US3673595A - Apparatus for electrostatic image-forming and processes for use therewith - Google Patents

Abstract

An electron beam tube for use in formation and recordation of electrostatic charge patterns has a face plate including a photoconductive layer and a conductive base which is transmissive to electron beams and is disposed intermediate the photoconductive layer and the tube electron beam emitter. Processes for forming electrostatic charge patterns in such face plate include the steps of placing an insulative charge-retaining layer in contact with the photoconductive layer, the insulative layer either being previously charged or being charged while in position on the photoconductive layer, and applying a voltage to the face plate and simultaneously irradiating the photoconductive layer with pattern-indicating electron beams. Electrostatic charge patterns thus-formed in the insulative layer may be developed in place or transferred and subsequently developed.

Description

United States Patent Inoue et al. 1 June 27, 1972 [54] APPARATUS FOR ELECTROSTATIC 3,196,011 7/1965 Gunther ..96/1 PC RMIN 4ND 3,234,019 2/1966 111111 IMAGE-F0 G PROCESSES 3,458,752 7/1969 Stowell ..346/74 EB FOR USE THEREWITH Inventors: Elichi Inoue; 'Keizo Yamaji; Hiroshi Tanaka; Takashi Saito, all of Tokyo, Japan Canon Camera Kabushiki Kaisha, Tokyo, Japan Filed: Feb. 20, 1969 Appl.No.: 800,961

Assignee:

Foreign Application Priority Data Feb. 27, 1968 Japan ..43/l2741 11.5. C1. ..346/74 ES, 96/1 PC, 101 1310. 13, 250/495 zc, 346/74 EB 1111.0. ..G03g 13 22, (303g 15/22 Field 61 Search ..346/74 ES, 74 EB; 101 010. 13; 96/1 R, 1 PC, 1 c; 250 495 c, 49.5 zc

References Cited REFERENCE OSCILLATOR Primary Examiner-Howard W. Britton AttorneyWatson, Leavenworth and Kelton ABSTRACT An electron beam tube for use in formation and recordation of electrostatic charge patterns has a face plate including a photoconductive layer and a conductive base which is transmissive to electron beams and is disposed intermediate the photoconductive layer and the tube electron beam emitter. Processes for forming electrostatic charge patterns in such face plate include the steps of placing an insulative chargeretaining layer in contact with the photoconductive layer, the insulative layer either being previously charged or being charged while in position on the photoconductive layer, and applying a voltage to the face plate and simultaneously irradiating the photoconductive layer with patternindicating electron beams. Electrostatic charge patterns thus-formed in the insulative layer may be developed in place or transferred and subsequently developed.

27 Chins, 16 Drawing Figures CIRCUIT DIN P'ATENTinJunz'r m2 sum 2 or 4 FIGS FIG.7

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PATENTEnJum m2 3.673.595 sum aor 4 PROCESSING STATION 49 so 47 PKTENTEnJum m2 7 Y 3.673.595

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'36 I 58 13 3. H 12 15 CRT NF "I 59 \i Ill 333%? 4 43 oron 42 MEM0R4Y3 4 i A a DELAY CIRCUIT APPARATUS FOR ELECTROSTATIC IMAGE-FORMING AND PROCESSES FOR USE THEREWITH The present invention relates to electrostatic recording and more particularly to electron tubes having a photoconductive member incorporated in the face plate thereof and to processes for use of such tubes in forming and recording electrostatic charge patterns in response to information signals.

Various methods are known for electrostatically recording information signals. For example, in the method disclosed in U.S. Pat. No. 2,879,422 issued to H.C. Borden et a1., a cathode ray tube is utilized having a face plate composed of conductive pins electrically insulated from each other and embedded in an insulative layer in the form of a matrix. Information signals are converted into electron beams by a cathode ray tube and the electron beams are passed through said pin conductors so as to cause gaseous discharge in a recording member, thereby forming electrostatic charge patterns on the recording member. In this method the density of conductor pins in the matrix significantly influences resolution. Since it is extremely difficult to arrange conductor pins in a desired high density in the matrix because of the construction of the face plate, the formation of electrostatic charge patterns having high resolution is impossible. Furthermore, in this method, electrostatic charge patterns are formed .by atmospheric discharge. Thus, pattem-forming discharges are greatly influenced by environmental conditions, and discharges may thus tend toward instability, thereby disturbing the indicated patterns or images. In addition, it is difficult to obtain high contrast electrostatic charge patterns by this method.

Another known method is disclosed in US. Pat. No. 3,132,206 issued to P.F. King. According to his method, information signals are first converted into fluorescent images upon the face plate of a cathode ray tube and such images are utilized as light images for electrophotographic recording in accordance with the Carlson process, i.e., projecting the images upon a xerographic plate to form electrostatic charge patterns on the photoconductive layer of said,plate. In this method, it is required that the photoconductive material have a relatively high resistance in order to retain the charges on the photoconductive layer. Therefore it is very difficult to employ highly sensitive photoconductive material having a relatively low resistance so that the sensitivity of this method is low and an electrostatic charge pattern having high contrast is not formed. Furthermore, according to this method the information signals are converted into light images and thereafter these light images are electrostatically recorded so that both efficiency and speed are inferior.

An object o f the present invention is to eliminate the above-described disadvantages in known conventional methods by providing a novel electrostatic recording tube and electrostatic charge pattern-forming and recording processes.

Specifically, an electrostatic recording tube according to the present invention has electron beam generating means, means for emitting said electron beams upon a face plate and other means incorporated in conventional electrostatic recording tubes. The novel face plate of the present invention has one fundamental arrangement including two layers, a thin layer electrode transmissive to electron beams and a photoconductive layer. Another fundamental face plate arrangement includes three layers, a thin layer electrode of the type described above, a photoconductive layer and a chargeretaining insulative layer. Furthermore, an airtight layer and any other suitable additional layers may be incorporated in the face plate, if required. The face plate of the present invention responds effectively to single or simultaneous emission of electron beams, voltage application and/or emission of radiation so that high contrast electrostatic charge patterns may be formed upon the surface of the face plate or on a recording member overlaid thereupon according to recording processes which will be described in detail hereinafter.

