DE2021386A1 - Method and device for electrophoretic imaging - Google Patents

Description

Patent attorneys Dipl.-Ing. F. Weickman, Dr. Ing.A / Weickmann

Dipl.-Ing. H. ¥ eιckmann, DiPL.-PHys. Dr. K. Fxncke Dipl.-Ing. F. A-Weickmann, Dipl.-Chem. B. Huber

8 MUNICH 27, DEN

MÖHLSTRAS5E 22, CALL NUMBER 48 3921722

XHA ■ - · ■■. :

XEROX CORPORATION, Rochester, FoYo 14603, V.St.Ac

Method and device for electrophoretic imaging

The invention relates to a "method and a device for electrophoretic imaging with an electrophoretic Image suspension, which in an electrical PeId between a first electrode and a barrier electrode is irradiated with image-wise distributed, activating electromagnetic "radiation.

In electrophoretic imaging, light-sensitive, radiation energy absorbing particles are used, which presumably assume a charge when suspended in a carrier liquid brought two electrodes and exposed them to an image-wise distributed radiation «A detailed description of such a thing The method is found in U.S. Patents 3,384,565, 3,384,566, and 3,383,993. The particles migrate in an imagewise fashion Spread through the suspension and create a visible image on one or both electrodes. Particles are used which are sensitive to light and evidently when exposed activating radiation experience a change in their own charge through interaction with one of the electrodes. For multicolor image Can produce different mixtures of two or more more differently colored types of particles as well as

009846/1638

loops with different sensitivity spectra are used will. The colors can be used independently of each other or in an aubtractive color synthesis » In a single-color process, the particles migrate when energy of each wavelength in the panchromatic spectrum of the Partial sensitivity hits the particles.

It has been found that images produced by the method described above occasionally show a non-uniformity of algae Show density or no constant contrast »Furthermore, the image generation device sometimes becomes during the imaging damagedο It is believed that these difficulties by varying corona discharge or air ionization between the electrodes during imaging, as one electrode is attached to the particle suspension approaches close to the other electrode »

To avoid the corona flashover between the electrodes in electrophoretic imaging, various proposals have been made. A corresponding method has been made is described in British Patent 1,174,831, it operates with one between the barrier electrode and the injecting one Electrode of an electrophoretic imaging device introduced before the generation of the electric field Liquids

Further procedures to avoid coronavirus rollovers or Air ionization between adjacent electrodes during imaging has been suggested. In one proceeding an element is arranged in front of or behind the contact area formed during the image generation with the electrodes, which element causes the air ionization between a Electrode and the element instead of between the two electrodes occurs · This will generally be a. Oorona oversole completely avoided «Another method used

009846/1638

- ■ 3 - - ■ .-. ■■■■■■. ■■

βϊήέ SpitreiX Elektröde with an electrical pad that is commutated behind "the barrier electrode surface. This Commutation of the locking electrode --- is carried out in such a way that at the beginning and at the end of the contact area formed between the two electrodes the electric field for one Corona-tJbersohlag is too weak

Another known device of the type mentioned above is described in British Patent 1 H9,665. With this device, the electric field is within the entire contact area of the electrodes and above also maintained with appropriately designed electrical connections ·. However, a corona flashover can occur not avoided in the area of close proximity of the two electrodes will· ,

The object of the invention is the Elektrophoretisohe To improve imaging in such a way that a corona flashover between the electrodes can no longer occur. This applies in particular to such arrangements with a large contact area between the two electrodes work · In the improved method, the blocking electrode can be used repeatedly or only once, as desired.

For a method of the type mentioned at the outset, this object is achieved according to the invention in that a blocking electrode with a surface that touches the image substance suspension over a large area in a contact zone over the surface with the image substance suspension The first electrode provided is unrolled and the contact is thus moved over the image suspension and that the electric field on an area within the contact zone is restricted. .

This process is compatible with all electrophoretic images

BATH ORIGINAL

generation facility feasible · There is only one Modification required to the effect that the electrical voltage is switched on to the blocking electrode in such a way that the electric field within the contact zone of the two electrodes is restricted. This is on the edges of the contact zone there is no longer an electric field that could generate air ionization or a corona flashover «,

The invention also provides a device for implementation of the above-mentioned method, which is designed in such a way that a connection device for the connection is provided between the electrical voltage source and the blocking electrode, which forms an electrical Field in an area within the contra zone between Locking electrode and image fabric suspension causes.

