second support arm 112 as a part of the movable part 102. It is advantageous to make the transverse thickness of also the second support arm 112 narrow, although it is not as much in the field of view of the user in the operating position and consequently its thickness does not have as much meaning to ergonomics of use.
An example of the general structure of the palm part 101 is seen well in figs. 5 and 6, in which the movable part has been omitted. Towards its second end (lower end in the drawings) the palm part 101 comprises a tubular section 501, so that the previously described movement of the movable part 102 with respect to the palm part 101 in said longitudinal direction 103 involves moving a portion of the movable part 102 inside said tubular section 501. Although not the only possible structural approach, this involves a number of advantages. It enables making the visible and touchable surface of the "handle" portion consist almost exclusively of the surface of the palm part 101, so that the user gets a firm and comfortable grip of the eyelash curler, and good support is offered for the user's hand for moving the movable part 102. It also enables making the mechanical structure of the palm part 101 thin and lightweight, with obvious advantageous consequences in manufacturing and ergonomics of use. Further, it enables making the sliding mechanism accurate, mechanically stable, and resistant to wear, yet structurally simple.
An opening 502 is provided in a first end (here: upper end) of the tubular section 501. As seen in figs. 1 to 4, the first end of the movable part 102 protrudes out of the opening 502 towards the first curling surface 104. A dent 503 or some other exception from the otherwise smooth surface may be provided on the other side of the palm part 101 approximately on the same level in the longitudinal direction 103 as the opening 502. Thus the user will intuitively hold the palm part 101 in her palm to that her thumb is at the location of the opening 502 and her index finger and/or middle finger rests at the dent 503 or the like. The symmetry of the design ensures that this position of the eyelash curler in the stronger hand of the user is the same, and equally intuitive, irrespective of whether the user is right-handed or left-handed.
Another opening 504 is provided at the second end (here: the lower end) of the tubular section 501. Through this other opening 504 the user may access the second end of the movable part, at which the lid of a battery compartment is advantageously provided, as will be described in more detail later.
An example of the general structure of the movable part 102 is seen in figs. 7 and 8, in which the palm part has been omitted. This example of a movable part 102 has been designed to fit together with a palm part 101 like that in figs. 5 and 6, so the lower portion 701 of the movable part 102 has an essentially constant cross section, designed and dimensioned to fit and slide inside the tubular section 501 in the palm part 101. A battery compartment 702 is provided in the lower portion 701 of the movable part 102 for receiving the battery from which the electric power will be taken for the heating function and possible other electronic functions. The battery compartment 702 may be dimensioned to receive for example one "AA" type battery, the standardized dimensions of which are 14.5 mm in diameter and 50.5 mm in length. The battery compartment 702 could be dimensioned also for one or more batteries of some other kind, including rechargeable batteries.
If the eyelash curler is to be run with a user-replaceable battery (or a rechargeable battery that should be taken out for recharging), it is advantageous to have a removably attached battery compartment cover 703 at some accessible location of the movable part 102. In the example shown here the battery compartment cover 703 is at the second end of the movable part 102, so that when the movable part 102 is in position within the palm part 101, the user may access the battery compartment cover 703 through the opening 504 at the lower end of the tubular section 501. If the eyelash curler comprises a built-in rechargeable battery, a charger interface may be provided in place of the battery compartment cover 703. It is also possible to provide both a charger interface and a battery compartment cover, if the eyelash curler is to be run with an exchangeable rechargeable battery.
It is advantageous to make the movable part 102 comprise a push pad 704 for making it easier for the user to effect the longitudinal movement mentioned above. For this reason it is advantageous if the push pad 704 is located at the region where the user's thumb will intuitively be in the normal operating position. Comparing figs. 7 and 8 to figs. 1 - 2 and 5-6 it is easy to see how the push pad 704 protrudes partly out of the opening 502. In this embodiment the push pad 704 is formed of a surface that is oriented at least partly obliquely or transversally with respect to the longitudinal direction 103, for enabling a human user to push the movable part 102 in the longitudinal direction 103 with her thumb. Alternatively or additionally, the push pad 704 could comprise a piece of material that creates a lot of friction, like soft rubber, and/or a matrix of ridges or hatch patterns for the same purpose.
Since the movable part 102 comprises electric parts, means are needed for conducting electric currents and signals between its various parts. Structural simplicity and ease of manufacturing can be achieved by making the movable part 102 comprise a flex circuit 705 that extends from (at least close to) the battery compartment 702 as far as to the first end of the movable part 102, where the electric heating element 712 is located. A single flex circuit 705 can be made to carry all electric connections between discrete electric parts of the eyelash curler. The flex circuit 705 is seen from the side in fig. 7, and in front view in fig. 8, although drawn with dashed lines in both because it is located inside the movable part 102.
