Hair curling device having wavy heating surfaces with asymmetrically sized crest and trough portions

Abstract

The techniques introduced here improve the effectiveness of a hair curling iron's heating surfaces without adding bulk. The device includes two elongated arms, each carrying a heating surface, connected by a pivot. The device's configuration allows the arms to open and close, forming a transverse wave-shaped heating area when the heating surfaces are interlocked with each other. Some embodiments of the heating area include a larger central wave that creates a dominant visual feature, and two smaller waves that can blend seamlessly with the adjacent large waves, resulting in an overall hairstyle that is full and voluminous. Some embodiments include hair volumizing cavity envelopes to reduce tension and friction, preventing hair pinching. Additionally, or alternatively, the crease-reduction gaps can reduce the likelihood of hair creases.

Description

RELATED APPLICATION(S)

[0001] This application claims priority to Chinese Invention Patent Application No. 202411177125.1, titled “Hair Curling Mechanism and Hair Curling Iron,” filed on Aug. 26, 2024; and to Chinese Utility Model Patent Application No. 202422076511.3, titled “Hair Curling Device,” filed on Aug. 26, 2024; each of which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] This disclosure relates generally to hair styling tools, and more particularly, to heating surface designs of hand-held hair curling irons.BACKGROUND

[0003] Hair curling irons are widely used hair styling tools commonly available on the market. These devices are typically powered by electricity, providing a convenient and efficient way to achieve various hairstyles. There are numerous types of hair curling irons, with one of the most commonly seen being the rotating curling irons (or curling wands). Rotating curling irons are popular for their ease of use and ability to create spiral curls. However, they are not without their drawbacks. One significant issue with rotating curling irons is their low efficiency. This inefficiency stems from the small amount of hair they can volumize at any given time, requiring users to spend more time achieving the desired look. Additionally, the styling versatility of these devices is limited, as they generally produce spiral-looking hairstyles (also known as the “ringlet,”“corkscrews,” or “princess hair”) rather than true wavy looking hairs. Another notable concern is the greater scalding hazard posed to users. The roll-type heating element in rotating curling irons is typically exposed, increasing the risk of accidental burns.

[0004] Another type of hair curling iron features “wavy” (hereinafter used synonymously with similar adjectives such as “waved,”“waving,” or “wave-shaped”) heating surfaces. These hair curling irons with waved heating surfaces are designed to create more pronounced and natural-looking waves compared to their roll-type counterparts. While these devices offer better styling results and reduced scalding risks, thanks to their design that typically covers the heating element more effectively, they are not without their own set of limitations. Conventional waving hair curling irons often suffer from inefficient use of their total heating surface area. This inefficiency necessitates larger sizes for these devices, making them cumbersome to use and inconvenient for travel.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] One or more embodiments of the present disclosure are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements.

[0006] FIG. 1A illustrates a perspective view of an embodiment of a hair curling device in accordance with the present disclosure.

[0007] FIG. 1B illustrates another perspective view showing the embodiment hair curling device of FIG. 1A in a closed position.

[0008] FIG. 2 illustrates an example cross-section A-A of the embodiment hair curling device shown in FIG. 1B.

[0009] FIG. 3 illustrates an example perspective view of the heating surfaces that can be implemented in the disclosed embodiment hair curling device.

[0010] FIG. 4 illustrates further implementation details of example heating surfaces that can be implemented in a hair curling iron introduced here.

[0011] FIG. 5 illustrates additional implementation details of example heating surfaces that are introduced here.DETAILED DESCRIPTION

[0012] References in this description to “an embodiment,”“one embodiment,” or the like, mean that the particular feature, function, structure, or characteristic being described is included in at least one embodiment of the present disclosure. Occurrences of such phrases in this specification do not necessarily all refer to the same embodiment. On the other hand, the embodiments referred to also are not necessarily mutually exclusive.

[0013] As mentioned above, while current hair curling irons on the market, whether rotating or waved, provide various styling options, they each have distinct disadvantages. Rotating curling irons struggle with efficiency and safety, while waving curling irons, although more effective in styling, are often bulky and inconvenient.

[0014] Introduced here, therefore, are techniques that can increase the effectiveness of a hair curling iron's heating surfaces without increasing the bulkiness of the overall device. According to the present disclosure, a hair curling device can include two arms, a first arm carrying a first heating surface, and a second arm carrying a second heating surface. Both arms are elongated in shape. The first and second heating surfaces are arranged to face each other, and the first and second arms are connected at a pivot. The pivot can allow a user to manipulate at least one of the first and second arms to form an open position where the first and second heating surfaces are not interlocked to each other, and a closed position where the first and second heating surfaces are interlocked to each other. When the device is in the closed position, the first and second heating surfaces together can form a heating area having a cross-section that resembles a transverse wave shape. As described in further details below in the present disclosure, in one or more embodiments, the transverse wave shape including a “crest portion” (or a “top half-wave portion”) and two “trough portions” (or two “bottom half-wave portions”). Each side of the crest portion has a trough portion. More specifically, the crest portion is located between, and adjacent to, the two trough portions, and the crest portion is connected to the two trough portions so as to form the transverse wave shape. Some embodiments provide that the two trough portions are symmetrical to each other about a vertical axis, yet asymmetrical to the crest portion about a lateral axis. In accordance with one or more embodiments, the crest portion has a larger dimension (e.g., size, length, width, height, radius, etc.) than the two trough portions.