In order to form electrostatic patterns upon the surface of the face plate, one fundamental recording process of the present invention comprises the steps of: maintaining the surface of the face plate of the electrostatic recording tube of the present invention at a predetermined potential level; emitting electron beams through the thin layer electrode upon the photoconductive layer while simultaneously applying a voltage to the face plate; and illuminating the photoconductive layer with blanket radiation to which the photoconductive layer is sensitive.

Another fundamental recording process of the present invention comprises the steps of: maintaining the face plate at a predetermined potential level; thereafter contacting closely thereupon a recording member or contacting closely upon the face plate a recording member which is previously maintained at a predetermined potential level or maintaining the face plate at a predetermined potential level with the overlying recording member in place; emitting electron beams through the thin layer electrode upon the photoconductive layer while simultaneously applying a voltage to said recording member; and thereafter removing the recording member from the face plate or illuminating the photoconductive layer with blanket radiation to which the photoconductive layer is sensitive, thereby forming electrostatic charge patterns upon the recording member.

Recording processes of the present invention may include the further steps of rendering visible the thus-formed electrostatic charge patterns by suitable means and manner such as coloring, frost, etc. so as to directly obtain permanent images for storage, and/or transferring the electrostatic charge patterns, as they are formed or visualized, to a copying member for further processing.

As described above, according to the present invention, the face plate incorporating the photoconductive layer is directly or indirectly maintained at a predetermined potential level and electron beams are emitted upon the face plate, over which is laid a charge-retaining insulative layer, while simultaneously applying a voltage to the face plate. By the interactions among the initial potential, the electron beams and said applied voltage, with or without the emission of blanket radiation, the electron beams controlled by image-defining signals are converted into electrostatic charge patterns for recording.

According to the present invention, the electron beams controlled by the image-defrning signals can be directly recorded as electrostatic charge patterns upon the charge-retaining insulative layer at high speed, thus-formed patterns being stable and having high contrast and resolution. One of the salient features of the present invention is that the recording process can be carried out even in ambient light.

One of the objects of the present invention is to provide a novel and improved electrostatic recording system.

Another object of the present invention is to provide an improved electrostatic recording tube, the face plate of which incorporates a photoconductive layer.

Another object of the present invention is to provide an improved recording tube for the formation of electrostatic charge patterns upon the face plate thereof.

A further object of the present invention is to provide an improved recording tube having means for applying blanket radiation to the face plate thereof.

A still further object of the present invention is to provide an improved recording tube for recording electrostatic charge patterns derived from electron beam signals controlled by information signals.

Another object of the present invention is to provide an improved electrostatic recording process comprising the steps of emitting electron beams upon a face plate incorporating therein a photoconductive layer while simultaneously applying a voltage thereto, thereby recording the electron beam signals in a charge-retaining member as stable electrostatic charge patterns having high resolution and high contrast.

An additional object of the present invention is to provide an improved recording process permitting the formation of high contrast electrostatic charge patterns even in ambient light.

A yet further object of the present invention is to provide an improved recording process for recording electron beam signals as permanent electrostatic charge patterns.

The above and other objects, advantages and features of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.

FIGS. la-lc show sectional views of face plates for electron tubes in accordance with the present invention.

FIGS. 2, 3 and 4 illustrate the principles of an electrostatic charge pattem-forming process of the present invention.

FIGS. 5 to 11 are explanatory views illustrating the principles of another electrostatic charge pattern-forming process of the present invention.

FIG. 12 is a schematic view illustrating the structure of a recording tube of the present invention and associated apparatus used in a recording process in accordance with the invention.

FIGS. 13 and 14 are schematic views illustrating apparatus used in other electrostatic charge pattem-forming and recording processes in accordance with the present invention.

FIG. 1 is an explanatory view illustrating fundamental structures of face plates for electrostatic recording tubes of the present invention. Referring to FIG. la, on charge-retaining insulative layer 1 is formed photoconductive layer 2 applied by spraying, coating, vacuum deposition or the like. Upon photoconductive layer 2 is formed thin layer electrode 3 by vacuum deposition or the like. Thus, the face plate is composed of three fundamental layers, charge-retaining insulative layer 1, photoconductive layer 2 and thin layer electrode 3.

FIG. lb illustrates another face plate according to the present invention. This-face plate is fundamentally composed of four laminated layers, that is, airtight layer 4 formed on the cathode ray tube in order to maintain a high degree of vacuum therein, thin layer electrode 3 formed by vacuum deposition or the like upon airtight layer 4, photoconductive layer 2 formed upon layer 3 by coating, vacuum-deposition or the like and charge-retaining insulative layer 1 formed upon photoconductive layer 2.

FIG. 1c illustrates another face plate according to the present invention similar to that shown in FIG. 1a with the exception that there is not charge-retaining insulative layer 1. This face plate is composed of thin electrode layer 3 and overlying photoconductive layer 2. It is of course possible to provide an airtight layer 4 overlying thin electrode layer 3 as in the face plate shown in FIG. lb. Furthermore, a charge control layer may be interposed between thin layer electrode 3 and photoconductive layer 2, and a layer for binding electric charges or any other suitable layer may also be formed upon or adjacent to the interface between photoconductive layer 2 and the insulative layer without adversely affecting the im' roved operation and effects of recording processes of the present invention.

Any material having high resistance to abrasion, relatively high electrical resistance and adapted to retain electric charge may be used for the insulative layer. The insulative layer material may be transparent or non-transparent to radiation to which photoconductive layer 2 is sensitive. Such insulating materials are, for example, macro-molecule films such as polyester resin, polypropylene resin, polycarbonate resin, polyethylene resin and other resins, glass, ceramic or the like coated with A1 SiO and other inorganic materials and said materials may be rendered nontransparent. Preferably the charge-retaining insulative layer is composed of one of or a mixture of the above materials or a lamination thereof and has a thickness from to 50 .1..

