US3323131A

US3323131A - Image control device with means to precharge the printing gap

Info

Publication number: US3323131A
Application number: US217725A
Authority: US
Inventors: Jack E Macgriff
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-08-17
Filing date: 1962-08-17
Publication date: 1967-05-30
Anticipated expiration: 1984-05-30

Description

May 30 1957 J. E. MaCGRlr-F 3,323,131

IMAGE CONTROL DEVICE WITH MEANS TO PRECHARGE THE PRINTING GAP Filed Aug. 17, 1962v sheeLS-Sheet l`- Mull 5 El ,3c INVENTOR. Jj Jack f. nume/FF.'

yMay 30, 1967 .E. MaCGRn-F 3,323,131

IMAGE CONTROL DEVICE. WITH MEAN-S TO PRECHARGE THE PRINTING GAP:

Filed Aug. l?, 1962 .f5 Sheets-Sheet 2 INVENTOR. JAC/f E. M46 @1e/PF.

Galand, /Zmnw/ #M May 30, 1967 J. E. MaOGRlr-F 3,323,131

IMAGE CONTROL DEVICE WITH MEANS TO PRECHARGE THE PRINTING GAP Filed Aug. 17, 1962 v 5 Sheets-sheet INVENIOR. .//CA/ Mac @eff/ United States Patent O 3,323,131 IMAGE CON'IRI. DEVICE WITH MEANS T0 PRE- CHAR-GE THE PRINTING GAP Jack E. MacGriif, Redford, Mich. (17255 Lalser Road, Detroit, Mich. 48219) Fixed Ang. i7, 1962, ser. No. 217,725 6 Claims. (Cl. 346-74) This is a continuation-in-part of my co-pending application No. 693,690 filed Oct. 31, 1957 now Patent 3,056,- 136 of 1962, on an image control device and method of printing, which is a continuation-in-part of application No. 410,090 filed Feb. 15, 1954, which latter application is now abandoned. Y

This invention relates to an image control device, a method of printing,V and more particularly to a sensitive image control device responsive to variations in light intensity focused from an image and in its responses t-o such variations adapted to control the flow of electrons to form an electrostatic pattern, and for control of deposition of charged pigment particles to form a visible image.

It is the object of the present invention to provide an improved sensitive image control mechanism.

It is the further object of the present invention to provide an improved and novel image control device for forming electrostatic patterns on a moving web of image receiving material, and to further make said electrostatic patterns visible by the deposition thereon of charged particles of finely divided pigment, with the amount of deposition controlled by variations in light intensity from an image to be printed focused upon the photosensitive portion 4of the image control device.

These and other objects will be seen from the following specication and claims in conjunction with the appended drawings in which:

FIG. l is a side elevational view of an electron emission c-ontrol device.

FIG. 2 is a fragmentary plan view thereof.

FIG. 3 is a fragmentary view, si-milar to FIG. 2 showing the emission conductors extending past the end of the support.

FIG. 4 is a side elevational View of the present control device, accelerating electrode, light source and electrical connections.

FIG. 4a is a perspective view on an enlarged scale of the light shield of FIG. 4.

FIG. 5 is a side elevational view of another form of control device as a modification of FIG. 4.

FIG. 6 is a fragmentary section taken on line 6 6 of FIG. 5.

FIG. 7 is a perspective view of another form of control device.

FIGS. 8a through 8d are progressive diagrams illustrating the forming of a unilateral rectifying junction layer upon the conductors of the control device.

FIGS. 9a, 9b and 9c are respectively fragmentary elevational, plan and perspective views showing the unilateral junction layer formed `over the conductors of an image control device.

FIG. 9d shows the same layer as formed within a depressed area of the insulating base.

FIG. 10a is a fragmentary elevational view showing one of the series lof bias emission conductors overlying the conductors of an image control device fragmentarily shown.

FIG. 10b is a perspective View of the series of bias emission conductors.

FIG. 11a is similar to FIG. 10a showing one type of hot cathode type of bias e-mission conductors.

FIG. 11b is a perspective View of said type of bias emission conductors.

ICC

FIG. 12 is a fragmentary schematic side elevational view of another form of image control device.

FIGS. 13a through 13d are fragmentary plan views showing different forms of emission conductors.

FIG. 14 is a fragmentary Aperspective view of another form of emission control device.

FIGS. 15a through 15e are respectively fragmentary, plan elevational and side views of the accelerating electrode of FIG. 14.

FIG. 15d is a fragmentary plan View corresponding to FIG. 15a.

FIGS. 16a, 16b, and 16e are respectively fragmentary plan, side and front elevational views of the insulating -base and conductors shown in FIG. 14.

FIG. 17 is a schematic view of the image control device substantially as shown in FIG. 14 illustrating its mode of use for forming electrostatic images or patterns on a receiving surface and the mode of transmitting images to the light sensitive control device and for rendering said images visible. i

FIG. 18 is a fragmentary perspective and schematic view of another form of control device.

