PATENT DOCUMENT

Publication Number: US-11181748-B1
Application Number: US-201916570516-A
Country: US
Kind Code: B1

Title: Head support for head-mounted display

Abstract:
A head-mounted display unit includes a display assembly and a head support coupled to the display assembly for supporting the head-mounted display unit on a head of a user. The head support includes a band and an adjustment mechanism coupled to the band to lengthen the head support. The adjustment mechanism includes a base and a spool coupled to the base, a tape that extends from the adjustment mechanism through the band, and one or more springs rotatably coupled at first ends to the spool and fixedly coupled at second ends to the tape. The springs apply force to the tape to maintain the tape in tension during expansion and retraction of the band.

Claims:
What is claimed is: 
     
       1. A head-mounted display unit, comprising
 a display assembly; and 
 a head support coupled to the display assembly that supports the head-mounted display unit worn on a head of a user, the head support comprising:
 a band having three or more castellations formed of a rigid material and having a flexible support material that is different from the rigid material; and 
 
 an adjustment mechanism coupled to the band to lengthen the head support and keep the band in tension during extension and retraction of the head support; 
 wherein the castellations define openings through which a portion of the adjustment mechanism is routed through the band; and 
 wherein during the extension of the head support, the flexible support material expands and the castellations move apart from each other, and during retraction of the head support, the flexible support material retracts and the castellations move toward each other. 
 
     
     
       2. The head-mounted display unit according to  claim 1 , wherein the band includes a power cable routed through at least some of the openings within the castellations and transmitting power from a power source to the display assembly, the castellations reducing friction between the power cable and the band. 
     
     
       3. The head-mounted display unit according to  claim 1 , wherein the adjustment mechanism comprises:
 a base; 
 a spool rotatably coupled to the base; 
 a spring rotatably coupled at a first end thereof to the base and fixedly coupled at a second end thereof to the spool; and 
 a cord that extends through the band and is fixedly coupled at a first end thereof to the spool, wherein the spring applies torque to the spool to maintain the cord in tension. 
 
     
     
       4. The head-mounted display unit according to  claim 3 , wherein the cord is routed through the openings within the castellations along the band and is fixedly coupled at a second end thereof to an attachment mechanism that removably couples the head support to the display assembly. 
     
     
       5. The head-mounted display unit according to  claim 1 , wherein the adjustment mechanism comprises:
 a base; 
 a spool coupled to the base; 
 a tape that extends from the adjustment mechanism through at least some of the openings in the castellations in the band; and 
 springs rotatably coupled at first ends thereof to the spool and fixedly coupled at second ends thereof to the tape; wherein the springs apply force to the tape to maintain the tape in tension during expansion and retraction of the band. 
 
     
     
       6. The head-mounted display unit according to  claim 5 , wherein the tape is fixedly coupled at one end thereof to the springs and fixedly coupled at another end thereof to an attachment mechanism that removably couples the head support to the display assembly. 
     
     
       7. The head-mounted display unit according to  claim 5 , wherein springs act in parallel to apply the force to the tape to maintain the tape in tension. 
     
     
       8. The head-mounted display unit according to  claim 1 , wherein the head support includes a first attachment mechanism that removably couples a first side of the head support to the display assembly and a second attachment mechanism that removably couples a second side of the head support to the display assembly. 
     
     
       9. The head-mounted display unit according to  claim 1 , wherein the flexible support material surrounds the castellations, and the castellations surround the portion of the adjustment mechanism routed through the band. 
     
     
       10. The head-mounted display unit according to  claim 1 , wherein the castellations are disposed within the flexible support material, the castellations providing shape and structure to the flexible support material. 
     
     
       11. The head-mounted display unit according to  claim 10 , wherein the adjustment mechanism includes one or more of a cord or a tape that forms the portion of the adjustment mechanism routed through the band, the castellations reducing friction between the cord and the flexible support material. 
     
     
       12. The head-mounted display unit according to  claim 1 , wherein the castellations are distributed along the band. 
     
     
       13. A head-mounted display unit comprising:
 a display assembly; and 
 a head support coupled to the display assembly that supports the head-mounted display unit worn on a head of a user with the display assembly extending across a front of the head of the user, the head support comprising:
 a band; and 
 an adjustment mechanism coupled to the band to lengthen the head support, the adjustment mechanism comprising:
 a base; 
 a spool rotatably coupled to the base; 
 a cord coupled to and wound about the spool; and 
 a spring rotatably coupled to the base and that transfers torque to the spool to maintain the cord in tension, the spring being positioned rearward of the display assembly and to one of a left side or a tight side of the head of the user when the head-mounted display unit is worn thereon. 
 
 
 
     
     
       14. The head-mounted display unit according to  claim 9 , wherein the band is formed from a flexible support material and includes rigid castellations disposed within the flexible support material, the castellations providing shape and structure to the flexible support material. 
     
     
       15. The head-mounted display unit according to  claim 14 , wherein the castellations define openings through which the cord is routed along an interior of the band, the castellations reducing friction between the cord and the flexible support material. 
     
     
       16. The head-mounted display unit according to  claim 15 , wherein the band includes a power cable routed through the openings within the castellations and transmitting power from a power source to the display assembly, the castellations reducing friction between the power cable and the flexible support material. 
     
     
       17. The head-mounted display unit according to  claim 16 , wherein the cord and the power cable are routed through alternating, opposing ones of the openings in successive ones of the castellations disposed along the band, the castellations reducing friction between the cord and the power cable. 
     
     
       18. A head-mounted display unit comprising:
 a display assembly; and 
 a head support coupled to the display assembly that supports the head-mounted display unit worn on a head of a user, the head support comprising:
 a band; and 
 an adjustment mechanism coupled to the band to lengthen the head support, the adjustment mechanism comprising:
 a base; 
 a spool rotatably coupled to the base; 
 a cord coupled to and wound about the spool; and 
 a spring rotatably coupled to the base and that transfers torque to the spool to maintain the cord in tension; 
 
 
 wherein a first end of the spring is rotatably coupled to the base and a second end of the spring is fixedly coupled to the spool to transfer the torque thereto, and the spool defines a spring channel that guides winding and unwinding of the spring around the spool. 
 
     
     
       19. The head-mounted display unit according to  claim 18 , wherein the spool defines a cord channel spaced from the spring channel that guides winding and unwinding of the cord around the spool. 
     
     
       20. A head-mounted display unit comprising:
 a display assembly; and 
 a head support coupled to the display assembly that supports the head-mounted display unit worn on a head of a user, the head support comprising:
 a band; and 
 an adjustment mechanism coupled to the band to lengthen the head support, the adjustment mechanism comprising:
 a base; 
 a spool rotatably coupled to the base; 
 a cord coupled to and wound about the spool; and 
 a spring rotatably coupled to the base and that transfers torque to the spool to maintain the cord in tension; 
 
 
 wherein the adjustment mechanism further includes a second spool, a first end of the spring is rotatably coupled to the base and a second end of the spring is fixedly coupled to the second spool to transfer the torque thereto, and the second spool transfers the torque from the spring to the spool to maintain the cord in tension. 
 
     
     
       21. The head-mounted display unit according to  claim 20 , wherein the spool includes a first gear and the second spool includes a second gear that engages the first gear to transfer the torque between the spool and the second spool. 
     
     
       22. The head-mounted display unit according to  claim 21 , wherein the spool rotates about a first axis, and the second spool rotates about a second axis that is parallel with the first axis and spaced radially apart therefrom. 
     
