fig1 through 4 illustrate an exemplary folding chair incorporating features of the present invention . first , with reference to fig1 , the folding chair includes a front support frame 1 , a rear support frame 2 , a first link 31 , and second link 32 , a chair seat 4 , and a backrest 5 . the folding chair is selectively positionable between a functional or unfolded position ( fig1 ) and a storage or folded position ( fig4 ). the chair seat 4 comprises a seat member 41 , a first support bracket 42 , and a second support bracket 43 . the front support frame 1 comprises a right front leg 11 and a left front leg 21 . a front base bar 13 joins the right front leg 11 and the left front leg 21 . as such , the right front leg 11 , left front leg 21 and front base bar 13 form a substantially u - shaped member . the front base bar 13 is curved , and there are two bases 555 located thereon . however , the front base bar 13 can be disposed at any location along the length of right front leg 11 and left front leg 21 below the chair seat 4 to provide strength therebetween . likewise , the rear support frame 2 comprises a right rear leg 12 and left rear leg 22 . a rear base bar 23 joins the right rear leg 12 and the left rear leg 22 . as such , the right rear leg 12 , left rear leg 22 , and rear base bar 23 forms a substantially u - shaped member . the rear base bar 23 is curved , and there are two bases 556 located thereon . however , the rear base bar 23 can be disposed at any location along the length of right rear leg 12 and left rear leg 22 below the chair seat 4 to provide strength therebetween . the front support frame 1 and the rear support frame 2 are preferably hollow structures . this type of structure , in addition to reducing the weight of the folding chair , increases its rigidity and resistance to bending . with reference now to fig2 , the right front leg 11 has a first upper terminal point 111 . there are two holes , 112 and 113 , exposed outwardly in the mid - section thereof . hole 112 is the location where the first link 31 and the right front leg 11 are pivotally coupled by means of a rivet 311 . hole 113 is the location where the first support bracket 42 and the right front leg 11 are pivotally coupled by means of a rivet 312 . the left front leg 21 has a second terminal point 121 . there are two holes , 122 and 123 , exposed outwardly in the mid - section thereof . hole 122 is the location where the second link 32 and the left front leg 21 are pivotally coupled by means of a rivet 321 . hole 123 is the location where the second support bracket 43 and the left front leg 21 are pivotally coupled by means of a rivet 322 . the right rear leg 12 extends upwardly , where there is a third terminal point 26 . a first end cap 28 is disposed at the top end of the right rear leg 12 . there are two holes 212 and 213 exposed outwardly and formed at an end thereof . hole 212 is the location where the first link 31 and the right rear leg 12 are pivotally coupled by means of a rivet 331 . hole 213 is the location where the first support bracket 42 and the right rear leg 12 are pivotally coupled by means of a rivet 332 . the left rear leg 22 extends upwardly , where there is a fourth terminal point 27 . a second end cap 29 is disposed at the top end of the left rear leg 22 . there are two holes 222 and 223 exposed outwardly and formed at an end thereat . hole 222 is the location where the second link 32 and the left rear leg 22 are pivotally coupled by means of a rivet 341 . hole 223 is the location where the second support bracket 43 and the left rear leg 22 are pivotally coupled by means of a rivet 342 . the first link 31 is pivotally connected to the right front leg 11 and the right rear leg 12 at holes 112 and 212 , respectively . the first support bracket 43 is pivotally connected to the right front leg 11 and the right rear leg 12 at holes 113 and 213 . respectively . the pivot connections at holes 112 , 212 , 113 and 213 , thus form a foldable four - bar linkage . when the chair is in the use or unfolded position , the outer side 14 of the central part of the right front leg 11 rests on the upper end 24 of the first end cap 28 of the right rear leg 12 . likewise , the second link 32 is pivotally connected to the left front leg 21 and the left rear leg 22 at holes 122 and 222 , respectively . further , the second support bracket 43 is pivotally connected to the left front leg 21 and the left rear leg 22 at holes 123 and 223 , respectively . the pivot connection at holes 122 , 222 , 123 and 223 thus form a foldable four - bar linkage . when the chair is in the use or unfolded position , the outer side 15 of the central part of the left front leg 21 rests on the upper end 25 of the second end cap 29 of the left rear leg 22 . washers 61 , 62 , 63 and 64 are disposed between chair seat 4 and front support frame 1 and the rear support frame 2 . the washers restrict movement in the left and right directions of the chair seat 4 relative to the front support frame 1 and rear support frame 2 . in addition , they facilitate rotation of the chair seat 4 relative to the front support frame 1 . fig3 shows a perspective view of the chair viewing the chair from underneath the chair seat 4 . the chair seat 4 comprises a light - weight seat member 41 , a first support bracket 42 , a second support bracket 43 , and a cross - bar 44 . the chair seat 4 is