FIG. 19 is a schematic illustration similar to FIG. 17 showing another embodiment andmode of printing.

FIG. 20 is a schematic view of a wiring diagram and circuitry of a modified image control device of increased sensitivity.

FIG. 21 is a fragmentary plan View taken in the direction of the arrows Z1 in FIG. 20.

FIG. 22a is a fragmentary elevational view of the image control device shown in FIG. 20.

FIG. 22b is a fragmentary elevational view illustrating the relationship between the conductors 2 and 70 of FIG. 20. v.

FIG. 23 is a fragmentary side elevational view of a modiiication of the present control device.

FIG. 24 is a similar view of the control device of FIG. 18 with the circuits fragmentarily shown.

FIG. 25a is a fragmentary perspective view of a wedgeshape form of receiving electrode.

FIG. 25b shows the same electrode with curved receiving edge for engagement with the adjacent image web.

FIGS. 26-27 are plan, elevational views of another means of supplying a bias potential. j l

It will be understood that the above drawings illustrate merely `several preferred embodiments of the invention, and that other embodiments are contemplated Within the `scope of the claims hereafter set forth.l A' v .In my co-pending application No. 693,690, the printing apparatus has an electronic image control device as illustrated in FIGS. 1 and 2 of this'application, and generally designated at 35, which includes a non-electrically conductive insulating base 1, which may be glass, plastic, or any non-electric conducting material; and mounted thereon are a plurality of horizontally disposed parallel spaced conductors 2 arranged in a rowQTh'ese are .001 to .005 inch wide and spaced apart to 500 per lineal inch. These are secured to the base inV insulated spaced relation to each o-ther.

A light-sensitive layer 4 is mounted over conductors 2 and in contact therewith, said light-sensitve fil-m being made from selenium, for example, which has a relatively high electrical resistance and has a characteristic of changing its electrical resistance when' exposed to light;

This image control device 35 is shown in elevation on an enlarged scale in FIG. 1, whereas FIG. 2 is a fragmentary plan view thereof.' f

Mounted upon the light-sensitive layer 4 and in contact therewith is a transparent electrode layer 5, which is adapted for connection by the wire lead 30 to a suitable source of current. Mounted over the transparent electrode layer 5 and in longitudinal alignment with insulating cover 3 is a transparent protective -c-overing layer 6 to complete the image control device 35.

The transparent electrode layer 5 may be a thin evaporated transparent iilm of an electrically conductive metal such vas platinum, silver, or stannous cloride, for example. Transparent electrode layers are well known. By transparent electrode layer is meant a layer of electrode material that is transparent to the radiation of portions of the electro-magnetic spectrum extending from the infrared through the ultra-violet. Thhis electrode layer must be transparent or translucent to light so that variations in light intensity of an original image will control the electrical conductivity of the light-sensitive layer 4 in FIG. 1.

In my copending application 693,690, in order to form electrostatic patterns with the device of 35, the image 7 sought to be reproduced is affixed or otherwise secured to the outer surface of the rotatable drum 8, which has a central axis of rotation 22, such as is in FIG. 17 herein.

The light 9 upon the exterior of drum 8 illuminates a strip of image 7, and this illuminated strip or the image 19 thereof, is projected by the lens 10 through a horizontally elongated slot 28 of light shield 18, FIGS. 4 and 4a, and thence to the direction changing mirror 11.

The image 7 is thus projected through transparent cover 6, through the transparent electrode layer 5, and onto the light-sensitive layer 4 for regulating the internal resistance thereof and in turn controlling the quantity and flow of electrons through the respective conductors 2 from the current lead 29 as in FIG. 17 which is connected to the electrode layer 5. It will be understood that the mirror could be eliminated where the image line 7 is so arranged as to be focused -directly upon the light-sensitive layer, such as the image line 36, illustrated in FIG. 2 of my original co-pen-ding application, Ser. No. 693,690.

A moving web of paper or other image re-ceiving material 12 extends around and passes over the revolving drum 13, the axis of rotation of drurn 13 being parallel to the axis of rotation of drum 8.

As shown in FIG. l of my original co-pendin-g application, and as in FIG. 17 herein, in the event that a transparent image 7 is employed upon the drum 8, the light source 9 may be positioned upon the interior of drum 8, rather than the exteriorally arranged light 9, which is adapted for use in conjunction with opaque images.

In my original co-pending application, the outer ends of conductors 2, corresponding to conductor 2 herein, may extend outwardly beyond the end of the image control device 35, FIG. 1, and lie in aplane parallel to drum axis 21, the same ends of said conductors :being spaced a short distance, for example, approximately 0.001 to 0.010 inch from moving web 12, FIG. 17. There is provided a stationary electrode blade or comb 14, which has a horizontally disposed thin elec-tron receiving edge 23, Which is preferably formed with a series of longitudinally spaced comb-like projections 24, FIG. a. The number of projections per inch is the same as the number of emission conductors 2 per inch, as indicated in FIG.` 5 of my original co-pending application No. 693,690, said blade being connected to the return wire lead 31 similar to what is shown in FIG. 17, for completing the high voltage circuit. Said electrode blade 14 of FIG. 1 of my original copending application is shown on an `enlarged scale in FIG. 4 of that application and FIG. 5 is a fragmentary bottom plan view thereof showing comb-like projections 24.