The invention is described below with reference to the embodiments shown in the figures. Figures 1-3 show embodiments of devices for performing the method according to the invention _o

1 shows a photoelectrophoretic imaging device with an injecting electrode 10, "which consists of a transparent glass base 12 and an electrically conductive layer 14 applied to it. The glass and the coating layer are optically transparent. For this purpose, a glass coated with tin oxide can be used, for example which is commercially available under the name NESA glass available from Pittsburgh Plate glass Co. ₀ Any other suitable arrangement can be also used _e on the injecting electrode 10 is a thin layer 16 is disposed finely divided photosensitive particles in a non-conductive carrier liquid This is the image material suspension required for image generation. '

009846/1638

BATH ORIGINAL

- 5 - ■■ '■'. ■■■.

Near the electrode 10 and the suspension 16, a barrier electrode 18 is provided, the barrier layer 20 on several leadership role]! 22, 24 and 26 is arranged. This lead the layer 20 such that it extends over the entire width of the electrode 10, they form a caterpillar-like arrangement which, when driven by a motor M-1, extends over the injecting electrode 10 moved away. This places parts of the barrier layer 20 on the surface of the injecting Electrode applied and removed from it. Of the The person skilled in the art is able to drive the barrier electrode arrangement known and is therefore not further described

In the following, a "light-sensitive" particle "shall be used such a particle can be understood that after initial Binding to the injecting electrode when exposed to an electric field and an activating electromagnetic field Radiation changes its polarity and differs from the injecting one Electrode drifts. An "injecting electrode" is an electrode that apparently charges in light-sensitive Injected substances that are activated by electromagnetic radiation in an electrical field. A "blocking electrode" is an electrode that is activated on contact with photosensitive particles do not have a charge in so many Particles injected that these migrate from her. A "suspension" is to be understood as meaning a system that consists of in a solid, a liquid or a (Jas dispersed Consists of solid particles. The ones described below Suspensions consist of those dispersed in a carrier liquid Solids. A more detailed theoretical explanation of the processes involved in electrophoretic imaging can be found refer to the aforementioned US patents.

The barrier electrode assembly includes three roles that are used to Serve storage and guidance of the electrode tape. The outer

0098Λ6 / 1638

Ren rollers 22 and 26 are made of any material that is preferably hard and relatively rigid Properties are not critical, but the outer rollers 22 and 26 should advantageously be made of a conductive material Substance exist and the potential of the conductive surface 14 of the injecting electrode 10 lead. This causes accumulations of charge avoided on the surface 20 of the barrier electrode. The middle roller 24 is said to have a conductive core have or consist of conductive material and touch the inner surface of the barrier electrode material 20, wel- ^ ches is a material with a high dielectric constant. For example, Tedlar, a polyvinyl fluoride from E.I. DuPont de Nemours Co., Inc., Can be used. the Roller 24 is connected to a voltage source via a switch 30 28 connected. An electric field is created between the injecting electrode 10 and the conductive roller 24, when switch 30 is closed. The blocking electrode surface 20 and the suspension are located between the two 16.

The electric field is generated in the region of the roller 24 when the blocking electrode arrangement 18 is moved over the suspension 16 on the injecting electrode 10. This ψ movement is represented by an arrow. The image is generated with a projection system that consists of a light source 32, a slide 34 and an optical system 36. It projects an image of the slide through the injecting electrode 10 onto the suspension 16.

In Fig. 2 is a device for photoelectrophoresis Represented image generation that works according to the method according to the invention and whose blocking electrode has the shape of a « changeable belt 58 has. The injecting electrode 10 is designed as a cylinder. On a circumferential surface 40 are Different for the implementation of the fotoelectrophoretisohen Processed required® process ata-feions seen. There-

009846/1638

• 2Q2138S

to belongs to a device 42 for supplying an image material suspension 16 from a container 44. A line 46 brings the suspension to a feed element 48, with the one more or less evenly thin layer of the suspension 16 is generated on the injecting electrode 40

To irradiate the suspension with activating electromagnetic isolating Radiation in the area of the blocking electrode 18, an optical system is provided. This contains a radiation source 50 and a positive film 52 between the barrier electrode ίο and the injecting electrode 40 with the optics 54 and mirrors 55 and 56 is imaged · It can be here any other suitable optical system can also be used, that in the contact zone 57, which creates a large-area contact between the electrodes, images an image.