Examples of places where the flex circuit 705 can be advantageously used for electric connections are shown with marked ovals in fig. 7. At locations 706 and 707, electric connections can be made to the negative and positive terminals respectively of a battery received in the battery compartment 702. Battery connectors soldered onto contact pads on the flex circuit 705 can be used for this purpose, or a part of the flex circuit 705 itself can be bent to make connection with one or more poles of the battery. At location 708 control electronics can be built and connected to the flex circuit 705. Examples of control electronics include - but are not limited to - power converters, timers, and processing circuits. Control electronics can be directly soldered onto contact pads on the flex circuit 705, and/or pieces of wires can be used to make the connections. At location 709 connections can be made to one or more operating switches, and example of which is the operating switch 801 shown in fig. 8. An operating switch could also be located within the area of the push pad 704. At location 710 connections can be made to one or more other user interface elements, like the indicator LEDs 802 and 803 shown in fig. 8 as examples. At location 711 connections can be made to one or more electric heating elements, examples of which are described in more detail later.
As shown in figs. 7 and 8, the upper end of the flex circuit 705 is embedded, in one way or the other, in the second plate 111 located at the first end of the movable part 102. Figs. 9 and 10 show an example of how said upper end of the flex circuit 705 may look like. A narrow neck 901 of the flex circuit 705 extends through the second arm 112 that supports the second plate 111. Inside the second plate 111 the flex circuit branches into two petals 1001 and 1002, each of which extends into the respective end of the second plate 111. Conductive tracks on the flex circuit 705 are not separately shown in the drawings, but they follow the generally branching form of the flex circuit, providing electric connections to resistors 902 that together with this part of the flex circuit 705 constitute the electric heating element 712. The resistors 902 may be discrete, preferably surface-mounted components on the flex circuit 705, or they may consist at least partly of portions of conductive tracks on the flex circuit 705 that have been specifically designed to make their electric resistance higher than the resistance of regular conductive tracks on the flex circuit.
Figs. 11 and 12 illustrate certain exemplary advantageous features of a structure of the second plate 111, of which the electric heating element 712 is a part. The parts are shown in exploded view in figs. 11 and 12, so that in the actual product they would be placed tightly on top of each other in the vertical direction. It is advantageous to place the electric heating element 712 not directly visible and accessible, but under at least one surface layer of the second curling surface 105, because this way the electric heating element 712 will remain more protected. In the arrangement of figs. 11 and 12 such surface layer(s) comprise(s) a piece of elastic material 1101 that is detachably attached to a support 1102 located at the first end of the movable part. Using elastic material involves the advantage that a very soft and delicate pressing effect can be obtained for the eyelashes that get caught between the curling surfaces. Making the piece of elastic material 1101 detachable involves the advantage that the user may easily detach and replace it regularly, on order to maintain high standards of hygiene during long-term use of the eyelash curler or when another user borrows the eyelash curler.
At the same time of being elastic, the material of the piece of elastic material 1101 should be a reasonably good conductor of heat. Suitable materials can be found among silicone rubbers, for example, and their heat conducting properties may be tuned, if needed, with additives mixed with the base material during manufacture.
In the embodiment of figs. 11 and 12 the support 1102 is a support box with a bottom 1103 and edges 1104. The detachable attachment of the piece of elastic materials 1101 in the support 1102 may be as simple as pushing the piece of elastic materials 1101 into place in the support 1102, so that its elasticity and the friction between it and the walls 1104 of the support keep it in place.
The electric heating element 712 is of the same kind in figs. 11 and 12 as in figs. 9 and 10 above. The narrow neck 901 of the flex circuit goes through an opening 1201 in the support 1102, which leads to a conduit inside the second support arm 112. Thus in the assembled configuration the electric heating element 712 is located in the support box, in the space delimited by the walls 1104. In order to reduce wasted heat that would be conducted to other parts of the structure than the second curling surface, the electric heating element 712 may be separated from the bottom 1103 of the support 1102 by an array of protrusions 1202 in said bottom. The form and distribution of the protrusions is not important, as long as they fulfil the heat insulation function; instead of the dot-like protrusions there could be for example parallel ribs or the like.
An additional protective layer 1105 may be provided between the piece of elastic material 1101 and the electric heating element 712. The protective layer 1105 may be for example a piece of adhesive tape, and its purpose is to keep the resistors of the electric heating element 712 covered and protected when the user replaces the piece of elastic material 1101.
The dimensions and design of the curling surfaces may be considered next with reference to mainly figs. 13 to 15. The dimensioning of the curling surfaces must take into account the fact that people have differently sized eyes.
