the apparatus 1 shown in fig1 has parts that are examples of the elements recited in the claims . the apparatus 1 is a handheld welding shield . it is used to shield a welder &# 39 ; s eyes from sparks and intense light emitted from a part being welded . the shield 10 includes a shield plate 10 , a tinted lens 12 installed in the shield plate 10 , and a handle 14 . grasping the handle 14 , the welder holds the shield plate 12 up in front of his face while welding . this enables the welder to view the part being welded through the lens 12 while shielding his eyes from the light and sparks . fig2 is an exploded view of the shield plate 10 and the lens 12 . the lens 12 is a piece of transparent material , preferably glass , that is darkly tinted to let only a portion of the light through . it has front and rear surfaces 22 and 24 . it further has a rectangular periphery defined by a top and bottom ends 32 and 34 and two opposite sides 36 and 38 . as shown in fig2 and 3 , the shield plate 10 is centered on perpendicular longitudinal and lateral axes 41 and 43 . the plate 10 includes a wall 40 with front and rear surfaces 46 and 48 . the wall 40 is pan - shaped , with the rear surface 48 defining a shield cavity 49 . the wall 40 has a rectangular periphery defined by laterally extending top and bottom edges 52 and 54 and two opposite longitudinally extending side edges 56 and 58 . the handle 14 projects longitudinally downward from the bottom edge 54 and is laterally centered between the side edges 56 and 58 as shown in fig4 and 5 , the wall 40 has a rectangular opening 60 defined by top and bottom edges 62 and 64 of the wall 40 and two opposing side edges 66 and 68 of the wall 40 . as shown in fig5 , the opening 60 is bracketed by a lip 70 that projects rearwardly from the rear surface 48 of the wall 40 . the lip 70 extends along the full lengths of the two side edges 66 and 68 and along portions of the upper and lower edges 62 and 64 . the lip 70 has a generally rectangular rear edge 72 that brackets the wall opening 60 and abuts the front face 22 of the lens 12 ( fig2 ) when the lens 12 is installed on the shield plate 10 . a lower bracket 80 extends laterally along , and is adjacent to , the bottom edge 64 of the wall opening 60 . the lower bracket 80 has a cross - sectional profile shown head - on in fig6 . this profile is uniform along the length of the bracket 80 . it is characterized by a laterally extending channel 81 . the channel 81 is bounded on three sides by first and second inner side surfaces 82 and 84 and an inner end surface 86 of the bracket 80 . the channel 81 is configured to closely receive the bottom 34 of the lens 12 when the lens 12 is mounted on the shield plate 10 . accordingly , a width wl of the bracket cavity 81 , which is the distance between the inner side surfaces 82 and 84 , equals , at least approximately , a thickness t ( fig2 ) of the lens 12 . first and second outer side surfaces 92 and 94 of the bracket 80 are respectively parallel to the first and second inner side surfaces 82 and 84 . first and second opposite outer end surfaces 96 and 98 extend from the first outer side surface 92 to the second outer side surface 92 . an opening 99 in the second outer end surface 98 provides access to the cavity 81 . the lower bracket 80 and the bottom edge 64 of the wall opening 60 are connected together along their lengths by a hinge 110 . the hinge 110 extends laterally along an edge 112 of the bracket 80 where the first outer side surface 92 and the second outer end surface 98 meet . in this example , the hinge 10 is a living hinge , molded as a one - piece structure with the wall 40 and the lower bracket 80 . it bridges the bracket 80 and the shield wall 40 and is sufficiently thin and flexible to function as a hinge between them . as indicated by arrow 113 , the hinge 110 enables the lower bracket 80 to be pivoted away from its initial as - molded position shown in fig6 . concurrently , the hinge 110 resiliently urges the lower bracket 80 back toward its initial as - molded position . the bracket 80 is flexible , but not as flexible as the living hinge 110 . an upper bracket 120 extends laterally along , and is adjacent to , the top edge 62 of the wall opening 60 . the upper bracket 120 has a cross - sectional profile shown head - on in fig6 . as with the lower bracket 80 , the profile of the upper bracket 120 is characterized by a laterally extending channel 121 . the channel 121 is bounded on three sides by first and second opposite inner side surfaces 122 and 124 and an inner end surface 126 of the bracket 120 . the upper channel 121 is configured to closely receive the top 32 of the lens 12 ( fig2 ) when the lens 12 is installed on the shield plate 10 . accordingly , a width wu of the upper channel 121 , which is the distance between the inner side surfaces 122 and 124 , equals , at least approximately , the thickness t ( fig2 ) of the lens 12 . the upper bracket 120 further has first and second outer side surfaces 132 and 134 . a first outer end surface 136 extends from the first outer side surface 132 to the second outer side surface 134 . a second outer end surface 138 extends from the first outer side surface 132 to a front opening 139 of the channel 120 . a third outer end surface 140 extends from the front opening 139 , in a direction away from the first outer side surface 132 , to the second outer side surface 134 . the upper bracket 120 and the upper edge 62 of the wall opening 60 are connected together along their lengths by a hinge 150 . the hinge 150 extends laterally along an edge 152 of the bracket 120 where the first outer side surface 132 and the second outer end surface 138 meet . in this example , the hinge 150 is a living hinge molded as a one - piece structure with the wall 40 and the upper bracket 120 . it bridges the wall 40 and the upper bracket 120 and is sufficiently thin and flexible to function as a hinge between them . as indicated by arrow 153 , the hinge 150 enables the upper bracket 120 to be pivoted away from its initial as - molded position shown in fig6 . concurrently , the hinge 150 resiliently urges the upper bracket 120 back toward its initial position . the upper bracket 120 is flexible , but not as flexible as the living hinge 150 . the profile of the upper bracket 120 is not uniform along its length . as shown in fig4 , the second outer side surface 134 recedes toward the upper edge 62 with increasing proximity to the laterally opposite sides 160 of