Materials for the photoconductive layer are: Se, S, SeTe, CdS, CdSe and other chalcogenide compounds; photoconductive metal oxides such as ZnO, PhD and so on; inorganic photoconductive materials; and organic photoconductive materials such as antracene compounds, carbazoles, etc. A single coating of photoconductive material as described above may be used and a binding agent may be added thereto or mixtures of the above described materials may be used. Altematively, laminates may be used. The thickness of the photoconductive layer is preferably less than 200 u.

Thin layer electrode 3 is used as the anode of the electrostatic recording tube and serves as an opposing electrode when a voltage is applied to the face plate so that charges may travel between the thin layer electrode and the photoconductive layer. Materials for thin layer electrode 3 must satisfy these operating conditions and may be composed of a transparent conductive material, such as Au or the like having a thickness of approximately A, an opaque thin layer having a thickness of 1,000 to 10,000 A or other conductive thin layers depending upon the application.

Airtight layer 4 maintains a high degree of vacuum in the electrostatic recording tube and serves as an auxiliary reinforcing member for the face plate. The use of this airtight layer causes the electron beams to be partially adsorbed, thus reducing the efliciency of the recording tube, but this inefficiency is offset by advantageous maintenance of a high degree of vacuum in the recording tube. For example, a metallic thin layer or the like about 1 p. in thickness reinforced by mica or mosaic-shaped grating a few microns in thickness may be used.

For joining the layers, various kinds of binders and adhesives may be used. Satisfactory results can be attained by the use of epoxy resin series adhesives, polyester resin series adhesives, other polymer adhesives or varnish in which vinyl chloride, vinyl acetate copolymer, polyvinyl alcohol or the like is dissolved in a solvent.

The process for forming electrostatic charge patterns according to the present invention will now be described. FIGS. 2 to 11 schematically illustrate processes for forming electrostatic charge patterns according to the present invention and the states of charges in each step of the processes. First, the process practiced upon the face plate shown in FIG. la will be described with reference to FIGS. 2 through 4. In the first step, the face plate is provided with a predetermined potential as shown in FIG. 2, and in the second step, electron beams 8 are directed upon photoconductive layer 2 through thin layer electrode 3 and simultaneously a voltage is applied to the face plate as shown in FIG. 3 so that an electrostatic charge pattern is formed as shown in FIG. 3. Furthermore, blanket radiation L to which photoconductive layer 2 is sensitive is directed thereupon, thereby forming a high contrast electrostatic charge pattern on charge-retaining insulative layer 1 of the face plate as shown in FIG. 4.

As shown in FIG. 2, in darkness or in light, insulative layer I is charged by corona discharge device 5 or any other suitable well known means such as an electrode roller, a friction charging means or the like, connected to a high voltage source (not shown). In this case, thin layer electrode 3 is grounded at as 6. Thus, a predetermined potential is maintained across the face plate, a negative potential level in this case.

When the surface of the insulative layer is charged positively, charges of opposite polarity will be bound at the interface between insulative layer 1 and photoconductive layer 2 or adjacent thereto. These charges are composed of free carriers, photocarriers in photoconductive layer 2, or carriers injected from the thin layer electrode or a mixture thereof. Such charges will be bound either in darkness or in light. Even if the charges upon the surface of insulative layer I are removed and the layer is in darkness, the bound charges remain unchanged.

Next, as shown in FIG. 3, electron beams 8 corresponding to information signals are directed to photoconductive layer 2 through thin layer electrode 3 from the inside of the electrostatic recording tube. In this case, by means of a well known suitable charging means such as corona discharge means 7 or an electrode roller friction charging means which is connected to a high voltage source (not shown), a voltage of polarity opposite to that of said charges, i.e., a positive voltage in this case, is simultaneously applied to insulative layer 1.

When photoconductive layer 2 has p-type conductivity, it is preferable to initially charge the surface of insulative layer 1 negatively and then to charge the surface positively when electron beams are applied to the photoconductive layer.

When the electron beams and said voltage are simultaneously applied to the photoconductive layer, photoconductive layer 2 of the face plate must be shielded from ambient light. For this purpose, insulative layer 1 may be rendered nontransparent to radiation to which photoconductive layer 2 is sensitive. Alternatively, the shielding plate of charging means 7 may be made of non-transparent materials or may be provided with extensions along both sides thereof as shown at 7. Alternatively, any other means suitable for shielding the face plate from ambient light may be provided, or the process of forming electrostatic patterns may be conducted in a darkroom.

When application of the voltage to insulative layer 1 and exposure of photoconductive layer 2 to electron beams occur simultaneously, charges initially provided on the surface of insulative layer 1 are discharged less at dark portion D of photoconductive layer 2 because of the positive charges bound therein. On the other hand, at exposed portions L where electron beams are incident upon photoconductive layer 2, carriers are produced whereby the resistance of these portions of the photoconductive layer is decreased, and thereby the bound charges are easily released. Consequently, negative charges upon the insulative layer surface corresponding to portions L of photoconductive layer 2 are substantially discharged by the negative polarity corona so that these portions of the surface of the insulative layer are positively charged whereby electrostatic charge patterns corresponding to the signals applied are formed as shown in FIG. 3.

In this case, the thus-formed pattern would be adversely affected if carriers generated by electron beam excitation disperse in photoconductive layer 2. But most of such carriers are considered to move in the direction of the electric field due to bound charges, that is in the direction perpendicular to the surface of and transversely of the thickness of the photoconductive layer. Therefore, the thickness of photoconductive layer 2 may be suitably arranged such that the resulting electrostatic charge patterns are not adversely affected in practice.