[0015] The resulting hairstyle showcases a larger, more defined wave at the center, which becomes the dominant visual feature. While the two other waves may be smaller, they naturally fall behind the larger one and seamlessly connect to either the previous or the next larger wave, helping to create a continuously flowing wave pattern. This design gives the hair a full, voluminous look without making the curls appear choppy or uneven. Under gravity, the result is a hairstyle with added dimension and a more glamorous finish. Thus, the hair curling mechanisms and devices disclosed here can enhance the impact of the larger waves while allowing the smaller ones to blend in seamlessly, without making the curling device bulkier or harder to use.

[0016] Some embodiments of the present disclosure can further include hair volumizing cavity envelopes (e.g., cavity envelopes 330, discussed below) in the heating area. In these embodiments, the additional feature of hair volumizing cavity envelopes can help prevent the user's hair from getting pinched during the device's operation. By creating a buffer zone, these envelopes reduce or remove the tension and friction between the two hair heating surfaces as the surfaces are manipulated by the user toward each other when the user operates the hair curling device. This feature can help ensure that, when the device is opened or closed, the user's hair is less likely to be pinched or pulled, making the hair curling and volumizing process both smoother, safer, and more comfortable. In addition, certain embodiments have crease-reduction gaps (e.g., gaps 340, discussed below) arranged around the lateral edges of the hair heating surfaces when they are interlocked to reduce the probability of hair creases.

[0017] Overall, the embodiments of the present disclosure can address and overcome the aforementioned limitations of the traditional hair curling irons, offering a better looking, more efficient, versatile, and user-friendly hair curling solution.

[0018] In the following description, numerous specific details are set forth to provide a thorough understanding of the present disclosure. It will be apparent to one skilled in the art that the techniques introduced here may be practiced without these specific details. In other instances, well-known features, such as specific fabrication techniques, are not described in detail in order to not unnecessarily obscure the present disclosure. References in this description to “an example,”“one example,” or the like, mean that a particular feature, structure, material, or characteristic being described is included in at least one implementation of the present disclosure. Thus, the appearances of such phrases in this specification do not necessarily all refer to the same example. On the other hand, such references are not necessarily mutually exclusive either. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more examples. Also, it is to be understood that the various exemplary implementations shown in the figures are merely illustrative representations and are not necessarily drawn to scale.

[0019] The terms “coupled” and “connected,” along with their derivatives, may be used herein to describe structural relationships between components. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular examples, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may be used to indicate that two or more elements are in either direct or indirect (with other intervening elements between them) physical or electrical contact with each other, and / or that the two or more elements co-operate or interact with each other (e.g., as in a cause and effect relationship).

[0020] FIG. 1A illustrates a perspective view of an embodiment of a hair curling device 500 in accordance with the present disclosure. FIG. 1B illustrates another perspective view showing the embodiment hair curling device 500 of FIG. 1A in a closed position, whereas the same device 500 is illustrated in FIG. 1A in an open position. With simultaneous reference to FIGS. 1A and 1B, the various features of hair curling device 500 are explained below.

[0021] As shown in FIGS. 1A and 1B, the hair curling device 500 includes a first elongated arm 510 that extends along a longitudinal axis, and a second elongated arm 520 that extends along the same longitudinal axis. The elongated first arm 510 carries a first heating surface 512, and the elongated second arm 520 carries a second heating surface 522. The first heating surface 512 and the second heating surface 522 are arranged respectively on the first elongated arm 510 and the second elongated arm 520 such that the two surfaces 512 and 522 face each other. Further, the first and second elongated arms 510 and 512 are connected to each other at a pivot 530. As depicted in FIGS. 1A and 1B, the pivot 530 can allow a user of the hair curling device 500 to manipulate (e.g., by hand) the first elongated arm 510 and / or the second arms 520 in a relative manner, such as move towards or apart from each other. With the pivot 530, the user can maneuver the first and second arms 510 and 520 to form (1) an open position (e.g., as shown in FIG. 1A) where the first heating surface 512 and the second heating surface 522 are not interlocked, and (2) a closed position (e.g., as shown in FIG. 1B) where the first heating surface 512 and the second heating surface 522 are interlocked. When the first and second heating surfaces 512 and 522 are interlocked (i.e., when the hair curling device 500 is in the closed position), the two heating surfaces 512 and 522 together are arranged to form a heating area for hair curling.