In operation of my original device in application 693,- 690, light 19 from the image 7 falling upon the lightsensistive surfaceY 4 changes the electrical resistance of the photo-conductive material between the transparent electrode 5 and the individual emission conductor opposite thereof 2, permitting electrical discharge from the emission end of said conductor across the space in the direction of the receiving electrode 14.

In operation, the voltage necessary to provide said emission must be in excess of the ionization potential of the system consisting of the emission conductor 2, the receiving electrode 14, the image web 12, and the space between.

After this system Iis brought to ionization potential, voltage in excess of this level will permit discharge or liow of electrons from the emission ends of conductors 2, said excess voltage being the signal potential.

It is the object of this invention provide an improved .image control device that provides a constant bias voltage that retains the system consisting of the emission conductor 2, the receiving electrode 14, the image receiving web 12 and the space between at a level not quite equal to the ionization potential of said system, with the signal voltage corresponding to the light received from the original image 7 being in excess of this bias ionization volage.

FIGS. 1 and 2 of this application correspond to FIGS. 6 and 7 of my'original co-pending application 693,690.

FIG. 3 shows how the electron emission conductors 2 can extend past the end of the insulating supporting base 1, if desired, as shown at 58.

It is contemplated in this invention that the parallel electron emission conductors 2 Will be retained at the potential not quite equal to the ionization potential of the system previously described, said potential being supplied by an electron emission source Separate from the light-controlled photo-conductive surface Which supplies the signal potential to said emission conductors.

FIG. 4 shows such a device.

Spaced parallel emission conductors 2 are retained on an insulating non-electrically conducting base 1. A photoc-onductive layer 4 is affixed in contact with said conductors, and a transparent electrode 5 positioned over the photoconductive surface. A wire lead 30 connects said transparent electrode with a source of potential.

A layer 40 is also positioned over the conductors 2, said layer being connected through an electrode layer 41 yand a conductor 42 to a source of bias potential.

Said layer 40, while supplying bias potential to the individual insulating conductors 2, through unilateral rectifying junctions, retains said conductors 2 in insulated relation to each other.

FIG. 5 is another such device, with the photoconductive layer 4 being `affixed to one side of the conductors 2, and the bias potential unilateral rectifying junction layer 40 being applied to the other side of the conductors. This device is generally designated as 69.

A method of forming the layer upon the conductors is shown in FIGS. 7 and 8a through 8d.

In FIG. 7, the insulating base 1 has 'a depressed area on which the transparent conductor 5 is alixed. The light sensitive layer, here shown as a multiple-layer configuration p,n,p, is affixed on top of the transparent conductor, and the individual discharge conductors 2 placed on top of the light sensitive layer. FIG. 7 shows how a single or multiple-layer photo-conductive control can be devised underneath the parallel conductors 2.

FIGS. 8a through 8d show how unilateral rectifying junctions can also be positioned underneath the conductors. Photo-conductive junctions may be formed in a similar manner.

A conducting electrode 41 is positioned on top of a depressed area of the insulating base 1. A semi-conductor 40 is positioned on top of the conducting layer, with a doped surface 42. Conductors 2 are formed -on top of this surface by photo-etching as is well known in the art, and as is described in my co-pending application 693,690.

The areas 43 between the individual conductors 2 in FIG. 8b are etched out, leaving unilateral rectifying junc.- tions 42 between the semi-conductor 40 and the conductors 2.

This area 43 can be filled with an electrically insulating material, such as glass, plastic, etc., as at 44 in FIG. Sc.

A photo-sensitive layersuch as selenium, for example, can be formed over this structure as in FIG. 8d, shown at 4; the transparent conductor S, and an insulating cover 3 may be placed over that. This forms a device as is shown in FIGS. 5 and 6.

Either the light-sensitive layer, or the bias-supply layer can be formed rst, conductors formed, and the other layer applied last, depending upon the structure desired.

The bias potential supplied to the emission conductors 2 can be supplied either through a semiconducting unilateral connecting layer 40 as shown in FIGS. 4 through 8, or through a discharge potential in a vacuum.

FIGS. 9a, 9b and 9c show the unilateral layer 40 formed over the conductors 2. In FIG. 9d, this layer is formed in a depressed area in the insulating base 1.

In FIGS. 10a and 10b, a potential is connected through Wire 42 to a series of interconnected emission conductors 24, said conductors being interconnected by the strip 53. These conductors can be formed by photo-etching a continuous conducting layer on the insulating base 51, as is well known to those versed in the art.

