Patent Application
20230145671
The present disclosure relates to apparatuses affixing a wearable electronic device to the user's anatomy. In particular the disclosure relates to straps for the purpose of providing a snug fit for an electronic wearable device comprising an optical heart rate sensor in order to improve heart rate measurements.
The fit of a strap for a wearable electronic device is important not only for providing a comfortable using experience but also for ensuring reliable operation of the device. Several attempts have been made to improve the fit of a strap by optimizing its stretching properties, as discussed in US 20160255921 A1 and US20170065038A1.
A challenge of designing contemporary smart wearable devices is the need to use a particular material in the strap. Leather, in particular, is appreciated by consumers for its durability but also for aesthetic reasons. However, both natural and artificial leather grades have turned out be far from optimal as the base material of a strap for a wearable electronic device because leather has limited compliance properties for ensuring a snug fit.
Accordingly there remains a need to develop a leather strap for a wearable electronic device that would provide for a good fit required by sensors of the electronic device.
The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.
According to a first aspect of the present disclosure, there is provided a wearable electronic device with a strap. The strap features a first layer of microfiber and a second layer of natural or artificial leather as an outer layer. A layer of elastic adhesive attaches the first layer to the second layer. The first layer is a structural part of the strap, which structural part dominantly defines the mechanical properties of the strap, whereas the second layer is a façade complying to the first layer. The thickness of the layer of elastic adhesive is smaller than the thickness of the first layer and second layer. The wearable electronic device comprises an optic heart rate sensor housed in the enclosure.
Certain embodiments of the invention may include one or more features from the following list:
Considerable benefits are gained with aid of the present invention.
By using leather as the façade outer layer of a laminated strap, the benefits of leather may be had while pursuing technical properties that are beneficial for smart devices requiring reliable skin contact. On the other hand, by using microfiber material as the raw material of the inner layer of strap, elasticity is gained in one dimension and lost in another. This enables orientation of the strap fabric such that, once closed into a loop, the elasticity of the strap ensures a reliable fit of the wearable electronic device on the user. The relatively soft microfiber material of the strap, in turn, facilitates compliance with minor contours on the users anatomy, such as protruding bones, etc. By having relatively little elasticity in the transversal dimension, the strap maintains a good deformation resistance. Such benefits are particularly useful in applications in which the wearable electronic device features an optical heart rate sensor, the accuracy of which is greatly dependent on a uniform contact with the user's skin. Optical heart rate or pulse measurement is performed with a sensor arrangement with light emitters and light sensors placed at the watch case bottom. The measurement is disturbed by ambient light reaching the sensor or sensors from the sides if the watch does not stay in good contact with the skin. Also the oscillations or vibrations of the wrist tissue at the sensors from when the wrist is moving, for example when running, causes signal noise thus making the measurement more difficult. The problems with the reliability of the measurement are worsened if the watch is relatively heavy and loosely fit. On the other hand, an overly tight watch strap would be too uncomfortable. It is therefore desirable to have a snug fit with a comfortable feel in order to make a desirable product with good quality. In other words, the novel strap construction has the potential in improving the accuracy of heart rate signal acquired with optical heart rate sensors enclosed in a wearable electronic device.
These benefits could not be gained by constructing the strap entirely of leather.
Additionally, the inner layer, which is in permanent contact with the skin, may be cleaned with effective substances that could not be applied to leather.
In the following certain exemplary embodiments are described in greater detail with reference to the accompanying drawings, in which:
In the following numerous embodiments are described with a strap featuring a strip made from at least two materials layered on each other as a structural layer and as a façade layer. The façade layer is intended as a decorative cover layer, which is not supposed to provide structural load carrying properties to the strap. Accordingly, the façade layer is preferably more flexible than the structural layer. The structural layer and the façade layer are attached to each other with an adhesive layer, wherein the adhesive and façade layer are preferably set to withstand, i.e. not break at, the maximum designed flex or deformation of the strap. Throughout this description the structural layer is referred to as an inner or first layer and the decorative cover layer is referred to as a façade or second layer.