[0022] More specifically, many examples of the hair curling device 500 are electrically powered and include an electrical power cord 540 for connection to an electrical power outlet (e.g., 100V-240V). However, depending on the implementation, some embodiments of the hair curling device 500 may be battery or otherwise portably powered and those embodiments may not necessarily have a fixed power cord such as the power cord 540 depicted in FIG. 1A. In addition to the elements already introduced above (e.g., the arms 510, 512, and the heating surfaces 512, 522), the hair curling device 500 can further include a number of control interface buttons 552-556 as well as a display 560 for user friendly operations. For example, to operate the hair curling device 500, the user can connect the power cord 540 of the device 500 to an electrical power source and activate the device 500 via a power button 556. Temperature adjustment can be facilitated through a temperature adjustment button 552. In some embodiments, the temperature button 552 allows the user to select within a range of 250° F. to 450° F., and in some of these examples, the device 500 can show the chosen temperature on the display 560. Moreover, certain embodiments can provide an adjustable timing function, which can be controlled via a time setting button 554. In one or more examples, the curling time duration can be adjusted from, e.g., 5 to 30 seconds, and the set duration can be indicated on the display 560.

[0023] To perform hair curling, the user first puts the hair curling device 500 in the open state in which the first contact surface 110 and the second contact surface 220 are far away from each other. After setting the desired curling parameters (e.g., via buttons 552, 554, and 556) for the given instance of application, the user can then select a section of hair (e.g., hair 502), and place the hair between the heating surfaces 512 and 522. Next, the user puts the device 500 into a closed position, which allows the heating surfaces 512 and 522 to clamp the hair 502. When the heating surfaces 512 and 522 are interlocked (i.e., when the device 500 is in the closed position), the clamping mechanism should secure the hair with sufficient force to hold it without causing damage. In addition to a timer (which can be controlled by the button 554), the hair curling device 500 can include a sensor 570 that can detect whether the first arm 510 and the second arm 520 are in the closed position. Depending on the embodiment, the sensor 570 can be a magnetic-based sensor (or a Hall sensor), a piezoelectric sensor, a proximity sensor, or another suitable type of sensor. The sensor 570 can be arranged at a suitable location between the first and second arms 510 and 520, e.g., such as shown in FIG. 1A, and the device 500 can further include a prompt mechanism (e.g., a buzzer or another audiovisual device, not shown for simplicity). The functional implementation for these components (e.g., timer circuitry, power control circuitry, etc.) can be integrated into the curling device's controller (not shown for simplicity).

[0024] In some embodiments, the timer is electrically connected to the prompt mechanism, and when the hair curling device 500 is in the closed position, the sensor 570 can automatically activate the timer, starting a countdown. Once the set time elapses, the timer can send an electrical signal to the prompt mechanism, which then can emit a sound, for example, to alert the user that the styling time is complete. Upon completion of the pre-set time (e.g., as signaled by an audible indicator), the user opens the clamp so that heating arms 510 and 520 move to the open position again to allow the resulting, curled hair section to be released. This process can be repeated by the user as required (e.g., until the entire head of hair is styled). In many embodiments, the device 500 also includes an automatic shut-off feature that deactivates the heating element (e.g., one shown later in FIG. 2 as element 400, discussed below) after a period of inactivity, reducing the risk of overheating. In one or more embodiments, the arms 510 and 520 can be shaped such that they form a handle 504 for user ergonomics. The arms'cover material can be one of temperature resistant and insulating so as cover the heating surfaces 512 and 522, thus reducing the possibility of potential scalding hazard for the user. Specifically, in some embodiments, the outer walls of the first arm 510 and the second arm 220 can be covered with a thermal insulation layer 580 that is arranged to further improve the thermal insulation of the hair curling device 500, thereby reducing or avoiding potential scalding that may be caused by the outer wall of the first arm 510 and the second arm 520 if they accidentally become in contact with the human body in the process of use. In many examples, this thermal insulation layer 580 is configured with a material with low thermal conductivity. For example, the thermal conductivity can be within a range of 0.005-0.6W / (m·K), and this material can be suitable PET material, PA material, silicon-based material, and so forth. The selection of the material should allow the thermal insulation layer 570 to be formed on the outer wall of the arms 510 and 520, and should factor in the convenience for processing and production, and the production cost. In some embodiments, the same material can also have a suitably high friction coefficient for anti-slipping effect, making it convenient for the user to have a firm grip of the handle 504 during use.