the upper bracket 120 . in fact , at the laterally opposite sides 160 , the entire second inner side surface 124 and a portion of the inner end surface 126 are absent . as shown in fig5 , first and second upper retaining bosses 171 and 172 and first and second lower retaining bosses 173 and 174 extend rearwardly from the rear surface 48 of the wall 40 . the first bosses 171 and 173 are adjacent to the first edge 66 of the opening 60 . the second bosses 172 and 174 are adjacent to the second edge 68 of the opening 60 . each boss 171 , 172 , 173 and 174 has an abutment surface 176 facing laterally inward . the abutment surfaces 176 are configured to abut the sides 36 and 38 ( fig2 ) of the lens 12 when the lens 12 is in the installed position . the shield plate 10 can be injection molded . the molding process entails 1 ) injecting heat - softened plastic resin between front and rear core faces of a mold ( not shown ), 2 ) waiting for the plastic to harden , 3 ) retracting the front and rear cores away from the shield plate , and 4 ) ejecting the shield plate from the mold . the as - molded configuration of the shield plate 40 is shown in fig6 . in this configuration , the channels 80 and 120 are open toward the wall opening 60 in that the channel openings 99 and 139 face forward toward the wall opening 60 . this enables the front core of the mold to form the channels 81 and 121 along with features of the front surface 46 . after the plastic hardens , the front core can be withdrawn from the bracket channels 81 and 121 when being retracted from the front surface 46 . accordingly , formation of the upper and lower channels 81 and 121 does not require additional cores , which would be the case if the channels 81 and 121 were open in a longitudinal or lateral direction . the lens 12 ( fig2 ) can be installed in the shield plate 12 as follows . first , as indicated by arrow 113 , the lower bracket 80 is pivoted about its hinge 110 rearward and downward from its initial , as - molded , position . this continues until the bracket 80 reaches a second position in which the lower channel 80 is open toward the upper channel 121 , i . e ., the lower channel opening 99 faces the upper channel 121 , as shown in fig7 . then the lens 12 is inserted into the lower channel 81 . next , the third outer end surface 140 is pushed rearward by a finger . as indicated by arrow 181 , this pivots the upper bracket 120 rearward about its living hinge 150 rearward and upward from its initial as - molded position . this continues until the bracket 120 reaches a second position in which the upper channel opening 139 faces the opposite channel 81 , as shown in fig8 , and the third outer end surface 140 is above the lens 12 . concurrently , as indicated by arrow 183 in fig7 , the lens 12 is tilted rearward about the lower channel 81 . this continues until the third outer end surface 140 is above the lens 12 , as shown in fig8 . the tilting motions indicated by arrows 181 and 183 in fig7 are enabled , but resisted , by the flexibility of the brackets and hinges 80 , 120 , 110 and 150 . next , as indicated by the arrow 185 in fig8 , the lens 12 is pivoted forward toward the wall opening 60 . while pivoting increasingly forward , as indicated by arrow 187 in fig9 , the top 32 of the lens 12 slides against the third outer end surface 140 of the bracket 120 . in doing so , the lens 12 pushes the third outer end surface 140 increasingly higher as indicated by arrow 189 . concurrently , the third outer end surface 140 resiliently bears down against the lens 12 , thus pressing it into the first channel 81 . as the lens 12 continues forward ( arrow 187 ), the third outer end surface 140 rides up ( arrow 189 ) and over the lens 12 . the lens 12 thus finally snaps into its installed position , shown in fig1 . the installed position is characterized by the following features : the first outer surfaces 92 and 132 of both brackets 80 and 120 abut the rear surface 48 of the wall 40 . the channel openings 99 and 139 face each other . a field of view is bounded longitudinally by the hinges 110 and 150 ( fig5 ). the brackets 80 and 120 , including the second inner side surfaces 82 and 122 of the brackets 80 and 120 , do not cross into the field of view . the bracket channels 81 and 121 capture the lens 12 . forward movement of the lens 12 is prevented by abutment of the front surface 22 of the lens 12 against both the rear edge 72 of the lip 70 and the first inner surfaces 82 and 122 of the brackets 80 and 120 . rearward movement of the lens 10 is prevented by abutment of the rear surface 24 of the lens 12 against the second inner surfaces 84 and 124 of the brackets 80 and 120 . as shown in fig1 , lateral movement of the lens 12 is limited , and prevented , by abutment of the sides 36 and 38 of the lens 12 against the abutment surfaces 176 of the retaining bosses 171 , 172 , 173 and 174 ( fig5 ). as is apparent in fig1 , the lens 12 can be removed from the shield plate 40 by pushing up on the third outer end surface 140 of the upper bracket 120 to release the lens 12 . the lens 12 can then be tilted rearward and lifted out of the lower bracket 80 . this written description uses examples to disclose the invention , including the best mode , and also to enable any person skilled in the art to make and use the invention . the patentable scope of the invention is defined by the claims , and may include other examples that occur to those skilled in the art . such other examples are intended to be within the scope of the claims if they have elements that do not differ from the literal language of the claims , or if they include equivalent structural elements with insubstantial differences from the literal language of the claims .
an apparatus includes a wall defining an opening . a first bracket is connected to the wall and defines a first channel . a second bracket is located across the wall opening from the first bracket and defines a second channel . a hinge connects the second bracket to the wall such that the second bracket can pivot from a first position in which the second channel is open toward the wall opening to a second position in which the second channel is open toward the first channel . the brackets are configured to retain the lens in an installed position in which the lens extends across the wall opening , the first bracket captures a first end of the lens , the second bracket is in its second position , and the second channel captures a second end of the lens .