Let us first turn to the strap 100, which is shown in a planar spread-out configuration in
The second part 120 acts as the male part of a two-part strap and comprises a tip 123 for entering through the buckle 113 and a sequence of holes 124 for receiving the a tongue 114. In the present field, such strap parts are referred to as “long pieces”. As indicated above, the buckle mechanism could be replaced with an alternative, whereby the second part 120 would include a Velcro attachment piece, a magnet, a clasp part, a quick coupler, etc. The second part 120 has three sections, namely an attachment end 120A at one end for attachment to the wearable electronic device 200, a closing end 120C at the other end for accommodating the attachment to the first strap part 110, and an intermediate section 120B there between.
The first layer 111A of the strip 111 is made from microfiber. In other words, the first layer 111A comprises microfiber base material. The first layer 111A, when processed into a part of the strap part, may include further materials, such as glue or texture yarn or silicone pads attached to the inner surface, but the base of the strip is formed by a microfiber cloth. The thickness of the first layer 111A may be at most 3 mm, such as in the range of 1 to 2 mm. The microfiber material is preferably ultra-microfiber, such as Ultrasuede®. The microfiber material may comprise polyester or polyamide or other suitable fiber material, such as carbon fiber, and polyurethane or other suitable flexible polymer as a binder, such as silicone.
The first layer 111A extends along the entire longitudinal dimension X of the strip 111. The first layer 111A may optionally, as shown, extend through the loop sections 111B, 111D. Alternatively, the first layer 111A may terminate before the loop section 111B, 111D or either one of them.
According to a particular embodiment the microfiber comprises 65 to 80 weight-% of polyester ultra-microfiber which is non-woven with 35 to 20 weight-% of non-fibrous polyurethane binder.
The first layer 111A extends along the longitudinal dimension X to form an inner layer of the strip. The first layer 111A is oriented such that it exhibits greater elasticity in the longitudinal dimension X than in the transversal dimension Y. The difference in the elastic modulus between the longitudinal dimension X and the transversal dimension Y may be 20% or more, preferably 50% or more, 100% or more, 200% or more, or by more than one or two order of magnitude.
The strip 111 features a second layer 111C made of natural or artificial leather forming the façade of the strap 100. Suitable types of leather include cow leather skived into a relatively thin layer. The thickness of the second layer 111C is quite small so that it has a minimal effect on the elasticity of the strip 111. Accordingly, the thickness of the second layer 111C may be less than 1 mm, such in the range of 0.2 to 0.9 mm, particularly between 0.5 and 0.8 mm.
The second layer 111C forms the façade of the strip 111 and, thus, faces away from the user, whereby it is not subjected to skin oils. To fully cover the visible part of the strip 111, the second layer 111C extends along the entire longitudinal dimension X of the strip 111 but also through the loop sections 111B, 111D.
In other words, the inner layer 111A is intended to face the user and be in contact with the user's skin. For this purpose, majority of the inner layer 111A is exposed. In other words, only the minority of the surface area of the inner layer 111A may, according to one embodiment, be covered.
The layers 111A, 111C are attached to each other by gluing for example with a thermosetting adhesive there between. Accordingly, there is a layer of elastic adhesive or heat activated bonding layer between and the layers 111A, 111C fixing the layers 111A, 111C together. The layer of elastic adhesive is very thin, at least thinner than first and second layer 111A, 111C. It is preferred that the layer of elastic adhesive is so thin that it cannot be observed with the naked eye with unimpeded vision at a 20 cm distance in broad daylight. The adhesive may penetrate in part or entirely into the layers 111A, 111C. The adhesive selected is preferably strong and compliant to allow the strip 111 to stretch in the longitudinal dimension. Suitable adhesives include thermosetting adhesives, such as a thermoplastic polyurethane film that is melt to activate the bonding properties. Other examples include adhesives that are applied in liquid form and can be cured by drying or heating. It is preferable that the selected adhesive is at least as elastic as the microfiber of the first layer 111A, 121A so as to prevent delamination, when exposed to stretch. It is at least preferable that the adhesive is not a limiting factor in the stretching ability of the strap 100. During manufacturing a blank of microfiber and leather may be laminated into two layers with elastic glue or heat activated bonding layer and then cut to the final shape or the strip is first cut from blanks of microfiber and leather, which are then processed into the shape shown in the FIGURES.
