PATENT DOCUMENT

Publication Number: US-11490697-B2
Application Number: US-201916591511-A
Country: US
Kind Code: B2

Title: Consistently-tight watch band

Abstract:
A watch band is disclosed. The watch band maintains a substantially constant tension throughout changes in its length while worn by a user. Such changes in length may occur automatically to accommodate changes in the size and circumference of a user&#39;s wrist as they move their wrist normally. By maintaining a constant tension, the watch band also maintains a constant force on the user&#39;s wrist, and causes a watch body attached to the watch band to also maintain a constant force on the user&#39;s wrist. This can increase a user&#39;s comfort, since the watch will not get tighter or constrict their wrist as they straighten and bend their wrist. It can also help optimize operation of any sensors in the watch band or watch body that benefit from being held against the user&#39;s wrist with a constant force, such as some physiological sensors.

Claims:
What is claimed is: 
     
       1. A watch band comprising:
 a first band portion that is connectable to a first side of a watch body; 
 a second band portion that is connectable to a second side of the watch body; and 
 a constant-force spring connecting the first band portion to the second band portion, wherein the constant-force spring is pre-loaded to a substantially constant tension that is maintained:
 when a user expands the watch band to don the watch band on a wrist of the user; and 
 when the watch band is worn throughout motion of a wrist of the user. 
 
 
     
     
       2. The watch band of  claim 1 , wherein:
 the first band portion comprises a rack; and 
 the second band portion comprises a pinion gear, wherein the constant-force spring applies a substantially constant torque to the pinion gear. 
 
     
     
       3. The watch band of  claim 2 , wherein:
 the rack is positioned on an inner surface of the first band portion; and 
 the first band portion extends through an opening of the second band portion to align the rack with the pinion gear, wherein the constant-force spring draws the first band portion into the opening of the second band portion. 
 
     
     
       4. The watch band of  claim 1 , wherein:
 the first band portion is a link; 
 the second band portion is a connector; and 
 the watch band further comprises:
 a first shaft rotatably fixed to the link, wherein the constant-force spring is coiled around the first shaft; and 
 a second shaft extending through a hole of the connector and a slot of the link to slidably couple the link to the connector. 
 
 
     
     
       5. The watch band of  claim 4 , wherein:
 the first band portion is one of multiple first band portions; 
 the second band portion is one of multiple second band portions; and 
 the constant-force spring is one of multiple constant-force springs, wherein each pair of adjacent first and second band portions are connected by one of the multiple constant-force springs. 
 
     
     
       6. The watch band of  claim 1 , further comprising:
 an extension housing, wherein the first band portion and the second band portion extend within the extension housing; 
 wherein:
 the constant-force spring is a first constant-force spring; 
 the first band portion is coupled to the extension housing by the first constant-force spring; and 
 the second band portion is coupled to the extension housing by a second constant-force spring. 
 
 
     
     
       7. The watch band of  claim 6 , wherein the extension housing comprises:
 a first section receiving the first band portion; and 
 a second section receiving the second band portion, wherein the first section and the second section are separable from and attachable to each other by a connection interface. 
 
     
     
       8. A watch band comprising:
 a first band portion that is connectable to a first side of a watch body; 
 a second band portion that is connectable to a second side of the watch body; and 
 a constant-force spring connecting the first band portion to the second band portion, wherein the constant-force spring is pre-shaped into a tightly wound roll that resists deflection with a substantially constant force. 
 
     
     
       9. The watch band of  claim 8 , wherein:
 the first band portion comprises a rack; and 
 the second band portion comprises a pinion gear, wherein the constant-force spring applies a substantially constant torque to the pinion gear. 
 
     
     
       10. The watch band of  claim 9 , wherein:
 the rack is positioned on an inner surface of the first band portion; and 
 the first band portion extends through an opening of the second band portion to align the rack with the pinion gear, wherein the constant-force spring draws the first band portion into the opening of the second band portion. 
 
     
     
       11. The watch band of  claim 8 , wherein:
 the first band portion is a link; 
 the second band portion is a connector; and 
 the watch band further comprises:
 a first shaft rotatably fixed to the link, wherein the constant-force spring is coiled around the first shaft; and 
 a second shaft extending through a hole of the connector and a slot of the link to slidably couple the link to the connector. 
 
 
     
     
       12. The watch band of  claim 11 , wherein:
 the first band portion is one of multiple first band portions; 
 the second band portion is one of multiple second band portions; and 
 the constant-force spring is one of multiple constant-force springs, wherein each pair of adjacent first and second band portions are connected by one of the multiple constant-force springs. 
 