positioned between the right front and rear legs 11 , 12 and the left front and rear legs 21 , 22 . in one embodiment , the seat member 41 is a blow - molded , hollow , plastic structure . the seat member 41 includes an upper surface and a lower surface 45 . the outer contour of the upper surface of the seat member 41 is preferably curved . in addition , the upper surface is slightly concave towards the center of the seat member 41 . thus , it provides a comfortable seating surface . in addition , the lower surface 45 of the seat member 41 has four grooves 46 and many recesses 47 that are slightly concave towards the center of the seat member 41 . the grooves 46 and recesses 47 can increase the resistance of the seat member 41 to bending and evenly distribute the weight of the user when sitting thereon . in addition , the grooves 46 enable the user to grasp the chair seat 4 easily when folding . on the lower surface 45 of the seat member 41 , a first attachment recess 411 and second attachment recess 412 are formed on the right and left side , respectively . in addition , at each end of the ridges 411 , 412 , are formed slots 413 , 414 , 415 and 416 which extend into the seat member 41 . the first support bracket 42 and second support bracket 43 is disposed in the first attachment recess 411 and second attachment recess 412 , respectively . as shown in fig2 , the first support bracket 42 is l - shaped . support bracket 42 includes a first lateral side 421 , a first bottom side 422 , a first flange 423 , and a second flange 427 . when disposed in the first attachment recess 411 of the seat member 41 , the first flange 423 and the second flange 427 are inserted into the first slot 413 and the second slot 415 . the first lateral side 421 and the first bottom side 422 are then secured to the first attachment recess 411 using rivets 425 . similarly , the second support bracket 43 is l - shaped . the second support bracket 43 includes a second lateral side 431 , a second bottom side 432 , a third flange 433 , and a fourth flange 437 . when disposed in the second attachment recess 412 of the seat member 41 , the two second flanges 433 and 437 are inserted into the third slot 414 and the fourth slot 416 , respectively . the second lateral side 431 and the second bottom side 432 are then secured to the second attachment recess 412 using rivets 435 . the first support bracket 42 and the second support bracket 43 fix the movement relative to the seat member 41 and evenly distribute the weight of the user on the seat member while also reducing the weight of the folding chair . a cross - bar 44 passes through the seat member 41 , providing a connection between the first support bracket 42 and the second support bracket 43 and thus creates an h - shape support structure . the cross - bar 44 fixes the movement of the seat member 41 relative to the first support bracket 42 and the second support bracket 43 . the use of the cross - bar 44 strengthens the seat member 41 , causing the stress in chair seat 4 to be distributed and reducing the tendency of breakage or weakening at the connections between the front support frame 1 , the rear support frame 2 , the first support bracket 42 , and the second support bracket 43 . thus , it extends the service life of the folding chair . in one embodiment , the backrest 5 is a hollow , blow - molded plastic structure . preferably , the backrest 5 is curved , concave toward the front of the chair , providing a comfortable structure for users to rest against . the backrest 5 is positioned on the first upper terminal point 111 of the right front leg 11 and the second upper terminal point 121 of the left front leg 21 . the backrest 5 contains apertures at the ends of a bottom surface , which apertures are configured to receive the ends 111 , 121 of right front leg 11 and left front leg 21 . preferably , the backrest 5 can be press - fit onto the front support frame 1 . in addition , the backrest 5 can be secured thereto with two rivets 51 . the chair is selectively foldable between a use position ( fig1 ) and a storage position ( fig4 ). when folded , the front support frame 1 and the rear support frame 2 are parallel to each other . the seat 4 is also substantially parallel to the back rest 5 . this folding structure is easy to fold , extremely compact , and does not cause undue stress on the connections between the front support frame 1 , the rear support frame 2 , and the chair seat 4 . the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics . the described embodiments are to be considered in all respects only as illustrative and not restrictive . the scope of the invention is , therefore , indicated by the appended claims rather than by the foregoing description . all changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope .
a folding chair is provided having a first front leg , a second front leg , a first rear leg , a second rear leg , a first link , a second link , a chair seat , and a backrest . the chair seat includes a seat member , a first support bracket , a second support bracket , and a cross - bar connecting the first and second support brackets . the first front leg , the first rear leg , the first link , and the first support bracket form a first four - bar linkage . the second front leg , the second rear leg , the second like , and the second support bracket form a second four - bar linkage .