Next, as shown in FIG. 4, radiation to which photoconductive layer 2 is sensitive is directed thereupon uniformly. At this time, portions L on which electron beams were incident remain unchanged while the high resistance of portion D, on which less electron beams were incident in the previous step, is rapidly reduced and portion D becomes conductive. Consequently, the charges bound at the interface between insulating layer 1 and photoconductive layer 2 or adjacent thereto disappear except those charges bound by charges which remain on the surface of the insulative layer. This state of the charges is shown in FIG. 4 and it will be seen that an electrostatic pattern having contrast higher than that formed in the previous step is formed upon insulative layer 1.

The uniform or blanket radiation used in this step is selected in accordance with the properties of the photoconductive layer, and for example visible light rays radiated from the sun, tungsten lamps, fluorescent lamps, etc., ultraviolet rays, infrared rays, X-rays and any other radiation may be used. The radiation is not limited to the direction shown, i.e., from the transparent insulative layer side, as shown in FIG. 4, but may be transmitted from inside of the electrostatic recording tube, that is through thin layer electrode 3, when the electrostatic recording tube has a radiation emission means as will be described in more detail hereinafter.

When this method is employed, the above described process can be practiced even in the light by rendering insulative layer 1 non-transparent to the blanket radiation. Thus-formed electrostatic charge patterns may be transferred to another insulative copying member for storage or preservation. Altematively, electrostatic charge patterns upon the face plate may be developed by well-known electrophotographic methods, such as the magnet brush method, the cascade method, the far brush method, the spray method or the liquid processing method, etc. and then may be transferred to a copying member. Thereafter, the face plate may be cleaned by any suitable method such as brushing the face plate with a fur brush, etc. well known in the art of electrostatic photography. The face plate may thus be used repetitively.

It should be noted that in the above-discussed process, a positive or negative pattern may be produced as needs demand. Furthermore, according to the present invention it is not necessary to directly charge the photoconductive layer as in the case of conventional electrostatic photographic processes. As described hereinabove, in the present invention the charge-retaining insulative plate is charged initially so that charges provided upon the insulative layer may bind charges of opposite polarity at the interface between photoconductive layer 2 and insulative layer 1 or adjacent thereto so that not only high resistance photoconductive materials, which are required in conventional electrophotography, but also relatively low resistance and highly sensitive photoconductive materials may beused in the present invention. Therefore, highly sensitive and high contrast electrostatic charge patterns may be formed because of such highly sensitive photoconductive layer and the unique pattern-forming processes of the present invention.

The process for forming electrostatic charge patterns upon the face plate shown in FIG. 10 will now be described with reference to FIGS. 5 through 1 1. In operation, insulative layer 1 is charged with a predetermined polarity as shown in FIG. 5 and in the second step insulative layer 1' is placed in close contact with photoconductive layer 2 of the face plate so that the face plate may be maintained at a predetermined potential level as shown in FIG. 6. In the third step, electron beams 8' are emitted through thin layer electrode 3 upon photoconductive layer 2 while a potential is simultaneously applied to the face plate as in FIG. 7, thereby forming the electrostatic charge pattern shown in FIG. 7. Thereafter, in the fourth step, blanket radiation 9' is directed upon photoconductive layer 2 as shown in FIG. 8 or insulative layer 1 is removed from photoconductive layer 2 of the face plate as shown in FIG. 10. In the final step, electrostatic charge patterns are formed upon insulative layer 1' as shown in FIGS. 9 and 11.

The above-described process will now be described in more detail. First, in darkness or in light, both surfaces of layer 1 are provided with opposite polarity charges by any suitable wellknown means such as a double corona discharger, electrode roller friction charging means, etc. Thus, insulative layer 1' is uniformly electrically charged as shown in FIG. 5. Next, the thus-charged insulative layer is placed in close contact with photoconductive layer 2 of the face plate so that the face plate is maintained at a predetermined potential, a negative potential in this case. Thus, the face plate is electrically charged as shown in FIG. 6 in similar manner to the charging described in the first-discussed embodiment of the pattem-forming process of the present invention. Then, as shown in FIG. 7, electron beams 8' corresponding to the information signals are directed upon photoconductive layer 2 through thin layer electrode 3 from inside the electrostatic recording tube. Concurrently, by means of any suitable charging means such as corona discharge means 7 or the like connected to a high voltage AC source (not shown), AC voltage is applied to insulative layer 1'. In this case, photoconductive layer 2 of the face plate must be shielded against ambient light rays when electron beams are directed upon the photoconductive layer and AC voltage is applied to the face plate as in the case of the above-discussed embodiment of the present invention.

In the next step, as shown in FIG. 8, radiation 9 to which the photoconductive layer is sensitive is directed uniformly upon photoconductive layer 2 and the face plate retains charge as shown in FIG. 8, having a high contrast electrostatic charge at portions not exposed to electron beams. Thereafter insulative layer 1' is removed from photoconductive layer 2 as shown in FIG. 9.

On the other hand, when insulative layer 1' is removed from photoconductive layer 2 as shown in FIG. 10 instead of irradiation thereof as shown in FIG. 8, insulative layer 1' retains the case when said radiation is employed.

In order to permanently preserve the electrostatic charge patterns formed upon insulative layer 1' as shown in FIGS. 9 and 11, any suitable process known in the art of the electrophotography may be employed. For example, wet or dry methods may be employed so as to render the patterns visible. Alternatively, the patterns may be rendered visible by frost methods. Thus-formed visible patterns are fixed and thereafter transferred to another copying member for storage. Furthermore, it is also possible to electrostatically transfer the electrostatic charge images upon insulative layer 1 to a suitable charge-retaining member, which in turn is processed in the manner described above so as to render the images visible for recording.