     
     
       13. The watch band of  claim 8 , further comprising:
 an extension housing, wherein the first band portion and the second band portion extend within the extension housing; 
 wherein:
 the constant-force spring is a first constant-force spring; 
 the first band portion is coupled to the extension housing by the first constant-force spring; and 
 the second band portion is coupled to the extension housing by a second constant-force spring. 
 
 
     
     
       14. The watch band of  claim 13 , wherein the extension housing comprises:
 a first section receiving the first band portion; and 
 a second section receiving the second band portion, wherein the first section and the second section are separable from and attachable to each other by a connection interface. 
 
     
     
       15. A watch band comprising:
 a first band portion that is connectable to a first side of a watch body; 
 a second band portion that is connectable to a second side of the watch body; and 
 a constant-force spring connecting the first band portion to the second band portion, wherein the constant-force spring is coiled about an axis and provides tension that is substantially constant as the constant-force spring transitions between:
 a first position with a first number of turns about the axis; and 
 a second position with a second number of turns about the axis. 
 
 
     
     
       16. The watch band of  claim 15 , wherein:
 the first band portion comprises a rack; and 
 the second band portion comprises a pinion gear, wherein translational motion of the rack causes the pinion gear to rotate about a shaft, such that, while the constant-force spring provides the tension that is substantially constant, the constant-force spring further applies a substantially constant torque to the pinion gear. 
 
     
     
       17. The watch band of  claim 16 , wherein:
 the rack is positioned on an inner surface of the first band portion; and 
 the first band portion extends through an opening of the second band portion to align the rack with the pinion gear, wherein the constant-force spring draws the first band portion into the opening of the second band portion. 
 
     
     
       18. The watch band of  claim 15 , wherein:
 the first band portion is a link; 
 the second band portion is a connector; and 
 the watch band further comprises:
 a first shaft rotatably fixed to the link, wherein the constant-force spring is coiled around the first shaft; and 
 a second shaft extending through a hole of the connector and a slot of the link to slidably couple the link to the connector. 
 
 
     
     
       19. The watch band of  claim 18 , wherein:
 the first band portion is one of multiple first band portions; 
 the second band portion is one of multiple second band portions; and 
 the constant-force spring is one of multiple constant-force springs, wherein each pair of adjacent first and second band portions are connected by one of the multiple constant-force springs. 
 
     
     
