Dispenser for flexible sheet material and a perforating mechanism adapted to be used therein

Abstract

A mechanism for perforating a web of flexible sheet material which is adapted to be used in a flexible sheet material dispenser, said mechanism comprising; a rotatably mounted roller, a rotatably mounted knife positioned adjacent the roller and having a radially outward portion defining a cutting edge for perforating the web as the web passes between the roller and the knife, the roller being operatively connected to the knife for synchronous rotation therewith and having a slot therein for receiving the radially outward knife portion as the knife rotates past the roller, and means associated with the knife for orienting the cutting edge substantially in the direction in which the radially outward knife portion moves with respect to the web during the entrance of the portion into the slot so that when the portion enters the slot the cutting edge will effectively perforate the web.

We claim: 
     
       1. In a dispenser for flexible sheet material including, a chassis adapted to be attached to a wall, means operatively connected to said chassis for rotatably supporting a roll of flexible sheet material, means operatively connected to said chassis for guiding a web of flexible sheet material from said roll to a position to be grasped by a user so that the user may pull the web out of the dispenser, and a mechanism operatively connected to said chassis for perforating said web at intervals therealong to divide the web into individual sheets, the improvement wherein said perforating mechanism comprises, a rotatably mounted roller, a rotatably mounted knife positioned adjacent said roller and having a radially outward portion defining a cutting edge for perforating the web as the web passes between the roller and the knife, said roller being operatively connected to said knife for synchronous rotation therewith and having a slot therein for receiving said radially outward knife portion as the knife rotates past the roller, and means associated with said knife for orienting said cutting edge substantially in the direction in which said radially outward knife portion moves with respect to the web during the entrance of said portion into said slot so that when the portion enters the slot, the cutting edge will effectively perforate the web, and wherein said dispenser further comprises a mechanism associated with said perforating mechanism for stopping the rotation of said knife and said roller and thus arresting the movement of the web after a predetermined length of the web has been withdrawn from the dispenser, and a variable timing means associated with said stop mechanism for controlling the period of time during which the stop mechanism is effective to stop the rotation of the knife and the roller. 
     
     
       2. In a dispenser for flexible sheet material including, a chassis adapted to be attached to a wall, means operatively connected to said chassis for rotatably supporting a roll of flexible sheet material, means operatively connected to said chassis for guiding a web of flexible sheet material from said roll to a position to be grasped by a user so that the user may pull the web out of the dispenser, and a mechanism operatively connected to said chassis for perforating said web at intervals therealong to divide the web into individual sheets; the improvement wherein said perforating mechanism comprises, a rotatably mounted roller, a rotatably mounted knife positoned adjacent said roller and having a radially outward portion defining a cutting edge for perforating the web as the web passes between the roller and the knife, said roller being operatively connected to said knife for synchronous rotation therewith and having a slot therein for receiving said radially outward knife portion as the knife rotates past the roller, and means associated with said knife for orienting said cutting edge substantially in the direction in which said radially outward knife portion moves with respect to the web during the entrance of said portion into said slot so that when the portion enters the slot, the cutting edge will effectively perforate the web; and wherein said dispenser further comprises a mechanism associated with said perforating mechanism for stopping the rotation of said knife and said roller and thus arresting the movement of the web after a predetermined length of the web has been withdrawn from the dispenser; and wherein said perforating mechanism further comprises a second rotatably mounted roller operatively connected to said first-mentioned roller for synchronous rotation therewith, said knife being mounted on said second roller; and wherein said stop mechanism comprises a camming pin operatively connected to said second roller for rotation therewith, a stop lever pivotally connected to said chassis and having a cam follower and a stop lug integrally affixed thereto, said cam follower being positioned in the rotational path of said camming pin, and said stop lug being movable into the rotational path of said camming pin upon the engagement of said pin with said follower for stopping the rotation of the pin and said second roller, and thereby stopping the rotation of said knife and said first roller, so that after said predetermined length of the web has been withdrawn from the dispenser a user may tear an individual sheet of the web from the portion thereof remaining within the dispenser along the perforations last-produced in the web by said cutting edge, and means connected to said stop lever for moving said stop lug out of the rotational path of said camming pin so that after said individual sheet has been torn from said remaining web portion an additional predetermined length of the web may be withdrawn from the dispenser. 
     
     
       3. A dispenser as recited in claim 2, further comprising a variable timing means connected to said stop lever for controlling the length of time of the stop lug remaining in the rotational path of the camming pin. 
     
     
       4. A dispenser as recited in claim 3, wherein said timing means comprises a pair of resilient vacuum cups, one of said cups being attached to said stop lever and the other of said cups being attached to said chassis, said cups being engageable in vacuum-gripping relationship when said stop lug is positioned in the rotational path of said caming pin, and valve means associated with one of said cups for regulating the flow of air between the cups when the cups are in vacuum-gripping relationship. 
     
