Abstract:
A strap for a pulse measuring device, wherein the strap includes an indicator configured to indicate tightness of the strap. A portable pulse measuring device having a strap configured to fasten the portable pulse measuring device on a human; and a mechanical indicator configured to indicate tightness of the strap are also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is Continuation of U.S. Ser. No. 14/895,390 filed Dec. 2, 2015 which is the U.S. national phase of PCT Application No. PCT/FI2014/050471 filed on Jun. 11, 2014, which claims priority to FI Patent Application No. 20135640 filed on Jun. 11, 2013, the disclosures of which are incorporated in their entirety by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to a strap for a portable pulse measuring device and to a portable pulse measuring device comprising a strap. 
       BACKGROUND 
       [0003]    Pulse can be measured using, for example, portable pulse measuring devices. A portable pulse measuring device may measure pulse optically. Another possibility is to use a separate heart rate belt around one&#39;s chest, and the belt then transmits measured pulse signals wirelessly to a monitoring device, for example, attached on a wrist or to an application running in a mobile phone. 
         [0004]    The optical pulse measurement is based on the fact that light is emitted by a light source towards body tissue and at least one detector is configured to detect the intensity of reflected light after propagation through the human body tissue. There are several challenges when measuring pulse optically. The optical measurement is based on light absorption changes caused by blood flow in a lighted area. If the shape of the lighted area changes during the measurement, for example, due to movement of the pulse measuring device, the measurement is disturbed. Thus, for example, movements of a hand and of a human cause errors to the measurement in many ways. In order to avoid problems in the measurement, the portable pulse device needs to be as stable as possible in relation to skin and needs to minimize mechanical changes in tissue area during movement. 
         [0005]    There are many ways to address the above problems. One solution is to tighten a strap of pulse a measuring device more. The problem, however, is that a user may tighten the strap too much, which in turn is uncomfortable and prevents blood flow in tissue. In turn, too loose tightening of the strap allows the portable pulse measuring device to move too much in relation, for example, to a wrist and body tissue. 
         [0006]    It is possible to solve the above problems by design, for example, by making the device light, by optimizing the friction between skin and the device by material selection, or by making the device or strap of the device wider. Although these aspects may alleviate the problems in some cases, the basic problem still remains—how to provide an optimal strap tightening for a strap of a pulse measuring device. 
       SUMMARY 
       [0007]    According to one aspect, there is provided a strap for a portable pulse measuring device. The strap comprises an indicator configured to indicate tightness of the strap. 
         [0008]    In one embodiment the strap is a stretchable strap comprising a non-stretchable sliding part built-in in the stretchable strap, wherein the stretchable strap comprises a section through which the indicator on the non-stretchable sliding part is visible. 
         [0009]    In one embodiment the strap is a stretchable strap comprising a stretchable sliding part built-in in the stretchable strap, the stretchable sliding part being less stretchable than the stretchable strap, wherein the stretchable strap comprises a section through which the indicator on the stretchable sliding part is visible. 
         [0010]    In one embodiment the indicator is provided by knitting the strap such that it provides a meter showing the level of tightness of the strap. 
         [0011]    According to another aspect, there is provided a portable pulse measuring device comprising a strap configured to fasten the portable pulse measuring device on a human; and a mechanical indicator configured to indicate tightness of the strap. 
         [0012]    In one embodiment the mechanical indicator is arranged into a link part connected to a main body of the portable pulse measuring device and to which the strap is attached. 
         [0013]    In one embodiment the link part comprises a window in which the mechanical indicator is movable to indicate the tightness of the strap. 
         [0014]    In one embodiment the link part comprises a rotating part to which the strap is attached. The indicator is attached to the rotating part such the when the rotating part rotates, the indicator moves in the window. 
         [0015]    In one embodiment the link part comprises a sliding part to which the strap is attached. The indicator is attached to the sliding part such that when the sliding part moves, the indicator moves in the window. 
         [0016]    According to another aspect, there is provided a strap for a portable pulse measuring device, wherein the strap comprises an indicator configured to indicate tightness of the strap, wherein the strap is a stretchable strap comprising a non-stretchable sliding part built-in in the stretchable strap and wherein the stretchable strap comprises a section through which the indicator on the non-stretchable sliding part is visible. 
         [0017]    According to another aspect, there is provided a strap for a portable pulse measuring device, wherein the strap comprises: an indicator configured to indicate tightness of the strap, wherein the strap is a stretchable strap comprising a stretchable sliding part built-in in the stretchable strap, the stretchable sliding part being less stretchable than the stretchable strap and wherein the stretchable strap comprises a section through which the indicator on the stretchable sliding part is visible. 
         [0018]    According to another aspect, there is provided a strap for a portable pulse measuring device, wherein the strap comprises an indicator configured to indicate tightness of the strap, wherein the indicator is provided by knitting the strap such that it provides a meter showing the level of tightness of the strap. 
