Electrode-shunting method of producing electrophotographic pictures and apparatus therefor

Claim 3

Method according to claim 1 characterized by the fact that step c, the exposing of the photoconductive layer, is effected with a color separation of the master, and the toner brought into said space in step (b) is suitably adapted to the color separation, whereby a partial color image of the master is produced.

Claim 4

Method according to claim 2, characterized by the fact that by repetition of steps (b) through (e) with a plurality of successive discrete color separations and respective toners adapted thereto, successive partial color images are formed on the same image support, a full color image being produced by superimposing the successive partial color images.

Claim 5

method according to claim 3, characterized by the fact that for each color separation a toner of complementary color to same is used in the related step (b).

Claim 6

Method according to claim 3, characterized by the fact that first of all a yellow partial color image is produced and then a magenta partial color image and finally a cyan color partial image, these color partial images being superimposed on each other on the same support.

Claim 7

Method according to claim 3, characterized by the fact that, as a further step f, each partial image produced on the support is dried on its surface and preferably after removal of excessive toner as an intervening step (e), the same support then being used in a further cycle of steps (b) through (f) for the production of another partial image until a full color image is obtained.

Claim 8

Method according to claim 1, characterized by the fact that the polarity of said electrode associated with the photoconductive layer is opposite the polarity of said charged toner particles brought into said space, whereby, in the case of a positive master, a positive image is produced, and in the case of a negative master, a negative image is produced.

Claim 9

Method according to claim 1, characterized by the fact that the polarity of said electrode associated with the photoconductive layer is the same as the polarity of the toner particles brought into said space, whereby, in the case of a positive master, a negatige image is produced, and in the case of a negative master, a positive image is produced.

Claim 10

Method according to claim 1, characterized by the fact that paper is used as support for the image.

Claim 11

Method according to claim 1, characterized by the fact that plastic is used for the support for the image.

Claim 12

Method according to claim 1, characterized by the fact that glass is used as support for the image.

Claim 13

Method according to claim 1, characterized by the fact that metal is used as support for the image.

Claim 14

Method according to claim 1, characterized by the fact that textile material is used as support for the image.

Claim 15

Method according to claim 1, characterized by the fact that the support for the image is wetted before the introduction of the toner into said space.

Claim 16

Method according to claim 14, characterized by the fact that said toner particles are dispersed in a discrete solvent and further including the step of wetting the support with a wetting liquid of the same type as the solvent of the toner before said image support comes into contact with the toner.

Claim 17

Method according to claim 1, characterized by the fact that, as a further step (f), the support bearing the image is coated in a thin layer, preferably after prior drying as an intervening step (e), with an agent increasing the transparency and durability of the image.

Claim 18

Method according to claim 16, wherein the said agent is taken from the group consisting of lacquers, resins, low-melting polymers, and waxes.

Claim 19

In an electrophotographic apparatus having imaging means (12) including a light path (17) for forming a light image of a master (11); a first electrode (1) and a second electrode (5) spaced therefrom; and a voltage source (14); the combination of a switch (13) having two positions, said electrodes being connected across said voltage source with the switch in one position and connected to each other with the switch in the other position, a photoconductive layer (4) associated with said first electrode (1) and adapted to form a conductivity image corresponding to the master upon exposure of said layer (4) to said light image, an image support (6) arranged on the second electrode (5), and a fluid (8) having charged toner particles dispersed therein and being located in the space (7) between the two electrodes, said charged toner particles undergoing a an initial migration in a first direction in response to placing the switch in said one position during at least a part of said exposure of the photoconductive layer to the light image and undergoing a further migration in response to subsequent placing of the switch in a second direction in said other position, whereby a toned image is formed on said image support.

Claim 20

In an electrophotographic apparatus having imaging means (12) including a light path (17) for forming a light image of a master (11); a first electrode (1) and a second electrode (5) spaced therefrom; and a voltage source (14); the combination of a switch (13) having two positions, said electrodes being connected across said voltage source with the switch in one position and connected to each other with the switch in the other position, a photoconductive layer (4) associated with said first electrode (1) and adapted to form a conductivity image corresponding to the master upon exposure of said layer (4) to said light image, an image support (6) arranged on the second electrode (5), and a fluid (8) having charged toner particles dispersed therein and being located in the space (7) between the two electrodes, said charged toner particles undergoing a an initial migration in a first direction in response to placing the switch in said one position during at least a part of said exposure of the photoconductive layer to the light image and undergoing a further migration in response to subsequent placing of the switch in a second direction in said other position, whereby a toned image is formed on said image support.

Claim 21

Apparatus according to claim 18, characterized by imaging means (12) having a shutter (16) settable to given exposure times.

Claim 22

Apparatus according to claim 18, characterized by color filters (18, 19, 20) selectably insertable into said light path (17).

Claim 23

Apparatus according to claim 20, characterized by said color filters being color separation filters such as red L599, violet U438, green U525.

Claim 24

Apparatus according to claim 18, characterized by a gray filter (21) selectably insertable in said light path (17).