[0025] As an additional feature, to make carrying the hair curling device 500 more convenient, some embodiments can include a closing lock 590, which can include two states: locked and unlocked. For example, in these embodiments that implement the closing lock 590, when the hair curling device 500 is in the closed position (i.e., when the heating surfaces 512 and 522 are interlocked, such as shown in FIG. 1B), the closing lock 590 can be switched between locked and unlocked states. When in the locked state, the closing lock 590 includes an internal mechanical mechanism that can keep the hair curling device 500 in the closed position, thus reducing its space occupancy and making it more compact and convenient for travelling. When in the unlocked state, the internal mechanical mechanism in the closing lock 590 allows the first and second arms 510 and 520 of the hair curling device 500 to move freely in order for the user to manipulate and between the open and closed positions, thereby enabling the user to operate as needed for hair curling.

[0026] In accordance with the present embodiments, when in the hair curling device 500 is in the closed position, the first heating surface 512 and the second heating surface 522 are interlocked and together form a heating area. The various features of this heating area are described in further detail below with respect to FIGS. 2-5. Note that, to facilitate a better understanding of the disclosed mechanisms and device features, a three-axis system 501 is adopted in the present disclosure to represent the three dimensions of the hair curling device 500. The first axis is the longitudinal axis introduced above, which extends along the same direction as the elongated arms 510 and 520. The second axis is a lateral axis that is perpendicular to the longitudinal axis. The longitudinal axis and the lateral axis together form a plane on which the hair curling device 500 (as well as the heating area) sits. The third axis is a vertical axis that is perpendicular to the plane that is formed by the longitudinal and lateral axes. The three-axis system 501's orientation with respect to the hair curling device 500 is illustrated in FIG. 1B.

[0027] FIG. 2 illustrates an example cross-section A-A of the hair curling device 500 shown in FIG. 1B (i.e., when the device 500 is in a closed position). FIG. 3 illustrates an example perspective view of a heating area 300 that can be implemented in the hair curling device disclosed here. Specifically, FIG. 3 shows a first heat conducting structure 100 that can be installed on, e.g., the first elongated arm 510 (of FIG. 1A), and a second heating conducting structure 200 that can be installed on, e.g., the second elongated arm 520 introduced above. As illustrated in FIG. 3, the heating area 300 is formed by the first and second heating surfaces (of first and second heat conducting structure 100 and 200, respectively) when they join and interlock with each other, i.e., when the hair curling device is in the closed position.

[0028] Continuing with the description above, an example hair curling mechanism disclosed here includes a first heating surface (e.g., heating surface 512), which can be implemented as a part of a first heat conducting structure 100. The mechanism also includes a second heating surface (e.g., heating surface 522) that can be implemented as a part of a second heat conducting structure 200. Both the first and the second heat conducting structures 100 and 200 can be made of suitable, thermally conductive material. As shown in FIG. 2, the heating surface of the first heat conducting structure 100 is configured to face toward the heating surface of the second heat conducting structure 200 such that, when the hair curling iron (e.g., device 500) is in the closed position, both the first and second contact surfaces form a heating area 300 (in FIG. 3) for receiving hair can be formed between them.

[0029] As discussed, the hair curling mechanism of the present embodiments has two positions: open and closed. In the open position, the heat conducting structures 100 and 200 (as well as the heating surfaces thereof) are separated from each other, allowing the user to place hair between them. In accordance with the present disclosure, when the hair curling device is in the closed position, the heating area 300 can be formed between the first and second heating surfaces. Both the first and second heating surfaces are continuous, i.e., the surfaces are without any interruption or break. In this way, the wave-shaped heating area (or space) is also continuous, with no gaps, allowing hair to be clamped securely and avoiding any hair escaping the heating area during the curling process. Notably, in some embodiments, when the contact surfaces are in the closed position and when there is no hair, at least part of these surfaces (e.g., crest 310 and trough 320, discussed below) are in physical contact.

[0030] FIG. 4 illustrates further implementation details of example heating surfaces that can be implemented in a hair curling iron introduced here. With simultaneous reference to FIGS. 2 and 3, various features of the heating conducting structures 100 and 200, including the heating area 300, are discussed in further detail below with respect to FIG. 4.

[0031] As shown in FIG. 4, the heating area 300 generally has a cross-section that resembles a transverse wave shape. More specifically, when the first and second heating surfaces (of the heat conducting structures 100 and 200, respectively) are interlocked, together the two surfaces form a heating area 300 having a cross-section that resembles a transverse wave shape. In particular, the transverse wave shape resembles the English letter “W” or “M” (or a stylized “A” letter, or a Greek letter “Ω”). In accordance with the present disclosure, the transverse wave shape includes a crest portion 301 (that has the appearance of a “top half-wave”) and two trough portions 302 (that have the appearance of two “bottom half-waves”). The crest portion 301 is located between, and adjacent to, the two trough portions 302. Said another way, the heating area 300 features a crest portion 301 with an arc-shaped structure, and two trough portions 302, one on each side of the crest portion 301. For purposes of discussion here, the highest point of the crest portion 301 defines a crest 310 (or “crest point”) in the transverse wave shape, whereas the lowest points of the two trough portions 302 define two troughs 320 (or “trough points”) in the transverse wave shape.