         [0019]    According to another aspect, there is provided a portable pulse measuring device comprising a strap configured to fasten the portable pulse measuring device on a human; and a link part, wherein the strap is connected to the link part and wherein the link part comprises a mechanical indicator configured to indicate tightness of the strap. 
         [0020]    According to another aspect, there is provided a portable pulse measuring device comprising a strap according to any of the above aspects to fasten the portable pulse measuring device on a human. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    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: 
           [0022]      FIG. 1A  discloses an arrangement comprising a mechanical indicator configured to indicate tightness of a strap of a portable pulse measuring device according to one embodiment of the invention. 
           [0023]      FIG. 1B  discloses a cross-section view of the arrangement of  FIG. 1A . 
           [0024]      FIG. 2  discloses an arrangement comprising a mechanical indicator configured to indicate tightness of a strap of a portable pulse measuring device according to one embodiment of the invention. 
           [0025]      FIG. 3  discloses a strap for a portable pulse measuring device according to one embodiment of the invention. 
           [0026]      FIG. 4  discloses a strap for a portable pulse measuring device according to one embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]      FIG. 1A  discloses an arrangement comprising a mechanical indicator configured to indicate tightness of a strap  102  of a portable pulse measuring device according to one embodiment of the invention. 
         [0028]    A link part  100  of the portable pulse measuring device provides an attachment point to a strap  102 . The link part  100  may be removably attachable to a main body (not shown) of the portable pulse measuring device, or alternatively, the link part  100  may be an integral part of the main body. The link part  100  includes a fixed axle  106 . A sliding part and a resilient member, for example a spring  108 , are arranged around the fixed axle  104 . Instead of the spring, any other resilient member may be used. A rotation blocker  110  is attached to the sliding part  108  in order to prevent the sliding part  108  to rotate around the fixed axle  106 . A rotating non-sliding part  104  is arranged as an outmost element and the strap  102  is in contact with the rotating non-sliding part  104  in a section of its circumference, as illustrated in  FIG. 1A . Reference number  112  indicates that the strap  102  is attached to the rotating non-sliding part  104 . The link part  100  includes a window  114 , for example a hole, in which an indicator is movable and the location of the indicator in the hole  114  depends on the tightness of the strap  102  when a user of the portable pulse measuring device fastens the device, for example, around his wrist. 
         [0029]    In one embodiment, the indicator is attached to the rotating non-sliding part  104  and thus it moves when the rotating non-sliding part  104  rotates. The indicator may be a peg which moves in the window  114 . In another embodiment, the indicator is a plate movable in the window  114  and it comprises a scale. A pointer has been arranged in the link part  100 . When the plate moves as a result of pulling the strap, the pointer points to a certain point in the scale on the plate. 
         [0030]    As illustrated in  FIG. 1A , the hole  114  may take a form of a slot which is radially arranged in relation to the fixed axle  106 . Reference number  116  refers to a cross-section which is illustrated in more detail in  FIG. 1B . 
         [0031]    In one embodiment, the window  114  is a hole in the link part. In another embodiment, the link part  100  comprises transparent section through which the indicator can be seen. For example, the link part  100  may be partly or wholly made of plastic and it may be partly or wholly transparent. 
         [0032]      FIG. 1B  discloses a cross-section view of the arrangement of  FIG. 1A . As illustrated in  FIG. 1B  the rotating non-sliding part  104  partially directly surrounds the fixed axle  106  and is arranged to be rotatable about the fixed axle  106 . The remaining part of the fixed axle  106  not directly surrounded by the rotating non-sliding part  104  is occupied by a spring  118  and a non-rotating sliding part  120 . 
         [0033]    When the strap  102  is pulled the rotating non-sliding part  104  rotates around the fixed axle  106 . An inclined surface  122  of the rotating non-sliding part  104  faces towards an inclined surface  124  of the sliding non-rotating part  120 . When the rotating non-sliding part  104  rotates it presses the sliding non-rotating part  120 , and due to the inclined surfaces  122  and  124 , the sliding non-rotating part  120  moves and compresses the spring  118 . Although not illustrated in  FIG. 1B , this action also moves the indicator in the hole  114 . When the pulling stops and the tightness of the strap  102  is reduced, the spring  118  presses the sliding non-rotating part  120  and the sliding non-rotating part  120  generates a rotating force for the rotating non-sliding part  104  and thus the rotating non-sliding part  104  turns to its relaxed position. 
         [0034]      FIG. 2  discloses an arrangement comprising a mechanical indicator configured to indicate tightness of a strap  202  of a portable pulse measuring device according to one embodiment of the invention. Whereas  FIG. 1A  disclosed a turning force indicator  FIG. 2  discloses a sliding force indicator. 