When positioned over the electron emission conductors 2, in a vacuum, the discharge as at 57 occurs when the unit, generally indicated at 61, is properly connected to a source of potential. This is a cold'cathode device.

A hot cathode device is schematically shown in FIGS. lla and 11b, with a heater, 54, maintaining the cathode 55 at a predetermined temperature. Electron control shield 56 directs the electron emission 57 towards the electron emission conductors 2.

Such a device is lshown in FIG. 12, with the hot cathode device generally designated as 59 shown inside `a chamber 50', in which is maintained a vacuum.

The chamber 50 is sealed to the electron emission conductors 2 and insulating base 1' by the insulating iillet 65 which can be low temperature sealing glass applied as a frit and fused by heat.

The light-sensitive layer 49 shown here affixed to the transparent electrode 5, is retained in a vacuum inside transparent chamber 5t), with the discharge at 60 controlled by the light source 19. The accelerating electrodes 14 and 14' designate this device as a double-ended unit which will control the formation of two electrostatic patterns at the same time on the image transversely movable webs 12 and 12'.

The conductors 2 of the device shown in FIGS. 1, 2, 4, 5, 6, 7 and 8, have generally been designated as parallel emission conductors. These are shown in FIG. 13a. The shape of these conductors can be varied, as shown in FIGS. 13b through 13d.

The electron emission ends of the conductors are generally designated at 76, with the general designation of 80 being the photoconducting surface and the transparent electrode.

In FIG. 13b, the area under the photoconductor, generally designated at 45, is wider than the electron emission conductor 2. The distance between the emission ends of the conductor, here designated as A and B, must have the same ratio of distance as that under the photoconductor as a and b. Y

In FIG. 13C, the part of the conductor under the photosensitive surface is diamond shaped, and in FIG. 13d the emission ends of the conductors at 76 are smaller than the parts of the conductors generally designated as 47, under the light sensitive surface.

By proper design lof the emission conductors 2 in relation to the part of the conductor -under the photosensitive surface, the inter-electrode capacitance and light-sensivity of the electron emission control device can be varied. Such a device as has been described can either be a solid state semi-conducting assembly, or an electron-discharge device which operates in a vacuum.

A vacuum device, different from the one described in FIG. 12 is shown in FIG. 14. A hollow glass tube 50 is slotted. An Yinsulating non-conducting base 1 on which are aixed emission conductors 2', is positioned in the slot so that the emission ends of the conductors 2 are outside of the vacuum chamber. A series of electron emission conductors on the device generally designated at 61, Iand formerly described in FIGS. 10a and 10b, are positioned over the electron emission conductors 2 so that the emission conductors receive electrons from the device 61 which is connected through the wire 42 and the directional diode 63 to a source of potential.

A light-sensitive emission source, generally designated at 35 and described in FIGS. l and 2, is positioned with the electron emission conductors of said device respectively in contact with the conductors 2. An insulating electron shield 62 is placed between the two emission sources.

Fillets of low temperature sealing glass 65 fuse the electron emission conductor assembly to the vacuum chamber, and the interior units are positioned and affixed in a manner well known to those skilled in the art.

The transparent electrode of the device 35 is connected to a source of potental by lead 29, and the exterior accelerating electrode 14 is also connected by lead 31 as shown in the diagram FIG. 14.

In operation, light 19 fai-ling on the light-sensitive portions of the emission control 35 permits electrons to be discharged to individual emission conductors 2 depending upon where the light falls; -at the same time, lall electron emission cond-uctors 2 receive a bias potential from the device 61.

Because the signal potential from the conductors of the device 35 is in excess of that potential supplied by the device 61, individual emission conductors 2 are raised to a potential equal to the sum of the voltages supplied. Thus the emission conductors 2', the accelerating electrode generally designated at 14, and a space between are retained at the potential controlled by the device 61, with a variable signal potential supplied by the device 35 controlling the electron discharge between ends of individual emission conductors 2 and the accelerating electrode 14.

The accelerating electrode at 14 can be fashioned as shown in 15a through 15d, -with individual conductorsZS iconnected by a conducting strip 53 lphoto-etched on an insulating base 51 in a manner well known to those skilled in the art. These emission conductors can extend past the ends of the insulating base as shown in FIG. 15d, at 58. The electron emission conductors of the device shown in FIG. 14 can be fashioned in a manner well known to those skilled in the art, as shown in FIG. 16a throug-h 16C, with the conductors photo-etched, from .a conducting layer applied to a non-conducting insulating base 1.