[0032] According to the present embodiments, the two trough portions 302 are symmetrical to each other about a vertical axis. That is, the two trough portions 302 are the same in size, dimension, shape, and other geometry when they are compared to each other around the vertical axis. On the other hand, the two trough portions 302 are asymmetrical to the crest portion 301 about a lateral axis. In other words, the two trough portions 302 are different in size, dimension, shape, and / or other geometry when they are compared to the crest portion 301 around the lateral axis. In the embodiment depicted in FIG. 4, the crest portion 301 is larger (e.g., wider and taller) than the trough portion 302. The physical, structural dimension of the crest portion 301 (when compared to the two trough portions 302) that is larger can include, e.g., height, width, and / or radius. In some examples, the dimension of the crest portion 301 is at least 25%-30% larger than that of the trough portion 302. Note that the sense that the crest portion 301 is larger than the trough portion 302 should not be limited to only a particular way of measurement that is discussed here; a person having ordinary skills in the art would appreciate that other suitable ways of measurement can be applied for practicing the disclosed techniques as well. Also, while the illustrated embodiments have one large crest portion and two small trough portions (which are the preferred embodiments), the disclosed techniques are similarly applicable to embodiments where they have two large trough portions and one small crest portion; the latter are less preferred embodiments because they are not as efficient as the former where the prevailing, the available real estate is maximally utilized by the large crest portion. Also, the terms “crest portion” and “trough portion” are merely used here in a relative sense for purposes of facilitation the discussion; the disclosed techniques are similarly applicable regardless of the exact naming of the half-wave looking heat conducting structures.

[0033] Overall, this arrangement of one larger crest portion 301 paired with two smaller crest portions 302 on the sides allows hair placed in the cavity to form a larger wave shape in the middle and relatively smaller arcs on the sides, catering to user preferences and addressing prior technical issues. The two trough portions 302 are symmetrically arranged with respect to the crest portion 301, making the entire size of the curling mechanism smaller (as opposed to, e.g., two or three half-waves that are sized as the large crest portion 301), more portable, and capable of creating larger wavy curls (e.g., when compared to a similarly sized hair curler but having equally-sized half-waves).

[0034] Specifically, depending on the embodiments, the height difference between the crest 310 and the trough 320 (i.e., distance A4 in FIG. 4) can range between 20 mm-32 mm. The width (or the arc size) of the crest portion 301 (i.e., distance A1 in FIG. 4) can range between 17 mm-27 mm. Note that, for purposes of discussion here, the width of the crest portion 301 is measured at the widest points (in the lateral axis) of the crest portion 301. The disclosed embodiments allow the curling mechanism to form a large wave shape and accommodate more hair, enhancing styling efficiency. Note, however, that it is observed in the present disclosure, if the height distance between the crest 310 and the trough 320 (A4) is less than 20 mm or greater than 32 mm, then the wave shape can become less aesthetically pleasing. Similarly, if the width of the crest portion 301 (A1) is less than 17 mm, then it can become difficult to achieve a desirable large wave shape for the hair, and if the width of the crest portion 301 is greater than 27 mm, then the resulting wave shape can become too large and less attractive. As such, many embodiments of the present disclosure adopt a crest portion width of 17 mm-27 mm and a crest-trough height difference of 20 mm-32 mm so that the hair curling device remain reasonably sized while being capable of creating large wave hairstyles.

[0035] Furthermore, depending on the implementation, a central angle of the crest portion can be less than or equal to 180 degrees and, in many examples, close to 180 degrees. Many embodiments also provide that a central angle of the trough portion 302 can be less than 180 degrees. In other words, at least in certain embodiments, a central angle of the crest portion is larger than a central angle of the trough portions.

[0036] This can result in a more pronounced curl near the crest portion (e.g., crest portion 301) and a gentler curl near the trough portion (e.g., trough portion 302), thus can further increase the visually appeals of the resulting wavy hair. According to a number of examples, a diameter difference between an arc of the crest portion and an arc of the trough portion can range from 3 mm to 6 mm, which can also enhance the natural look of the curls. Note that, for purposes of the discussion here, the term “central angle” means an angle whose apex is the center of a hypothetical circle that is of a general approximation of a subject half-wave portion (e.g., the crest portion 301 or the through portion 302) and whose legs are the radii intersecting the hypothetical circle in two distinct points on the heating surface of the subject half-wave portion. That is to say, the mere usage of the terms “central angle,”“radius,”“diameter,” or other geometry terminology in the present disclosure is not to be construed in a strict sense, i.e., it is not meant to limit the shape of a given half-wave portion to that of a perfect circle. In addition, some embodiments of the present disclosure can further include hair volumizing cavity envelopes 330 in the heating area 300. As introduced above, in these embodiments, the additional feature of the hair volumizing cavity envelopes 330 can help prevent the user's hair from getting pinched during the device's operation.