     
       23. The head-mounted display unit according to  claim 22 , further comprising a third spool that rotates about a third axis that is parallel to and spaced radially apart from the first axis and the second axis, wherein the first end of the spring is rotatably coupled to the base by being fixedly coupled to the third spool. 
     
     
       24. A head-mounted display unit comprising:
 a display assembly; and 
 a head support coupled to the display assembly at supports the head-mounted display unit worn on a head of a user, the head support comprising
 a band that extends around the head of the user from a left side to a right side of the head of the user and engages the head of the user when the head-mounted display is worn thereon, the band being formed of a stretchable material; and 
 an adjustment mechanism coupled to the band to lengthen the head support, the adjustment mechanism comprising:
 one of a cord or a tape that extends through and is movable within the band and extends around the head of the user from the left side to the right side of the head of the user; 
 one or more springs that transfer force to the one of the cord or the tape to maintain the tape in tension during expansion and retraction of the band; and 
 a base and a spool coupled to the base, wherein the one or more springs are rotatably coupled at first ends to the spool and fixedly coupled at second ends to the one of the cord or the tape to apply force to the one of the cord or the tape to maintain the one of the cord or the tape in tension during expansion and retraction of the band. 
 
 
 
     
     
       25. A head-mounted display unit comprising:
 a display assembly; and 
 a head support coupled to the display assembly that supports the head-mounted display unit worn on a head of a user the head support comprising:
 a band that extends around the head of the user from a left side to a right side of the head of the user and engages the head of the user when the head-mounted display is worn thereon, the hand being formed of a stretchable material; and 
 an adjustment mechanism coupled to the band to lengthen the head support, the adjustment mechanism comprising: 
 
 one of a cord or a tape that extends through and is movable within the band and extends around the head of the user from the left side to the tight side of the head of the user; 
 wherein the band is formed from a flexible support material and includes rigid castellations disposed within the flexible support material, the castellations providing shape and structure to the flexible support material. 
 
     
     
       26. The head-mounted display unit according to  claim 25 , wherein the castellations define openings through which the one of the cord or the tape is routed along an interior of the band, the castellations reducing fiction between the tape and the flexible support material. 
     
     
       27. The head-mounted display unit according to  claim 26 , wherein the band includes a power cable routed through the openings within the castellations and transmitting power from a power source to the display assembly, the castellations reducing friction between the power cable and the flexible support material. 
     
     
       28. The head-mounted display unit according to  claim 27 , wherein the head support includes an attachment mechanism that removably couples the head support to the display assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/821,664, filed Mar. 21, 2019, and U.S. Provisional Patent Application No. 62/736,531, filed Sep. 26, 2018, each of which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to a display system and, in particular, head-mounted display units and supports therefor. 
     BACKGROUND 
     Head-mounted displays (HMD) are electronic devices that display graphics to a user wearing the head-mounted display, for example, when participating in activities related to computer-generated, augmented, virtual, and/or mixed realities. The head-mounted display may be worn by a user for extended durations, so comfort and fit are a high priority for a user. Existing head-mounted displays can be attached to or include comfort headbands, for example, comprised of elastic and/or silicone material, but many sizing options are required for this type of headband to sufficiently cover the spectrum of head sizes of users wearing the head-mounted display. 
     Additionally, different users will position a headband in different orientations to achieve a comfortable fit for the head-mounted display, changing forces experienced along various portions of the headband when the different users wear the head-mounted display in different orientations. The variety of forces experienced by the various portions of the headband can change both performance and comfort of the headband. 
     SUMMARY 
     Disclosed herein are implementations of a head-mounted display unit and head supports therefor. 
     A head-mounted display unit includes a display assembly and a head support coupled to the display assembly that supports the head-mounted display unit worn on a head of a user. The head support includes a band and an adjustment mechanism coupled to the band to lengthen the head support and keep the band in tension during extension and retraction of the head support. There are castellations disposed within band, and the castellations define openings through which a portion of the adjustment mechanism is routed through the band. 
     A head-mounted display unit includes a display assembly and a head support coupled to the display assembly that supports the head-mounted display unit worn on a head of a user. The head support includes a band and an adjustment mechanism coupled to the band to lengthen the head support. The adjustment mechanism includes a base, a spool rotatably coupled to the base, a spring rotatably coupled at a first end to the base and fixedly coupled at a second end to the spool, and a cord that extends through the band and is fixedly coupled at a first end to the spool. The spring applies torque to the spool to maintain the cord in tension. 
     A head-mounted display unit includes a display assembly and a head support coupled to the display assembly that supports the head-mounted display unit worn on a head of a user. The head support includes a band and an adjustment mechanism coupled to the band to lengthen the head support. The adjustment mechanism includes a base, a spool coupled to the base, a tape that extends from the adjustment mechanism through the band, and springs rotatably coupled at first ends to the spool and fixedly coupled at second ends to the tape. The springs apply force to the tape to maintain the tape in tension during expansion and retraction of the band. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. 
         FIG. 1  is a side view of a head-mounted display unit in a retracted state and an expanded state (dashed lines). 
         FIG. 2  is a top view of the head-mounted display unit of  FIG. 1  in the retracted state and the expanded stated (dashed lines). 
         FIG. 3  is a cross-sectional view of an adjustment mechanism of the head-mounted display unit of  FIG. 1  in the retracted state taken along line  3 - 3  in  FIG. 2 . 
         FIG. 4  is a cross-sectional view of the adjustment mechanism of the head-mounted display unit of  FIG. 1  in the expanded state taken along line  4 - 4  in  FIG. 2 . 
         FIG. 5  is a side view of another head-mounted display unit in a retracted state and an expanded state (dashed lines). 
         FIG. 6  is a top view of the head-mounted display unit of  FIG. 5  in the retracted state and the expanded stated (dashed lines). 
         FIGS. 7A and 7B  are cross-sectional views of a band of the head-mounted display unit of  FIG. 5  taken along line  7 - 7  in  FIG. 5 . 
         FIG. 8A  is a cross-sectional view of an adjustment mechanism of the head-mounted display unit of  FIG. 5  taken along line  8 - 8  in  FIG. 6 . 
         FIG. 8B  is a cross-sectional view of an adjustment mechanism of the head-mounted display unit of  FIG. 5  taken along line  8 - 8  in  FIG. 6 . 
         FIG. 9  is a side view of another head-mounted display unit in a retracted state and an expanded state (dashed lines). 
         FIG. 10  is a top view of the head-mounted display unit of  FIG. 9  in the retracted state and the expanded stated (dashed lines). 
         FIGS. 11A and 11B  are cross-sectional views of a band of the head-mounted display unit of  FIG. 9  taken along line  11 - 11  in  FIG. 9 . 
         FIG. 12  is a cross-sectional view of an adjustment mechanism of the head-mounted display unit of  FIG. 9  taken along line  12 - 12  in  FIG. 10 . 
         FIG. 13  is a cross-sectional view of a band of the head-mounted display unit of  FIG. 9  taken along line  13 - 13  in  FIG. 9 . 
     