As previously mentioned, the structural layer and the façade layer are attached to each other with an adhesive layer, wherein the adhesive and façade layer are preferably set to withstand, i.e. not break at, the maximum designed flex or deformation of the strap. This can be tested so that one measures the flex of the strap for example in a 200 kN static strap test. Accordingly, the façade layer may be tested to ensure that it is able endure the measured stretch of the strap. The exemplary 200 kN test force can be replaced with any test that measures the flex of the strap in the foreseen use purpose. In other words, the strap is designed to exhibit an inherent flex. Only several flex cycles ensure that the façade layer does not suffer damage or become delaminated.
The adhesive attachment may be reinforced with stitching, particularly at the vicinity of either or both of the loop sections 111B, 111D. In the illustrated example only the loop section 111D at the closing end 110C is provided with a double-line stitching that penetrates both layers 111A, 111C.
The first layer 111A, 121A is a structural part of the strap 100 that dominantly defines the mechanical properties of the strap 100. The second layer 111C, 121C, on the other hand, is merely a façade that complies to the properties of the strap largely set set by first layer 111A, 121A. It may be seen that the second layer 111C, 121C has at most 20% impact on the mechanical properties of the strap 100. For example, if a property of first layer 111A, 121A, such as stretch properties, flexibility, or tensile strength, is measured both in isolation of the second layer 111C, 121C and with the second layer 111C, 121C, the difference of the measured values without the second layer compared to measured values with the second layer may be at most 30%, preferably at most 20%, most preferably less than 20%.
The first part houses fixture 112, such as a spring bar, within the strip 111 enclosed by the loop section 111B. The spring bar 112 is used for attachment to the wearable electronic device 200. The spring bar 112 may be operated with a release mechanism 118 for toggling the movable pin of the spring bar 112 between a deployed and retracted state. The release mechanism 118 may be accessible through a respective opening provided to the strip 111. The buckle 113 comprises a comparable bar (not shown in the FIGURES), around which the loop section of the strip 111 is wound. The preferably beveled ends of the strip 111 meet at a seam 117, 119 which is closed by gluing. According to another embodiment, the ends of the strip 111 at the seam 117, 119 is closed by a thermoset adhesive. According to another embodiment, the ends of the strip 111 at the seam 117, 119 is closed by contact glue. According to another embodiment, the ends of the strip 111 at the seam 117, 119 is closed by welding. According to another embodiment, the ends of the strip 111 at the seam 117, 119 is closed by sewing.
According to another embodiment, in which the second layer 111C is made of artificial leather, such as one comprising PVC and/or PU, the ends of the strip 111 at the seam 117, 119 is closed by melting the layers 111A, 111C together by applying heat. In particular, the artificial leather may comprise a polyester substrate with a thermoplastic polyurethane top layer that provides soft feel and texture that resembles that of natural leather. Indeed the artificial leather is selected from a synthetic material that mimics the properties and surface texture of natural leather. The synthetic material may be a soft elastomer material, such as silicone. The artificial leather may alternatively comprise natural base material, such as coated banana leaves or coated fiber extracted from banana leaves.
The thickness of the second layer 111C, 121C is preferably set to match the stretching properties of the first layer 111A, 121A. As microfiber is inherently more elastic than natural or synthetic leather, the thickness of second layer 111C, 121C is relatively small compared to the first layer 111A, 121A. Absolute matching of stretching properties between the layers is not required but it is preferable to set the difference in elasticity between the first layer 111A, 121A and second layer 111C, 121C at most 20%. In other words, the difference in elastic modulus along the longitudinal dimension X is preferably at most 20% between the layers 111A, 121A; 111C, 121C.
As the second layer 111C, 121C and the adhesive layer between the first and second layer are noticeably thinner than the first layer 111A, 121A, it is foreseen that the second layer 111C, 121C or the adhesive layer or both the second layer 111C, 121C and the adhesive layer is or are more flexible than the first layer 111A, 121A. Accordingly, the flexibility of the first layer 111A, 121A is decisive for the flexibility of the strap 100. In other words, the properties of the first layer 111A, 121A dominate the properties of the strap 100A.