FIG. 18 and FIG. 24 show still another -concept of the control device, with the bias voltage supplied 'by vacuum discharge from the device generally designated at 61, said discharge being shown at 59. The signal voltage is supplied through the semi-conducting photo-sensitive layer shown at 4, and the transparent electrode 5. A vacuum 64 is retained inside of the transparent housing 50. The device of FIG. 14 is shown in :operation in FIG. 17. This is similar to the device described in FIG. 1 of my original co-pending application 693,690 except that the part 81 is substituted for the part generally shown at 35 in the original application. Rectilinear strips of light 7 from the image 7 are focused through the lens 10 onto the photo-sensitive surface of the device 35. An emission of electrons to individual conductors 2', as shown at '60, is controlled by the light.

The conductors 2', the accelerating electrode 14, the image receiving web 12, the space between are retained at a level not quite equal to the ionization potential system 'by the device generally designated at 61, connected through wire 42 and the unidirectional diode 63 to a source of potential. As the drum 8 is rotated in synchronization with the drum 13, and the original image Web y68 is moved in synchronization with the image receiving web 12, an electrostatic pattern is formed on image web 12 corresponding to the original image 7. This electrostatic pattern can be made visible by particles of charged '7 pigment supplied from a pigment generator 16, conduit 25, and a blower 17.

The electron emission control device can be controlled by light `images from more than one master image at the same time. In FIG. 17, lens 10 and lens 10 `and lens 10", for example simultaneously focus

light images

19, 19 and 19" respectively on the light-sensitive layer of part 35. Light focused by lens 10 and lens 10 is fed through a mirror -which both reflects light and transmits it, and light from lens 10 is fed through a prism, for example, to show two modes of operation.

By this arrangement, the electron emission control conductors 2 in FIG. 17 are lactuated by the sum of the light from all sources falling on the photo-sensitive surface lying between the transparent electrode and the adjacent emission conductor, and the electrostatic pattern formed on image receiving surface 12 is a combination or montage of all master images.

If desired, this electrostatic pattern can be made visible at a later spot, by particles of charged pigment capable of Ibeing deposited upon an electrostatic pattern, as shown at 66. The method of developing electrostatic patterns is well known to those versed in the art.

At station 67, the pigment deposited on the electrostatic pattern at station. 66 can be fused to the web lby heat, chemical, or other means.

Still another embodiment of this invention is shown in FIG. 19. A device such as described in FIGS. 4, 5, and 6, generally designated at 69, is positioned in proximity to a drum assembly Which Ihas a layer 71, capable of retaining electrostatic charges, affixed to the conducting drum 72.

As light from an image affixed to drum 8 is reilected through the lens 10 and mirror 11 to the photo-sensitive surface of the device 69, an electrostatic pattern is formed on the surface 71 of the drum. As the drum 72 rotates in synchronization with the drum 8, and the image web 12, particles of charged pigment, generally designated at 73 are affixed to the electrostatic pattern on the surface 71 of the drum. As the drum 72 rotates, the pigment particles which are affixed at station 73 are transferred to the image web 12 due to the potential difference between the drum and the transfer drum or electrode 13.

A suitable means for erasing the electrostatic pattern and any particles which adhere to the drum surface 71 before the next rotation can be provided, as is well known to those skilled in the art, and can consist of fur brushes, corona discharge, or other means.

The advantage of a system show in FIG. 19 is that the variations in image Web 12, such as are found in paper, plastic, etc., do not affect the formation of the original electrostatic pattern, since the ionization potential between the drum 71-72 and the device 69 is constant.

Another method for providing bias potential is shown in FIGS. 26 and 27. Bias conduct-ors generally designated at 77 are positioned between each emission conductor `2. Said conductors 77 are interconnected by a conducting strip 78 and to a source of bias voltage, so that all are retained atY the same potential. An insulating layer 79 over each bias conductor isolates it from the photo-sensitive layer 4 and the transparent electrode 5 which supply the signal potential to the electron emission conductors 2.

-In such a device, the bias emission conductors and the electron signal emission conductors alternate, and by suitable connection in a circuit provide control of the ionization level of the device and the space between the electron emission ends and the image receiving web. Such an arrangement also isolates the electron emission conductors 2 from each other and can be used to control the inter-electrode capacitance effect.

A method to increase the sensitivity of an image control device is shown in FIGS. 20, 21, 22, and 23. FIG. 20 is a schematic view of the cirouit involved. A row of electron emission conductors 71, are retained in insulated spaced relation to each other, FIG. 21. An accelerating electrode generally designated at 14 and an image receiving web at 12 Iare similar to those already described.

A series of bias emission conductors generally designated at 52 maintain the electron emission conductors 71, the web 12, the accelerating electrode 14- and the space between at a potential not quite equal to the ionization level of the system. Y

A series of electron emission conductors which are retained in the same parallel spaced relation as the electron emission conductor-s '71, are positioned so that the emission ends of conductors 71B` will supply electrons to the conductors 71 in absence of any control field 4,3.A

The image control device generally designated at 3,5, which has a series of parallel emission conductors retained in spaced relation to each other, generally designated at 2, is positioned so that the emission conductors 2 are in proximity to the emission ends of conductors 70 and the receiving ends of conductors 71.