In a kind of an optimal case the dimensioning of the curling surfaces would be such that if the whole array of eyelashes in one eye is considered as a two-dimensional area, this whole area could be conveniently covered (i.e. caught between the curling surfaces) in one go. In other words, in the direction that follows the horizontal width of an eyelid the curling surfaces should extend exactly as far as there are eyelashes in the user's eye, and the curvature of the proximal edge of the curling surfaces should closely follow the outer edge of the eyelid. In practice this would lead to a requirement that eyelid curlers with curling surfaces of different width and curvature should be manufactured for different users.
A more practical approach is to make the curling surfaces slightly narrower in the horizontal direction than the mean horizontal width of a typical human eyelid. This way a user with small eyes may cover the whole array of eyelashes in each one eye in one go, without getting the feeling that the eyelash curler would be too wide or clumsy for her. A user with larger eyes may need to curl the eyelashes of each eye with two consecutive presses side-by-side, but this is not a serious drawback, because at the same time she may utilize the transversal movement of the eyelash curler between the presses to neatly match the curvature of just her eye.
In the longitudinal direction of an individual eyelash, at least some part of the curling surfaces should extend far enough so that even the longest naturally encountered human eyelashes will remain between the curling surfaces for their whole length. Here the differences in eyelash length between various users is not a problem, because shorter eyelashes will just reach to some distance between the curling surfaces, without the further-reaching length of the curling surfaces causing any inconvenience.
As seen in fig. 12 for the part of the second curling surface, each of the first and second curling surfaces is limited on one side by a concave eyelid-side edge. In the cross section of fig. 13 this is the edge 1301 for the first curling surface and edge 1302 for the second curling surface. Each of the first and second curling surfaces extends for more than 8 millimetres from the respective eyelid-side edge towards a respective distal edge, which is edge 1303 for the first curling surface and edge 1304 for the second curling surface in fig. 13. This dimension is to preferably accommodate the whole length of any naturally occurring individual human eyelash. A double-headed arrow illustrates the more than 8 millimetres distance in fig. 13.
Between the eyelid- side edge 1301 or 1302 and the respective distal edge 1303 or 1304 said first and second curling surfaces comprise one or more ridges or grooves directed parallel to the respective eyelid-side edge, at least one ridge in one of the first and second curling surfaces being met by a corresponding groove in the other. In the example of fig. 13 all ridges in one of the curling surfaces are met by a corresponding groove in the other, except for a narrow zone closest to the eyelid-side edge. The upper bevel 1305 in the first curling surface faces a corresponding but differently directed lower bevel 1306 in the second curling surface. The upper and lower bevels 1305 and 1306 are there to keep the sensitive outer edge of the eyelid of the user from being caught between the curling surfaces.
Immediately next to the upper bevel 1305, the first curling surface comprises a protruding ridge 1307 that is parallel to the eyelid-side edge 1301 of the first curling surface and displaced from it by less than 3 mm. This ridge 1307 is generally V-shaped, and met by a corresponding groove in the second curling surface. A prominent ridge of this kind at a location where it will come close to the base of each individual eyelash has been found to be very efficient in creating a nice, long-lasting curled form for the eyelashes.
Fig. 14 illustrates a cross section of the curling surfaces in one alternative embodiment. Features common with the embodiment of fig. 13 are the existence of the eyelid- side edges 1301 and 1302 and the corresponding distal edges 1303 and 1304, as well as the more-than-8-millimetres distance therebetween. Also in the embodiment of fig. 14 the first curling surface comprises the prominent V-shaped protruding ridge 1307 parallel to the eyelid-side edge 1301 of the first curling surface and displaced from it by less than 3 mm. As a difference to the embodiment of fig. 13 the second curling surface does not exactly match the form of the first curling surface, but just follows generally its outline between the eyelid-side edge 1301 and the distal edge 1303. In fig. 14 the cross section of the second curling surface is concavely curved, but it could be flat or convex, and/or it could comprise differently directed facets.
When a not-exactly-matching second curling surface like that in fig. 14 is pressed against the corresponding first curling surface, it is advantageous (although not mandatory) that the second curling surface is made of elastic material, because that ensures that it will be the design of the first curling surface that has the most influence on the final curled form of the eyelashes. Thus when it is said that the curling surfaces engage at least partly upon the longitudinal movement of the movable part, this engaging may be approximate, and it may at least partly involve an elastic deformation of one of the curling surfaces.
The curling surfaces of the embodiment of fig. 14 do not exhibit similar upper and lower bevels as those marked with the reference designators 1305 and 1306 in fig. 13. The aim of keeping the sensitive outer edge of the eyelid of the user from being caught between the curling surfaces is nevertheless achieved, because closest to the eyelid- side edges 1301 and 1302 the curling surfaces are not exact counterparts of each other. Pressing these curling surfaces together leaves a wedge-shaped protective gap between the eyelid-side edges also in this embodiment.