The exemplary wearable electronic device 200 takes the form a smart watch. The enclosure of the wearable electronic device 200 includes two attachment points at opposing ends of the enclosure; one for each spring bar 112, 122 of the strap parts 110, 120. Naturally, the spring bar attachment could be replaced with other foreseeable attachment mechanisms, such as affixer-secured or clenched bars, sliding coupler parts in a corresponding attachment groove on the enclosure, magnets, etc.
The enclosure of the wearable electronic device 200 preferably also includes an optical heart rate sensor 201, whereby the benefits of the novel strap may be utilized for the purpose of ensuring a reliable fit between the wrist of the user and the sensor optics. Optical heart rate or pulse measurement is performed with a sensor arrangement with light emitters and light sensors placed at the watch case bottom. The measurement is disturbed by ambient light reaching the sensor or sensors from the sides if the watch does not stay in good contact with the skin. Also the oscillations or vibrations of the wrist tissue at the sensors from when the wrist is moving, for example when running, causes signal noise thus making the measurement more difficult. The problems with the reliability of the measurement are worsened if the watch is relatively heavy and loosely fit. On the other hand, an overly tight watch strap would be too uncomfortable. It is therefore desirable to have a snug fit with a comfortable feel in order to make a desirable product with good quality.
The use of the strap 100 is straight-forward. The wearable electronic device 200 is placed on the desired anatomic location of the user, such as the wrist. The strap parts 110, 120 are coupled to each other by inserting the tip 123 through the buckle 114, by pulling a desired amount of tension into the strap 100 and securing the strap into a loop around the anatomic location by inserting the tongue 114 into a corresponding hole 124 of the second strap part 120. Once closed into a loop, the elasticity of the strap 100 along the longitudinal dimension X ensures a reliable fit of the wearable electronic device 200 on the user. The microfiber material of the strap 100, in turn, facilitates compliance with minor contours on the users anatomy, such as protruding bones, etc. By having relatively little elasticity in the transversal dimension, the strap maintains a good deformation resistance. The relatively small stretch in the transversal dimension Y, i.e. along the width of the strap, facilitates sturdy attachment to the hardware of the device, e.g. to the spring bar and buckle. If the strap would be relatively compliant in the transversal dimension Y, the excess elasticity could compromise attachment to the wearable electronic device. The relative resistance to elastic deformation in the transversal dimension Y minimizes fatigue in the adhesive layer between the strap layers 111A, 111C; 121A, 121C.
The strap 100 may be further enhanced by including a reflective yarn pattern, an embedded auxiliary battery, etc. The base material of the strap may be treated with a anti-bacterial supplement for making the strap more suitable for a sporting device application.
In the examples described with reference to
According to an alternative embodiment, the strip may comprise a third layer positioned on the inside of the strip, i.e. attached against the inner layer as an inner façade layer for skin contact. While this embodiment may not achieve the hygiene benefits of microfiber, it may provide a familiar leather “feel” preferred by some users. It is nevertheless preferred that the additional inner façade layer shares its properties with the outer façade layer so as to not compromise the stretch properties predominantly defined by the inner microfiber layer sandwiched between the façade layers. By applying an inner and outer façade leather layer the stretch properties of the strip may be affected approximately 20 to 30 percent. According to the tri-layer embodiment, the inner façade layer may extend across the strip between the ends thereof or as a patch adhered to and covering the inner microfiber layer, whereby either or both ends of the strip would be covered by the outer façade layer extending over the end.
Conversely, according to a particular embodiment, the layered structure of the strip consists of only three layers, i.e. the first layer 111A, 121A facing the user, the second layer 111C, 121C as an outer layer, and the layer of elastic adhesive there between. Naturally, the strap may include hardware, such as a buckle, and/or reinforcing stitching, which are not seen as components of the layered structure.
It is also foreseen to attach the layers together by welding along transversal seams, if the artificial leather is constructed of raw material, which enables welding. Such an embodiment could be constructed without the elastic adhesive layer.
It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment.
As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.
While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.
The verbs “to comprise” and “to include” are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of “a” or “an”, i.e. a singular form, throughout this document does not exclude a plurality.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20216139 | Nov 2021 | FI | national |