    
    
     DETAILED DESCRIPTION 
     A head-mounted display unit having a head support configured to support the head-mounted display unit on different-sized heads of a variety of users is described below. The head support includes a band (e.g., a headband) that extends around the heads of the users and one or more adjustment mechanisms that allow the head support to provide generally constant force (e.g., a nominal force+/−10% as depicted on a force by distance curve) irrespective of the length of the band, the position of the adjustment mechanism, or the position of the head support as worn by the variety of users. 
     Referring to  FIGS. 1 and 2 , a head-mounted display unit  100  (HMD) includes a display assembly  110  and a head support  120 . The display assembly  110 , for example, includes a housing  112  and various electronics therein, such as one or more displays  114 , sensors  116  (e.g., detecting gaze and/or user status), and power electronics  118 , which are depicted schematically and in dashed lines to illustrate being hidden from view. 
     The head support  120  is coupled to left and right sides of the display assembly  110  (e.g., to the housing  112 ), extending rearward of the display assembly  110  and between the left and right sides thereof. When the head-mounted display unit  100  is worn on a head of a user, the display assembly  110  extends across a front of the head of the user (i.e., the face of the user), while the head support  120  extends rearward along left and right sides of the head of the user and across a rear of the head of the user. Thus, the display assembly  110  and the head support  120  cooperatively extend around the head of the user. 
     The head support  120 , as referenced above, is adjustable in length between a retracted position (solid lines) and an extended position (dashed lines) and is configured to provide a generally constant force regardless of the length thereof. The head support  120  includes a band  130 , one or more attachment mechanisms  140   a ,  140   b  (e.g., two as shown on the left and right sides), and one or more adjustment mechanisms  150   a ,  150   b  (e.g., two as shown on the left and right sides). 
     The band  130  forms a primary portion of the head support  120 , which engages the head of the user to support the head-mounted display unit  100  worn on the head of the user. Each of the attachment mechanisms  140   a ,  140   b  removably couples the head support  120  to the display assembly  110 . Each of the adjustment mechanisms  150   a ,  150   b  extends between one of the attachment mechanisms  140   a ,  140   b  and the band  130  and allows the head support  120  to change length overall by changing the length between the band  130  and the attachment mechanisms  140   a ,  140   b . Though two adjustment mechanisms  150   a ,  150   b  are shown as acting from opposing sides of the head support  120 , the head support  120  may alternatively employ a single adjustment mechanism (e.g., adjustment mechanism  150   a ). 
     The band  130  is flexible to accommodate different shapes of heads of the users. The band  130  may, for example, be formed of or otherwise include an elastic or silicone material. The band  130  may also be configured to transfer electrical power from a power source (e.g., an external battery) to the display assembly  110 . For example, the band  130  may include a flexible circuit  131  extending from a power connector  132  to the attachment mechanism  140   b , either bypassing or extending through the adjustment mechanism  150   b . The attachment mechanism  140   b  electrically connects to a corresponding power connector (not shown) of the display assembly  110 . The flexible circuit  131  (hidden; illustrated in dash-dot lines) may, for example, be embedded in the elastic or silicone material of the band  130  or otherwise hidden from view by the material of the band  130 . The flexible circuit  131 , while being flexible, may be inelastic, such that the band  130 , or the portion of the band having the flexible circuit  131 , is also inelastic. 
     Referring to  FIGS. 3 and 4 , the adjustment mechanism  150   b  of the head support  120  shown in  FIGS. 1 and 2  is configured as a telescoping mechanism having a stationary telescoping structure  360 , a sliding telescoping structure  370 , and a tension mechanism  380  generally contained by the stationary telescoping structure  360  and/or the sliding telescoping structure  370 . The stationary telescoping structure  360  is stationary relative to the display assembly  110  when coupled thereto, while the sliding telescoping structure  370  slides relative to the stationary telescoping structure  360  and, thereby, moves relative to the display assembly  110 . 
     The sliding telescoping structure  370  is positioned within the stationary telescoping structure  360  and slides relative thereto between a retracted position ( FIG. 3 ) and an extended position ( FIG. 4 ). The stationary telescoping structure  360  may, for example, be fixedly coupled to the display assembly  110  (e.g., via the attachment mechanisms  140   b ), while the sliding telescoping structure  370  may be fixedly coupled to the band  130 . As the sliding telescoping structure  370  moves between the retracted position ( FIG. 3 ) and the extended position ( FIG. 4 ), the length of the head support  120  (e.g., the distance between the band  130  and the attachment mechanism  140   b ) increases. 
     The sliding telescoping structure  370  and the stationary telescoping structure  360  may have complementary and constant cross-sectional shapes (e.g., ovular, rectangular, etc.), such that an outer surface of the sliding telescoping structure  370  engages an inner surface of the stationary telescoping structure  360  and slides therealong. Instead or additionally, the sliding telescoping structure  370  and/or the stationary telescoping structure  360  may include guides (e.g., nylon slides, not shown) that engage and slide against the corresponding surface of the other. The sliding telescoping structure  370  and the stationary telescoping structure  360  may further includes stops (not shown) that prevent relative movement therebetween, that is, from retracting beyond the retracted position or extending beyond the extended position. While the sliding telescoping structure  370  is described as being within the stationary telescoping structure  360 , the stationary telescoping structure  360  may instead be within the sliding telescoping structure  370 . 
     The tension mechanism  380  applies force between the sliding telescoping structure  370  and the stationary telescoping structure  360 , such that the head support  120  is in tension when engaging and extending around the head of the user. The tension mechanism  380  is, for example, configured to apply a generally constant tensive force between the sliding telescoping structure  370  and the stationary telescoping structure  360  irrespective of a position of the sliding telescoping structure  370  in respect to the stationary telescoping structure  360 . 
     As shown in  FIG. 3 , the tension mechanism  380  includes a base  381  (e.g., a chassis), bosses  382 ,  383 , a cord  384 , a pulley  385 , and constant-force extension springs  386 ,  387 ,  388 . 
     The base  381  is fixedly coupled to the stationary telescoping structure  360 . The bosses  382 ,  383  are fixedly coupled to the base  381 . 
     The cord  384  is inelastic and extends through the base  381  in a serpentine manner, so as to form three segments that are generally parallel with each other. A first end  384   a  of the cord  384  can be fixedly coupled to the base  381 , for example, proximate the attachment mechanism  140 . A second end  384   b  can be coupled to the sliding telescoping structure  370 , for example, proximate the band  130  (e.g., fixedly coupled directly to the sliding telescoping structure  370  as shown in dashed line in  FIGS. 3 and 4 ). Between the first end  384   a  and the second end  384   b , the cord  384  is wound approximately 180 degrees around the boss  382  of the base  381  and approximately 180 degrees around the pulley  385 . 
     The pulley  385  slides relative to the base  381  back and forth generally parallel with the segments of the cord  384 . The constant-force extension spring  386  applies a generally constant force between the base  381  and the pulley  385 . The constant-force extension spring  386 , for example, includes several coils of a flat metal material (e.g., steel, copper) that extend between an inner end  386   a  and an outer end  386   b . As the outer end  386   b  is extended relative to the inner end  386   a , the constant-force extension spring  386  applies a generally constant force to the outer end  386   b  over a length of travel (e.g., corresponding to movement between the retracted and extended positions). The constant-force extension spring  386  is positioned around another boss  383  of the base  381  with the inner end  386   a  wrapped around the boss  383 , allowing rotation of the constant-force extension spring  386  and/or the boss  383  relative to the base  381 . The outer end  386   b  of the constant-force extension spring  386  is fixedly coupled to the pulley  385 . 