The image control device 35 is shown in FIGS. l and 2, and has been described before, with a photo-sensitive layer applied across the conductors and a transparent electrode over that. The emission ends of the conductors 2 can be positioned as shown in FIG. 22a, between the sets of parallel conductors A and B. (Letters A-B in FIG.

2O designate a system comprising an emission conductor 70, a corresponding electron emission conductor 71, and the receiving electrode 14. The designation C-E is the same as the C-E shown in FIG. 20, of the emission control conductor y2.)

So the ends of these conductors 2, shown at 58 can be between the gaps which are between the conductors 70 and 71, or close to them, as shown in FIGS. 22a and 22h.

A plan view taken on line 291-21 of FIG. 20 is shown in FIG. 21.

The conductor C-E is the control conductor. Each system compri-sing a bias conductor 52, shown at D, the emission conductor 71, and the signal supply conductor 711, is numbered 1, 2, 3, y4, as consecutive systems in a row.

All of the signal supply conductors 741 are interconnected and retained at the same potential.

Depending upon the light received by the device 3S in proximity to any electron emission conductor 2, said conductor 2 voltage varies.

. Because the potential supplied to the conductors 2 is more negative than that supplied to the emission conductors 7d, light which permits a discharge from the transparent electrode to the emission conductor 2 on any particular row, for example, that shown in row 3 in FIG. 21, establishe-s a field 43 which inhibits emission of electrons from conductor 70, row 3, to conductor 71.

The device 35 acts like a control grid between the cathode 711 and the receiving conductor 71 which might Ibe termed .the plate in a triode device. The device 52 and the conductors 71 could also be termed a diode device. So the device in PIG. 20 and 21 could be termed a diode-triode emission control device.

One configuration of this is shown in FIG. 213. Parallel emission conductors 71 and 70 are formed on an insulating base 73 in a manner well known to those skilled in the art, and can be formed by photo-etching, etc. These conductors can be formed as one conductor, and then a gap as shown at 75 machined in the plate.

Parallel insulated conductors are formed on both sides of an insulating medium 74, as shown at 5-2 and 2. The conductors 52 become the bias conductors, and the conductors 2 the signal control or grid conductors.

A light-sensitive l-ayer 4 and a transparent electrode 5 complete the device, which is enclosed in a transparent tube of insulating material, such as glass, 50. A vacuum is maintained as shown `at 64.

With suitable connections to the device and an accelerating electrode generally designated at 52', the emission ends 76 of the electron emission conductors 71 are retained at a potential determined bythe electron emissions from conductors 52 which are connected through Wire 42 Vand unilateral diode 63 to a source of potential. Light falling on the photo-sensitive surface inhibits electrons from the signal source 70, and no discharge occurs from 76 to the receiving electrode 52'.

Absence of light over the photo-sensitive -surface at any electron emission conductor 2 decreases the control iield and permits discharge from corresponding conductors 70 to corresponding conductor 71, increasing the potential on the emission end of the conductor 76 above the ionization level of the system consisting of the emission conductor 76, the accelerating electrode 52', the space between, permitting a discharge at that particular spot.

The wedge-shaped electrode 52' is shown in FIG. 25a, with the electron receiving edge 23 :and the wire connection 31 to the source of potential.

F-IG. 25h shows that this electron receiving edge 23 can be a rounded surface of a small diameter, for example, 0.001 inch to permit direct passage of an image web 12 over said electrode without a revolving drum being positioned between the accelerating electrode of the image control device.

These image control devices may control two images at once, as in the device shown in FIG. 24. It is contemplated that the photo-sensitive surface, which varies in electrical resistance as light strikes it, can be la single layer surface such as selenium, or a multiple layer surface such as a doped p,n,p germanium, doped silicon, or other multiple-layer photo-conductor, as are well known to those skilled in the art.

The original image 7 can be wrapped around the drum 8, or can be passed as a continuous web as shown at 68 in FIG. 17.

It is contemplated that the semi-conductor which furnishes the unilateral potential to the electron emission conductors 2, as shown in FIGS. 4, 5, 6, and 8a through 8d, can be -a multiple layer configuration which provides a source of potential to each conductor, but retains them in insulated spaced relation.

For the device as shown in FIG. 17, and a spacing between the emission ends of the conductors 2 and the image web 12 of about 0.001 inch, the ionization level of the system consisting of the emission conductor, the accelerating electrode, the image web `and the space between may be in the order of 600 to 800 volts.

The extra signal level necessary to provide emission from the ends of the conductors 2' and form an electrostatic pattern on the surface of the Iimage web 12 may be from 20 to 200 volt-s, depending upon the material of the image web and the electrostatic pattern desired.

In the device shown in FIGS. 20, and Z3, the potential across the photo-sensitive layer 4 is only a fraction of the signal voltage supplied by the signal emission conductor 70 to the electron emission conductor 71.