[0037] Particularly, as illustrated in FIG. 4, the heating area 300 includes two hair volumizing cavity envelopes 330. Each hair volumizing cavity envelope 330 is located at about a waist location where the crest portion 301 meets one of the two trough portions 302. As can be seen in FIG. 4, the cross-section of the hair volumizing cavity envelope 330 resembles an English letter “S” (or a reverse “S,” depending on which cavity envelope 330 is being the subject and observed from which viewpoint). According to the present disclosure, the embodiments of the hair volumizing cavity envelopes 330, being located between the crest portion 301 and the trough portions 302, have a gap that is the widest at the waist point and gradually tapers (or grows narrow) toward the crest 310 and the troughs 320. This shape of the cavity envelope 330 can help secure the user's hair and reduce the chance of hair slipping from the thermal conducting structures 100 and 200. In this way, the hair volumizing cavity envelopes 330 can help achieve a more even heat distribution, thereby generating better curling results. Also, the continuous, wider middle section of the cavity envelopes 330 can allow for more hair to be accommodated without escaping. More specifically, by creating a buffer zone, these envelopes 330 reduce or remove the tension and friction between the two hair heating surfaces (e.g., surfaces 512 and 522, FIG. 1A) as the surfaces are manipulated by the user toward each other when the user operates the hair curling device (e.g., device 500, FIG. 1A). This feature can help ensure that, when the device is opened or closed, the user's hair is less likely to be pinched or pulled, making the hair curling and volumizing process both smoother, safer, and more comfortable. From a practical point of view, the addition of the hair volumizing cavity envelopes330 can promote better fitment (e.g., by having a tolerance for process variation) when heat conducting structures 100 and 200 are massively produced, and they can ensure a proper, continuous heating area can be formed between the heating structures 100 and 200 when the curling mechanism is in the closed position.

[0038] In one or more embodiments, a maximum clearance A2 of the hair volumizing cavity envelop 330 can range from 0.5 mm-2 mm (i.e., measured when the hair curling mechanism is in the closed position). With this gap (as delineated as A2), the hair located between the crest 310 and the troughs 320 can be better situated (e.g., more closely and tightly confined) within the space and can have a better contact with the first heating surface (e.g., surface 512, FIG. 1A) of the first heat conducting structure 100 as well as the second heating surface (e.g., surface 522, FIG. 1A) of the second heat conducting structure 200. This can further improve the heating area 300 for the hair by ensuring more uniform heating. It is observed in the present disclosure, however, that if the maximum distance (or the widest gap) of the hair volumizing cavity envelope 330 is less than 0.5 mm, then it may become inconvenient to close the curling hair mechanism due to the friction from fitment issues. On the other hand, if the maximum distance (or the widest gap) of the hair volumizing cavity envelope 330 is greater than 2 mm, then the hair located between the crest 310 and the troughs 320 may not have good contact with the first and second heating surfaces (e.g., surfaces 512 and 522, FIG. 1A).

[0039] Moreover, certain embodiments of the disclosed hair curling devices can include crease-reduction gaps 340 that are arranged around the lateral edges of the hair heating surfaces when the heating surfaces are interlocked to reduce the probability of hair creases. Specifically, the crease-reduction gaps 340 are formed when the first and second arms of the hair curling device (e.g., arms 510 and 520 of device 500, FIG. 1A) are in the closed position.

[0040] As the embodiment depicted in FIG. 4 shows, the crease-reduction gaps 340 are progressively widened from the trough 320 toward the lateral edges of the hair curling mechanism. In some embodiments, because the trough portions 302 are located closer (as compared to the crest portion 301) to the outer edges of the hair curling mechanism, the trough portions 302 are so arranged that they slightly but progressively open toward the outer, lateral edges of the heating area 300, thereby forming the crease-reduction gaps 340 as depicted. This can be achieved through careful designs of the shapes on the lateral edges of the heat conducting structures 100 and 200. As shown in FIG. 4, the gap in the heating area 300 from the troughs 320 moving towards the lateral edges of the curling mechanism gradually increases, which can reduce the probability of crease formation in the hair at or around the edge of the heating area 300, and therefore the crease-reduction gaps 340 can further enhance the aesthetic appeal of the resulting hair.