     With the force applied by the constant-force extension spring  386  between the boss  383  and the pulley  385 , the pulley  385  applies force to the cord  384  to place the cord  384  in tension between the boss  382  of the base  381  and the sliding telescoping structure  370 . Due to mechanical advantage of the pulley  385 , the force of the constant-force extension spring  386  is equal to double the tension of the cord  384 . The force of the constant-force extension spring  386  and, thereby, the tension of the cord  384 , remain generally constant as the sliding telescoping structure  370  and, thereby, the cord  384 , move the distance between the retracted position ( FIG. 3 ) and the extended position ( FIG. 4 ). 
     In the embodiment shown in  FIGS. 3 and 4 , to apply tension between the stationary telescoping structure  360  and the sliding telescoping structure  370 , the constant-force extension springs  387 ,  388  can be coupled at first ends  387   a ,  388   a  to the sliding telescoping structure  370  (e.g., rotatable about bosses, not numbered) and at second ends  387   b ,  388   b  to the stationary telescoping structure  360 . The constant-force extension springs  387 ,  388  maintain a generally-constant tension between the stationary telescoping structure  360  and the sliding telescoping structure  370  as elongation ( FIG. 4 ) and retraction ( FIG. 3 ) of the sliding telescoping structure  370  occurs. The additional constant-force extension springs  387 ,  388  are described here and shown in  FIGS. 3 and 4  as two in number but can number between one and many to provide appropriate tension, force generation, and smooth, controlled elongation ( FIG. 3 ) and retraction ( FIG. 3 ) of the sliding telescoping structure  370 . 
     Referring to  FIGS. 5 and 6 , a head-mounted display unit  500  is a variation of the head-mounted display unit  100  and includes the display assembly  110  (described above) and a head support  520 . As with the head support  120 , the head support  520  is adjustable in length between a retracted position (solid lines) and an extended position (dashed lines). The head support  520  is configured to provide a generally constant force regardless of the length thereof. The head support  520  includes a band  530 , one or more attachment mechanisms  140   a ,  140   b  (as described above; e.g., two as shown on the left and right sides), and one or more adjustment mechanisms  550   a ,  550   b  (hidden; illustrated in long-dash lines; e.g., two as shown on the left and right sides). 
     As with the band  130 , the band  530  forms a primary portion of the head support  520  and engages the head of the user to support the head-mounted display unit  100  worn on the head of the user. The band  530  is formed of or otherwise includes a stretchable material, such as silicone, a constant-force structure, an engineered textile, an engineered elastomer, and/or a folded material (e.g., accordion, honeycomb, etc.) that provides structure and allows expansion and retraction of the band  530 . As with the band  130 , the band  530  may also be configured to transfer electrical power from a power source (e.g., an external battery) to the display assembly  110 . For example, the band  530  may include a power cable  531  (hidden; illustrated in dash-dot lines) that, as with the flexible circuit  131 , extends from a power connector  532  to the attachment mechanism  140 , either bypassing or extending through the adjustment mechanism  550 . 
     Each of the attachment mechanisms  140   a ,  140   b  removably couples the head support  520  to the display assembly  110 . One of the attachment mechanisms  140   b  also electrically connects to a corresponding power connector (not shown) of the display assembly  110 . 
     The adjustment mechanisms  550   a ,  550   b  (e.g., two as shown) each include a cord  551   a ,  551   b  (hidden; illustrated in short dashed lines) that extends through the band  530  and is retractable into and extendable from the corresponding adjustment mechanism  550   a ,  550   b , thereby shortening and lengthening, respectively, the head support  520 . In the case of the head support  520  including two adjustment mechanisms  550   a ,  550   b  as shown, each of the cords  551   a ,  551   b  extends from one of the adjustment mechanisms  550   a ,  550   b  and is fixedly coupled to one of the attachment mechanisms  140   b ,  140   a . Each of the cords  551   a ,  551   b  is routed through castellations in the band  530  as further described in reference to  FIG. 7A . In the case of the head support  520  including only one adjustment mechanism (e.g., as described in reference to  FIG. 7B ), a single cord  551  may extend from the adjustment mechanism on one side of the head-mounted display unit  500  and be fixedly coupled to the other side thereof (e.g., to the opposing attachment mechanism). 
     As the cords  551   a ,  551   b  retract into and extend from the adjustment mechanisms  550   a ,  550   b  to span different lengths between the two sides of the head-mounted display unit  500 , the band  530  similarly decreases or increases in length. The stretchable material forming or included within the band  530  may also surround the adjustment mechanisms  550   a ,  550   b.    
     In the example of  FIG. 5 , the power cable  531  is arranged in a serpentine manner (e.g., with alternating sinusoidal shapes) within the band  530  so as to not restrict expansion and retraction of the band  530  as it stretches and contracts to fit heads of varying users. Maintaining shape and tension of the band  530  while allowing movement of the power cable  531  and the cords  551   a ,  551   b  within the band  530  can be further supported using the castellations as described in reference to  FIGS. 7A and 7B  and the adjustment mechanisms  550   a  described in reference to  FIG. 8 . 
     Referring to  FIG. 7A , the band  530  of  FIGS. 5 and 6  is shown in shaded cross-section. At this cross-sectional location, the band  530  includes the power cable  531  (e.g., with a dotted pattern), a castellation  533  (e.g., with a diagonal line pattern), support material  534  (e.g., with a horizontal line pattern), and the cords  551   a ,  551   b  (e.g., with cross-hatch patterns). An outer cover, for example, a fabric material, is not shown. 
     The castellation  533  acts as a support for the band  530  and can be formed of a rigid, smooth material, for example, a polymer or a low-friction polycarbonate with or without anti-friction coating, that allows smooth movement of the power cable  531  and the cords  551   a ,  551   b  through the band  530  while prohibiting the power cable  531  and the cords  551   a ,  551   b  from frictionally interfering with the support material  534  or each other. The castellation  533  acts, for example, as a washer or bearing inside the sleeve of support material  534 . 
     The power cable  531  extends through a first opening  535  in the castellation  533 , the cord  551   a  extends through a second opening  536  in the castellation  533 , the cord  551   b  extends through a third opening  537  in the castellation  533 , and a fourth opening  538  in the castellation  533  is empty in this example, though other routings are possible that allow the band  530  to stretch without interference between the power cable  531  and the cords  551   a ,  551   b . The castellation  533  is shown with four openings  535 ,  536 ,  537 ,  538 , but any number of openings from one to many are possible. The size of the openings  535 ,  536 ,  537 , 538  can also vary, and features can be added to the castellation  533  (e.g., rollers, surface treatments, bearings, etc.) to further reduce friction caused by movement of the power cable  531  and the cords  551   a ,  551   b  within the band  530 . 
     The support material  534  can be formed of or otherwise include a stretchable material, such as silicone or an engineered elastomer, that allows expansion and retraction of the band  530  while providing support and locating features (not shown) for the castellation  533 . In another example (not shown), the support material  534  can be formed of a constant-force structure, an engineered textile with a set geometric pattern, and/or a folded material (e.g., accordion, honeycomb, etc.) Though a single castellation  533  is shown in  FIG. 7A  for descriptive purposes, the band  530  generally includes multiple castellations similar to the castellation  533  distributed along the band  530 , and the power cable  531  can be routed through the band  530  in a serpentine or sinusoidal manner, alternating routing through upper and lower (e.g., opposing) openings  535 ,  538  in successive castellations to better allow for expansion and retraction of the band  530  while reducing friction between the power cable  531  and the cords  551   a ,  551   b . This alternating routing is consistent with the routing pattern shown for the power cable  531  in  FIG. 5 . 
     Referring to  FIG. 7B , the band  530  of  FIGS. 5 and 6  is shown in shaded cross-section in an alternative configuration to that of  FIG. 7A . For example, the band  530  in  FIG. 7B  includes the power cable  531  (e.g., with a dotted pattern), the castellation  533  (e.g., with a diagonal line pattern), support material  534  (e.g., with a horizontal line pattern), and a singular cord  551  (e.g., with a cross-hatch pattern). An outer cover, for example, a fabric material, is not shown. The power cable  531  extends through a first opening  535  in the castellation  533  and the cord  551  extends through a second opening  536  in the castellation  533  in this example, consistent with use of a single adjustment mechanism vs. multiple adjustment mechanisms  550   a ,  550   b.    