         [0035]    A link part  200  of the portable pulse measuring device provides an attachment point to the strap  202 . The link part  200  may be removably attachable to a main body (not shown) of the portable pulse measuring device or alternatively the link part  200  may be an integral part of the main body. The link part  200  includes a fixed axle  216 . A rotating part  214  is arranged to be rotatably attached to the fixed axle  216 . The strap  202  is arranged to be partially in contact with the rotating part  214  on the circumference of the rotating part  214 , as disclosed in  FIG. 2 . A sliding part  204  is arranged in the link part  200  and the strap  202  is attached to the sliding part  204 . 
         [0036]    A first spring blocker  208  is arranged in the link part  200  and a second spring blocker is arranged in the sliding part  204 . A spring  206  is arranged between the first spring blocker  208  and the second spring blocker  210 . In one embodiment, the sliding part  204  comprises guiders which keep the sliding part  204  on its sliding track in the link part  200 . When the strap  202  is pulled, the sliding part  204  moves and the spring  206  compresses. Instead of the spring  206 , any other resilient member may be used. 
         [0037]    The link part  200  also includes a window  212  through which an indicator  218  in the sliding part  204  or attached to the sliding part  204  can be seen. In one embodiment, the window  212  is a hole in the link part  200 . In another embodiment, the link part  200  comprises a transparent section through which the indicator in the sliding part  204  or attached to the sliding part  204  can be seen. For example, the link part  200  may be partly or wholly made of plastic. Furthermore, it may be partly or wholly transparent. 
         [0038]    As an example of the indicator,  FIG. 2  discloses that the sliding part includes three patterns for indicating the tightness of the strap  202 . Only one pattern can be seen in whole at a time through the window  212  in the link part  200 . It is evident that  FIG. 2  discloses only one example of a possible indicator. In another embodiment, an elongated slot may be arranged in the link part  200  and an indicator attached to the sliding part  204  moves in the elongated slot and indicates the current tightness of the strap  202 . 
         [0039]      FIG. 3  discloses a strap  300  for a portable pulse measuring device according to one embodiment of the invention. The strap  300  and a sliding part  302  are attached to a fixation part  304  via which they can be attached to a portable pulse measuring device body part. In the embodiment disclosed in  FIG. 3 , an indicator  310  indicating tightness of the strap  300  is included in the strap  300  itself. The strap  300  is stretchable. A sliding part  302  that is not stretchable, or has different stretching properties than the stretchable strap  300 , is built-in in the stretchable strap  300 . The sliding part  302  is configured in the stretchable strap  300  so that when the strap  300  stretches, the sliding part  302  remains unstretched. In other words, to achieve this functionality a cavity may be arranged in the strap  300  for the sliding part so that the sliding part  302  does not move when the strap  300  is stretched. The sliding part  302  has been equipped with one or more patterns, i.e. indicators  310 , to indicate the tightness of the strap. 
         [0040]    When the strap is pulled (i.e. when a user fastens the portable pulse measuring device comprising the strap, for example, onto his wrist and tightens the strap), the strap stretches and an indicator hole  308  moves in relation to the non-stretchable sliding part  302 . A pattern indicating the tightness of the strap  300  is then visible via the hole  308 . 
         [0041]    In another embodiment of  FIG. 3 , the strap  300  is a stretchable strap comprising a sliding part  302  built-in in the stretchable strap  300 . The sliding part  302 , however, is stretchable but less stretchable than the stretchable strap  300 . In other words, when the strap  300  is pulled (i.e. when a user fastens the portable pulse measuring device comprising the strap, for example, onto his wrist and tightens the strap), the strap  300  stretches, and at the same time, also the sliding part  302  stretches but less than the strap  300 . An indicator hole  308  arranged in the strap  300  moves in relation to the sliding part  302 , and an indicator  310  is visible through the indicator hole  308 . 
         [0042]      FIG. 4  discloses a strap  400  for a portable pulse measuring device according to one embodiment of the invention. As in the embodiment of  FIG. 3 , the strap  400  of the embodiment of  FIG. 4  is stretchable. The strap  400  has been specially configured so that when the strap  400  is stretched, it shows a meter  404  showing the tension level of the strap  400 . The strap  400  may include a numerical scale  402  or some other type of a scale or pattern to provide information about the tension/tightness of the strap  400 . The meter  404  can be achieved, for example, by a special knitting of the strap  400  wholly or partially. When the strap  400  is stretched, the special knitting enables the meter  404  to be seen indicating the tension/tightness of the strap  400 . 
         [0043]    A benefit of the embodiments disclosed in  FIGS. 1A, 1B and 2-4  is that the guided adjustment of tightness of the strap enables the use of the portable pulse measuring device in various operating situations. Moreover, the solution enables optimal strap tightness and avoids excessive loosening or tightening. Furthermore, the disclosed solution also takes into account physiological variations between individuals. Furthermore, the embodiments disclosed in  FIGS. 1A, 1B and 2-4  are also advantageous when measuring pulse with pulse measuring devices that use optical pulse measurement techniques since undesired movements of the device may cause disturbances in the measurements. With the disclosed embodiments it is possible to ensure optimal strap tightness of the strap. 
         [0044]    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 claims.