Abstract:
A collapsible chair has a frame and a cover attaching thereto. The frame has a left side stand and an identical right side stands, which linked by four pairs of scissoring linking bars. A hook frame and a pillar frame are provided pivotally linked to the frame. The pillar frame has side pillars securely formed thereon and the hook frame has hooks defined in an end thereof. The hooks and the pillars are able to engage when the collapsible chair is fully expanded, which makes the collapsible chair self-stable and much safer: a loose or broken soft cover or attachment thereof to the frame will not cause breakdown of the whole frame which may serious injure the user.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a collapsible chair, and more particularly, to a collapsible chair the frame of which is self-stable, meaning that it itself has an ultimate position of expanding without aid of the soft cover attaching thereon. 
     2. Description of Related Art 
     Conventional collapsible chairs always have a limit expanding position depends on a sustaining force from one or more soft covers attaching to frames thereof. This kind of collapsible chairs has some drawbacks. Firstly, once the soft covers pulling the collapsible frame become loose or broken, the whole structure of the collapsible chair might deform or even disintegrate. This may bring much danger to a user sitting on. Secondly, for such conventional collapsible chairs, in order to make the chair safer, the soft covers have to be strong and tough enough. This will increase a cost of both material and manufacturing. 
     BRIEF SUMMARY OF THE INVENTION 
     The main object of the invention is to provide a self-stable frame will be much safer: a loose or broken soft cover or attachment thereof to the frame will not cause breakdown of the whole frame which may serious injure the user. 
     Another object of the invention is to provide a self-stable collapsible chair the strength and toughness of the soft cover of which will be much lowered, which means a reduced producing cost. 
     In order to accomplish aforementioned objects, the invention provides a collapsible chair having a frame having a left side stand and an identical right side stands, each side stand having a level ground bar, an upright front leg, and an upright rear leg; a left front, a left rear, a right front, and a right rear connecters respectively and securely fixed to a top of the left front, left rear, right front, and right rear legs; a left attaching bar being securely fixed to the left front and the left rear connectors, and a right attaching bar being securely fixed to the right front and the right rear connectors; a left front, a left rear, a right front, and a right rear sleeves respectively and slidably covering on the left front, left rear, right front, and right rear legs; a left front, a left rear, a right front, and a right rear upper linking bars each having an upper end pivotally linked respectively to the left front, left rear, right front, and right rear connecters; a left front, a left rear, a right front, and a right rear lower linking bars each having an lower end pivotally linked respectively to the left front, left rear, right front, and right rear sleeves; the left front upper and lower linking bars, the left rear upper and lower linking bars, the right front upper and lower linking bars, the right rear upper and lower linking bars being respectively hinged together around a left front, a left rear, a right front, and a right rear pins at roughly a middle portion respectively thereof and able to rotate with each other; free ends of the left front and the right front upper linking bars, free ends of the left rear and the right rear upper linking bars, free ends of the left front and the right front lower linking bars, free ends of the left rear and the right rear lower linking bars being respectively linked together and able to rotate with each other; a hook frame having a right handle bar and a pair of identical protruding right arms, the protruding right arms being respectively and pivotally linked to the right front and the right rear pins; and, a pillar frame having a left handle bar and a pair of identical protruding left arms, the protruding left arms being respectively and pivotally linked to the left front and the left rear pins; each the left arms having a side pillar securely formed thereon and each the right arms having a hook defined in an end thereof; and, a soft cover attached on the left and the right attaching bars. 
     These and other objectives, features, and advantages of the present invention will become apparent from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view showing the preferred embodiment of the collapsible chair of the invention. 
         FIG. 2  is a schematic perspective view showing a frame of the collapsible chair shown in  FIG. 1  without a cover. 
         FIG. 3  is another schematic perspective view showing the frame shown in  FIG. 2 . 
         FIG. 4  is a partially enlarged view showing portion A of  FIG. 2 . 
         FIG. 5  is a partially enlarged view showing portion B of  FIG. 3 . 
         FIG. 6  is a schematic perspective view showing another embodiment of the collapsible chair of the invention. 
         FIG. 7  is a schematic perspective view showing a frame of the collapsible chair shown in  FIG. 7  without a cover. And, 
         FIG. 8   a  through  8   d  are perspective views showing an operation of folding and expanding of the collapsible chair shown in  FIGS. 6 and 7 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Shown in  FIG. 1  is the preferred embodiment of the collapsible chair. The collapsible chair has a frame  1  and a soft cover  2  attached on the frame  1 . The frame  1  and the soft cover attaching thereon are in an fully expanded position. 