       20. The watch band of  claim 15 , further comprising:
 an extension housing, wherein the first band portion and the second band portion extend within the extension housing; 
 wherein:
 the constant-force spring is a first constant-force spring; 
 the first band portion is coupled to the extension housing by the first constant-force spring; and 
 the second band portion is coupled to the extension housing by a second constant-force spring; 
 the extension housing comprises:
 a first section receiving the first band portion; and 
 a second section receiving the second band portion, wherein the first section and the second section are separable from and attachable to each other by a connection interface.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 15/269,710, filed Sep. 19, 2016, the disclosure of which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The described embodiments relate generally to watch bands. More particularly, the present embodiments relate to watch bands that maintain a substantially constant tension when worn. 
     BACKGROUND 
     Watch bands may become tight around a user&#39;s wrist as the user moves their wrist. Such tightening can be uncomfortable. 
     SUMMARY 
     The present disclosure describes watch bands that maintain a substantially constant tension despite changes in their lengths while worn by a user. Such changes in length may occur automatically to accommodate changes in the size and circumference of a user&#39;s wrist as they move their wrist normally (e.g., moving it from straight, with a smaller circumference, to bent, with a larger circumference). By maintaining a constant tension, the watch bands may also maintain a constant force on the user&#39;s wrist, and they may cause a watch body attached to the bands to also maintain a constant force on the user&#39;s wrist. This can increase a user&#39;s comfort, since the watch will not get tighter or constrict their wrist as they straighten and bend their wrist. It can also help optimize operation of any sensors in the watch band or watch body that benefit from being held against the user&#39;s wrist with a constant force, such as some physiological sensors (e.g., some heart rate sensors). 
     Some embodiments of the watch band include repetitive compliant mechanisms that are each movable between a closed and an open position, and which move between the closed and open positions sequentially. The repetitive compliant mechanisms may themselves form the watch band, or at least the expandable portion of it. Each repetitive compliant mechanism may only insubstantially and temporarily change the tension in the overall band as it moves between the open and closed position, so the overall tension in the watch band remains substantially constant. 
     Other embodiments of the watch band include separate band portions that are movable relative to each other. The separate band portions may be connected together to form the watch band by constant-force springs. So when a user moves the portions away from each other or together by bending or straightening their wrist, the overall length of the watch band changes to accommodate the wrist, but the constant-force springs between the moving band portions maintain a constant overall tension in the watch band. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG. 1  shows a watch worn on a straight wrist of a user. 
         FIG. 2  shows a watch worn on a bent wrist of a user. 
         FIG. 3  shows a cross section taken through line  3 - 3 ′ of  FIG. 1   
         FIG. 4  shows a cross section taken through line  4 - 4 ′ of  FIG. 2 . 
         FIGS. 5 and 6  show tension-extension curves for watch bands. 
         FIG. 7  shows a watch with a watch band that includes repetitive compliant mechanisms. 
         FIG. 8  shows a portion of the watch band of  FIG. 7 . 
         FIGS. 9-12  show the watch band of  FIG. 7  at different lengths. 
         FIGS. 13-15  show a portion of the watch band of  FIG. 7  as the repetitive compliant mechanisms open, alongside diagrammatic representations of the portion. 
         FIG. 16  shows a tension-extension curve for a watch band of  FIG. 7 . 
         FIG. 17  shows a constant-force spring. 
         FIG. 18  shows a watch with a watch band that includes a rack-and-pinion mechanism with a constant-force spring. 
         FIG. 19  shows a portion of the watch band of  FIG. 18 . 
         FIG. 20  shows a detailed representation of the rack-and-pinion mechanism of the watch band of  FIG. 18 . 
         FIG. 21  shows a portion of a watch band that includes links connected by constant-force springs. 
         FIG. 22  shows an exploded view of a link and connectors of the watch band of  FIG. 21 . 
         FIGS. 23 and 24  show cross sections along lines  23 - 23 ′ and  24 - 24 ′, respectively, of  FIG. 21 . 
         FIG. 25  shows a representative cross-section of a watch with a watch band that includes an expansion housing connected to watch band portions by constant-force springs. 
         FIG. 26  shows a detailed view of the expansion housing of  FIG. 26 . 
         FIG. 27  shows a watch with a watch band that includes a constant-force pillow. 
         FIG. 28  shows a watch with a watch band that includes a shape-memory segment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following descriptions are not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the claims. 
     The following disclosure relates to a watch band that can maintain a substantially constant force while changing its length. For instance, when a wearer bends their wrist, the watch band may expand to accommodate the larger circumference of a bent wrist and may apply the same force to the user&#39;s wrist while doing so. This can increase the user&#39;s comfort, since the band expands with the user&#39;s wrist without applying greater force, rather than constricting or pinching the wrist or getting tighter as some non-extendable watch bands would. It can also help the watch perform optimally for functions that depend on a substantially constant force against the user&#39;s wrist. For example, some physiological sensors of the watch may benefit from being held against the user&#39;s wrist at a substantially constant force. 