     
       5. A dispenser as recited in claim 2, wherein the position of said camming pin is adjustable with respect to said second roller so that said knife and said first roller may be stopped while said last-produced perforations are either inside or outside the dispenser. 
     
     
       6. A dispenser as recited in claim 5, further comprising means operable when said knife and said fist roller are stopped with said last-produced perforations inside the dispenser for rotating the knife and the first roller automatically after said stop lug has moved out of the rotational path of said camming pin so that the leading edge of the web will be moved outside the dispenser to a position to be grasped by a user. 
     
     
       7. A dispenser as recited in claim 4, wherein said one cup is made of a relatively hard resilient material and said other cup is made of a relatively soft resilient material to thereby minimize the compression force required to engage the cups in vacuum-gripping relationship. 
     
     
       8. In a dispenser for flexible sheet material including a chassis adapted to be attached to a wall, means operatively connected to the chassis for rotatably supporting a roll of flexible sheet material, means operatively connected to the chassis for guiding a web of flexible sheet material from said roll to a position to be grasped by a user so that the user may pull the web out of the dispenser, a mechanism operatively connected to the chassis for perforating said web at intervals therealong to divide the web into individual sheets, said perforating mechanism including a rotatably mounted roller, a rotatably mounted knife positioned adjacent said roller and having a radially outward portion defining a cutting edge for perforating the web as the web passes between the roller and the knife, said roller being operatively connected to said knife for synchronous rotation therewith and having a slot therein for receiving said radially outward knife portion as the knife rotates past the roller, a stop mechanism associated with said perforating mechanism for stopping the rotation of said knife and said roller and thus arresting the movement of the web after a predetermined length of the web has been withdrawn from the dispenser, and a variable timing means associated with said stop mechanism for controlling the period of time during which stop mechanism is effective to stop the rotation of the knife and the roller; the improvement wherein said timing means comprises a pair of resilient vacuum cups, one of said cups being attached to said stop mechanism and the other of said cups being attached to said chassis, said cups being engageable in vacuum-gripping relationship when said stop mechanism stops the rotation of the knife and the roller, said one cup being made of a relatively hard resilient material and said other cup being made of relatively soft resilient material to thereby minimize the compression force required to engage the cups in said vacuum-gripping relationship, and valve means associated with said one cup for regulating the flow of air between the cups when the cups are in vacuum-gripping relationship. 
     
     
       9. A dispenser as recited in claim 8, wherein said stop mechanism is adjustable with respect to said perforating mechanism so that said knife and said roller may be stopped while the perforations last-produced in the web by cutting edge are either inside or outside the dispenser. .Iadd. 10. In a dispenser for flexible sheet material including, a chassis adapted to be attached to a wall, means operatively connected to said chassis for rotatably supporting a roll of flexible sheet material, means operatively connected to said chassis for guiding a web of flexible sheet material from said roll to a position to be grasped by a user so that the user may pull the web out of the dispenser, a perforating mechanism operatively connected to said chassis for perforating said web at intervals therealong to divide the web into individual sheets, said perforating mechanism including a rotatably mounted knife-receiving roller, a rotatably mounted knife positioned adjacent said knife-receiving roller and having a radially outward portion defining a cutting edge for perforating the web as the web passes between the knife-receiving roller and the knife, said knife-receiving roller being operatively connected to said knife for synchronous rotation therewith and having a slot therein for receiving said radially outward knife portion as the knife rotates past the roller, and a stop mechanism associated with said perforating mechanism for stopping the rotation of said knife and said roller and thus arresting the movement of the web after a predetermined length of the web has been withdrawn from the dispenser; the improvement wherein said guiding means comprises a rotatably mounted upper pinch roll positioned adjacent said knife-receiving roller and spaced from said knife in the direction opposite to the normal direction of movement of the web through the dispenser, a rotatably mounted lower pinch roll positioned adjacent said knife-receiving roller and spaced from said knife in the direction of the normal direction of movement of the web through the dispenser, said lower pinch roll also being movable toward and away from said knife-receiving roller, and biasing means for urging said lower pinch roll toward said knife-receiving roller, whereby the lower pinch roll moves away from said knife-receiving roller against the urging of the biasing means when a user initially pulls on the web so that the web is pulled tautly against the knife-receiving roller, and the upper and lower pinch rolls cooperate with the knife-receiving roller when the knife and knife-receiving roller are rotated to insure that the web is held tautly about the knife-receiving roller. .Iaddend..Iadd. 11. A dispenser as recited in claim 10 wherein said upper pinch roll also is movable toward and away from said knife-receiving roller and wherein the dispenser further comprises an additional biasing means for urging said upper pinch roll toward said knife-receiving roller. .Iaddend.