Electrostatic copying apparatus

A cutting apparatus for use in cutting copying paper sheets from a roll of copying paper in an electrostatic copying apparatus of the type including means for feeding copying paper along a copying paper path, a moving member moving along an exposure path during exposure of an original document to be copied, and a pivotally mounted paper cut detecting member positioned along the path of the moving member to be pivoted thereby to an actuated position, said cutting apparatus comprising:

• a fixed blade immovably mounted on a frame, said fixed blade having a longitudinally straight cutting edge;
• a rotary shaft mounted for rotation on said frame;
• a rotary blade fixed to and carried by said rotary shaft for rotation therewith, said rotary blade having a spirally curved cutting edge adapted to cooperate with said straight cutting edge of said fixed blade to cut a copying paper sheet;
• a boss member fixed to said rotary shaft;
• a gear rotatably mounted about said rotary shaft, said gear rotating continuously during operation of the copying apparatus, said gear having a boss directed toward said boss member;
• a ratchet wheel mounted about said boss member and said boss;
• a spring positioned inwardly of said ratchet wheel and surrounding said boss member and said boss, said spring having a first end connected to said boss member and a second end connected to said ratchet wheel, said spring being wound to tighten in a rotating direction on said boss member and said boss;
• said ratchet wheel having extending from diametrically opposite positions of the perphery thereof a control tooth and a rotation lock tooth;
• a double cog member having a control cog and a rotation lock cog, said double cog member being mounted on said frame for pivotal movement between a first position, at which said control cog engages said control tooth thereby preventing tightening of said spring, and a second position, at which said control cog is out of engagement with said control tooth, thereby enabling said spring to tighten and transmit rotation of said gear to said rotary shaft and said rotary blade, and at which said rotation lock cog engages said rotation lock tooth after a predetermined rotation of said rotary blade and to prevent further rotation thereof;
• the length by which said rotation lock tooth extends from the periphery of said ratchet wheel being greater than the length by which said control cog extends from said periphery, thus ensuring engagement of said rotation lock tooth by said rotation lock cog;
• an inclinable member mounted on said frame and adapted to be moved to a pivoted position by the paper cut detecting member upon movement thereof to the actuated position thereof;
• and
• said double cog member having contact means, contacted upon movement of said inclinable member to said pivoted position thereof, for enabling pivoting of said double cog member from said first position thereof to said second position thereof.