     Referring to  FIG. 8A , the adjustment mechanism  550   a  of  FIGS. 5 and 6  includes a base  800 , a spool  810 , and constant-force extension springs  820 ,  821 . Though two constant-force extension springs  820 ,  821  are shown and described here, the number of constant-force extension springs may vary from one to many. The adjustment mechanism  550   a  may further include a housing  830  that surrounds and covers from view the base  800 , the spool  810 , and the constant-force extension springs  820 ,  821 . The housing  830  is coupled to, surrounds, or may form a portion of the base  800 . 
     The spool  810  is rotatably coupled to the base  800 . For example, the base  800  may include a boss  801  (e.g., protrusion or post) that is received by a central aperture of the spool  810  and around which the spool  810  rotates. 
     The constant-force extension springs  820 ,  821  can apply tangential force to the spool  810 , so as to generate torque. The constant-force extension springs  820 ,  821  are configured as the constant-force extension springs  386 ,  387 ,  388  described in  FIGS. 3 and 4 , for example, being formed of several coils of a flat metal material (e.g., steel, copper) that extend between inner ends  820   a ,  821   a  and outer ends  820   b ,  821   b . Each of the constant-force extension springs  820 ,  821  rotate around one of two bosses  802 ,  803  of the base  800  with inner ends  820   a ,  821   a  rotatable around the respective bosses  802 ,  803 , allowing a rotating motion relative to the bosses  802 ,  803  and/or the base  800 . The outer ends  820   b ,  821   b  of the constant-force extension springs  820 ,  821  are coupled to the spool  810  (e.g., being received in a spring channel or other guide mechanism thereof) and can overlay each other or be spaced along a perimeter of the spool  810  allowing the constant-force extension springs  820 ,  821  to wind or wrap (and unwind or unwrap) around the spool  810 . 
     Given the wrapping-style configuration, the constant-force extension springs  820 ,  821  can apply the tangential force to the spool  810  to create torque about the boss  801  of the base  800 . As the spool  810  is rotated, the constant-force extension springs  820 ,  821  are either wound about the spool  810  (e.g., in the spring channel or other mechanism referenced above) or unwound from the spool  810  depending on the direction of rotation (e.g., clockwise or counterclockwise). 
     The cord  551   b  is also coupled to the spool  810  to apply a tangential force to the spool  810  opposite the constant-force extension springs  820 ,  821 . The cord  551   b  is wrapped or wound (and unwrapped or unwound) about the spool  810 , for example, in a cord channel (not shown) adjacent the one or more spring channels (not shown). The base  800  may include a boss  804  that guides extension and retraction of the cord  551   b  both into and out of the adjustment mechanism  550  and around the spool  810 . In operation, the cord  551   b  may be guided by the boss  804  and extend out from the adjustment mechanism  550   a  into the band  530 , threading through the castellation  533  in the opening  536  as shown and described in  FIG. 7A . In another embodiment, another constant-force extension spring (not shown) may wind or wrap around the boss  804  and supply additional tension to the cord  551   b  in the manner similar to the constant-force extension springs  387 ,  388  described in respect to  FIGS. 3 and 4 . 
     The adjustment mechanism  550   a  may also include a gearing mechanism (not shown) that allows either one or both of the extension springs  820 ,  821  to apply tangential force to the spool  810 , thus allowing for different levels of generally constant force as appropriate to different usage situations of the head-mounted display unit  500 . For example, a user relaxing on the couch with the head-mounted display unit  500  may prefer a lighter tension than a user watching or playing a rousing game of tennis using the head-mounted display unit  500 . A variety of constant-force tension levels may also be achieved by changing a diameter of the spool  810 , thus changing the mechanical advantage. 
     Referring to  FIG. 8B , as an alternative to the adjustment mechanism  550   a ,  550   b , the head support  520  may instead include one or more adjustment mechanisms  850 . The adjustment mechanism  850  includes the base  800 , the housing  830 , and the cord  551   a  as generally described with respect to the adjustment mechanism  550   a . The adjustment mechanism  850  further includes a first spool  860 , a second spool  861 , an extension spring  851 , and a third spool  870 . The first spool  860  rotates about a first boss  860   a  that forms a first axis of rotation and is thereby rotatably coupled to the base  800 . The second spool  861  rotates about a second boss  861   a  that forms a second axis of rotation and is thereby rotatably coupled to the base  800 . The third spool  870  rotates about a third boss  870   a  that forms a third axis of rotation and is thereby rotatably coupled to the base  800 . The first, second, and third bosses  860   a ,  861   a ,  870   a  are spaced apart and may be formed integrally with the housing  830  or otherwise coupled thereto. The first, second, and third axes are parallel with and spaced apart radially from each other, for example, in three-spaced apart positions with a line extending therethrough. 
     The extension spring  851  is coupled to, wound about, and extends between the first spool  860  and the second spool  861  to transfer torque therebetween and ultimately to the third spool  870 . As is shown, a first end of the extension spring  851  is rotatably coupled base  800 , for example, being fixedly coupled to the first spool  860  to rotate therewith and being wound therearound in a first direction (i.e., clockwise starting from the center). A second end of the extension spring  851  rotatably coupled to the base  800 , for example, being fixedly coupled to the second spool  861  to rotate therewith and being wound therearound in a second direction, opposite the first (i.e., clockwise starting from the center). The extension spring  851  extends between the first spool  860  and the second spool  861  such that movement and torque is transferred therebetween. The first spool  860  and the second spool  861  may have different radii (e.g., with the second spool  861  being larger), such that the tangential force applied therebetween (i.e., at the radius) results in differential torque output thereof and unequal movement. 
     Torque is transferred between the second spool  861  and the third spool  870  via a geared relationship. The second spool  861  includes a first gear  861   b  that rotates in unison therewith (e.g., being coupled thereto or formed therewith), while the third spool  870  includes a second gear  870   b  that rotates in unison therewith (e.g., being coupled thereto or formed therewith). The first gear  861   b  engages the second gear  870   b  (e.g., being enmeshed therewith) to transfer torque between the second spool  861  and the third spool  870 . The torque output and rotation of the second spool  861  and the third spool  870  are in opposite rotational directions. As shown, first gear  861   b  of the second spool  861  and the second gear  870   b  of the third spool  870  may have the same diameter and tooth count, resulting in the same torque output and rotational speed as each other, but may instead have different diameters and/or tooth count. The first gear  861   b  may have a radius that is smaller than the radius of the second spool  861 , while the second gear  870   b  may have a larger radius than the third spool  870 . 
     The cord  551   a  is coupled to and wound about the third spool  870 , such that the torque transferred by the extension spring  851  to the third spool  870  maintains the cord in tension. As discussed previously, the torque transferred from the extension spring  851  to the second spool  861 , and from the second spool  861  to the third spool  870  via the geared connection. 
     While the axes of rotation of the spools  860 ,  861 ,  870  are spaced apart radially, it is further complicated that the third spool  870  (i.e., for the cord  551   a ) may be coupled to, be coaxial, and rotate in unison with the second spool  861 , but this relationship would lead to a thicker (i.e., in the axial direction) adjustment mechanism with the cord  551   a  and the extension spring  851  being wound in parallel planes. Instead, as is shown, by spacing apart the spools radially, the adjustment mechanism  850  achieves a lesser thickness, which may be advantageous to reduce distance by which the head support  520  protrudes from the head of the user. 
     The adjustment mechanism  550   a  and/or the adjustment mechanism  850  may be used on either or both sides of the head-mounted display unit  500  to generate tension along the cord  551   b , for example, as adjustment mechanisms  550   a ,  550   b . Alternatively, the adjustment mechanism  550   a  (or multiple adjustment mechanisms similar to adjustment mechanism  550   a ) may be located in the middle of the band  530 , for example, proximate to the power connector  532 , such that the cord  551   b  extends toward the ears of a user in two directions. An advantage of the adjustment mechanism  550   a  described in  FIG. 8  is that no change in length of the head support  520  occurs at the location of the adjustment mechanism  550   a , which generally allows the ears and the temples of a head of a user to be unaffected by length changes of the head support  520 . In other words, length changes of the head support  520  of  FIGS. 5-8  are restricted to length changes of the band  530 , which may be less noticeable and/or more desirable in terms of comfort for a variety of users. 