Claim 25

Apparatus according to claim 18, characterized by a mirror (22) which deflects said light path (17) towards the photoconductive layer (4).

Claim 26

Apparatus according to claim 18, characterized by said first electrode (1) being a transparent conductive layer (3) applied to a glass plate (2).

Claim 27

Apparatus according to claim 24, characterized by a layer (3) of tin oxide as electrode (1).

Claim 28

Apparatus according to claim 18, characterized by the photoconductive layer (4) being applied over a transparent electrode (1).

Claim 29

Apparatus according to claim 18, characterized by second electrode (5) being arranged equidistant from the first electrode (1), said first electrode (1) having the photoconductive layer (4) arranged thereon.

Claim 30

Apparatus according to claim 18, wherein the photoconductive layer (4) has a surface facing the support (6) and the support (6) has a surface facing the photoconductive layer (4), and characterized by a distance d of less than 2 mm between said facing surfaces.

Claim 31

Apparatus according to claim 18, characterized by an arrangement of the first and second electrodes (1, 5) such that they are movable with respect to each other.

Claim 32

Apparatus according to claim 29, characterized by the fact that the movability is limited by an adjustable stop (31).

Claim 33

Apparatus according to claim 18, characterized by an arrangement of photoconductive layer (4) and second electrode (5) such that they are movable with respect to each other.

Claim 34

Apparatus according to claim 18, wherein a displaceable holding device (26) receives image support (6) and second electrode (5), and further including guide means (27) for the displacement thereof.

Claim 35

Apparatus according to claim 18, characterized by a loading device (32) for loading the second electrode (5) with a support (6).

Claim 36

Apparatus according to claim 18, characterized by a wetting device (37) for the support (6), said wetting device being movable relative thereto during production of an image.

Claim 37

Apparatus according to claim 18, characterized by a toner feed device (46) for the feeding of at least one toner fluid (8 or 48'', 4848'''''') into the space (7) between the two electrodes (1, 5).

Claim 38

Apparatus according to claim 18, characterized by a holding device (26) for the second electrode (5), said holding device being movably supported.

Claim 39

Apparatus according to claim 18, characterized by means (61, 62) which serve to clean the photoconductive layer (4) after said further migration of toner particles.

Claim 40

Apparatus according to claim 37, wherEin said means to clean the photoconductive layer (4) comprises a wiper (61) and a roller (62).

Claim 41

Apparatus according to claim 56, characterized by a cleaning device (18) for removing excess toner on the image support (6).

Claim 42

Apparatus according to claim 39, wherein said cleaning device (56) includes a shiftable roller, and characterized by the fact that a cleaning roller (62) is moved in a path past the photoconductive layer (4) for cleaning thereof, and the cleaning device (56) is arranged in the path of said cleaning roller (62) such that upon passage of the cleaning roller (62) past the cleaning device (56) the shiftable roller (58) thereof is shifted to a position such that it is touched by the passing cleaning roller (62) and thereby stripped of adhering toner.

Claim 43

Apparatus according to claim 18, characterized by a drying device (57) for at least drying the surface of an image on support (6).

Claim 44

Apparatus according to claim 18, characterized by a control device for at least partially automatic control of the course of image production.

Claim 45

Apparatus according to claim 18, characterized by presence of a protective layer on photoconductive layer (4), said protective layer being of material more wear resistant than the photoconductive layer, said material being taken from the group consisting of Teflon, SiO2 and silicon nitride.

Claim 46

The herein-described electrophotograph obtained by a. providing a photoconductive layer spaced from an image support adjacent thereto, and electrodes respectively associated therewith, b. bringing a dispersion of charged toner particles into the space between said layer and said support, while shunting the electrodes, c. exposing the photoconductive layer to a light image of the master, thereby producing with respect to said layer, a conductivity image corresponding to the master, d. applying an electric field across said space by means including the electrodes during at least part of the exposure, said field causing migration of the charged toner particles in a first direction with change of toner particle charge as controlled by said conductivity image, and e. again shunting the electrodes, whereby a further migration of toner particles occurs in a second direction to form a visible image of the master on the image support, and f. fixing said visible image on said image support.

Claim 47

The herein-described electrophotograph obtained by a. providing a photoconductive layer spaced from an image support adjacent thereto, and electrodes respectively associated therewith, b. bringing a dispersion of charged toner particles into the space between said layer and said support, while shunting the electrodes, c. exposing the photoconductive layer to a light image of the master, thereby producing with respect to said layer, a conductivity image corresponding to the master, d. applying an electric field across said space by means including the electrodes during at least part of the exposure, said field causing migration of the charged toner particles in a first direction with change of toner particle charge as controlled by said conductivity image, and e. again shunting the electrodes, whereby a further migration of toner particles occurs in a second direction to form a visible image of the master on the image support, and f. fixing said visible image on said image support.

Claim 48

The electrophotograph of claim 44, wherein a full color image is obtained by repetitive cycling of steps b through e with the same image support, a discrete color separation being provided in step (c) of each cycle, and a respective toner adapted thereto being used in step b of the related cycle, thereby forming partial color images superimposed on the image support to yield the desired full color image.