     In a particular embodiment, a watch band may be formed with a pattern of discontinuities through itself. The discontinuities may allow portions of the band to separate and move away from each other as the band is extended. The discontinuities may form spring-like segments that compress past an inflection point to individually expand discrete segments of the band in a sequence. These segments may be tuned to allow for extension and contraction of the watch band while maintaining a substantially constant tension in the band. 
     In some other embodiments, a watch band may include a mechanism including constant-force springs connecting portions of the band. These constant-force springs can allow the portions of the band to move relative to each other while maintaining a substantially constant tension in the band. 
     In still other embodiments, a watch band may include a compressible pillow along its interior circumference that can compress to increase the interior circumference. This can operate as an effective expansion of the band as the available area within it is increased, such as to accommodate the change in circumference of a user&#39;s wrist within the band circumference. The compressible pillow may be formed of compressible foam, for example, or may be a bladder valved to maintain a substantially constant pressure. 
     These and other embodiments are discussed below with reference to the figures. However, those skilled in the art will readily appreciate that the detailed description given herein with respect to these figures is for explanatory purposes only and should not be construed as limiting. 
       FIG. 1  illustrates a watch  100  in phantom lines worn on a wrist of a user. Watch  100  has a watch body  102  held on the wrist by a watch band  104 , which is connected to watch body  102  at opposing ends of watch band  104 . In  FIG. 1  the user&#39;s wrist is in a neutral, straight position.  FIG. 2  shows the user&#39;s wrist in a bent position. In the bent position the user&#39;s wrist around which watch band  104  extends becomes larger, increasing its circumference. 
     The change in size of the user&#39;s wrist between the straight and bent positions is represented in  FIGS. 3 and 4 .  FIG. 3  shows a cross-section through watch  100  on the user&#39;s wrist in the neutral, straight position, taken along line  3 - 3 ′ of  FIG. 1 . In this position watch band  104  around the wrist has a circumference C 1 , which corresponds to the circumference of the straight wrist due to its contact with the wrist throughout most of its length. Watch band  104  may be in tension T 1 , which applies a force F 1  from watch body  102  to the wrist. 
       FIG. 4  shows a cross-section through watch  100  on the user&#39;s wrist in the bent position, taken along line  4 - 4 ′ of  FIG. 2 . In this position the wrist becomes larger due to natural physiology: when the wrist bends, lower tendons tighten and compact the lower portion of the wrist, increasing its circumference at the area of watch  100 . Watch band  104  around the wrist experiences a similar increase in circumference (to circumference C 2 ) to accommodate the larger wrist. 
     A non-extendable watch band may prevent or limit a user from moving their wrist from the straight to the bent position, or may cause discomfort when doing so, as the watch band may simply tighten around the wrist. An extendable watch band that stretches its material may allow movement from straight to bent, but may get tighter and tighter as the wrist&#39;s size increases. For example, if watch band  104  is such an extendable watch band, the tension in watch band  104  may increase to tension T 2 , which is substantially higher than T 1 , as represented by the linear tension-extension curve of the graph in  FIG. 5 . The force applied by watch body  102  may similarly increase to force F 2 , which is substantially higher than F 1 . Since a watch band that is too tight is more uncomfortable than a watch band that is too loose, the tendency of a watch band to tighten as a user moves their wrist may encourage the user to wear their watch loosely. A loose-fitting watch may degrade the usefulness of sensors in the watch that rely on contact with the wrist (e.g., physiological sensors such as heart rate sensors). A loose-fitting watch may also be uncomfortable to wear. 
     Embodiments of the present invention maintain a substantially constant tension in watch band  104  (e.g., such that T 2  is substantially the same as T 1 ) even as watch band  104  changes length (i.e., as the distance along the watch band between its ends increases or decreases) through a predetermined range (e.g., changes by at least 10 millimeters). The change in length may accommodate a wrist&#39;s change in size through the wrist&#39;s range of motion, and may be driven by the change in size of the wrist. The substantially constant tension in watch band  104  maintains a substantially constant force applied by watch band  104  to the user&#39;s wrist (e.g., such that F2 is substantially the same as F1), thereby increasing the user&#39;s comfort, improving performance of sensors, and encouraging optimal band tightness around the wrist. 
       FIG. 6  shows an exemplary tension-extension curve for such constant-force watch bands  104  as described herein. As shown, throughout the range of motion between a straight wrist and a bent wrist, watch band  104  maintains a substantially constant tension. The substantially constant tension may coincide with a predetermined target tension at which comfort and sensor performance are optimized. 