Fig. 15 illustrates a cross section of the first curling surface in another alternative embodiment. Features common with the embodiments of figs. 13 and 14 are the existence of the eyelid-side edge, seen at point A in fig. 15, and the corresponding distal edge, seen at point G, as well as the more-than-8-millimetres distance therebetween. Also in the embodiment of fig. 15 the first curling surface comprises the prominent V-shaped protruding ridge parallel to the eyelid-side edge of the first curling surface and displaced from it by less than 3 mm. The tip of the V-shaped protruding ridge is seen as point B in fig. 15.
If the location of the eyelid-side edge - seen at point A in the cross section of fig. 15 - is taken as the origin, examples of the Cartesian coordinates of the marked points in fig. 15 are: A(0.0,0.0); B(1.3,-0.6); C(1.7,1.0); D(1.0,2.6); E(1.0,3.7); F(0.2,5.0); G(5.5,6.3). Since the horizontal coordinate of point C is larger than that of points D, E, and F, it is not possible to make a second curling surface that would exactly match the first curling surface of fig. 15 and available for completely engaging with it through a direct vertical movement from below. The second curling surface may nevertheless engage at least most of the area between the edges illustrated by points A, B, and C in fig. 15, and a suitably elastically deformable second curling surface may be made to engage even further parts of the first curling surface. Yet another possibility is to form the sliding joint between the palm part and the movable part so that at the upper end of the movement the upper end of the movable part tilts outwards, so that this tilting movement makes the second curling surface engage an even larger portion of the first curling surface of the kind shown in fig. 15.
Figs. 16 and 17 illustrate an example of how it is by no means mandatory to have a tubular section at one end of the palm part. In the embodiments of figs. 16 and 17 the lower end of the palm part 101 comprise a cradle-formed section 1601, in which the movable part 101 is configured to execute its longitudinal movement. At the same time it may be noted that the designations "palm part" and "movable part" are just names that are used in this text to refer to the two main mechanical parts of the eyelash curler in a consistent and concise way. These names are not meant to limit the way in which the user holds the eyelash curler in her hand.
Fig. 18 shows an example of how the electric parts of the eyelash curler may look like in a circuit diagram. A control circuit 1801 is the central functional part, and it can be realized as an integrated circuit for example. A battery 1802 that is received in the battery compartment of the eyelash curler provides the operating power, and an operating switch 1803 together with one or more indicator lights 1804 and 1805 constitute a simple user interface. The electric heating element is represented by a resistor 1806, and a thermal sensor 1807 is provided for enabling the control circuit 1801 to get a feedback measurement from the temperature of the electric heating element.
The control circuit 1801 is advantageously configured to direct, as a response to the user pressing the operating switch 1803, a regulated current from the battery 1802 to the electric heating element 1806. If a battery of a voltage 1.5 volts is used and the magnitude of the regulated current is about 1 A, the electric power that heats up the electric heating element is about 1.5 W. It has been found that a resistance value close to one ohm may be suitable to enable heating the second curling surface to a temperature of about 60 degrees centigrade in about one minute. Concerning battery life, an alkaline battery of the AA size may be considered as an example. At the time of writing this text an AA alkaline battery may have the capacity of about 2800 mAh for example. Drawing a current of 1 A for one minute will consume about 17 mAh, so the battery could last for about 165 times of use.
The control circuit 1801 may use the indicator lights 1804 and 1805 to inform the user about the proceeding of the heating, for example so that a first signal given with the indicator lights 1804 and 1805 is an acknowledgement that the pressing of the switch 1803 has been noticed and that the heating is going on. A second, different kind of a signal with the indicator lights 1804 and 1805 may be a ready-signal, telling the user that the desired temperature has been reached so that actual use of the eyelash curler can begin.
Other kinds of signals can be given with the indicator lights 1804 and 1805, for example to inform the user that the battery is running low, or that a timed switch-off of the heating is imminent. In general it is advantageous that the operating switch 1803 functions as a toggle switch, so that a press on the switch 1803 switches the device on if it was off, and vice versa. It is also advisable to equip the control circuit 1801 with a timer that it can use to switch off the heating if the user has not used the device for a certain period of time.
It is possible to equip the control circuit 1801 with a short-distance wireless transceiver that implements a short-distance wireless communications standard, like the Bluetooth, ZigBee, or NFC standard for example. Such a control circuit would enable expanding the user interface of the eyelash curler to another electronic device nearby, like a smartphone for example. Such another electronic device could be used to implement extended user interface functions, like setting the values of configuration parameters; keeping a log of use; downloading updated software; sorting out possible problems in use; or the like.
It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the appended claims.

