Motion picture projector

Claim 2

In a motion picture projector having film threading and forward projection modes, means defining a film path, a projection gate located along the film path, and means for advancing the leading end of a filmstrip introduced into the projection gate along the film threading path when the projector is in its film threading mode, a rotary drive sprocket wheel located along the film path subsequent to the projection gate for moving the film along the film path in a direction from the projection gate to said drive sprocket wheel when the projector is in its forward projection mode and a film guide member movable between a first position between the film threading Path and said sprocket wheel to prevent film in the film threading path from contacting said sprocket wheel and a second position remote from the film path to permit the film in the film path to be engaged by said sprocket sheet, the improvement comprising: means for holding said film guide member in its first position, said holding means comprising (1) first and second members coupled together to permit at least limited movement of said guide member toward and away from its second position when it is in its first position, and (2) a spring coupled to said guide member and urging said member away from its second position and toward its first position; sensing means for detecting the presence of film along the film path subsequent to said drive sprocket wheel, said sensing means including an electrical switch and means for actuating said switch in response to movement of said film guide member against the spring force; and means responsive to the detection of film by said sensing means for moving said film guide member from its first toward its second position.

Claim 3

A motion picture projector as defined in claim 1 wherein said means for holding said film guide member in its first position includes an electromechanical device selectively energizable through said switch.

Claim 4

A motion picture projector having a film threading path, a projection gate, and an intermittently operated film feeding member adjacent the projection gate for advancing film through the gate in forward and reverse directions, said projector comprising: a rotary drive sprocket wheel located along the film threading path subsequent to the projection gate for moving the film along the film path in a direction from the projection gate to said sprocket wheel when film is being intermittently advanced through the gate in a forward direction; means for preventing the film from contacting said sprocket wheel when the film is being intermittently advanced through the gate in a reverse direction; a movable snubber member adapted to engage at least one surface of the reach of film extending between the projection gate and said sprocket wheel, said snubber member being mounted for movement transversely of the reach of film it engages from a first position, wherein said snubber forms a loop of film between the gate and said sprocket wheel equal to at least one frame length of the film when the film feeding member is not advancing film to (1) a second position, to which it is moved by the reach of film it engages in response to operation of the intermittent film feeding member to advance film through the gate in a reverse direction by one frame and to correspondingly foreshorten said film loop and (2) a third position out of engagement with the film; a spring normally urging said snubber member to said first position, said spring being sufficiently stiff so that said snubber normally oscillates at a normal frequency corresponding to the frequency of the intermittent film feeding member, over a path of a length corresponding to the advancement of one frame length of the film; and means for moving said snubber member to its third position when the film is being intermittently advanced through the gate in a forward direction.

Claim 5

A motion picture projector having a film threading path, a projection gate, and an intermittently operated film feeding member adjacent the projection gate for advancing film through the gate in forward and reverse directions, said projector comprising: a rotary drive sprocket wheel located along the film threading path subsequent to the projection gate for moving the film along the film path in a direction from the projection gate to said sprocket wheel when film is being intermittently advanced through the gate in a forward direction; means for preventing the film from contacting said sprocket wheel when the film is being intermittently advanced through the gate in a reverse direction; a movable snubber member adapted to engage at least one surface of the reach of film extending between the projection gate and said sprocket wheel, said snubber member being mounted for movement transversely of the reach of film it engages from a first position, wherein said snubber forms a loop of film between the gate and said sprocket wheel equal to at least one frame length of the film when the film feeding member is not advancing film to (1) a second position, to which it is moved by the reach of film it engages in response to operation of the intermittent film feeding member to advance film through the gate in a reverse direction by one frame and to correspondingly foreshorten said film loop and (2) a third position out of engagement with the film; a spring normally urging said snubber member to said first position, said spring being sufficiently stiff so that said snubber normally oscillates at a normal frequency corresponding to the frequency of the intermittent film feeding member, over a path of a length corresponding to the advancement of one frame length of the film; and means for moving said snubber member to its third position when the film is being intermittently advanced through the gate in a forward direction.

Claim 6

A motion picture projector having film threading and forward projection modes, a projection gate, and means for advancing the leading end of a filmstrip introduced into the projection gate along a film threading path when the projector is in its film threading mode, said projector comprising: a rotatable shaft mounted adjacent said film path subsequent to the projection gate; drive means for rotating said shaft; a sprocket wheel mounted on said shaft for rotation therewith said wheel being positioned with respect to the film path for moving the film along the film path in a direction from the projection gate to said sprocket wheel when the projector is in its forward projection mode; sensing means for detecting the pResence of film along the threading path subsequent to said sprocket wheel; a film guide member rotatably mounted on said shaft and movable between a first position between the film threading path and said sprocket wheel to prevent film in the film threading path from contacting said sprocket wheel and a second position remote from the film path to permit the film in the film path to be engaged by said sprocket wheel; a pair of engageable clutch parts; means interconnecting one of said clutch parts and said shaft; means interconnecting the other of said clutch parts and said guide member for moving said guide member between its first and second positions upon engagement of said clutch parts; and means responsive to the detection of film by said sensing means for engaging said clutch to move said guide member to its second position.