     As used herein, substantially constant tension or substantially the same tension refers to tension that changes or is different by less than 0.5 Newtons (e.g., less than 0.2 Newtons). As used herein, substantially constant force or substantially the same force refers to a force that changes or is different by less than 0.5 Newtons (e.g., less than 0.2 Newtons). 
       FIG. 7  shows a watch  700 , which includes a watch body  702  coupled to a constant-force watch band  704 . When worn, constant-force watch band  704  maintains a substantially constant tension and applies a substantially constant force to a wearer&#39;s wrist throughout changes in circumference of the wrist, as described above. Watch band  704  accomplishes this through repetitive compliant mechanisms  706 , which form at least a portion of the length of watch band  704 . 
     Watch band  704  is shown flat in  FIGS. 8-15  to better explain its operation; however the operation described applies to watch band  704  when coupled to watch body  702  and worn by a user.  FIG. 8  shows an enlarged view of a portion of watch band  704 , which includes multiple repetitive compliant mechanisms  706 . Repetitive compliant mechanisms  706  are formed by discontinuities  708  through a substance  710  of watch band  704 , which allow portions of substance  710  to move relative to each other as watch band  704  lengthens or shortens. Substance  710  may be an elastomer, and repetitive compliant mechanisms  706  may be formed monolithically together of substance  710 . In some embodiments, watch band  704  is formed entirely of the same material (e.g., a monolithic elastomer), which can simplify manufacturing (e.g., through injection molding). 
     Each repetitive compliant mechanism  706  includes a pair of opposing spring segments  712 . Each opposing spring segment  712  extends from a ground joint  714  to a pivot joint  716 . Pivot joint  716  may be connected to a pivot joint  716  of an adjacent repetitive compliant mechanism by a link  718 . 
     Repetitive compliant mechanisms  706  may overlap. For example, a pivot joint  716  for one repetitive compliant mechanism  706  may be a ground joint  714  for an adjacent overlapping repetitive compliant mechanism  706  that shares a spring segment  712 , as shown in  FIG. 8 . Such overlapping repetitive compliant mechanisms  706  may be oppositely-oriented to each other. Such overlapping repetitive compliant mechanisms are shown in  FIG. 8 , but not separately diagrammed or numbered, for clarity. 
       FIGS. 9-12  show a lengthening of watch band  704  under substantially constant tension. As the length of watch band  704  increases from  FIG. 9  to  FIG. 12  (length L 1 &gt;length L 2 &gt;length L 3 &gt;length L 4 ) its density per unit length may decrease, but corresponding tensions T remain substantially constant. Maximum and average width W of watch band  704  also remains substantially constant. As used herein, substantially constant width or substantially the same width refers to width that changes or is different by less than 5 millimeters (e.g., less than 2 millimeters). 
     Maintaining substantially constant tension and width through substantial change in length (e.g., greater than 10 millimeters) is accomplished through the sequential extension of repetitive compliant mechanisms  706 . As shown in  FIG. 9 , each repetitive compliant mechanism begins in a closed non-extended position. As length increases in  FIG. 10 , some repetitive compliant mechanisms  1002  have opened to an extended position, while other repetitive compliant mechanisms  1004  are in the process of moving to the open extended position. As length increases in  FIG. 11 , repetitive compliant mechanisms  1004  have opened and still other repetitive compliant mechanisms  1102  have begun to open. This process repeats with additional repetitive compliant mechanisms  706  until lengthening stops or until all repetitive compliant mechanisms have opened, as shown in  FIG. 12 . By opening sequentially (i.e., not all simultaneously), any small increase in tension attributable to the movement of a repetitive compliant mechanism  706  between positions is fleeting and unnoticeable, and maintains the overall tension on watch band  704  substantially constant. 
       FIGS. 13-15  show enlarged views of the transition of a repetitive compliant mechanism  706  from the non-extended (closed) position to the extended (open) position, alongside diagrammatic representations of their operation. As watch band  704  lengthens, repetitive compliant mechanism  706  transitions from the non-extended position of  FIG. 13  to the intermediate position of  FIG. 14 . In this transition, forces F of spring segments  712  increase against each other and tension T on link  718  increases a small amount—not enough to raise the overall tension on watch band  704  above substantially constant, but enough to draw pivot joint  716  downward and compress spring segments  712 . Angles θ between spring segments  712  and link  718  increase, and force F between spring segments  712  at pivot joint  716  increases. 
     After the angles between spring segments  712  and link  718  pass 90 degrees (i.e., as an angle between opposing spring segments  712  passes 180 degrees) as shown in  FIG. 15 , spring segments  712  are able to expand again and push repetitive compliant mechanism  706  into the extended position, suddenly decreasing tension T on link  718 . As watch band  704  continues to lengthen, tension T on link  718  gradually increases until it reaches a magnitude sufficient to draw another repetitive compliant mechanism  706  from the non-extended position to the extended position in a similar way (still an insubstantial magnitude of tension). For example, as shown in  FIG. 15 , ground joints  714  of a lower repetitive compliant mechanism  706  are connected to ground joints  714  of an upper repetitive compliant mechanism by ground joint links  1502 , thus allowing the increasing tension to act on the upper repetitive compliant mechanism  706  to transition it from the non-extended position to the extended position. 