     Referring to  FIGS. 9 and 10 , a head-mounted display unit  900  is a variation of the head-mounted display units  100 ,  500  and includes the display assembly  110  (described above) and a head support  920 . As with the head supports  120 ,  520 , the head support  920  is adjustable in length between a retracted position (solid lines) and an extended position (dashed lines). The head support  920  is configured to provide a generally constant force regardless of the length thereof. The head support  920  includes a band  930 , one or more attachment mechanisms  140   a ,  140   b  (as described above; e.g., two as shown on the left and right sides), and one or more adjustment mechanisms  950   a ,  950   b  (hidden; illustrated in long-dash lines; e.g., two as shown on the left and right sides). 
     As with the bands  130 ,  530 , the band  930  forms a primary portion of the head support  920  and engages the head of the user to support the head-mounted display unit  100  worn on the head of the user. The band  930  is formed of or otherwise includes a stretchable material, such as silicone, a constant-force structure, an engineered textile, an engineered elastomer, and/or a folded material (e.g., accordion, honeycomb, etc.) that provides structure and allows expansion and retraction of the band  930 . As with the bands  130 ,  530 , the band  930  may also be configured to transfer electrical power from a power source (e.g., an external battery) to the display assembly  110 . For example, the band  930  may include a power cable  931  (hidden; illustrated in a dash-dot line) that extends from a power connector  932  to the attachment mechanism  140  along a serpentine path as shown, either bypassing or extending through the adjustment mechanism  950   b.    
     Each of the attachment mechanisms  140   a ,  140   b  removably couples the head support  920  to the display assembly  110 . One of the attachment mechanisms  140   b  also electrically connects to a corresponding power connector (not shown) of the display assembly  110 . 
     In this example, the adjustment mechanism  950   a  includes a tape  952  (hidden; illustrated in short dashed lines) that extends through the band  930  and is retractable into and extendable from the adjustment mechanism  950   a , thereby shortening and lengthening, respectively, the head support  920 . The tape  952  can be inelastic, of singular construction, or formed from multiple parallel strands. In the case of the head support  920  including the single adjustment mechanism  950   a , the tape  952  may extend and retract from the adjustment mechanism  950   a  on one side of the head-mounted display unit  900  and be fixedly coupled to the other side thereof (e.g., to the attachment mechanism  140   b ). The tape  952  can be formed, for example, of manufactured fibers, such as a metal-spun liquid-crystal polymer or other flexible metal, that can both wrap or wind and support coupling of metallic constant-force extension springs. 
     As the tape  952  retracts into and is extended from the adjustment mechanism  950   a  to span different lengths between the two sides of the head-mounted display unit  900 , the band  930  similarly decreases or increases in length. The stretchable material forming or included within the band  930  may also surround the adjustment mechanism  950   a.    
     In the example of  FIG. 9 , both the power cable  931  of the band  930  and the tape  952  of the adjustment mechanism  950   a  extend generally linearly through the band  930  as it stretches and contracts to fit heads of varying users. Maintaining shape and tension of the band  930 , the power cable  931 , and the tape  952  while allowing movement of the power cable  931  and the tape  952  within the band  930  can be achieved using castellations as described in reference to  FIGS. 11A and 11B  and the adjustment mechanism  950   a  described in reference to  FIG. 12 . 
     Referring to  FIG. 11A , the band  930  of  FIGS. 9 and 10  is shown in shaded cross-section. At this cross-sectional location, the band  930  includes the power cable  931  (e.g., with a dotted pattern), a castellation  933  (e.g., with a diagonal line pattern), a support material  934  (e.g., with a horizontal line pattern), and the singular tape  952  (e.g., with a cross-hatch pattern). 
     The castellation  933  acts as a support for the band  930  and can be formed of a rigid, smooth material, for example, a polymer, that allows smooth movement of the power cable  931  and the tape  952  through the band  930  while prohibiting the power cable  931  and the tape  952  from frictionally interfering with the support material  934 . The castellation  933  acts, for example, as a washer or bearing inside the sleeve of support material  934 . 
     The power cable  931  extends through a first opening  935  in the castellation  933  and the tape  952  extends through a second opening  936  in the castellation  933  in this example, though other routings are possible that allow the band  930  to stretch without interference between the power cable  931  and the tape  952 . The castellation  933  is shown with two openings  935 ,  936 , but any number of openings from one to many are possible. The size of the openings  935 ,  936  can also vary, and features can be added to the castellation  933  (e.g., rollers, surface treatments, bearings, etc.) to further reduce friction caused by movement of the power cable  931  and the tape  952  within the band  930 . 
     The support material  934  can be formed of or otherwise include a stretchable material, such as silicone or an engineered elastomer, that allows expansion and retraction of the band  930  while providing support and locating features (not shown) for the castellation  933 . Though a single castellation  933  is shown in  FIG. 11A , the band  930  generally includes multiple castellations, such as the castellations further described in respect to  FIG. 13 . 
     Referring to  FIG. 11B , the band  930  of  FIGS. 9 and 10  is shown in shaded cross-section in an alternative configuration to that of  FIG. 11A . For example, the band  930  in  FIG. 11B  includes the castellation  933  (e.g., with a diagonal line pattern), support material  934  (e.g., with a horizontal line pattern), and two tapes  952   a ,  952   b  routed generally parallel to each other through the band  930  (e.g., with cross-hatch patterns). An outer cover, for example, a fabric material, is not shown. The tape  952   a  extends through a first opening  935  in the castellation  933  and the tape  952   b  extends through a second opening  936  in the castellation  933  in this example. The parallel tapes  952   a ,  952   b  are consistent with use of two adjustment mechanism  950   a ,  950   b  each capable of providing adjustable length to the head support  920   a.    
     Referring to  FIG. 12 , the adjustment mechanism  950   a  of  FIGS. 9 and 10  includes a base  1200 , a spool or boss  1210 , one or more constant-force extension springs  1220 ,  1221 ,  1222 , and a tape  952 . Though three constant-force extension springs  1220 ,  1221 ,  1222  are shown and described here, the number of constant-force extension springs may vary from one to many. Though the tape  952  is shown as a single piece coupled to the three constant-force extension springs  1220 ,  1221 ,  1222 , the tape  952  may be formed from three parallel pieces, each piece coupled to one of the constant-force extension springs  1220 ,  1221 ,  1222 . The adjustment mechanism  950   a  may further include a housing  1230  that surrounds and covers from view the base  1200 , the boss  1210 , the constant-force extension springs  1220 ,  1221 ,  1222 , and at least a portion of the tape  952 . The housing  1230  is coupled to, surrounds, or may form a portion of the base  1200 . 
     The spool or boss  1210  is rotatably coupled to the base  1200 . For example, the boss  1210  may be a cylindrical post spanning between walls of the base  1200 . In another example, the base  1200  may include a boss (not shown; e.g., a protrusion or post) that is received by a central aperture (not shown) of the spool or boss  1210  and around which the spool or boss  1210  rotates. The spool or boss  1210  serves to position the constant-force extension springs  1220 ,  1221 ,  1222  on the base  1200 . 
     The constant-force extension springs  1220 ,  1221 ,  1222  have first ends (not shown) wrapped or wound around the boss  1210  and second ends  1220   a ,  1221   a ,  1222   a  coupled to the tape  952 . The second ends  1220   a ,  1221   a ,  1222   a  are shown in long-dashed (hidden) lines as being covered by the tape  952  in this sectional view of the adjustment mechanism  950   a . The constant-force extension springs  1220 ,  1221 ,  1222  work in parallel to apply a generally constant force between the boss  1210  and the tape  952 . 
     The constant-force extension springs  1220 ,  1221 ,  1222  are configured as the constant-force extension springs  386 ,  387 ,  388  described in respect to  FIGS. 3 and 4 , for example, being formed of several coils of a flat metal material (e.g., steel, copper) that extend between the first ends (not shown) around the boss  1210  and the second ends  1220   a ,  1221   a ,  1222   a  coupled to the tape  952   a . Tension is generated by extension of the tape  952   a , for example, when the band  930  is stretched to fit a head of a user, and the constant-force extension springs  1220 ,  1221 ,  1222  are unwound from the spool  1210 . 