In the original device shown in FIG. 1 and FIG. 2, the ionization level potential plus the signal level potential must both come from the connection 30 through the transparent electrode and the photo-sensitive layer 4 to the emission conductor-2.

Reducing the Voltage through this photo-sensitive layer increases its sensitivity and linear response to light, in addition to providing longer life and other advantages. The response time is improved, the inter-electrode capacitance effect is reduced, and the device is generally an improvement in the art.

The resolution of the systems herein and heretofore described depend toa great extent on the spacing between the electron emission conductors.

This spacing is determined by the physical construction of the device and the interelectrode capacitance, among other factors.

One method of increasing the resolution of the electrostatic pattern and hence the visible pigment image de- 10 posited thereon is by decreasing the space between the emission conductors.

Another method is by using several s-uch devices all controlled by light from the same original ima-ge and spaced geometrically from each other but synchronized to form by superimposition their electrostatic patterns and images on the same web.

By longitudinally (in the direction of image receiving surface movement) displacing the devices lso that the patterns are superimposed in proper geometric location, and by laterally displacing the devices so that the electrostatic charges from the conductors of one such device fall between the electrostatic patterns of said other such devices, the spacing between the electrostratic charges and hence the resolution of the lfinally deposited pigmented image is increased without decreasing the spacing between individual conductors on the individual devices.

The device shown in my original application 693,690 can be termed a photo-diode device, since it acts like an individual photo-diode at each parallel conductor and controls the electron emission from the end of the conductor.

Such action is not possible from commercial transistors and photo-diodes, because the close spacing necessary for the parallel conductors cannot be attained, since these conductors are from 0.001 to 0.0005 inch in diameter and 0.005 to 0.001 inch apart in spacing.

The solid-state and vacuum devices described here operate in a manner which can be loosely described as a diode-photo-diode, and diode-photo-triode.

They have one non-light controlled electron emission source, and one light-controlled electron emission source, the rst establishing a bias potential not quite equal to the ionization level of the system described.

The drum shown in FIG. 19 can be a metallic drum 72 coated with an insulating surface 71 such as an insulating plastic material of mylar, etc., or it can be a metal drum, coated with yan insulating surface, which then has conductive spots formed on it, each spot acting as a miniature capacitor, said spots being 500 to 1,000 per lineal inch, for example.

Operation: with respect to FIGURE 17, speciiically the operation is as follows: l

(l) Prior to the printing operation the essential parts of applic-ants circuit are

lines

31 and 42,

conductors

2 and 14 and that portion of the resistor between line 31 and diode 63.

(2) Applicant has utilized the inherent capacitance between the electrodes 2' and 14 to place a D.C. bias across the printing gap (the space between 14 and 2').

(3) The equivalent circuit of this device is a R-C circuit across a battery. As a result of the exponentially decreasing current that ilows in the circuit the battery Volta-ge is impressed on the capacitor (printing gap).

(4) -By impinging light on photodiode (35) the printing gap now sees the summation of the potential from line 31 to line 29. 'Discharge across the printing gap is facilitated because it is necessary to only add a small voltage to the voltage across the gap.

Having `described my invention, reference should now be had to the following claims.

I claim:

1. An electron emission control device comprising an electrically non-conductive insulating support, a multi- .plicity of conductors retained in spaced insulated geometric relation on said support, with the one ends of each conductor adapted to emit electrons, a means for maintaining each conductor at a constant similar minimum potential, with said conductors being retained in insulated relation to each other, light-sensitive semi-conducting junctions connected to said conductors, and means connecting a second potential to each conduc-tor respectively through said junctions, with the resistance of said junctions respectively variable and dependent on the intensity of light displayed upon said junctions, and with the instantaneous potential on each of said conductors individually raised above said minimum potential to a value determined by the instantaneous resistance of said light sensitive junction, and an accelerating electrode spaced from and parallel to the emission ends of said conductors, with the sources of electric potential supplied to said conductors connected so that electrons which escape the emission ends of said conductors travel in the direction of said accelerating electrode.

2. The device of claim 1, and a receiving surface positioned between said emission ends of said conductors and said accelerating electrode, with a space between said conductor ends Iand said suface, means illuminating an original image with light, and displaying light from said image ontthe light-sensitive semi-conducting junction areas juxtaposed tol said emission conductors, with the intensity of said light determining the electrical resistance of said junction and hence the electric potential supplied to each conductor, with the constant minimum electric potential supplying a bias voltage not quite equal 'to the ionization potential of the system consisting of the emission conductor, the accelerating electrode, the receiving surface, and the space lbetween, and said variable additional potential supplied each conductor through said lightsensitive junction increasing the potential of said individual system above said ionization level so that electrons escape said emission end of said conductor and travel in the direction of said accelerating electrode to establish an electrostatic charge on the receiving surface opposite thereto, with the amount of said charge determined by the quantity of light displayed on said corresponding light-sensitive junction, said electrostatic charges on said receiving surface defining a predetermined electrostatic pattern determined by said original image.