So far the present invention has been described with references to particularly described embodiments of electrostatic charge and visual pattem-forming processes. It should be understood that the present invention includes the following processes:

a. A process for forming electrostatic charge patterns comprising the steps of: maintaining at a predetermined potential level the surface of a face plate of the type shown in FIG. la or b; directing electron beams controlled by signals through thin layer electrode 3 and upon photoconductive, layer 2 and simultaneously applying a voltage to insulative layer 1; and directing blanket radiation upon photoconductive layer 2, thereby forming an electrostatic charge pattern corresponding to the electron beam signals.

b. Processes comprising the steps of: maintaining at a predetermined potential level the surface of a face plate of the present invention, overlaying a charge-retaining recording member upon the surface of the face plate; directing electron beams controlled by signals through thin layer electrode 3 and upon photoconductive layer 2 and simultaneously applying a voltage to said recording member; and directing blanket radiation upon said photoconductive layer or removing said recording member from said face plate, thereby forming an electrostatic charge pattern corresponding to the beam signals.

c. Processes comprising the steps of: maintaining a charge retaining recording member at a predetermined potential level; overlaying said recording member upon a face plate of the present invention, thus maintaining the face plate at a predetermined potential level; directing electron beams controlled by signals through thin layer electrode 3 and upon photoconductive layer 2 and simultaneously applying a voltage to said recording member; and directing blanket radiation upon said photoconductive layer or removing the recording member from said face plate, thereby forming an electrostatic charge pattern corresponding to the electron beam signals.

d. Processes comprising the steps of: overlaying a charge retaining recording member upon the face plate of an electrostatic recording tube of the present invention; maintaining the face plate at a predetemiined potential level; directing electron beams controlled by information signals through thin layer electrode 3 upon photoconductive layer 2 and simultaneously applying a voltage to said recording member; and directing blanket radiation upon said photoconductive layer or removing said recording member from the face plate, thereby forming an electrostatic charge pattern corresponding to the electron beam signals.

In addition to the processes described above, the present invention further includes evident variations and modifications thereof insofar as they do not have adverse effects therein.

In the above-described processes, the initial potential for maintaining the face plate at a predetermined potential level may be a potential in the face plate itself or an external potential applied thereto. The predetermined potential level may be from minus thousands of volts to plus thousands of volts. Similarly, the voltage applied simultaneously with the emission of electron beams may be from minus thousands of volts to plus thousands of volts depending upon the initial potential level.

Means such as a corona discharger connected to either an AC or a DC power supply, an electrode roller, a friction charging means, a grounded roller, etc., may be employed for applying the secondary voltage.

The electrostatic charge patterns formed in the abovedescribed processes may be further processed by any suitable means known in the art of the electrostatic photography so as to transfer the patterns directly or indirectly to any suitable copying material for permanent recording.

The present invention will now be described with reference to an embodiment of an electrostatic recording tube of the invention. FIG. 12 illustrates the present invention as employed in hard copying" of information signals, such as video signals. In FIG. 12, electrostatic recording tube 10 includes an electron beam generafing means or electron gun comprising cathode 11, control grid 12, etc., and an electron beam emission control system comprising accelerating electrode 13, focusing grid 14 and deflecting coil 15 all disposed in an evacuated envelope. Electrostatic recording tube 10 is provided with face plate 16 and with radiation generation means 17. As shown in FIG. 1b, face plate 16 is composed of four layers. On the airtight layer, 4 p. in thickness and of high quality mica, an aluminum coating about 500 A in thickness is vacuum-deposited, and thereafter molten glass, having the composition of 60 atomic percent of Se, 30 atomic percent of As and 10 atomic percent of S, is applied uniformly thereupon and rapidly cooled from about 280 C. to room temperature so as to form a stable glass photoconductive layer about 60 p. in thickness. Then, these layers are attached with molten glass to a picture frame formed upon the base of the face plate made of chromium containing steel. On the free surface of the thus formed photoconductive glass a polyester film 25 p. in thickness is secured as a charge-retaining insulative layer by use of an adhesive, e. g., epoxy resin, thus providing face plate 16.

The mode of operation of recording tube 10 having face plate 16 will now be described. A unitary assembly including cleaner 18 composed of a fur brush, elastic rubber roller, etc., first corona discharging device 19, second corona discharging device 20 and processing device 21 composed of fur brush, magnet brush, etc. is moved across the face plate to clean the surface thereof. Then, a voltage of 6 KV is applied to first charging device 19, thereby electrically charging the surface of face plate 16 to about l,500 V. Next electron beams generated by cathode 11 are accelerated by accelerating electrode 13, are focused by focusing coil 14 and are then deflected vertically or horizontally by deflection coil 15. The electron beams are intensity-modulated by control grid 12 of the electron gun by information signals applied thereto, and the beams scan the surface of the face plate opposite the surface thereof to which a voltage is applied by second discharging device 20, which is moved in synchronism with the scanning of the electron beams. In this case, the slit width of second discharging device 20 is adjusted in accordance with the spot width of the electron beam.

After the signal electron beams have scanned the whole surface of the face plate simultaneously with application of voltage by second charging device 30, the whole surface of the face plate is illuminated by radiation emanating from irradiating means such as tungsten lamp 23, thereby forming a high contrast electrostatic pattern upon the face plate. The electrostatic charge pattern is processed by processor 21 to obtain visible images. The radiation is in the form of parallel light rays emitted from lamp 23, for example, a lOO-W tungsten lamp, through lens system 24, and slit 25 and illuminates the portions of the face plate previously scanned by the signal beams so as to blanketly irradiate the photoconductive layer. Reflecting mirror 26 and airtight wall 27 are provided as indicated. This embodiment has an advantage in that the development of the patterns formed can be immediately effected by means of processor 21 which is assembled integrally with cleaner l8, and charging devices 19 and 20. As much as about 800 V of contrast can be attained in the electrostatic charge patterns by applying +7 KV of DC voltage across a discharging wire 0.06 mm in diameter where the accelerating electrode is supplied with 30 KV after the initial charging operation.

