Abstract:
A disposable umbrella wherein the shaft and rib structure are of unitary molded plastic construction. The ribs are joined to a central hub attached to the shaft by a self-hinge having memory which causes the ribs to spring outwardly into a radially extending state when released from a collapsed state.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to umbrellas and, more particularly, to an umbrella which is of inexpensive molded plastic construction and adapted for one-time use and disposal. 
     People are often caught in a public place without an umbrella when the weather turns for the worse. Oftentimes, these people have one or more umbrellas at their home or office so they are loathe to spend a significant amount of money to purchase an additional umbrella. It would therefore be desirable to have an umbrella which can be manufactured and sold very inexpensively so that it can be used as a temporary umbrella and be disposed of after a single use. 
     It would also be desirable to provide such an umbrella which is of compact construction so that it can be sold through a vending machine. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided an umbrella which comprises a shaft and unitary rib structure. The shaft has first and second ends and the rib structure includes a central hub secured to the first end of the shaft and a plurality of substantially equiangularly spaced and equally long rib members extending radially outwardly from the central hub. The rib structure is molded of a plastic material and is relatively rigid except for the portions where the rib members are joined to the central hub. Each such joining portion is thinner than the remainder of each rib member to constitute a self-hinge where each rib member joins the central hub. This allows each rib member to be folded inwardly so as to be substantially parallel to the shaft with its distal end extending toward the second end of the shaft. Each self-hinge has memory so that when a rib member is released from its inwardly folded position it returns to a radially extending position. A membrane is secured to the plurality of rib members. Accordingly, the rib members can be folded about the respective self-hinges toward the shaft and thereafter held to place the umbrella in a collapsed state, and when the rib members are released they spring outwardly to return the umbrella to an extended state. 
     In accordance with an aspect of this invention, the rib structure is formed unitarily with the shaft. 
     In accordance with another aspect of this invention, the umbrella further includes a cover sleeve adapted to overlie the folded rib members and membrane to maintain the umbrella in the collapsed state. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing will be more readily apparent upon reading the following description in conjunction with the drawings in which like elements in different figures thereof are identified by the same reference numeral and wherein: 
     FIG. 1 is a perspective view, partially broken away, showing an umbrella constructed according to the present invention maintained in its collapsed state by a cover sleeve; 
     FIG. 2 shows the umbrella of FIG. 1 released from the cover sleeve prior to springing into its extended state; 
     FIG. 3 is an end view showing the umbrella in its extended state; 
     FIG. 4 is a side view showing the umbrella in its extended state; 
     FIG. 5 is a sectional view taken along the line  5 — 5  of FIG. 3; and 
     FIG. 6 is a sectional view taken along the line  6 — 6  of FIG.  3 . 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, shown therein is an umbrella, designated generally by the reference numeral  10 , constructed in accordance with the principles of this invention. The umbrella  10  includes a shaft  12  having a first end  14  and a second end  16  and further includes unitary rib structure having a central hub  18  secured to the first end  14  of the shaft  12 . Illustratively, the central hub  18  is formed unitarily with the shaft  12 , as best shown in FIG. 5, although the central hub  18  could be constructed as a disc secured to the shaft by a screw or the like. The rib structure further includes a plurality of substantially equiangularly spaced and equally long rib members  20  extending radially outwardly from the central hub  18 . Preferably, the shaft  12 , the central rub  18  and the rib members  20  are molded of a plastic material which is relatively rigid when cured. 
     As best shown in FIG. 5, the rib members  20  are of substantially uniform thickness so as to be relatively rigid except where each of the rib members  20  is joined to the central hub  18 . At this juncture, each of the rib members  20  is made thinner, as by being undercut at  22 , thereby forming a self-hinge. Accordingly, each of the rib members  20  can be folded inwardly about the self-hinge formed by the undercut  22  so as to be substantially parallel to the shaft  12  with its distal end extending toward the second end  16  of the shaft  12 . As is known, each of the aforedescribed self-hinges has “memory” so that if a rib member  20  is folded about its self-hinge and then released, the rib member  20  returns to a radially extending position, as shown in FIG.  5 . 
     The umbrella  10  also includes a membrane  24  covering the rib members  20  on the side of the rib members  20  away from the shaft  12 . The membrane  24  is formed with a central opening to fit over the central hub  18 . To secure the membrane  24  to the rib members  20 , the membrane  24  is folded about the distal end of each rib member  20  to form a hem  26  on the side of each rib member  20  toward the shaft  12 , as best seen in FIG. 6. A plurality of elongated strips  28  of sheet material are provided, one for each of the rib members  20 . Each strip  28  is secured to the hem  26 , extends below a respective rib member  20 , and is secured to the underside of the membrane  24  along opposite sides of the respective rib member  20 . Accordingly, each strip  28 , together with the membrane  24 , forms an elongated pocket which allows relative sliding movement between the rib member  20  and the membrane  24 . Preferably, the strips  28  and the membrane  24  are formed of the same plastic material and can be secured one to the other by any suitable means, such as, for example, by adhesive bonding, ultrasonic bonding, or the like. 
     To hold the umbrella  10  in its collapsed state, with the rib members  20  folded toward the shaft  12 , a cover sleeve  30  is provided. The cover sleeve  30  is a tubular member and can be either rigid or flexible with a length that need be no longer than the length of the rib members  20 . The cover sleeve  30  can also be relatively short, if desired, and is slipped over the collapsed umbrella  10  from the end having the central hub  18  in order to maintain the umbrella  10  in its collapsed state. Although the cover sleeve  30  is shown as being substantially as long as the rib members  20 , it is understood that its desired function can be performed with a much shorter sleeve. 
     To assist in removing the umbrella  10  from the cover sleeve  30 , a gripping member  32  is provided. The gripping member  32  is secured to the first end  14  of the shaft  12 . Illustratively, the gripping member  32  is in the form of a ring formed unitarily with the central hub  18  and the shaft  12 . 
     As discussed above, the umbrella  10  is designed for disposal after a single use. To assist in such disposal, the shaft  12  is formed with a weakened portion  34 , illustratively in the form of a circumferential groove, so that the shaft  12  can be broken by snapping it at the groove  34 . 
     Although in the drawings the shaft  12  is shown as being longer than the rib members  20 , to provide a compact construction which is amenable to packaging for use in a vending machine, it is contemplated that the shaft  12  would have substantially the same length as the rib members  20 . 
     Accordingly, there has been disclosed an umbrella of inexpensive molded plastic construction adapted for one-time use and disposal. While an illustrative embodiment of the present invention has been disclosed herein, it is understood that various adaptations and modifications to the disclosed embodiment are possible, and it is intended that this invention be limited only by the scope of the appended claims.