3. In the device of claim 2, and means for depositing charged particles upon said electrostatic pattern rendering said pattern visible.

4. An electron emission control Idevice comprising an electrically non-conductive insulating support, a multiplicity of conductors retained in spaced insulated geometric relation on said support, with the one ends of said conductors adapted to emit electrons, means for maintaining each conductorat a constant similar minimum potential, with said conductors being retained in insulated relation to each other, and means delivering a second constant electric potential to each conductor, with said conductors being retained in insulated relation to each other, and an electric field established between said second electric potential and said conductors, a light-sensiitive semi-conducting junction regulating said control eld, a third constant electric potential connected to said junction said junction regulating said field, with the intensity of any one geometric location in said control field variable at any particular instant from any other geometric location in said eld, said intensity at any said geometric location determined by the amount of light displayed `at said corresponding location on said light-sensitive junction, said electric field Variably inhibiting the flow of electrons from said second constant intensity potential to said conductors, with the potential onany emission conductor at any instant individually raised above said minimum potential to a value permitted from said second potential by said corresponding control field, said control field and hence said second potential being controlled by the intensity of light displayed on said corresponding light-sensitive junction, means illuminating an original image with light, and displaying light from said image on said lightsensitive junctions, an accelerating electrode parallel to and spaced vfrom said emission ends of said conductors, connecting said first and second potentials so that electrons which escape the emission ends of said conductors travel in the direction -of said accelerating electrode, with the said firs-t minimum potential not quite equal to the ionization potential of the system consisting of the emission conductor, accelerating electrode, and space between, and said second potential transferred to such conductors Variable and controlled by said electric field intermediate said second potential and said conductors, said transferred potential being in excess of said first constant minimum potential.

5. The device of claim 4, and a receiving surface positioned between said emission ends of said conductors and said accelerating electrode with a space between said conductors and said surface, with an electrostatic pattern formed on the receiving surface in response to light from said original image, said electrostatic charges on said receiving surface defining a predetermined electrostatic pattern defined by said original image, said electrostatic pattern capable of being made visible by deposition of charged particles thereon.

6. The device of claim S, and means for depositing charged particles of iinely divided pigment upon said electrostatic pattern, forming a visible image corresponding to said original image, said particles being capable of being affixed permanently to said receiving surface.

References Cited UNITED STATES PATENTS 2,716,826 9/ 1955 Huebner 346-74 X 2,890,923 6/ 1959 Huebner 346-74 X 2,933,556 4/1960 Barnes 34674 X 2,986,442 5/1961 Broding 346-74 3,066,298, ll/ 1962 McNaney 346-74 3,208,076 9/1965 Mott 346-74 3,234,561 2/l966 Stone 346-74 BERNARD KONICK, Primary Examiner.

V. P. CANNEY, Assistant Examiner.

Claims

1. AN ELECTRON EMMISSION CONTROL DEVICE COMPRISING AN ELECTRICALLY NON-CONDUCTIVE INSULATING SUPPORT, A MULTIPLICITY OF CONDUCTORS RETAINED IN SPACED INSULATED GEOMETRIC RELATION ON SAID SUPPORT, WITH THE ONE ENDS OF EACH CONDUCTOR ADAPTED TO EMIT ELECTRONS, A MEANS FOR MAINTAINING EACH CONDUCTOR AT A CONSTANT SIMILAR MINIMUM POTENTIAL, WITH SAID CONDUCTORS BEING RETAINED IN INSULATED RELATION TO EACH OTHER, LIGHT-SENSITIVE SEMI-CONDUCTING JUNCTIONS CONNECTED TO SAID CONDUCTORS, AND MEANS CONNECTING A SECOND POTENTIAL TO EACH CONDUCTOR RESPECTIVELY THROUGH SAID JUNCTIONS, WITH THE RESISTANCE OF SAID JUNCTIONS RESPECTIVELY VARIABLE AND DEPENDENT ON THE INTENSITY OF LIGHT DISPLAYED UPON SAID JUNCTIONS, AND WITH THE INSTANTANEOUS POTENTIAL ON EACH OF SAID CONDUCTORS INDIVIDUALLY RAISED ABOVE SAID MINIMUM POTENTIAL TO A VALUE DETERMINED BY THE INSTANTANEOUS RESISTANCE OF SAID LIGHT SENSITIVE JUNCTION, AND AN ACCELERATING ELECTRODE SPACED FROM AND PARALLEL TO THE EMISSION ENDS OF SAID CONDUCTORS, WITH THE SOURCE OF ELECTRIC POTENTIAL SUPPLIED TO SAID CONDUCTORS CONNECTED SO THAT ELECTRONS WHICH ESCAPE THE EMISSION ENDS OF SAID CONDUCTORS TRAVEL IN THE DIRECTION OF SAID ACCELERATING ELECTRODE.