Cap structure with elastic turnover cover
TITLE OF THE INVENTION 
     Cap Structure with Elastic Turnover Cover 
     This is a Division of Application Ser. No. 08/107,164 filed Aug. 17, 1993, now U.S. Pat. No. 5,361,920, which in turn is a Continuation of Application Ser. No. 07/828,895 filed Feb. 3, 1992, now abandoned. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a cap structure having an elastic turnover cover. The &#34;cap structure&#34; used herein is meant to include a cap and a container with a cap. 
     BACKGROUND ART 
     As a cap having an elastic turnover cover, there is known a cap which is integrally molded of a synthetic resin and having its cap body and cover hinged at three points, as is used in the container of Japanese Utility Model Laid-Open No. 34049/1988, for example. This cap is formed by integrally connecting a cap body and a cap opening cover into one piece by means of the three-point hinge. This three-point hinge structure is composed of: first two spaced hinges for connecting respective circumferential walls of the cap body and the cover placed thereon; an elastic band provided between the first two hinges; and second and third hinges for connecting each end of the elastic band to the cap body and the cover. The elastic band is formed into an L-shape such that it extends from the circumferential wall of the cap body to the top wall of the cover. 
     In order that the three-point hinged cap may be integrally molded of a synthetic resin, both the circumferential wall and the top wall of the cover are notched in accordance with the shape of the corresponding part of the elastic band for parting the mold. However, the notch on the top wall deteriorates the appearance of the cover. Even worse, the notch prevents the cover from completely sealing up the mouth of the cap body with the cover. 
     In order to eliminate the defects of the aforementioned example of the prior art, the present invention contemplates providing a cap structure having elastic bands which can be formed only at the respective circumferential walls of the cap body and the cover without notching the top wall of the cover, so that the cover may have an improved appearance and may seal up the mouth of the cap body in the closed position. 
     DISCLOSURE OF THE INVENTION 
     In an embodiment shown in FIGS. 1 to 5, if a cover 5 is pushed up from the open state of FIG. 5, a first end 12b of a curved elastic band 12 is allowed to move along an arc b which has a radius of a straight distance from the hinges 10 to the first end 12b, since the cover is turned on the hinges 10. Accordingly, the first end 12b deviates from an arc a, which has a radius of a straight distance from a second end 12a of the elastic band to the first end 12b. As a result, the elastic band extended against its elasticity until a dead center A defined by a point of intersection between the arc b and a straight line c containing the second end 12a and the hinges 10. And then, the elastic band is shrunken after the dead center A by its elastic controlling force so that the cover 5 is elastically turned over to establish the closed state. The cover opening operation could be likewise understood. 
     Incidentally, the elastic band 12 may have its intermediate portion curved to the front in the closed state of FIG. 4. 
     Another embodiment shown in FIGS. 6 to 8 is similar to the foregoing first embodiment. 
     A similar discussion applies to the case of a third embodiment shown in FIGS. 9 to 11. in this embodiment, each elastic band 12 is curved in a letter &#34;C&#34; not only in the open state but also in the closed state, in which it is received in a recess 13. According to this embodiment, the elastic bands 12 can be prevented from being forcibly extended more than their limits even when they through the dead center A at which they are extended to their maximum strokes. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Of FIGS. 1 to 5 showing one embodiment of the cap structure of the present invention: FIG. 1 is a perspective view showing the open state; FIG. 2 is a perspective view showing the closed state from the back; FIG. 3 is a top plan view showing the same; FIG. 4 is an enlarged section showing an essential portion; and FIG. 5 is an enlarged section showing an essential portion in the open state. Of FIGS. 6 to 8 showing a second embodiment: FIG. 6 is a perspective view showing the closed state from the back; FIG. 7 is a perspective view showing the open state; and FIG. 8 is an enlarged section showing an essential portion. Of FIGS. 9 to 11 showing a third embodiment: FIG. 9 is a perspective view showing the open state; FIG. 10 is a perspective view showing the closed state from the back; and FIG. 11 is an enlarged side elevation showing an essential portion. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     First of all, the first embodiment will be described with reference to FIGS. 1 to 5. 