     With reference to  FIGS. 2 ,  3  and  4 , in which the soft cover  2  is removed, the frame  1  has a left side stand  10  and an identical right side stands  10 ′ both of U-shape. Each side stand  10 / 10 ′ has a level ground bar  101 / 101 ′, an upright front leg  102   a / 102   a ′, and an upright rear leg  102   b / 102   b ′. A left front, a left rear, a right front, and a right rear connecters  11   a ,  11   b ,  11   a ′,  11   b ′ are respectively and securely fixed to a top of the left front, the left rear, the right front, and the right rear legs  102   a ,  102   b ,  102   a ′,  102   b ′. A left attaching bar  103  is securely fixed to the left front and the left rear connectors  11   a  and  11   b , and a right attaching bar  103 ′ is securely fixed to the right front and the right rear connectors  11   a ′ and  11   b ′. A left front, a left rear, a right front, and a right rear sleeves  12   a ,  12   b ,  12   a ′,  12   b ′ are respectively and slidably covering on the left front, the left rear, the right front, and the right rear legs  102   a ,  102   b ,  102   a ′,  102   b ′. A left front, a left rear, a right front, and a right rear upper linking bars  13   a ,  13   b ,  13   a ′,  13   b ′ each has an upper end pivotally linked respectively to the left front, the left rear, the right front, and the right rear connecters  11   a ,  11   b ,  11   a ′,  11   b ′. A left front, a left rear, a right front, and a right rear lower linking bars  14   a ,  14   b ,  14   a ′,  14   b ′ each has an lower end pivotally linked respectively to the left front, the left rear, the right front, and the right rear sleeves  12   a ,  12   b ,  12   a ′,  12   b ′. The left front upper and lower linking bars  13   a  and  14   a , the left rear upper and lower linking bars  13   b  and  14   b , the right front upper and lower linking bars  13   a ′ and  14   a ′, the right rear upper and lower linking bars  13   b ′ and  14   b ′ are respectively hinged together around a left front, a left rear, a right front, and a right rear pins  15   a ,  15   b ,  15   a ′, and  15   b ′ at roughly a middle portion respectively thereof and able to rotate with each other. Free ends of the left front and the right front upper linking bars  13   a  and  13   a ′, free ends of the left rear and the right rear upper linking bars  13   b  and  13   b ′, free ends of the left front and the right front lower linking bars  14   a  and  14   a ′, free ends of the left rear and the right rear lower linking bars  14   b  and  14   b ′, are respectively linked together and able to rotate with each other. The soft cover  2  is attached to the left and the right attaching bars  103  and  103 ′. 
     The frame  1  further has a hook frame  16  and a pillar frame  17  both of U-shape. The hook frame  16  has a right handle bar  161  and a pair of identical protruding right arms  162   a ,  162   b . The protruding right arms  162   a ,  162   b  are respectively and pivotally linked to the right front and the right rear pins  15   a ′ and  15   b ′. The pillar frame  17  has a left handle bar  171  and a pair of identical protruding left arms  172   a ,  172   b . The protruding left arms  172   a ,  172   b  are respectively and pivotally linked to the left front and the left rear pins  15   a  and  15   b . Together with reference to  FIG. 5 , each left arms  172   a ,  172   b  has a side pillar  173   a ,  173   b  securely formed thereon and each right arms  162   a ,  162   b  has a hook  163   a ,  163   b  defined in an end thereof. When the frame  1  is fully expanded, each couple of hook  163   a / 163   b  and side pillar  173   a / 173   b  is able to firmly engage, as especially shown in  FIG. 5 . At this position, the side stands  10 ,  10 ′, the linking bars  13   a ,  13   b ,  13   a ′,  13   b ′,  14   a ,  14   b ,  14   a ′,  14   b ′, the hook frame  16 , and the pillar frame  17  are locked and not able to move with respect to one another. 
     According to above description, it could be seen that at an ultimately expanded position of the collapsible chair, the frame  1  is self-stable and requires no pulling force from the soft cover attaching thereon. This means that a loose or broken soft cover will no longer cause breakdown of the whole frame  1  which may serious injure the user. And as another result, strength and toughness of the soft cover  2  will be able to be much lowered, which means a reduced producing cost. 
     Shown in  FIGS. 6 and 7  is another embodiment of the collapsible chair and the bare frame thereof. The difference between this and the preferred embodiment is that the collapsible chair further has a pair of U-shaped identical arm rests  18 ,  18 ′ pivotally linked to the left front and the left rear connectors  11   a  and  11   b , and the right front and the right rear connecters  11   a ′,  11   b ′, respectively, a pair of identical back frames  19 ,  19 ′ each pivotally linked to one of the arm rests  18 ,  18 ′, and a back soft cover  3  attaching on the back frames  19 ,  19 ′. 
       FIGS. 8   a  through  8   d  are perspective views showing an operation of folding and expanding of the collapsible chair shown in  FIGS. 6 and 7 . For better understanding of the movement of the frame  1 , the soft covers  2  and  3 , which effects the operation of folding and expanding slightly, are removed from the FIGs.  FIG. 8   a  shows a status when the collapsible chair is completely folded. A user is able to pull the U-shaped arm rests  18 ,  18 ′ outward with his two hands until they reach an upright position as shown in  FIG. 8   b . Then he is able to rotate the back frames  19 ,  19 ′ upward as shown in  FIG. 8   c . As shown in  FIG. 8   d , the user will be able to pull the left and the right handle bars  171  and  161  with his two hands outward until each couple of hook  163   a / 163   b  and side pillar  173   a / 173   b  firmly engage, as especially shown in  FIGS. 6 and 7 , the collapsible chair of the invention is fully expanded. A reverse operation will be able to fold the collapsible chair. The preferred embodiment shown in  FIGS. 1 and 2  is able to be similarly folded and expended, only without operations on the arm rests  18 ,  18 ′ and the back frames  19 ,  19 ′. 
     From above description, it is seen that the objects of the present invention have been fully and effectively accomplished. Embodiment of the invention has been shown and described for the purposes of illustrating the functional and structural principles of the present invention and is subject to change without departure from the invention&#39;s principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.