     To promote sequential, non-simultaneous opening, repetitive compliant mechanisms  706  of watch band  704  may be formed with different spring constants for their spring segments  712 . While the spring constant for the pair of spring segments  712  within a given repetitive compliant mechanism may be the same to promote even opening, the spring constants of a first repetitive compliant mechanism  706  may be lower than those of a second repetitive compliant mechanism  706  spaced apart in the length direction of watch band  704 , so that the first repetitive compliant mechanism  706  opens before the second repetitive compliant mechanism  706 . In some embodiments there are more than two different spring constants among repetitive compliant mechanisms  706  of a single watch band  704 , for example, at least five different spring constants (e.g.,  10  different spring constants). 
     As repetitive compliant mechanisms  706  open along with extension of watch band  704 , the tension-extension curve of watch band  704  may resemble the graph of  FIG. 16 . As can be seen, within a significant intended range of extension (greater than 10-20 millimeters), tension never changes by more than 0.2 Newtons. The curve exhibits a slight “sawtooth” up-and-down pattern within that range, due to the sequential opening of repetitive compliant mechanisms  706 , but the variations due to these individual openings are so small as to allow the overall tension on watch band  704  to remain substantially constant throughout the intended range of extension. The intended range of extension may include differences in circumference encompassing the range of motion of most adult human wrists (e.g., between straight and bent), possibly with additional range above and below the range of motion of most adult human wrists to accommodate those with larger- or smaller-than-normal wrists. For example, in the graph of  FIG. 16 , an average user must expand their watch band by say 30 millimeters from neutral (0 tension and extension) to fit it around their straight wrist, and the maximum increase in circumference for this user&#39;s wrist may be 10 millimeters, to a 40 millimeter total extension. 
     Since the intended range of extension begins around 15 millimeters and ends around 55 millimeters, a user with much smaller or much larger wrists, and/or with much smaller or much larger changes in circumference could also wear the same watch band and the band would maintain substantially the same tension and apply substantially the same force to each user. 
     In some embodiments, instead of or in addition to repetitive compliant mechanisms as described above, a watch band may include a constant-force mechanism including a constant-force spring that connects band portions that are movable relative to each other via the constant-force mechanism.  FIG. 17  shows an example constant-force spring  1700  such as may be used in the described embodiments. Constant force spring  1700  has been pre-tensioned and pre-shaped into a tightly wound roll that resists deflection with a substantially constant force. Thus, as constant-force spring  1700  is drawn from position  1702  to position  1704  relative to the axis  1706  of its coil under tension T, tension T remains substantially constant. The magnitude of the substantially constant tension may be adjustable by adjusting characteristics of the constant-force springs (e.g., positioning, number of coil turns), or by interchanging different constant-force springs with different characteristics. This can help watch bands provide an intended target constant force and accommodate a wide range of wrist sizes. 
     The overall length of the watch band (i.e., the distance between the ends of the band that connect to a watch body) can be increased or decreased by the motion of the separate band portions relative to each other, as will be described below. Constant force springs in the subsequently described embodiments may be pre-loaded to the substantially constant tension when a user expands the watch band to put it on, and may maintain the substantially constant tension within the watch band throughout motion of the user&#39;s wrist. 
       FIG. 18  shows a watch  1800 , which includes a watch body  1802  connected to a watch band  1804 . Watch band  1804  has two watch band portions, first watch band portion  1806  and second watch band portion  1808 . First watch band portion  1806  extends through an opening  1810  of second watch band portion  1808 . First watch band portion  1806  and second watch band portion  1808  may engage within opening  1810  by a rack-and-pinion mechanism. First watch band portion  1806  may include a rack  1900 , as shown in  FIG. 19 . Second watch band portion  1808  may include a pinion gear  1902 , which engages rack  1900 . Pinion gear  1902  may rotate around an axis shaft  1904  of second watch band portion  1808  extending across opening  1810 . 