The development of the formed patterns can be effected by applying negative toner to the patterns by means of a fur brush, thus obtaining a positive image. After development, processing mechanism 28 is disposed in close contact with the face plate for image transfer, fixing and collecting. Copying material 29, such as paper, is placed in close contact with face plate 16 and electrically conductive rubber roller 30, having an applied transferring bias voltage of from 1 KV to 1.5 KV, is rolled over the back surface of copying paper 29 so as to transfer the visible image onto the front surface of copying paper 29. Thereafter, processing mechanism 28 is removed from face plate 16 and copying paper 29 is wound up by rotating both paper supply reel 31 and take-up reel 32. Next, the image on copying paper 29 is fixed by means of fixing means When 6.4 KV AC voltage is applied instead of the aforesaid DC voltage of 7 KV for the secondary charging, a positive electrostatic charge pattern of about 600 v can be formed.

When a negative DC voltage of KV is initially applied by corona discharge so as to maintain the surface of the face plate at about =l,200 V and when instead of the secondary charging, a grounded metal roller is placed in close contact with the face plate so that the electron beams scan the face plate in synchronism with the motion of the roller, thereby causing selective discharge, electrostatic contrast of about 500 V may be attained.

Furthennore, according to the embodiment described hereinabove, electrostatic charge patterns can be directly transferred, without the necessity of the development thereof, after forming the electrostatic charge patterns by initial charging, second charging while simultaneously scanning the face plate by electron beams carrying information and blanket irradiation of the face plate. This will be described in more detail hereinafter. ln FIG. 12, transfer material 29, is an insulative film or paper, which is placed in close contact with the face plate by means of conductive rubber roller 30. Thereafter, a positive voltage of 2 KV is applied to this roller and then transfer material 29 is removed from the face plate.

By rolling the roller over the whole surface of transfer material 29 disposed in contact with the face plate, the electrostatic charge pattern thereupon is transferred to the transfer material. ln order to closely contact the transfer material upon the face plate and then remove the transfer material from the face plate while applying a potential thereto, feed rollers 34 and 35 of processing mechanism 28 are spaced from the face plate by approximately one centimeter and the rubber roller is so disposed as to press transfer material 29 on the face plate. Thereafter, roller 30 with said potential applied thereto is rolled upon the back surface of transfer material 29. The thus-formed electrostatic pattern is visualized, and fixed and the transfer material is then wound around take-up reel 32.

Since the processing such as development, transfer, etc. is all performable upon the face plate of the recording tube, full advantage is not taken, in the above-discussed embodiment, of one of the salient features of the face plate of the present invention, that is, high speed capability. Such full advantage is taken in another embodiment of the present invention as will be described hereinafter with reference to FIG. 13.

Charge-retaining recording member 36 is maintained at a predetermined potential level by means of a pair of electrodes 42 and 42' and is moved into contact with the face plate of the electrostatic recording tube by means of roller 60 and a suitable voltage is applied to the back surface of the recording member by means of electrode 59 in synchronism with the electron beam scanning operation, thus forming an electrostatic charge pattern. The thus-obtained electrostatic charge pattern on recording member 36 is developed and transferred at station 58 spaced from the face plate while another electrostatic charge pattern is being formed upon a new portion of recording member 36 then in contact with the face plate. Thus, high speed printing operation becomes possible in practice.

In systems for displaying input information and for reproduction of processed data and stored information, the latter embodiment of the present invention is best suited for providing permanent images of alpha-numerically displayed information.

The face plate used in this embodiment is fabricated in the following manner. Slots 5 mm in width are formed through a chromium base containing steel and a layer of high quality mica about 3 p. in thickness is fixed thereupon with molten glass. A coating of metallic electrode material 500 A in thickness is applied upon the mica layer and thereafter a mixture of 75 parts of solid solution of As se obtained by heating and melting Se and As in a sealed envelope and 25 parts of solid solution of A8283 obtained in a similar manner as described above and containing a small quantity of impurities such as In and Cl is vacuum deposited upon the metallic electrode coating so as to form a glass photoconductive layer. The thus-formed face plate is similar to the face plate shown in FIG. 1b but has no insulative layer 1.

Such face plate is secured, with the photoconductive layer being directed outwardly, to an electrostatic recording tube of the type described with radiation emission means 37 disposed therein. A high voltage xenon lamp with reflecting mirror 39 is used as radiation emission means 37 and the light therefrom uniformly irradiates the inner surface of the face plate through lens system 38. Synchronizing pulses generated in a reference oscillator 40 in response to input signals from memory 44 are applied to delay circuit 41 and the signals from the delay circuit actuate lamp 37 such that the lamp is turned on and off periodically out of phase with application of voltage to the electrode disposed in opposed relation to the face plate, such voltage application occurring simultaneously with the signal electron beam emission.

Recording member 36 is electrically charged to a predetermined potential level by means of opposed electrodes 42 and 42'. In this embodiment, recording member 36 is a synthetic insulative film made of bidirectionally elongated ethylene, styrene or propylene macro-molecular film. This film is charged by corona discharge so as to have a surface potential of about 2,000 V and then advanced to the face plate.

Next, the character-representing electron beams are emitted at an accelerating voltage of 25 KV and at a scanning velocity of 10 p, sec/cm, the accelerating electrode being supplied with a positive potential. For this purpose, character or code signals are applied to the grid electrode of the tube so as to intensity modulate generated electron beams and simultaneously to deflect such modulated beams to predetermined positions upon the face plate. When one line of characters is formed upon the face plate, the electrostatic charge pattern corresponding thereto is simultaneously formed upon the recording paper. During this time, the xenon lamp is unactuated and thus not illuminated. Thereafter, at the instant of termination of the emission of the character-representing electron bearns and of termination of voltage application by electrode 59, the out-of-phase pulse is applied to the lamp starting circuit and the lamp is illuminated for about 10 in sec. and then turned ofl.

During this irradiation, the bound, floating or stray charges in the photoconductive layer are released, and when the recording paper moves, new positive bound charge is formed. On the other hand, that portion of the recording paper upon which the formed electrostatic pattern resides with increased pattern contrast is advanced by roller 60 away from the face plate and is processed by means of the processing device at station 58.

The next succeeding electrostatic pattern is formed upon the next emission of signal beams with the simultaneous application of potential to the recording plate.

