Electrophotographic copier of transfer type

• US 3,951,540 A
• Filed: 09/25/1974
• Issued: 04/20/1976
• Est. Priority Date: 08/03/1970
• Status: Expired due to Term

• Current Assignee: Minolta Camera Kabushiki Kaisha
• Original Assignee: Minolta Camera Kabushiki Kaisha
• Inventors: Ogawa, Masaya
• Primary Examiner(s): Gonzales, John
• Application Number:
  US05/509,180
• Time in Patent Office: 573 Days
• Field of Search: 355/8, 355/65, 355/66
• US Class Current: 399/212
• CPC Class Codes: G03G 15/283 using a reusable recording medium in form of a band
• CPC Class Codes: G03G 15/30 in which projection is formed on a drum
• CPC Class Codes: G03G 21/0035 using a brush; Details of cleaning brushes, e.g. fibre density G03G21/0064 takes precedence; magnetic brushes G03G21/0047
• CPC Class Codes: G03G 2221/0005 Cleaning of residual toner

Abstract

An exposure optical system for continuously projecting the image of an original on a document table onto a moving photoreceptor includes a first carriage equipped with document illuminating means to be moved in synchronism with the photoreceptor and a second carriage to be moved at half the speed of the first carriage in operative relation thereto by a rotary member and equipped with a reflecting optical system. Thus the reciprocal movement of the carriages is effected with a simple mechanism to greatly reduce the space occupied by the exposure optical system and thereby provide a compact copier. Paper feed means includes a mechanism for temporarily interrupting the feed of paper and then intermittently sending out the paper to an image transfer station in synchronism with the movement of the photoreceptor. In order to rotate an endless support of the photoreceptor one turn more than the preset number of copies to be made, the switches of a program circuit for controlling the respective operations are opened and closed by a control member rotated in synchronism with the endless support.

Claims

1. An electrophotographic copier of the transfer type comprising:

a document table made of a transparent plate;

an exposure optical system of the slit scanning type having means for scanning the surface of an original document disposed below said document table and movable in parallel with said document table;

an endless support supporting a photoreceptor and disposed below said exposure optical system and movable at a constant peripheral speed;

an image forming and copying assembly disposed around said endless support including means for charging said photoreceptor composed of a corona discharger, an exposure window positioned at the terminal end of the light path of said exposure optical system for exposing the charged photoreceptor to produce an electrostatic latent image, developing means for visualizing electrostatic latent image with a toner transfer means for transferring the powder image onto copy paper, and cleaner means for cleaning the surface of said photoreceptor;

a copy paper supply station including paper supply roller means for dispensing sheets of paper to be made into final copies, paper feed means for feeding the dispensed paper to said transfer means, conveyor means for discharging transferred paper out of said copier, and means disposed over the transport path of said conveyor means for heat-fixing the toner image on said transferred paper;

a control member disposed in the interior of said copier and rotatable in a predetermined synchronous relation with said endless support in synchronism therewith; and

means including a program circuit for controlling the operation for a selective pre-selected number of copying cycles of said copier, and characterized in that;

said scanning means includes a first carriage synchronously driven in a predetermined relation to the moving speed of a photoreceptor support and a second carriage driven at half the speed of said first carriage, said first carriage being provided with a document illuminating system and a plane mirror for directing the image of the document to a plane mirror on said second carriage, said second carriage being provided with at least one plane mirror for reflecting the image of the original reflected by said plane mirror on said first carriage toward a projecting lens, the length of the light path from the surface of the document to said projecting lens being kept constant irrespective of the position of said first carriage; and

said scanning means includes guide rails parallel to said document table, a roller rotatably mounted on said second carriage and rolling along said guide rails and said first carriage rests on said roller rolling on said guide rails, said first carriage and said second carriage being moved in operative relation at a speed ration of 11/2 .

2. An electrophotographic copier of the transfer type comprising:

a document table made of a transparent plate;

an exposure optical system of the slit scanning type having means for scanning the surface of an original document disposed below said document table and movable in parallel with said document table;

an endless support supporting a photoreceptor and disposed below said exposure optical system and movable at a constant peripheral speed;

an image forming and copying assembly disposed around said endless support including means for charging said photoreceptor composed of a corona discharger, an exposure window positioned at the terminal end of the light path of said exposure optical system for exposing the charged photoreceptor to produce an electrostatic latent image, developing means for visualizing the electrostatic latent image with a toner, transfer means for transferring the powder image onto copy paper, and cleaner means for cleaning the surface of said photoreceptor;

a copy paper supply station including paper supply roller means for dispensing sheets of paper, paper feed means for feeding the dispensed paper to said transfer means, conveyor means for discharging transferred paper out of said copier, and means disposed over the transport path of said conveyor means for heat-fixing the toner image on said transferred paper;

a control member disposed in said copier and rotatable in a predetermined synchronous relation with said endless support; and

means including a program circuit for controlling the operation for a selective pre-selected number of cycle of said copier, and characterized in that;