Claims

An eyelash curler, comprising:
- a palm part (101) having a first end and a second end, a direction from said first end towards said second end defining a longitudinal direction (103),

- a movable part (102) having a first end and a second end, attached to said palm part (101) with a sliding joint that enables movement of the movable part (102) with respect to said palm part (101) in said longitudinal direction (103),

- a first curling surface (104) at said first end of the palm part (101),

- a second curling surface (105) at said first end of the movable part (102), configured to engage at least part of said first curling surface (104) upon said movement of the movable part (102),

- an electric heating element (712) configured to heat said second curling surface (105),

- a battery compartment (702) for receiving a battery, and

- a control circuit (1801) configured to control the flow of electric current between a battery received in said battery compartment (702) and said electric heating element (712);
characterized in that said electric heating element (712), said battery compartment (702), and said control circuit (1801) are all located in said movable part (102).
An eyelash curler according to claim 1, wherein said palm part (101) and said movable part (102) together constitute an elongated entity that is thicker towards said second end than said first end of the palm part (101), so that towards said second end said elongated entity constitutes a handle, a diameter of which is between 15 and 40 mm and a length of which is between 60 and 160 mm, to fit in a hand of a human user.
An eyelash curler according to any of claims 1 or 2, wherein:
- said first curling surface (104) is a part of a first plate (108), directed transversally with respect to said longitudinal direction (103) and supported by a first support arm (109) as a part of said palm part (101), and

- said first support arm (109) attaches to a middle part of said first plate (108), a transverse thickness (110) of said first support arm (109) being less than 10 mm at a location below said first plate (108) in said longitudinal direction (103).
An eyelash curler according to claim 3, wherein said second curling surface (105) is a part of a second plate (111), directed transversally with respect to said longitudinal direction (103) and supported by a second support arm (112) as a part of said movable part (102).
An eyelash curler according to any of the preceding claims, wherein towards said second end said palm part (101) comprises a tubular section (501), so that said movement of the movable part (102) with respect to said palm part (101) in said longitudinal direction (103) involves moving a portion (701) of said movable part (102) inside said tubular section (501).
An eyelash curler according to any of the preceding claims, wherein:
- each of said first (104) and second (105) curling surfaces is limited on one side by a concave eyelid-side edge (1301, 1302), and

- at least said first (104) curling surface extends for more than 8 millimetres from the respective eyelid-side edge (1301) towards a respective distal edge (1303).
An eyelash curler according to claim 6, wherein at least one of said first (104) and second (105) curling surfaces comprises one or more ridges or grooves directed parallel to the respective eyelid-side edge (1301, 1302).
An eyelash curler according to claim 7, wherein at least one ridge in one of the first (104) and second (105) curling surfaces is met by a corresponding groove in the other.
An eyelash curler according to any of claims 6 to 8, wherein said first curling surface (104) comprises a protruding ridge (1307) parallel to the eyelid-side edge (1301) of said first curling surface (104) and displaced from said eyelid-side edge (1301) by less than 3 mm.
An eyelash curler according to any of the preceding claims, wherein said electric heating element (712) is located under at least one surface layer (1101, 1105) of said second curling surface (105).
An eyelash curler according to any of the preceding claims, wherein said second curling surface (105) comprises a piece of elastic material (1101) detachably attached to a support (1102) located at said first end of said movable part (102).
An eyelash curler according to claim 11, wherein said support (1102) is a support box with a bottom (1103) and edges (1104), and wherein said electric heating element (712) is located in said support box and separated from said bottom (1103) by an array of protrusions (1202) in said bottom (1103).
An eyelash curler according to any of the preceding claims, wherein said movable part (102) comprises a flex circuit (705) that extends from said battery compartment (702) to said electric heating element (712) and carries all electric connections between discrete electric parts of the eyelash curler.
An eyelash curler according to claim 13, wherein said electric heating element (712) consists of resistors (902) attached to that end of the flex circuit (705) that extends to the first end of the movable part (102).
An eyelash curler according to any of the preceding claims, wherein said movable part (102) comprises a push pad (704) formed of a surface oriented at least partially obliquely or transversally with respect to said longitudinal direction (103) for enabling a human user to push said movable part (102) in said longitudinal direction (103).