Such synchronous operations are controlled by means of an oscillator, a delay circuit such as a flip-flop circuit and a phase-locked circuit, such as differentiating circuit. By these circuits synchronous operation of motor 43 is also controlled.

By this process electrostatic recording is effected upon recording paper of information in the form of characters. Such electrostatically recorded information can be made visible by applying toner in the processing device of station 58 or by any other means known in the electrostatic photography so that the record can be stored as permanent visual record.

In the above-described embodiment, recording insulative film 36 is moved over the face plate. In this case, when a suitable surface lubricant such as silicon oil, teflon oil, or the like is applied to the insulative layer or to the photoconductive layer when no insulative layer is provided, service life of the face plate is extended. The application of this surface lubricant is especially advantageous when the electrostatic charge pattern formed is immediately transferred through such liquid surface lubricant because better results will be attained.

Recording member 36 may be polyester film about 25 p. in thickness in the form of endless belt 45 as shown in FIG. 14. Endless belt 45 is driven by means of rollers 46 and 47 and is electrically charged to a predetermined potential level by means of charging device 48. A voltage is applied to this endless belt by electrode 51 simultaneously with the emission of electron beams upon the face plate 50 of electrostatic recording tube 49, thereby forming an electrostatic charge pattern upon film 45 as in the previous embodiment.

Thereafter, the electrostatic charge pattern upon film 45 is transferred to copy member 54 driven in the direction indicated by the arrow between supply reel 52 and take-up reel 53. Film 45 is pressed against copy member 54 by feed roll 55. Such transferred electrostatic charge pattern is developed and fixed at station 57 for permanent recording.

As described in detail hereinabove, according to the present invention electrostatic charge patterns having a strong exterior field and a high surface potential difference can be formed as compared with conventional methods such as the method in which a pattern on a fluorescent screen plate is copied by conventional electrostatic photographic methods, the method in which an electrostatic charge pattern is formed upon an insulative layer by direct gaseous discharge of electron beams, etc. Further advantages of the present invention are that the sensitivity is much improved and that operations can be performed even in ambient light.

What is claimed is:

l. Electrostatic image-forming apparatus comprising means operably responsive to information signals for emitting electron beams defining said image and plate means including a photoconductive layer and an electron beam transmissive conductive base underlying said photoconductive layer, said base intervening said electron beam emitting beams and said photoconductive layer, said electron beams rendering said photoconductive layer selectively conductive in accordance with said image.

2. The apparatus claimed in claim 1 including further means for applying to said photoconductive layer blanket radiation within the range of radiation sensitivity of said photoconductive layer.

3. The apparatus claimed in claim 1 wherein said photoconductive layer is a dispersion including cadmium sulfide and a binder material.

4. The apparatus claimed in claim 1 wherein said photoconductive layer is a dispersion including zinc oxide and a binder material.

5. The apparatus claimed in claim 1 wherein said photoconductive layer includes chalcogenide compounds.

6. The apparatus claimed in claim 1 including further an insulative member overlying said photoconductive layer.

7. The apparatus claimed in claim 6 including further means for applying to said photoconductive layer blanket radiation within the range of radiation sensitivity of said photoconductive layer.

8. The apparatus claimed in claim 7 wherein said insulative member is non-transparent to said radiation within the range of radiation sensitivity of said photoconductive layer.

9. A process for forming an electrostatic image by using apparatus comprising means operably responsive to information signals for emitting electron beams defining said image and plate means including a photoconductive layer and an electron beam transmissive conductive base underlying said photoconductive layer, said base intervening said electron beam emitting means and said photoconductive layer, said electron beams rendering said photoconductive layer selectively conductive in accordance with said image, said process comprising the steps of:

a. overlaying an insulative member on said photoconductive layer;

b. maintaining a potential of a first polarity across said plate means; and

1. while emitting said electron beams defining said image onto said base, 2. applying to said plate means a field tending to eliminate said first polarity potential, thereby forming said electrostatic image in said insulative member.

10. The process claimed in claim 9 further including a terminal step of removing said insulative member from said photoconductive layer, thereby increasing the contrast of said image formed in said insulative member.

11. The process claimed in claim 9 wherein said step of maintaining said potential of said first polarity across said plate means is practiced by applying charge of said first polarity to said overlying insulative member.

12. The process claimed in claim 9 wherein said step of maintaining said potential of said first polarity across said plate means is practiced by applying charge of said first polarity to said insulative member prior to practice of said step of overlaying said insulative member on said photoconductive layer.

13. The process claimed in claim 9 wherein said step of applying to said plate means a field tending to eliminate said first polarity potential is practiced by applying to said plate means a potential of polarity opposite to said first polarity.

14. The process claimed in claim 9 wherein said step of applying to said plate means a field tending to eliminate said first polarity potential is practiced by applying alternating current corona discharge to said plate means.

15. The process claimed in claim 9 wherein said photoconductive layer exhibits p-type semiconductivity and said first polarity is negative.

16. The process claimed in claim 9 wherein said photoconductive layer exhibits n-type semiconductivity and said first polarity is positive.

17. The process claimed in claim 9 wherein a surface lubricant is interposed between said overlying insulative member and the surface therebelow.

18. The process claimed in claim 9 including the further step of providing an insulative layer on a surface of said photoconductive layer prior to overlaying said insulative member on said surface.

19. The process claimed in claim 18 wherein a surface lubricant is interposed between said overlying insulative member and the surface therebelow.

20. The process claimed in claim 9 including the terminal step of applying to said photoconductive layer blanket radiation within the range of sensitivity of said photoconductive layer, thereby increasing the contrast of said image formed in said insulative member.

21. The process claimed in claim 20 including the further step of transferring said electrostatic image to a copying member.

22. The process claimed in claim 21 including the further step of visualizing said transferred electrostatic image on said copying member.

23. The process claimed in claim 22 including the further step of fixing said visualized image on said copying member.

24. The process claimed in claim 20 including the further step of visualizing said electrostatic image on said insulative member.

