Latex lid mounting apparatus
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an apparatus for mounting a lid on a beverage cup, more particularly to a latex lid mounting apparatus. 
     2. Description of the Related Art 
     Because of having flexible and stretchable natures, latex lids have been used widely in fast food stores to close the open upper ends of beverage cups. When mounting a latex lid on a beverage cup, the lower rim of the lid is pulled outward by the hands of a waiter or waitress. Then, the stretched lid is placed on the beverage cup, thus permitting the lower rim of the lid to automatically seal the open upper end of the cup. It is time-consuming to manually mount a latex lid on a beverage cup. 
     SUMMARY OF THE INVENTION 
     It is therefore the main object of this invention to provide an apparatus for mounting a latex lid on a beverage cup. 
     According to this invention, a latex lid mounting apparatus includes a seat body and a lid accommodating device with a replaceable lid container. A beverage cup is placed on a cup positioning plate. Lids are superposed in the container. When a rotary driving source is powered, an ascending assembly activates a lid holding unit to move up and down between an upper limit position and a lower limit position. The lid holding unit includes an outer ring, an inner ring journalled in the outer ring, several links connected to the inner and outer rings, and a plurality of paw elements carried on the inner and outer rings. A rotation control device regulates relative rotation between the inner and outer rings, so as to move the paw elements between an inner limit position and an outer limit position. Under the guidance of the rotation control device, the lid holding unit holds the lowermost lid immediately before reaching the upper limit position, while covering the open upper end of the cup with the lid immediately before reaching the lower limit position. The lid holding unit is activated by an upper microswitch to move downward when reaching the upper limit position, and is activated by a lower microswitch to move upward when reaching the lower limit position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     Other features and advantages of this invention will become apparent in the following detailed description of a preferred embodiment of this invention, with reference to the accompanying drawings, in which: 
     FIG. 1 is a partially exploded view of a latex lid mounting apparatus according to this invention; 
     FIG. 2 is a sectional side view showing the latex lid mounting apparatus of this invention; 
     FIG. 3 is an exploded view showing the lid holding unit of the latex mounting apparatus according to this invention; 
     FIG. 4 is a schematic view illustrating the operation of the lid holding unit of the latex lid mounting apparatus according to this invention; and 
     FIGS. 5 to 7 are schematic views illustrating how to move the lid holding unit of the latex lid mounting apparatus to move up and down under the control of a rotation control device in accordance with this invention; and 
     FIG. 8 is a schematic view illustrating how the paw elements of the latex lid mounting apparatus access the lower rim of the lowermost lid in accordance with this invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2, a latex lid mounting apparatus of this invention includes a seat body 1, an ascending assembly 2, a lid holding unit 3, an outer tube 4 and a rotary driving source 5. 
     The seat body 1 includes a lower positioning plate or cup positioning means (P1), two fixed intermediate positioning plates (P2), and a fixed upper positioning plate (P3). The lower positioning plate (P1) has a through hole (P11) with a large-diameter upper portion and a small-diameter lower portion. The lower end portion of a beverage cup is placed in the upper portion of the through hole (P11). Each of the intermediate positioning plates (P2) has an intermediate positioning hole (P21) formed therethrough in alignment with the through hole (P11). The upper positioning plate (P3) also has an upper positioning hole (P31) formed therethrough in alignment with the through hole (P11). An upper microswitch 111 and a lower microswitch 112 are connected to the driving source 5 and located above the intermediate positioning plates (P2). A guide member 121 is fixed on the seat body 1 below the intermediate positioning plates (P2). 
     The ascending assembly 2 includes an externally threaded drive tube 20, a drive ring 21, two positioning rings 22 and a window portion 23. The drive tube 20 extends in turn through the lower one of the intermediate positioning plates (P2), the lower positioning ring 22, the drive ring 21, the upper positioning ring 22 and the upper one of the intermediate positioning plates (P2), so as to position the drive ring 21 on the seat body 1. The drive ring 21 has an internally threaded portion 211 engaged threadably with the drive tube 20 so as to transfer the rotation of the drive ring 21 to a longitudinal movement of the drive tube 20, and also has an externally toothed portion 212 with an endless series of radial teeth. The window portion 23 is connected securely to the lower end of the drive tube 20. 
     Referring to FIG. 3, the lid holding unit 3 includes an inner ring 30, an outer ring 31, a paw assembly 32, a cover 33 and a guide rod 34. The outer ring 31 is screwed to the cover 33 which is connected securely to the window portion 23 of the ascending assembly 2. The outer ring 31 has an inward flange 311 at the lower end thereof, while the inner ring 30 has an annular downward flange 301 journalled within the inward flange 311, so as to confine the inner ring 30 between the cover 33 and the outer ring 31, in such a manner that the inner ring 30 can rotate in the outer ring 31. The paw assembly 32 includes four sets of alternate male links 321 and female links 322, which are angularly equally spaced apart from each other. Each of the male and female links 321, 322 has a fixed paw element (B1) positioned at the radial inner end thereof, and a recess (R) positioned at the radial inner end portion. Each of the male links 321 further includes a rotatable paw element (B2) mounted pivotally in the recess (R). As illustrated, the outer ring 31 is provided with eight circumferentially equidistant pivot pins 312 so as to connect pivotally to the outer ends of the male and female links 321, 322. Correspondingly, the inner ring 30 is provided with eight circumferentially equidistant guide elements 302. The inner end portions of the male and female links 321, 322 have lengthwise slide slots (S) in which the guide elements 302 are respectively received. The guide rod 34 is screwed to the bottom surface of the inner ring 30 and has an outer end which is outside of the outer ring 31. Accordingly, as best shown in FIG. 4, when the guide rod 34 is rotated clockwise, the paw elements (B1, B2) move to an inner limit position, as indicated by solid lines, in which the rotatable paw elements (B2) of the male links 321 are engaged with the fixed paw elements (B1) of the female links 322, so as to clamp the lower rim of the lowermost lid (L) therebetween. When the guide rod 34 is rotated counterclockwise, the paw elements (B1, B2) move to an outer limit position, as indicated by dotted lines. 