     In operation, the tape  952  may extend out from the adjustment mechanism  950   a  into the band  930 , threading through the castellation  933  in the opening  936  as shown and described in  FIG. 11A . Though one adjustment mechanism  950   a  is described in  FIG. 12 , two adjustment mechanisms  950   a ,  950   b  may be used, for example, each having three constant-force extension springs coupled to a tape (e.g., tapes  952   a ,  952   b ), the two tapes extending through opposing openings of castellations along the band  930  from opposite sides of the head support  920 . 
     In another example, the adjustment mechanism  950   a  may also include a gearing mechanism (not shown) that allows different combinations of the constant-force extension springs  1220 ,  1221 ,  1222  to apply force to the tape  952 , thus allowing for different levels of generally constant force applied to the tape  952  as appropriate to different usage situations of the head-mounted display unit  900 . A variety of constant-force tension levels may also be achieved by changing a diameter of the boss  1210 , thus changing the mechanical advantage. 
     In another embodiment, the adjustment mechanism  950   a  (or multiple adjustment mechanisms  950   a ,  950   b ) may be located in the middle of the band  930 , for example, proximate to the power connector  932 , such that the tape  952  of  FIG. 11A  (or the two tapes  952   a ,  952   b  of  FIG. 11B ) extend(s) toward the ears and the temples of a user. An advantage of the adjustment mechanism  950   a  described in  FIG. 12  is that no change in length of the head support  920  occurs at the location of the adjustment mechanism  950   a . Another advantage of the adjustment mechanism  950   a  described in  FIG. 12  is that additional connections, such as power connections or data connections, can be run along the tape  952 , for example, adjacent to the constant-force extension springs  1220 ,  1221 ,  1222 . 
     Referring to  FIG. 13 , the band  930  of  FIGS. 9 and 10  is shown in cross-section in a nominal or resting position (e.g., in solid line) and in an expanded or stretched position (e.g., in dotted line). At this cross-sectional location, the band  930  includes three castellations  933   a ,  933   b ,  933   c , a support material  934 , and the tape  952 . 
     The castellations  933   a ,  933   b ,  933   c  act as a support for the band  930  and can be formed of a rigid, smooth material, for example, a polymer, the defines openings through which smooth movement of the tape  952  occurs while at the same time prohibiting the tape  952  from frictionally interfering with the support material  934 . The castellations  933   a ,  933   b ,  933   c  act, for example, as washers or bearings inside the sleeve of support material  934 . 
     The support material  934  can be formed of or otherwise include a stretchable material, such as silicone or an engineered elastomer, that allows expansion and retraction of the band  930  while providing support and locating features (not shown) for the castellations  933   a ,  933   b ,  933   c . The locating features can restrict movement of the castellations  933   a ,  933   b ,  933   c  within the band  930 . 
     For example,  FIG. 13  shows that castellation  933   a  starts in a first position, denoted by  933   a   1 , when the band  930  is static or unstretched. When the band  930  stretches, castellation  933   a  can move to a second position, denoted by  933   a   2 . Similar static positions and stretched positions are shown for the castellations  933   b ,  933   c , that is, as denoted by  933   b   1  and  933   c   1  for the static positions and  933   b   2  and  933   c   2  for the stretched positions. The castellations  933   a ,  933   b ,  933   c  can move apart and toward each other during expansion and retraction of the support material  934  as the band  930  adjusts in length to fit heads of varying users while maintaining generally constant force using the tensioned tape  952 . Though three castellations  933   a ,  933   b ,  933   c  are shown in this example, dozens or even hundreds of castellations similar to these castellations  933   a ,  933   b ,  933   c  may be located along the band  930  within the support material  934 . 
     In the static position, the castellations  933   a   1 ,  933   b   1 ,  933   c   1  may be spaced between 1 and 5 millimeters apart from each other in order to retain the overall shape of the band  930  while reducing friction between the tape  952  and the support material  934 . In the extended or stretched position, the castellations  933   a   2 ,  933   b   2 ,  933   c   2  may be spaced between 5 and 15 millimeters apart to allow for compression and expansion of the support material  934  to achieve a total extension within the range of 40-80 millimeters for the overall band  930  while retaining generally constant force against heads of varying users wearing the head support  920 . 
     The tape  952  is denoted within  FIG. 13  as having a fixed portion (in solid line) and a retractable or windable portion (in dotted line). The tape  952  either winds or unwinds within the adjustment mechanism  950   a  (e.g., see  FIG. 12 ) as the band  930  expands or retracts. 
     The head supports  120 ,  520 ,  920  described above are shown including singular headbands (e.g., bands  130 ,  530 ,  930 ) that extend from a first temple of a user across a back of a head of the user to the other temple of the user. In other embodiments, additional or alternative headbands with corresponding adjustment mechanisms can be designed to extend from the first temple of the user across a top of the head of the user to the other temple of the user. In compound head supports of this type (not shown), greater comfort can be achieved, and the user could don the head support in a similar manner to that used to don, for example, a baseball cap, a tipping motion from back to front. 
     It should be noted that while different features are described in the specification with different identifiers (e.g., first, second, and third) to distinguish therebetween, the claims may use different identifiers to distinguish between different features recited therein, for example, based on the order in which claim elements are introduced. For example, with reference to the adjustment mechanism  850 , the third spool  870  as described in the specification may instead be recited in the claims as a spool or a first spool. 
     In general, a physical environment refers to a physical world that people can sense and/or interact with without aid of electronic systems. Physical environments, such as a physical park, include physical articles, such as physical trees, physical buildings, and physical people. People can directly sense and/or interact with the physical environment, such as through sight, touch, hearing, taste, and smell. 
     In contrast, a computer-generated reality (CGR) environment refers to a wholly or partially simulated environment that people sense and/or interact with via an electronic system. In CGR, a subset of a person&#39;s physical motions, or representations thereof, are tracked, and, in response, one or more characteristics of one or more virtual objects simulated in the CGR environment are adjusted in a manner that comports with at least one law of physics. For example, a CGR system may detect a person&#39;s head turning and, in response, adjust graphical content and an acoustic field presented to the person in a manner similar to how such views and sounds would change in a physical environment. In some situations (e.g., for accessibility reasons), adjustments to characteristic(s) of virtual object(s) in a CGR environment may be made in response to representations of physical motions (e.g., vocal commands). 
     A person may sense and/or interact with a CGR object using any one of their senses, including sight, sound, touch, taste, and smell. For example, a person may sense and/or interact with audio objects that create 3D or spatial audio environment that provides the perception of point audio sources in 3D space. In another example, audio objects may enable audio transparency, which selectively incorporates ambient sounds from the physical environment with or without computer-generated audio. In some CGR environments, a person may sense and/or interact only with audio objects. 
     Examples of CGR include virtual reality and mixed reality. 
     A virtual reality (VR) environment refers to a simulated environment that is designed to be based entirely on computer-generated sensory inputs for one or more senses. A VR environment comprises a plurality of virtual objects with which a person may sense and/or interact. For example, computer-generated imagery of trees, buildings, and avatars representing people are examples of virtual objects. A person may sense and/or interact with virtual objects in the VR environment through a simulation of the person&#39;s presence within the computer-generated environment, and/or through a simulation of a subset of the person&#39;s physical movements within the computer-generated environment. 
     In contrast to a VR environment, which is designed to be based entirely on computer-generated sensory inputs, a mixed reality (MR) environment refers to a simulated environment that is designed to incorporate sensory inputs from the physical environment, or a representation thereof, in addition to including computer-generated sensory inputs (e.g., virtual objects). On a virtuality continuum, a mixed reality environment is anywhere between, but not including, a wholly physical environment at one end and virtual reality environment at the other end. 
