Copying machines of the variable magnifying power type

Claim 2

In a copying machine of the type comprising an original supporting member adapted to support an original and a variable magnifying power type optical system including a projection lens for projecting the light image of said original and a reflective mirror located in the path of said light image, said projection lens and said reflective mirror being adjustable in a direction parallel with said original supporting member, the improvement which comprises means for feeding a photosensitive paper into the projection field of said optical system, and a photosensitive paper positioning member interlocked with said optical system through interlocking means for arresting said photosensitive paper at a predetermined exposure position in said projection field in accordance with a given magnifying power.

Claim 3

The copying machine according to claim 1 wherein said interlocking means comprises a plate cam movable with said projection lens, a follower operated by said plate cam, and an endless cord driven by said follower and connected to said photosensitive paper positioning member.

Claim 4

The copying machine according to claim 1 wherein said photosensitive paper positioning member includes a threaded rod connected to said projecting lens through said interlocking means, a manually operable nut mating with said threaded rod for adjusting the position of said photosensitive paper positioning member relative to said projection field, and means for guiding the movement of said photosensitive paper positioning member.

Claim 5

The copying machine according to claim 3 wherein said photosensitive paper positioning means further comprises an endless belt conveyor encircling said photosensitive positioning member and adapted to convey a photosensitive paper thereto, and a microswitch having an operating handle positioned in the path of said photosensitive paper for stopping the running of said endless conveyor belt when said operating handle is engaged with the leading edge of said photosensitive paper.

Claim 6

The copying machine according to claim 1 which further comprises a source of light for illuminating said original to form said light image and means interlocked with said optical system for varying the intensity of the light emanated by said source of light in accordance with the variation of the magnifying power.

Claim 7

The copying machine according to claim 5 wherein said means for varying the intensity of the light emanated by the source of light comprises a variable resistor connected in series therewith and means responsive to the movement of said projecting lens for varying said variable resistor.

Claim 8

The copying machine according to claim 1 which further comprises indicating means interlocked with said optical system for indicating a selected magnifying power.

Claim 9

The copying machine according to claim 1 which further comprises: black frame eliminating means including means for exposing to light the portions of said photosensitive paper located on the edge portions thereof for discharging said electrostatic charge from said portions thus retaining the electrostatic charge only in a predetermined area of said photosensitive paper upon which said light image is to be projected by said optical system.

Claim 10

In an electrophotographic copying machine of the type comprising an original supporting member adapted to suPport an original, a variable magnifying power type optical system including a projection lens for projecting the light image of said original and a reflective mirror located in the path of said light image, said projection lens and said reflective mirror being adjustable in the direction parallel with said original supporting member, means for depositing an electrostatic charge on the surface of an insulative paper thus sensitizing the same, means for conveying the photosensitive paper thus sensitized into a photosensitive paper positioning station in the projection field of said optical system, the improvement which comprises: black frame eliminating means including means for exposing to light the portions of said photosensitive paper located on the edge portions thereof for discharging said electrostatic charge from said portions thus retaining the electrostatic charge only in a predetermined area of said photosensitive paper upon which said light image is to be projected by said optical system, said black frame eliminating means comprising a casing, a first exposure unit including a first light source contained in said casing and a pair of spaced windows provided through a slide wall of said casing at portions corresponding to both side edges of said photosensitive paper, shutter means interlocked with said variable magnifying type optical system for varying the effective areas of said windows in accordance with a selected magnifying power, and a second exposure unit including a second light source contained in said casing and an elongated window formed through a side wall of said casing and having a width substantially equal to that of said photosensitive paper, said second exposure unit being operated so as to discharge the electrostatic charge on the upper edge of said photosensitive paper when it is maintained at a predetermined position in said photosensitive paper positioning station.

Claim 11

In an electrophotographic copying machine of the type comprising an original supporting member adapted to suPport an original, a variable magnifying power type optical system including a projection lens for projecting the light image of said original and a reflective mirror located in the path of said light image, said projection lens and said reflective mirror being adjustable in the direction parallel with said original supporting member, means for depositing an electrostatic charge on the surface of an insulative paper thus sensitizing the same, means for conveying the photosensitive paper thus sensitized into a photosensitive paper positioning station in the projection field of said optical system, the improvement which comprises: black frame eliminating means including means for exposing to light the portions of said photosensitive paper located on the edge portions thereof for discharging said electrostatic charge from said portions thus retaining the electrostatic charge only in a predetermined area of said photosensitive paper upon which said light image is to be projected by said optical system, said black frame eliminating means comprising a casing, a first exposure unit including a first light source contained in said casing and a pair of spaced windows provided through a slide wall of said casing at portions corresponding to both side edges of said photosensitive paper, shutter means interlocked with said variable magnifying type optical system for varying the effective areas of said windows in accordance with a selected magnifying power, and a second exposure unit including a second light source contained in said casing and an elongated window formed through a side wall of said casing and having a width substantially equal to that of said photosensitive paper, said second exposure unit being operated so as to discharge the electrostatic charge on the upper edge of said photosensitive paper when it is maintained at a predetermined position in said photosensitive paper positioning station.

Claim 12

The copying machine according to claim 9 wherein said elongated window has a width that slightly overlaps a predetermined area of said photosensitive paper in which said light image is to be projected by said optical system.

Claim 13

The copying machine according to claim 9 wherein said first and second exposure units are contained in independent compartments.

Claim 14

The copying machine according to claim 9 wherein said first exposure unit further comprises bucky grids positioned between said first light source and said shutter means.

Claim 15

The copying machine according to claim 9 wherein said shutter means comprises a pair of shutter plates respectively positioned between said first light source and said pair of windows and means for moving said shutter plates across said windows in accordance with a selected magnifying power.

Claim 16

The copying machine according to claim 9 which further comprises means for developing an electrostatic latent image formed on the sensitized area of said photosensitive paper corresponding to the projected latent image with a toner, and means for fixing the developed tonner image.