       FIG. 20  shows a detailed representation of rack  1900  and pinion gear  1902  of watch band  1804 . Pinion gear  1902  may include a constant-force spring  2000  (e.g., a constant-torque spring, also known as a constant rotational tension spring, as shown) fixed internally to axis shaft  1904  and externally to pinion gear  1902 . Constant-force spring  2000  may apply a substantially constant torque t around pinion gear  1902 . Teeth of pinion gear  1902  are positioned within grooves of rack  1900 , thus translational motion of watch band portions  1806  and  1808  causes rack  1900  to move relative to pinion gear  1902  and pinion gear  1902  to rotate relative to axis shaft  1904  to accommodate the motion. Throughout the motion, pinion gear  1902  maintains a substantially constant torque t around pinion gear  1902 , due to its connection to constant-force spring  2000 . Through the geared interconnection of first watch band portion  1806  and second watch band portion  1808  at pinion gear  1902  and rack  1900 , the substantially constant torque t thus maintains a substantially constant tension T between first watch band portion  1806  and second watch band portion  1808 . Thus, watch band  1804  can lengthen or shorten substantially via relative motion of rack  1900  and pinion gear  1902  while maintaining a substantially constant tension around a wearer&#39;s wrist. 
       FIG. 21  shows a portion of a watch band  2100 , which includes multiple links  2102  connected to each other by connectors  2104 . Links  2102  can move relative to each other to allow watch band  2100  to lengthen or shorten. In  FIG. 21 , links  2102  on the left side have been moved away from each other in an extended configuration, exposing connectors  2104 , while links on the right side remain together in a non-extended configuration. To maintain a substantially constant tension within watch band  2100 , each link  2102  is connected to its adjacent connectors  2104  by a constant-force spring  2200 , as shown in  FIG. 22 .  FIG. 22  shows an exploded view of a portion of watch band  2100 . 
     As shown in  FIG. 22 , each constant-force spring  2200  may extend between a link  2102  and a connector  2104 . Each constant-force spring  2200  may also extend in the width direction of watch band  2100  (e.g., extending greater than 50% or 70% of the width of watch band  2100 ), and may extend farther in the width direction than it does between link  2102  and connector  2104 . Each constant-force spring  2200  may be coiled around a shaft  2206  rotatably fixed to a link  2102 , and may terminate in a shaft  2202 . Shaft  2202  may be connected to an interior cavity of its corresponding connector  2104 . Shafts  2202  may extend between ends of connectors  2104 , in the width direction. Shafts  2202  may extend through holes  2204  of connectors  2104  and into slots  2208  of links  2102 . This arrangement allows connectors  2104  to move relative to links  2102 , and such motion will be limited by the corresponding motion of shafts  2202  within slots  2208 . The motion of multiple links  2102  relative to their adjacent connectors  2104  allows the overall length of watch band  2100  to lengthen or shorten substantially. 
     Constant force springs  2200  apply a substantially constant tension between each link  2102  and connector  2104  throughout their motion relative to each other, thereby applying a substantially constant tension to watch band  2100  overall as it lengthens and shortens.  FIGS. 23 and 24  show in cross section how constant-force springs  2200  extend and contract to apply substantially constant tension. In  FIG. 23  adjacent links  2102  are in a non-extended configuration, and their corresponding constant-force springs  2200  are similarly in a non-extended configuration. As links  2102  move to the extended configuration, shown in  FIG. 24 , constant-force springs  2200  similarly extend, and apply substantially constant tension as they do so. Thus, watch band  2100  can lengthen or shorten substantially via relative motion of links  2102  while maintaining a substantially constant tension T around a wearer&#39;s wrist. 
       FIG. 25  shows a cross-sectional side view of a watch  2500 , which includes a watch body  2502  connected to a watch band  2504 . Watch band  2504  has two watch band portions, first watch band portion  2506  and second watch band portion  2508 . First watch band portion  2506  and second watch band portion  2508  are connected through an extension housing  2510 . First watch band portion  2506  extends and terminates within a first opening  2512  of extension housing  2510  and second watch band portion  2508  extends and terminates within a second opening  2514  of extension housing  2510 . Watch band portions  2506  and  2508  can extend within openings  2512  and  2514  to different extents. In other words, the lengths of watch band portions  2506  and  2508  within extension housing  2510  are variable. This variability allows the overall length of watch band  2504  to lengthen or shorten. 
     Each watch band portion  2506  and  2508  is attached to extension housing  2510  by at least one constant-force spring  2600 .  FIG. 26  shows extension housing  2510  with an upper portion removed, to show its interior. As shown in  FIG. 26 , each constant-force spring  2600  may be coiled around a shaft  2602  fixed to extension housing  2510 , and may terminate at a connection with one of first watch band portion  2506  and second watch band portion  2508 . 
     As watch band  2504  is lengthened, ends of watch band portions  2506  and  2508  move away from each other within extension housing  2510 . Throughout this motion, constant-force springs  2600  maintain a substantially constant tension on watch band portions  2506  and  2508  through the connection of constant-force springs  2600  with extension housing  2510 . Thus, watch band  2504  can lengthen or shorten substantially via relative motion of watch band portions  2506  and  2508  while maintaining a substantially constant tension around a wearer&#39;s wrist. 
     In some embodiments, extension housing  2510  is monolithic. In other embodiments, extension housing  2510  is formed of two sections  2606  and  2608  separable and attachable (e.g., along a connection interface  2604 ). In such separable embodiments, extension housing  2510  may act as a clasp to help a user don or doff watch  2500  by attaching or detaching sections  2606  and  2608  from each other. 
