fig1 shows a top view of an improved embodiment of an arm for use with the present invention . arm 200 includes a semicircular portion 202 and an extending portion 204 attached thereto . semicircular portion 202 includes two arc portions 230 and 232 and an inner bore 234 . the two arc portions 230 and 232 are both recessed or undercut near their ends , as shown by the phantom lines 236 and 238 . thus , the inner bore 234 is not perfectly circular in shape near the ends of arc portions 230 and 232 . ends 240 and 242 of the arc portions 230 and 232 , respectively , are well radiused to prevent binding of the arm on the airflow tube during pivoting . extending portion 204 includes two flange portions 206 and 208 on which generally oval depressions 210 and 212 are respectively positioned . bridge engagement pins 214 and 216 are positioned at far ends of flange portions 206 and 208 , respectively , and project , respectively , upwardly and downwardly from the arm 200 . a space 218 separates the flange portions 206 and 208 and in this embodiment , it can be seen that there is no vertical web between the respective flange portions and the space 218 . also , it can be seen that the space 218 extends along a greater portion of arm 200 than does the embodiment shown in fig1 . thus , the cantilever arm portions of the arm of fig1 are longer than the cantilever arm portions of the arm of fig2 . further , the cantilever arm portions of the arm of fig1 are tapered along their length , such that the thickness of these portions is less near the pins than the semicircular portion 202 . compare the thicker section of the arm of fig1 shown in fig1 with the thinner section of the arm taken nearer the pin 214 shown in fig2 . even though the thickness of the cantilever arm portions of the arm of fig1 have been reduced as compared to the arm of fig2 , the width of these portions has been increased with respect to the arm of fig2 . compare the widths of the arm of fig1 shown in fig1 and 20 with the width of the arm of fig1 shown in fig1 . the increased width of the improved arm of fig1 provides a stiffness in the lateral plane that is about 8 times greater than the stiffness of the arm of fig2 . this increased stiffness prevents most accidental lateral deflections of the pins and would likely require a determined intentional action to laterally deflect the cantilever arm portions and pins . a male locking portion 220 is positioned inboard of pin 214 and a female locking portion 222 is correspondingly positioned inboard of pin 216 . the male and female locking portions are configured so as to be able to fittingly mate with one another when the two flanges portions 206 and 208 are pressed together . as seen in fig1 , a section along line 16 — 16 in fig1 , the female locking portion can be configured as a chevron - shaped slot correspondingly , the male locking portion 220 would be configured as a chevron - shaped projection to mate with the chevron - shaped slot of female locking portion 222 . the male and female locking portions can also have different shapes , as long as they will lockingly mate together when the two flange portions are pressed together . as with the arm 34 above , the arm 200 can be flipped over to provide the second arm of the forehead support and thus , only one mold is needed to cast both required arms . the lengths of the pins 214 and 216 are provided such that when the pins are pressed together to the extent allowed by the locking portions , the pins will clear the slots in the bridge , contrary to the pins of the related art arms . in a preferred embodiment , these improved arms are constructed of a polycarbonate , specifically , makrolon 2858 manufactured by bayer . there are several advantages to this improved arm embodiment . first , because the space 218 extends farther along the arm 200 , the lack of a web between the flanges 206 and 208 and the tapering of the cantilever arm portions , it is as easy or easier to press the pins 214 and 216 together when adjusting the forehead support , even with the increased lateral strength of the improved arms . this is especially important because during the adjustment while the mask is on the wearer &# 39 ; s head , the wearer cannot easily see the forehead support as he or she is performing the adjustment . the increased lateral strength helps resist accidental lateral deflection of the cantilever arm portions and pins , as well as providing a stronger support to the airflow tube . the end result is that at the outer portion of the arm 200 near the pins , the extending portion 204 has a greater stiffness and resistance to bending in the lateral or horizontal direction ( i . e ., the pivoting direction ) than it does in the vertical direction ( the non - pivoting direction ). this is contrary to the embodiment shown in fig1 - 13 where the stiffness and resistance to bending is greater in the vertical direction than in the horizontal direction . of course , the taper , shape and / or the thickness of the cantilevered arm portions can be altered to vary the stiffness of the cantilevered arm portions in the horizontal or vertical directions , as circumstances warrant . further , under certain circumstances , it is contemplated that the stiffness of the cantilevered arm portions in the vertical direction can be less , similar to , or even greater than the comparable stiffness of the cantilevered arm portions of the related art design in the vertical direction . the use of the wider flanges also allows the use of broader oval depressions 210 and 212 . these broader depressions better accommodate the wearer &# 39 ; s fingers and thus , give the wearer a more positive and more comfortable grip on the arms during adjustment . the provision of the male and female locking portions assures that the two flange portions remained aligned with one another during the pressing together of the pins 214 and 216 . thus , the pins are also maintained in alignment during compression , making it easier for both pins to align with their respective slots in the bridge during adjustment of the bridge . without the locking mechanism , the pins can be twisted and splayed with respect to another during compression , making it more difficult to position the pins in the desired respective slots in the bridge during adjustment . further , the locking portions also prevent the user from laterally deflecting the pins with respect to one another when disassembling the arm from the bridge . since the pins are short enough to clear the slots in the bridge when pressed together , the arm need not be rotated or the pins laterally displaced from one another to allow the pins to clear the slots in the bridge . this reduces that the chance that a user can operate the arms contrary to instructions and thereby place undue stresses on the arms that could lead to premature failure of the arms . finally , the provision of the undercut or recessed portions 236 and 238 on arc portions 230 and 232 reduces the amount of material of the arm that comes into contact with the airflow tube 12 ( or other pivot point ). this helps prevent sticking or binding of the arm as it is pivoted about the airflow tube during adjustment of the forehead support , as compared to the related arm embodiment . the radiused ends 240 and 242 are also less likely to catch and hang up on imperfections in the airflow tube during pivoting , as compared to the sharper ends of the related arm embodiment . thus , the arm 200 more easily pivots about the airflow tube during adjustment of the forehead support . these improvements in arm 200 thus make it easier to adjust the forehead support , as well as make it easier to disassemble the arms from the bridge to allow thorough cleaning of the bridge and other support components . they also help prevent actions by the user contrary to instructions that could increase the risk of breakage of the forehead support . while several improvements have been discussed above , it is contemplated that an improved forehead support according to the present invention need not utilize all such improvements but can utilize one or more of such improvements in various combinations . it is to be understood that while the invention has been described above in conjunction with preferred specific embodiments , the description and examples are intended to illustrate and not limit the scope of the invention .
the present invention discloses an adjustable forehead support for a nasal or full - face mask wherein the forehead support may be adjusted for the different shapes and sizes of a facial profile . the forehead support utilizes a dual - arm system that adjusts the position of the forehead support vis - á - vis the mask and / or airflow tube . the angle of the mask to the face may be adjusted with the present invention .