     Reference numeral 1 designates the body of a cap structure having a first circumferential wall 2. This first circumferential wall 2 is adapted to be fitted on the outer circumference of the neck of a container, when the body 1 is a cap. However, this first circumferential wall has its lower end shut out with a bottom wall when the cap structure is a container body. In the shown embodiment, the first circumferential wall 2 has its top covered with a top plate 4 having a pouring port 3, but this top plate 4 can be eliminated. 
     Indicated at reference numeral 5 is a cover which is molded, of polyethylene or the like, integrally with the aforementioned body 1. This cover 5 can be turned on later-described hinges to open or close the top of the outer circumference. In the cover 5, a second circumferential wall 7 depends from the outer circumference of a top wall 6 and can have its lower end placed on the upper end of the first circumferential wall 2. The first circumferential wall 2 and the second circumferential wall 7 are shaped into a true circle, as seen in a top plan view, and have their backs formed into a vertical wall 8 which in turn is formed with a groove 9 at its widthwise center. 
     The vertical walls 8 of the first and second circumferential walls 2 and 7, which are divided by the groove 9, have their respective upper and lower ends connected by curved hinges 10 and 10, as better seen from FIG. 4. Moreover, the upper end of a groove bottom of the first circumferential wall and the lower end of a groove bottom of the second circumferential wall are formed to merge into each other, and the first and second circumferential walls are formed in front of their merging portions with holes 11 and 11, which are extended downward and upward from the upper and lower ends of the individual circumferential walls to leave an elastic band 12 at the bottom of the groove 9 at the back of the holes 11 and This elastic band 12 is preliminarily curved such that the body 1 and the cover 5 are integrally molded of a synthetic resin such as polyethylene, as shown in FIG. 5, with the cover 5 being opened with respect to the body 1 and with the elastic band 12 being curved upward. The connecting portions between the upper and lower ends of the elastic band 12 and the second and first circumferential walls are so formed that they cannot be bent angularly. 
     The second embodiment, as shown in FIGS. 6 to 8, is not formed with the aforementioned vertical walls 8 and groove 9 of the foregoing first embodiment. In this second embodiment, the first and second circumferential walls 2 and 7, which are shaped into a true circle in a top plan view, are connected by a pair of hinges 10, 10 provided at the righthand and lefthand portions of the respective backs thereof. Each of the hinges is formed at leading ends of triangular projections 13 and 13 provided at the upper and lower ends of the first and second circumferential walls. Moreover, the elastic band 12 is extended through an interval of the hinges 10 and 10 and so tensioned between the lower part of the first circumferential wall and the upper part of the second circumferential wall. The upper and lower ends merge into the two circumferential walls in an unbendable manner. As in the first embodiment, the second embodiment has its cap structure molded with the body and the cover in the closed state. 
     FIGS. 9 to 11 show the third embodiment. In this embodiment, the first and second circumferential walls 2 and 7 having a top plan view of a true circle are connected at their rear upper and lower ends by the hinge 10 and at the righthand and lefthand sides of the hinge 10 by a pair of C-shaped elastic bands 12 and 12. These elastic bands are fitted in recesses 13, which are formed to extend between the upper and lower portions of the individual backs of the first and second circumferential walls 2 and 7. The recesses 13 have their lower end rear edges and upper end rear edges connected to the lower and upper ends of the elastic bands 12 through second and third hinges 14 and 15. 
     Like the foregoing other embodiments, the third embodiment is also formed in the open state, as shown in FIG. 9. 
     INDUSTRIAL APPLICABILITY 
     According to the construction thus far described, the cap structure of the present invention can be prevented from having its appearance deteriorated because it has no notch and can have its body top sealed up by the cover. Unlike the three-point hinged cap of the prior art, the elastic plates need not be mounted by notching the back of the circumferential wall of the cover and the top wall of the cover partially. In the structure of the third embodiment, moreover, the elastic bands are given the C-shaped longitudinal sections so that they can have their cover side ends passing over the dead centers while leaving a margin of further elastic deformations. Since, moreover, the C-shaped elastic bands are fitted in the recesses 13 formed in the backs of the first and second circumferential walls of the body and the cover when in the closed state, the elastic bands will not deteriorate the appearance of the cap structure.