     In some embodiments, instead of or in addition to repetitive compliant mechanisms and constant-force mechanisms as described above, a watch band may include a constant-force compression mechanism. For example, a watch band may include a constant-force pillow or a shape-memory segment that apply substantially constant force to a user&#39;s wrist by maintaining a substantially constant tension in the watch band. 
       FIG. 27  shows a watch  2700 , which includes a watch body  2702  connected to a watch band  2704 . Watch band  2704  includes a constant-force pillow  2706  on an interior side of watch band  2704 . When worn by a user, constant-force pillow  2706  may compress or expand as the user&#39;s wrist changes circumference. Throughout such compression and expansion, constant-force pillow  2706  may apply a substantially constant force F to the user&#39;s wrist, and thus maintain a substantially constant tension T in watch band  2704 . Through the compression and expansion of constant-force pillow  2706 , watch  2700  can accommodate changes in wrist circumference by correspondingly changing an interior circumference  2708  of watch band  2704 , while the overall length of watch band  2704  may remain unchanged. To apply such substantially constant force to a user&#39;s wrist, constant-force pillow  2706  may be formed of constant-force foam. 
     In some embodiments, instead of or in addition to being formed of constant-force foam, constant-force pillow  2706  may be formed of a bladder, filled with air. Such bladder may include an air intake  2710  and an air exhaust  2712 . Air exhaust  2712  may include a valve configured to exhaust air upon an increase in bladder pressure above a predetermined amount (e.g., in response to a user bending their wrist, which by increasing its circumference presses against bladder more forcefully, thereby increasing the internal pressure within the bladder). Air intake  2710  may include a valve configured to draw air into bladder upon a decrease in bladder pressure below a predetermined amount (e.g., in response to a user straightening their wrist, which by decreasing its circumference presses against bladder less forcefully, thereby decreasing the internal pressure within the bladder). 
       FIG. 28  shows a watch  2800 , which includes a watch body  2802  connected to a watch band  2804 . Watch band  2804  includes a shape-memory segment  2806 , having a natural shape curving toward an interior of watch band  2804 , within the area that a user would put their wrist. To don watch  2800 , a user must deform shape-memory segment  2806  out of the way, to accommodate the user&#39;s wrist. However, shape-memory segment  2802  is biased toward its natural shape, and so presses against the user&#39;s wrist in an attempt to return to its natural shape. Due to this bias, as a user&#39;s wrist changes circumference shape-memory segment  2806  may deform more or less to accommodate the circumference, all the while maintaining a substantially constant force F on the user&#39;s wrist, and a substantially constant tension T in watch band  2804 . 
     The foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. These exemplary embodiments are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. All specific details described are not required in order to practice the described embodiments. 
     It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings, and that by applying knowledge within the skill of the art, one may readily modify and/or adapt for various applications such specific embodiments, without undue experimentation, without departing from the general concept of the present invention. Such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments, based on the teaching and guidance presented herein. 
     The Detailed Description section is intended to be used to interpret the claims. The Summary and Abstract sections may set forth one or more but not all exemplary embodiments of the present invention as contemplated by the inventor(s), and thus, are not intended to limit the present invention and the claims. 
     The present invention has been described above with the aid of functional building blocks illustrating the implementation of specified functions and relationships thereof. The boundaries of these functional building blocks have been arbitrarily defined herein for the convenience of the description. Alternate boundaries can be defined so long as the specified functions and relationships thereof are appropriately performed. 
     The phraseology or terminology used herein is for the purpose of description and not limitation, such that the terminology or phraseology of the present specification is to be interpreted by the skilled artisan. 
     The breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined in accordance with the claims and their equivalents.

Metadata:
Filing Date: 20191002
Publication Date: 20221108
Grant Date: 20221108
Priority Date: 20160919
Inventors: WU, Yiwen
DE JONG, ERIK G.
ELY, COLIN M.
PANDYA, SAMEER
Assignee: APPLE INC
CPC Classifications: [{"code": "A44C5/027", "inventive": true, "first": false, "tree": "[]"}, {"code": "A44C5/0069", "inventive": true, "first": true, "tree": "[]"}, {"code": "A61B5/02438", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/681", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/02438", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/6843", "inventive": true, "first": false, "tree": "[]"}, {"code": "A44C5/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "A61B5/681", "inventive": true, "first": false, "tree": "[]"}, {"code": "A44C5/0069", "inventive": true, "first": true, "tree": "[]"}, {"code": "A61B5/681", "inventive": false, "first": false, "tree": "[]"}, {"code": "A61B5/02438", "inventive": false, "first": false, "tree": "[]"}, {"code": "A44C5/027", "inventive": true, "first": false, "tree": "[]"}, {"code": "A44C5/0069", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 68314921