[0041] In some embodiments, a maximum clearance A3 of the crease-reduction gaps 340 is 3 mm (i.e., measured when the hair curling mechanism is in the closed position). It is observed in the present disclosure, if the maximum clearance A3 of the crease-reduction gaps 340 is too small (e.g., less than 1 mm), then the hair located at the lateral edges of the heating area 300 may develop slight creases. In some examples, if the clearance A3 is close to zero, then the resulting hair may develop obvious creases and not desirable. Conversely, if the maximum clearance A3 of the crease-reduction gaps 340 is greater than 3 mm, then the hair located at the lateral edges of the heating area 300 may not fully contact the first heating surface (e.g., surface 512) of the first heat conducting structure 100 and the second heating surface (e.g., surface 522) of the second heat conducting structure 200, which can result in uneven heating. As such, in many cases, the disclosed the crease-reduction gaps 340 has a maximum clearance A3 that ranges from 1 mm to 3 mm.

[0042] As discussed above, the first heat conducting structure 100 and the second heat conducting structure 200 are configured as waved-shape structures. Note that it is desirable to have the thickness of the first thermal conductor 100 and the second thermal conductor 200 as uniform as practically feasible. Keeping the difference between the thicknesses of the thermal conductive parts as small as possible can assist in even heat distribution for the heating area 300. Further, embodiments of the curling hair mechanism introduced here can include heating elements 400 that are installed at strategic locations. With simultaneous reference to FIGS. 2 and 4, at least in some of the embodiments, the heating elements 400 can be located at the back side of the heating surfaces and near the crest 310 and / or the troughs 320. The arrangement of the heating elements 400 can promote heat to be transmitted more quickly and evenly, partially due to the relatively evenly spread locations across the heating surfaces in the heating area 300, and partially due to the uniform thickness of the heat conduction parts discussed above. With the aforementioned factors, together with the hair volumizing cavity envelopes 330, the heat generated by the heating piece 400 can be distributed to the hair more evenly and from both sides (i.e., from the heating surface of the structure 100 and the heating surface of the structure 200), which can further shorten the hair curling time and improve the efficiency in hairstyling. In one or more examples, the heating elements 400 are of a positive-temperature-coefficient heating element (or “PTC heating element”) type that can self-regulate the temperature when it is supplied by a given voltage. In other examples, the heating elements 400 can be of a Metal Ceramics Heater (“MCH”) type, and in some of these examples, the implemented MCH type heating element is free of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyls, polybrominated diphenyl ethers, and other harmful substances, for the benefit of user's health.

[0043] FIG. 5 illustrates additional implementation details of example heating surfaces (e.g., surfaces 512 and 522, FIG. 1A) that are introduced here. Similar to what is discussed above, a first heat conducting structure 601 and a second heat conducting structure 602 are shown as in an interlocked state (e.g., when the arms 510 and 520 in FIG. 1A are in the closed position). The cross-section of the heat conducting structures 601 and 602 together form a heating area that resembles a transverse wave shape having a crest portion and two trough portions (such as discussed above with respect to FIG. 4). The highest point of the crest portion defines a crest 610 in the transverse wave shape, and the lowest points of the two trough portions define two troughs 620 in the transverse wave shape.

[0044] As shown in FIG. 5, the crest 610 and the two troughs 620 form an isosceles triangle that has two legs 603 of equal length (A6) as well as two base angles (β) of equal measure. The isosceles triangle also has a base 604 of a length (A5), and an apex angle (α). Although in the embodiment depicted in FIG. 5, the isosceles triangle that is formed is not an equilateral triangle; however, the present disclosure includes certain embodiments where the triangle formed by the crest 610 and the troughs 620 is an equilateral triangle. Depending on the embodiments, the isosceles triangle that is formed by the crest 610 and the troughs 620 can have an apex angle α that is between 45 degrees and 70 degrees, and more specifically, the apex angle α in some examples can range between 55 degrees and 65 degrees. Additionally, in accordance with a plurality of embodiments, the length A6 of two legs of the isosceles triangle can range between 25 mm to 45 mm. In one or more embodiments, the length A5 of the base of the isosceles triangle is between 30 mm to 50 mm. Even more specifically, in one or more embodiment, a height difference A4 between the crest 610 and the troughs 620 is 32.5 mm, the base length A5 of the isosceles triangle formed by the crest 610 and the two troughs 620 is 46.3 mm, and the length A6 of the two legs of the isosceles triangle is 40.1 mm. In another embodiment, a height difference A4 between the crest 610 and the troughs 620 is 24.2 mm, the base length A5 of the isosceles triangle formed by the crest 610 and the two troughs 620 is 33.3 mm, and the length A6 of the two legs of the isosceles triangle is 29.5 mm.