said scanning means includes a first carriage synchronously driven in a predetermined relation to the speed of the photoreceptor support and a second carriage driven at half the speed of said first carriage, said first carriage being provided with a document illuminating system and a plane mirror for directing the image of the document to a plane mirror on said second carriage, said second carriage being provided with at least one plane mirror for reflecting the image of the original reflected by said plane mirror on said first carriage toward a projecting lens, the length of the light path from the surface of the document to said projecting lens being kept constant irrespective of the position of said first carriage; and

said scanning means includes a scanning wheel coupled with the endless support drive by way of an electromagnetic clutch and having a circumference equal to the length of said endless support, said wheel being rotatable at a peripheral speed equal to the linear speed of said support, interconnecting belts extending from the outer periphery of said wheel to said first carriage for advancing said first carriage in forward and reverse directions respectively, and a wind-up spring wound up when said wheel is driven in a forward direction, and said carriages are forwardly advanced by the forward rotation of said wheel and actuate a switch for disengaging said electromagnetic clutch upon completion of said forward travel, whereupon said wheel is reversed to return said carriages under the restoring action of said spring.

3. An electrophotographic copier of the transfer type comprising:

a document table made of a transparent plate;

an exposure optical system of the slit scanning type having means for scanning the surface of an original document disposed below said document table and movable in parallel with said document table;

an endless support supporting a photoreceptor and disposed below said exposure optical system and movable at a constant peripheral speed;

an image forming and copying assembly disposed around said endless support including means for charging said photoreceptor composed of a corona discharger, an exposure window positioned at the terminal end of the light path of said exposure optical system for exposing the charged photoreceptor to produce an electrostatic latent image, developing means for visualizing the electrostatic latent image with a toner, transfer means for transferring the powder image onto copy paper, and cleaner means for cleaning the surface of said photoreceptor;

a copy paper supply station including paper supply roller means for dispensing sheets of copy paper, paper feed means for feeding the dispensed paper to said transfer means, conveyor means for discharging transferred paper out of said copier, and means disposed over the transport path of said conveyor means for heat-fixing the toner image on said transferred paper;

a control member disposed in said copier and rotatable in a predetermined synchronous relation with said endless support; and

means including a program circuit for controlling the operation for a selective pre-selected number of cycles of said copier, and characterized in that;

said scanning means includes a first carriage synchronously driven in a predetermined relation to the speed of the photoreceptor support and a second carriage driven at half the speed of said first carriage, said first carriage being provided with a document illuminating system and a plane mirror for directing the image of the document to a plane mirror on said second carriage, said second carriage being provided with at least one plane mirror for reflecting the image of the original reflected by said plane mirror on said first carriage toward a projecting lens, the length of the light path from the surface of the document to said projecting lens being kept constant irrespective of the position of said first carriage; and

said scanning means includes a member rotatable in synchronism with the movement of said carriages, a shock absorbing mechanism functioning at the terminal position of return travel of said first and second carriages, said shock absorbing mechanism comprising a pin mounted on said rotatable member, a rotary plate having a recess for releasably engaging said pin, an extendable arm having one end pivoted to said rotary plate and the other end supported on a fixed pin and a spring coupled to said arm so as to exert a shock absorbing action on said rotary plate simultaneously with the engagement of said pin by said recess.

4. An electrophotographic copier of the slit exposure type for forming an electrostatic image of an original document on a moving member comprising:

a scanning means for projecting an image of the original onto said moving member including a first carriage synchronously driven in a predetermined relation to the moving speed of said moving member and a second carriage driven at half the speed of said first carriage, said first carriage being provided with an original illuminating system and a mirror for directing the image of the original to said second carriage provided with at least one mirror for reflecting the image of the original reflected by said mirror on said first carriage toward a projecting lens, the length of the light path from the original to said projecting lens being kept constant irrespective of the position of said first carriage; and

said scanning means further including guide rails parallel to the movement of said first and second carriages and a rotatory member rotatably mounted on said second carriage and rolling along said guide rails, said first carriage resting on said rotatory member rolling on said guide rails, said first and second carriages being moved in operative relation at a speed ratio of 11/2.

5. An electrophotographic copier of the slit exposure type for forming an electrostatic image of an original document on a moving member comprising:

a scanning means for projecting an image of the original onto said moving member including a first carriage synchronously driven in a predetermined relation to the moving speed of said moving member and a second carriage driven at half the speed of said first carriage, said first carriage being provided with an original illuminating system and a mirror for directing the image of the original to said second carriage provided with at least one mirror for reflecting the image of the original reflected by said mirror on said first carriage toward a projecting lens, the length of the light path from the original to said projecting lens being kept constant irrespective of the position of said first carriage; and

said scanning means further including a first and second guide rail parallel to the movement of said first and second carriages with the first rail mounted on said first carriage and the second rail supporting said second carriage, a rotatory member rotatably mounted between said first and second rails and rotatable with respect to the movement of said first rail, the ratio of the movement speed of said first rail to that of said rotatory member being 11/2 so that said first and second carriages are moved in operative relation at a speed ratio of 11/2.