Claim 7

A motion picture projector having film threading and forward projection modes, a projection gate, and means for advancing the leading end of a filmstrip introduced into the projection gate along a film threading path when the projector is in its film threading mode, said projector comprising: a rotatable shaft mounted adjacent said film path subsequent to the projection gate; drive means for rotating said shaft; a sprocket wheel mounted on said shaft for rotation therewith said wheel being positioned with respect to the film path for moving the film along the film path in a direction from the projection gate to said sprocket wheel when the projector is in its forward projection mode; sensing means for detecting the pResence of film along the threading path subsequent to said sprocket wheel; a film guide member rotatably mounted on said shaft and movable between a first position between the film threading path and said sprocket wheel to prevent film in the film threading path from contacting said sprocket wheel and a second position remote from the film path to permit the film in the film path to be engaged by said sprocket wheel; a pair of engageable clutch parts; means interconnecting one of said clutch parts and said shaft; means interconnecting the other of said clutch parts and said guide member for moving said guide member between its first and second positions upon engagement of said clutch parts; and means responsive to the detection of film by said sensing means for engaging said clutch to move said guide member to its second position.

Claim 8

A motion picture projector as defined in claim 4 wherein said means interconnecting said other clutch part and said guide member comprises: a rotatable cam member coupled to said other clutch part; a movable lever; a cam follower on said lever adjacent said cam member; a spring biasing said cam follower into engagement with said cam member; and means interconnecting said lever and said guide member for simultaneous movement.

Claim 9

A motion picture projector as defined in claim 5 wherein said interconnecting means comprises: a pinion coupled to said guide member concentric with said shaft; and a rack on said lever in meshing engagement with said pinion.

Claim 10

A motion picture projector as defined in claim 6 wherein: said pinion is movable at least a slight distance relative to said rack at least when said guide member is in its first position; and said sensing means includes (1) means for moving said guide member and said pinion relative to said lever and said rack in response to the presence of film along the threading path subsequent to said sprocket wheel, and (2) means for detecting such movement of said guide member.

Claim 11

A motion picture projector as defined in claim 7 wherein said means for engaging said clutch parts comprises an electromechanical device actuatable in response to the detection of movement of said guide member by said sensing means.

Claim 12

A motion picture projector having film threading and forward projection modes, a projection gate, and means for advancing the leading end of a perforated filmstrip introduced into the projection gate along a film threading path when the projector is in its film threading mode, said projector comprising: a rotary drive sprocket wheel located along the film path subsequent to the projection gate for moving the film along the film path in a direction from the projection gate to said sprocket wheel when the projector is in its forward projection mode; a movable loop former adapted to engage one surface of the reach of film extending between the projection gate and said sprocket wheel, said loop former being mounted for movement transversely of the reach of film it engages from (1) a first position, wherein said loop former forms a predetermined size loop of film between the gate and said sprocket wheel, to (2) a second position spaced from the film path, whereby the film may take a shorter path between the projection gate and said sprocket wheel; means for holding said loop former in its first position when the projector is in its threading mode; a film guide member movable between a first position between the film threading path and said sprocket wheel to prevent film from contacting said sprocket wheel and a second position remote from the film path to permit the film to be engaged by said sprocket wheel; means for holding said film guide member in its first position; sensing means for detecting the presence of film along the threading path subsequent to said drive sprocket wheel; means responsive to the detection of film by said sensing means for moving said film guIde member from its first to its second position; and means for moving said loop former from its first to its second position as said guide member is moved from its first to its second position, whereby the reach of film extending between the projection gate and said sprocket wheel will be shortened as the film closes upon said sprocket wheel, thereby effecting relative motion between the film and the sprocket wheel to insure proper alignment of the sprocket teeth and the film perforations.

Claim 13

A motion picture projector having film threading and forward projection modes, a projection gate, and means for advancing the leading end of a perforated filmstrip introduced into the projection gate along a film threading path when the projector is in its film threading mode, said projector comprising: a rotary drive sprocket wheel located along the film path subsequent to the projection gate for moving the film along the film path in a direction from the projection gate to said sprocket wheel when the projector is in its forward projection mode; a movable loop former adapted to engage one surface of the reach of film extending between the projection gate and said sprocket wheel, said loop former being mounted for movement transversely of the reach of film it engages from (1) a first position, wherein said loop former forms a predetermined size loop of film between the gate and said sprocket wheel, to (2) a second position spaced from the film path, whereby the film may take a shorter path between the projection gate and said sprocket wheel; means for holding said loop former in its first position when the projector is in its threading mode; a film guide member movable between a first position between the film threading path and said sprocket wheel to prevent film from contacting said sprocket wheel and a second position remote from the film path to permit the film to be engaged by said sprocket wheel; means for holding said film guide member in its first position; sensing means for detecting the presence of film along the threading path subsequent to said drive sprocket wheel; means responsive to the detection of film by said sensing means for moving said film guIde member from its first to its second position; and means for moving said loop former from its first to its second position as said guide member is moved from its first to its second position, whereby the reach of film extending between the projection gate and said sprocket wheel will be shortened as the film closes upon said sprocket wheel, thereby effecting relative motion between the film and the sprocket wheel to insure proper alignment of the sprocket teeth and the film perforations.