[0045] In the above-described manners, the disclosed hair curling devices include features that can enhance the functionality and quality of hairstyling. By ensuring uniform and closer contact between the hair and the heating surfaces, the devices can better utilize the limited real estate available, provide better results with fuller and more voluminous, large-curled wavy hair with consistent heating, and achieve so without necessarily adding bulk. The introduced techniques and mechanisms also improve the uniformity and efficiency of the heating area, reducing the time required for curling hair and leading to a more efficient hairstyling process. Additionally, the disclosed embodiments include various aspects that enable easy operation, reduce hair pinching, minimize the risk of hair creases, and enhance scalding prevention. Overall, the resulting devices deliver a better user experience as well as more aesthetically pleasing curls.

[0046] The foregoing description of various embodiments of the claimed subject matter has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed. Many modifications and variations will be apparent to one skilled in the art. Embodiments were chosen and described in order to best describe the principles of the invention and its practical applications, thereby enabling those skilled in the relevant art to understand the claimed subject matter, the various embodiments, and the various modifications that are suited to the particular uses contemplated.

[0047] Although the Detailed Description describes certain embodiments and the best mode contemplated, the technology can be practiced in many ways no matter how detailed the Detailed Description appears. Embodiments may vary considerably in their implementation details, while still being encompassed by the specification. Particular terminology used when describing certain features or aspects of various embodiments should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific embodiments disclosed in the specification, unless those terms are explicitly defined herein. Accordingly, the actual scope of the technology encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the embodiments.

[0048] The language used in the specification has been principally selected for readability and instructional purposes. It may not have been selected to delineate or circumscribe the subject matter. It is therefore intended that the scope of the technology be limited not by this Detailed Description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of various embodiments is intended to be illustrative, but not limiting, of the scope of the technology as set forth in the following claims.

Claims

1. A hair curling device comprising:an elongated first arm carrying a first heating surface; andan elongated second arm carrying a second heating surface;wherein the first and second heating surfaces are arranged to face each other,wherein the first and second arms are connected at a pivot, the pivot allowing user manipulation of at least one of the first and second arms in a relative manner to form (1) an open position where the first and second heating surfaces are not interlocked, and (2) a closed position where the first and second heating surfaces are interlocked,wherein the first and second heating surfaces, when interlocked, together form a heating area having a cross-section that resembles a transverse wave shape, the transverse wave shape including a crest portion and two trough portions, the crest portion being located between, and adjacent to, the two trough portions, andwherein the two trough portions are symmetrical to each other about a vertical axis, yet asymmetrical to the crest portion about a lateral axis.

2. The device of claim 1, wherein the crest portion has a larger dimension than the two trough portions.

3. The device of claim 2, wherein said larger dimension includes height, width, and / or radius.

4. The device of claim 2, wherein said larger dimension is at least 25% larger.

5. The device of claim 2, wherein the heating area includes two hair volumizing cavity envelopes, each cavity envelope located at about a waist location where the crest portion meets one of the two trough portions.

6. The device of claim 5, wherein a cross-section of a hair volumizing cavity envelope resembles an English letter “S.”7. The device of claim 5, wherein a lateral dimension of a cavity envelope is between 0.5 mm to 2 mm.

8. The device of claim 1, wherein, when the first and second arms are in the closed position, two crease-reduction gaps are formed, each crease-reduction gap located at one of the two outer lateral edges of the interlocked first and second heating surfaces.

9. The device of claim 8, wherein a width of a crease-reduction gap is between 1 mm to 3 mm.

10. The device of claim 1, wherein the highest point of the crest portion defines a crest in the transverse wave shape, wherein the lowest points of the two trough portions define two troughs in the transverse wave shape, and wherein the one crest and the two troughs form an isosceles triangle but not an equilateral triangle.

11. The device of claim 10, wherein the isosceles triangle that has an apex angle that is between 45 degrees and 70 degrees.

12. The device of claim 10, wherein the isosceles triangle that has an apex angle that is between 55 degrees and 65 degrees.

13. The device of claim 10, wherein the length of two legs of the isosceles triangle is between 25 mm to 45 mm.

14. The device of claim 10, wherein the length of the base of the isosceles triangle is between 30 mm to 50 mm.

15. The device of claim 10, wherein a height difference between the crest and the two troughs is between 20 mm to 32 mm.

16. The device of claim 10, wherein a width of the crest portion is between 17 mm to 27 mm.

17. The device of claim 1, wherein the transverse wave shape resembles the English letter “W” or “M.”18. The device of claim 1, wherein a central angle of the crest portion is larger than a central angle of the trough portions.

19. The device of claim 1, further comprising:a sensor that detects whether the first and second arms are in the closed position; anda timer that is coupled to the sensor,wherein, when the first and second arms are in the closed position, the sensor is configured to trigger the timer to start.

20. The device of claim 19, further comprising:a switch operable to adjust the timer by a user, wherein the timer is configured to control an operation mode of the device.

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