     In some MR environments, computer-generated sensory inputs may respond to changes in sensory inputs from the physical environment. Also, some electronic systems for presenting an MR environment may track location and/or orientation with respect to the physical environment to enable virtual objects to interact with real objects (that is, physical articles from the physical environment or representations thereof). For example, a system may account for movements so that a virtual tree appears stationery with respect to the physical ground. 
     Examples of mixed realities include augmented reality and augmented virtuality. 
     An augmented reality (AR) environment refers to a simulated environment in which one or more virtual objects are superimposed over a physical environment, or a representation thereof. For example, an electronic system for presenting an AR environment may have a transparent or translucent display through which a person may directly view the physical environment. The system may be configured to present virtual objects on the transparent or translucent display, so that a person, using the system, perceives the virtual objects superimposed over the physical environment. Alternatively, a system may have an opaque display and one or more imaging sensors that capture images or video of the physical environment, which are representations of the physical environment. The system composites the images or video with virtual objects and presents the composition on the opaque display. A person, using the system, indirectly views the physical environment by way of the images or video of the physical environment, and perceives the virtual objects superimposed over the physical environment. As used herein, a video of the physical environment shown on an opaque display is called “pass-through video,” meaning a system uses one or more image sensor(s) to capture images of the physical environment and uses those images in presenting the AR environment on the opaque display. Further alternatively, a system may have a projection system that projects virtual objects into the physical environment, for example, as a hologram or on a physical surface, so that a person, using the system, perceives the virtual objects superimposed over the physical environment. 
     An augmented reality environment also refers to a simulated environment in which a representation of a physical environment is transformed by computer-generated sensory information. For example, in providing pass-through video, a system may transform one or more sensor images to impose a select perspective (e.g., viewpoint) different than the perspective captured by the imaging sensors. As another example, a representation of a physical environment may be transformed by graphically modifying (e.g., enlarging) portions thereof, such that the modified portion may be representative but not photorealistic versions of the originally captured images. As a further example, a representation of a physical environment may be transformed by graphically eliminating or obfuscating portions thereof. 
     An augmented virtuality (AV) environment refers to a simulated environment in which a virtual or computer-generated environment incorporates one or more sensory inputs from the physical environment. The sensory inputs may be representations of one or more characteristics of the physical environment. For example, an AV park may have virtual trees and virtual buildings, but people with faces photorealistically reproduced from images taken of physical people. As another example, a virtual object may adopt a shape or color of a physical article imaged by one or more imaging sensors. As a further example, a virtual object may adopt shadows consistent with the position of the sun in the physical environment. 
     There are many different types of electronic systems that enable a person to sense and/or interact with various CGR environments. Examples include head mounted systems, projection-based systems, heads-up displays (HUDs), vehicle windshields having integrated display capability, windows having integrated display capability, displays formed as lenses designed to be placed on a person&#39;s eyes (e.g., similar to contact lenses), headphones/earphones, speaker arrays, input systems (e.g., wearable or handheld controllers with or without haptic feedback), smartphones, tablets, and desktop/laptop computers. A head mounted system may have one or more speaker(s) and an integrated opaque display. Alternatively, a head mounted system may be configured to accept an external opaque display (e.g., a smartphone). 
     The head mounted system may incorporate one or more imaging sensors to capture images or video of the physical environment, and/or one or more microphones to capture audio of the physical environment. Rather than an opaque display, a head mounted system may have a transparent or translucent display. The transparent or translucent display may have a medium through which light representative of images is directed to a person&#39;s eyes. The display may utilize digital light projection, OLEDs, LEDs, uLEDs, liquid crystal on silicon, laser scanning light source, or any combination of these technologies. The medium may be an optical waveguide, a hologram medium, an optical combiner, an optical reflector, or any combination thereof. In one embodiment, the transparent or translucent display may be configured to become opaque selectively. Projection-based systems may employ retinal projection technology that projects graphical images onto a person&#39;s retina. Projection systems also may be configured to project virtual objects into the physical environment, for example, as a hologram or on a physical surface. 
     As described above, one aspect of the present technology is the gathering and use of data available from various sources, such as from sensors  116  or user profiles, to improve the delivery to users of content associated with the display  114 . The present disclosure contemplates that in some instances, this gathered data may include personal information data that uniquely identifies or can be used to contact or locate a specific person. Such personal information data can include demographic data, location-based data, telephone numbers, email addresses, twitter ID&#39;s, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other identifying or personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, the personal information data can be used to deliver targeted content that is of greater interest to the user. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used to provide insights into a user&#39;s general wellness or may be used as positive feedback to individuals using technology to pursue wellness goals. 
     The present disclosure contemplates that the entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities should implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining personal information data private and secure. Such policies should be easily accessible by users and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate and reasonable uses of the entity and not shared or sold outside of those legitimate uses. Further, such collection/sharing should occur after receiving the informed consent of the users. 
     Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. Hence different privacy practices should be maintained for different personal data types in each country. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, in the case of user-profile-based delivery of content, the present technology can be configured to allow users to select to “opt in” or “opt out” of participation in the collection of personal information data during registration for services or anytime thereafter. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified upon downloading an app that their personal information data will be accessed and then reminded again just before personal information data is accessed by the app. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing specific identifiers (e.g., date of birth, etc.), controlling the amount or specificity of data stored (e.g., collecting location data a city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, content can be displayed to users by inferring preferences based on non-personal information data or a bare minimum amount of personal information, such as the content being requested by the device associated with a user, other non-personal information available to the device, or publicly available information.

Metadata:
Filing Date: 20190913
Publication Date: 20211123
Grant Date: 20211123
Priority Date: 20180926
Inventors: WILLIAMSON, Heidi
STRYKER, JAMES A.
GALLAHER, ANDREW
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B2027/0161", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/0093", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B2027/0154", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/0176", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/163", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B2027/0154", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/0176", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B27/0176", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/163", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B2027/0154", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 78703726