25. The process claimed in claim 24 including the further step of transferring said visualized image to a copying member.

member.

27. The process claimed in claim 24 including the further step of fixing said visualized image on said insulative member.

(SEAL) Attest:

McCOY M. GIBSON .JR. c. MARSHALL DANN Attesting Officer Commissioner of Pate nts UTTI ED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3,673,595 v I Dated June27 1972 Inventor(s) Eiichi Inoue et- 81.

It is certified that error app earsin the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Item [73], Titlepage, "Canon Camera Kabushiki Kaisha should read --Canon Kabushiki Keishacol; 3, line 39 "not" should read --no--. 3., line 'e'tf'iPFFfig'fri-ih0 d read --anthracene--.

Col'. 4, line 14, "adsorbed" should read --absorbed--.

139 l 7.19;. ar,'r' rshv uldumread.rriur Col. 9, li e ehould read Signedand sealed this-14th day of January 1975.

(mm Po-1050 (10-69) uscoMM-Dc 60376-P69 U.S. GOVERNMENT PRINTING OFFICE: 1969 0-366-334 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION- Patent No. 3,673, 595 v Dated June 27 1972 Ihventor(s) Eiichi Inoue et a1.

It is certified that errer appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Item [73] Titlepage, "Canon Camera Kabushiki Kaisha" 7 should read --Canon Kabushiki Kaisha-- Col; 3, line 39, "not" should read --no--.

Col. 3,

line ??%9ep.'v'..ho d ead --anthracene--.

Col. 4, line l-4, "adsorbed" should read "absorbed".-

.LCQ ,uwlsi sm79 'V' r". sh ulslnreraslnrziur U C 01. 9, lirle shoul read "7' V--.

Signed and sealed this 14th day of January 1975.

(SEAL) Attest:

McCOY M. GIBSON JR. 0'. MARSHALL DANN Attesting Officer Commissioner of Patents PC4050 USCOMM-DC scams9 US. GOVERNMENT PRINTING OFFICE: 969 0-366335

Claims (27)

1. 2. applying to said plate means a field tending to eliminate said first polarity potential, thereby forming said electrostatic image in said insulative member.
2. 2. The apparatus claimed in claim 1 including further means for applying to said photoconductive layer blanket radiation within the range of radiation sensitivity of said photoconductive layer.
3. 3. The apparatuS claimed in claim 1 wherein said photoconductive layer is a dispersion including cadmium sulfide and a binder material.
4. 4. The apparatus claimed in claim 1 wherein said photoconductive layer is a dispersion including zinc oxide and a binder material.
5. 5. The apparatus claimed in claim 1 wherein said photoconductive layer includes chalcogenide compounds.
6. 6. The apparatus claimed in claim 1 including further an insulative member overlying said photoconductive layer.
7. 7. The apparatus claimed in claim 6 including further means for applying to said photoconductive layer blanket radiation within the range of radiation sensitivity of said photoconductive layer.
8. 8. The apparatus claimed in claim 7 wherein said insulative member is non-transparent to said radiation within the range of radiation sensitivity of said photoconductive layer.
9. 9. A process for forming an electrostatic image by using apparatus comprising means operably responsive to information signals for emitting electron beams defining said image and plate means including a photoconductive layer and an electron beam transmissive conductive base underlying said photoconductive layer, said base intervening said electron beam emitting means and said photoconductive layer, said electron beams rendering said photoconductive layer selectively conductive in accordance with said image, said process comprising the steps of: a. overlaying an insulative member on said photoconductive layer; b. maintaining a potential of a first polarity across said plate means; and c.
10. 10. The process claimed in claim 9 further including a terminal step of removing said insulative member from said photoconductive layer, thereby increasing the contrast of said image formed in said insulative member.
11. 11. The process claimed in claim 9 wherein said step of maintaining said potential of said first polarity across said plate means is practiced by applying charge of said first polarity to said overlying insulative member.
12. 12. The process claimed in claim 9 wherein said step of maintaining said potential of said first polarity across said plate means is practiced by applying charge of said first polarity to said insulative member prior to practice of said step of overlaying said insulative member on said photoconductive layer.
13. 13. The process claimed in claim 9 wherein said step of applying to said plate means a field tending to eliminate said first polarity potential is practiced by applying to said plate means a potential of polarity opposite to said first polarity.
14. 14. The process claimed in claim 9 wherein said step of applying to said plate means a field tending to eliminate said first polarity potential is practiced by applying alternating current corona discharge to said plate means.
15. 15. The process claimed in claim 9 wherein said photoconductive layer exhibits p-type semiconductivity and said first polarity is negative.
16. 16. The process claimed in claim 9 wherein said photoconductive layer exhibits n-type semiconductivity and said first polarity is positive.
17. 17. The process claimed in claim 9 wherein a surface lubricant is interposed between said overlying insulative member and the surface therebelow.
18. 18. The process claimed in claim 9 including the further step of providing an insulative layer on a surface of said photoconductive layer prior to overlaying said insulative member on said surface.
19. 19. The process claimed in claim 18 wherein a surface lubricant is interposed between said overlying insulative member and the surface therebelow.
20. 20. The process claimed in claim 9 including the terminal step of applying to said photoconductive layer blanket radiation within the range of sensitivity of said photoconductive layer, thereby increasing the contrast of said image formed in said insulative member.
21. 21. The process claimed in claim 20 including the further step of transferring said electrostatic image to a copying member.
22. 22. The process claimed in claim 21 including the further step of visualizing said transferred electrostatic image on said copying member.
23. 23. The process claimed in claim 22 including the further step of fixing said visualized image on said copying member.
24. 24. The process claimed in claim 20 including the further step of visualizing said electrostatic image on said insulative member.
25. 25. The process claimed in claim 24 including the further step of transferring said visualized image to a copying member.
26. 26. The process claimed in claim 25 including the further step of fixing said transferred visualized image on said copying member.
27. 27. The process claimed in claim 24 including the further step of fixing said visualized image on said insulative member.

Images