     Again referring to FIGS. 1 and 2, the outer tube 4 extends through the drive tube 20 of the ascending assembly 2 and has an upper end outward flange (40a) placed on the upper surface of the upper positioning plate (P3), so as to prevent the outer tube 4 from downward movement. An inward flange (40b) is provided on the lower end portion of the outer tube 4 so as to support a tubular lid container 41 thereon. The lid container 41 has an open lower end and an open upper end which extends from the upper end of the outer tube 4 so that the user can easily replace the lid container with a new lid container, having a cylindrical chamber in which a plurality of latex lids (L) are superposed. Four circumferentially equidistant L-shaped hanging arms 411 are provided on the lower end of the outer tube 4 and have radially inwardly extending end portions. The inward flange (40b) has an inner diameter approximate to that of the lid container 41 so as to allow downward movement of the lids (L) through a space defined by the inward flange (40b) of the outer tube 4. The end portions of the L-shaped hanging arms 411 of the outer tube 4 are spaced apart from the inward flange (40b) at a distance which allows the rim of the lowermost lid (L) to be supported on the hanging arms 411. Accordingly, referring to FIG. 8, the fixed paw elements (B1) can move to a position (P) in a direction as indicated by an arrow (A1), while the rotatable paw elements (B2) can move to a position (P&#39;) in the same direction (A1). At this time, the paw elements (B1, B2) are at the same level as that of the lower rim of the lowermost lid (L). Then, the fixed paw elements (B1) and the rotatable paw elements (B2) move toward each other so as to access the lower rim of the lowermost lid (L) in directions (A2, A3), thereby seizing the lowermost lid (L). 
     In this embodiment, the rotary driving source 5 is a motor 51 with an externally threaded motor shaft 511. An endless driving belt 52 has an endless series of teeth 521 provided on the inner surface thereof which is trained on the motor shaft 511 and the drive ring 21, so as to rotate the drive ring 21, thereby activating the drive tube 20 to move up and down. Because the outer ring 31 is secured to the drive tube 20, the drive tube 20 moves the lid holding unit 3 between an upper limit position and a lower limit position. 
     The guide rod 34 and the guide member 121 constitute a rotation control device for the inner ring 30 and the outer ring 31. Again referring to FIG. 1, the guide member 121 has a base portion 1211, an upper projection 1212 secured to the upper portion of the base portion 1211, and a lower projection 1213 secured to the lower portion of the base portion 1211 and spaced apart from the upper projection 1212. 
     Referring to FIG. 5, the upper projection 1212 has a first guiding surface which has an inclined first section (G11) having a lower end extending from the base portion 1211 to the left a distance greater than that of the adjacent portion of the lower projection 1213, a vertical second section (G12) connected at the lower end thereof to the upper end of the first section (G11), an inclined third section (G13) connected at the lower end thereof to the upper end of the second section (G12), and a vertical fourth section (G14) connected at the lower end thereof to the upper end of the third section (G13). The first section (G11) is located relative to the end of the guide rod 34 so that the end of the guide rod 34 can come into engagement with the lower end portion of the first section (G11) during upward movement of the lid holding unit 3 from the lower limit position. The sliding movement of the end of the guide rod 34 along the inclined first section (G11) urges the paw elements (B1, B2) to move inward from the outer limit position. The sliding movement of the end of the guide rod 34 along the vertical second section (G12) moves the paw elements (B1, B2) upward to level with the lower rim of the lowermost lid (L), so as to position the fixed paw elements (B1) on the inner side of the lower rim of the lowermost lid (L), and to position the rotatable paw elements (B2) on the outer side of the lower rim of the lowermost lid (L). The sliding movement of the end of the guide rod 34 along the inclined third section (G13) moves the paw elements (B1, B2) to the inner limit position, so as to clamp tightly the lower rim of the lowermost lid (L) therebetween. The sliding movement of the end of the guide rod 34 along the vertical fourth section (G14) urges the lid holding unit 3 to carry the lowermost lid (L) therewith to move upward a distance. 
     The lower projection 1213 has a second guiding surface which has an inclined first section (G21) having an upper end extending from the base portion 1211 to the right a distance greater than that of the adjacent portion of the upper projection 1212, and a vertical second section (G22) connected at the upper end thereof to the lower end of the first section (G21). The first section (G21) is located relative to the end of the guide rod 34 so that the end of the guide rod 34 can come into engagement with the upper end portion of the first section (G21) during downward movement of the lid holding unit 3 from the upper limit position. The sliding movement of the end of the guide rod 34 along the inclined first section (G21) urges the paw elements (B1, B2) to move from the inner limit position to the outer limit position. The sliding movement of the end of the guide rod 34 along the vertical second section (G22) moves the lid holding unit 3 to the lower limit position. When coming into engagement with the open upper end of the cup immediately before the lid holding unit 3 reaches the lower limit position, the lid (L) separates from the lid holding unit 3 and remains on the cup. 
     With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated in the appended claims.