The barrier electrode 18 is a tape 58 made of a material with high dielectric constant and a specific resistance

stood by more than 10 ohm cm. This tape is from a supply roll 60 over the guide roll !! 62 and 64 guided on the take-up roller 66 between the guide rollers 62 and 64, which hold the tape 58 on the cylindrical electrode surface 40, is a device for generating an electrical Field provided. In the case shown, this is a corona discharge device in the form of a corotron 68, which with a (not shown) electrical voltage source connected is and between the barrier electrode tape 58 and the injecting Electrode 40 generates an electric field running through the suspension 16. The corotron or one similar device may be a direct current or an alternating current discharge for the field at the barrier electrode.

The guide rollers 62 and 64 are preferably conductive and have the same potential as the injecting electrode 40. This creates a corona overlay between the belt 58 and

009846/1638

BATH ORIGINAL

of the surface 40 of the injecting electrode 10. Typical voltages used in this device during exposure are in the range between 300 and 5000 volts between the electrode surfaces near the corotron 68 _O since the tape 58 has a high dielectric constant and

7 due to its specific resistance of 10 ohm cm or

is more non-conductive, the electric charge spreads of the belt 58 near the corotron 68 does not over the edges the contact zone 57 between the strip and the surface fe 40 of the injecting electrode 10. The corotron can be used to Avoidance of an electrical flashover to rollers 62 and 64 must be shielded if the voltages and clearances are such that flashover could occur.

The exposure of the photoelectrophoretic suspension takes place in the area between the belt 58 and the electrode surface 40, where an electric field sufficient for image generation must be present during the exposure. This area is the contact zone. Its extent is denoted by 57. The electric field is restricted exactly to the boundary layer between the belt 58 and the electrode surface 40 so that ea does not exist at such locations where the electric w to yet Sindo over the range 57, the take-up reel 66 is driven such that the Band 58 is in rolling contact with the surface 40 of the injecting electrode 10 in the direction of the arrow shown.

The image 72 for the final copy is fed to an adhesive tape 74, which with the guide rollers 76 and 78 against the injecting electrode is depressed. The image 72 is transferred onto the adhesive tape 74 in this way then fixed by placing a film or in a suitable fixing chamber 80, for example by the action of heat will·

In Figure 3 is a further embodiment of a device

009846/1638

BATH ORIGINAL

for carrying out the method according to the invention, which is modified compared to the arrangement shown in FIG Blocking electrode 18 works. The tape is over as flat Plate-shaped injecting electrode 10 led away. Although the advantage of continuous image generation according to FIG. 2 is not achieved with this device, the The function of the device is similar to that shown in FIG. because the blocking electrode surface 82 with a high dielectric constant is in rolling contact with the suspension 16 on the conductive surface 14 of the injecting electrode 10.

The guide rollers 84 and 86 cause contact between the electrode surfaces within a moving contact zone, they can be conductive, but this is not absolutely necessary. They preferably carry the potential of the conductive Surface 14 of the injecting electrode 10 to prevent the formation of oorona flashovers between the two surfaces to avoid. The commutator bar 88 is connected to a high voltage source which generates a voltage of approximately 300 to 5000 volts relative to the injecting electrode 10. Furthermore, the rail creates a pressure within the contact zone ο The exposure takes place in connection with Fig.1 described manner. The commutator rail88 holds the electric field on an area within the contact zone between the blocking electrode surface 82 and the conductive surface 14 of the injecting electrode 10. The order is adjusted in such a way that no air ionization and no corona flashover occurs at the edges of the contact zone.

The invention has been described above on the basis of exemplary embodiments, but is not limited to these. Al-

009846/1638

■■■ · ' ^ßA0

- ίο -

le within the scope of the following claims other possible embodiments or further developments are encompassed by the basic idea of the invention.

009846/1638

SAD ORIGINAL

Claims (11)

- Tt - Claims Method for electrophoretic imaging with a electrophoretic image suspension in a electric field between a first electrode and a blocking electrode ir> i.t image-wise distributed, activating electromagnetic radiation is irradiated, characterized in that a blocking electrode (18) with one the image substance suspension (16) in a contact zone large area in contact with the 3ildatoffauapension (16) provided first electrode (10) unrolled and thus the contact zone over the image material recess (16) is moved and that the electrical Field is restricted to an area within the contact zone. 2. Einricntung for carrying out the method according to claim 1, iiiit a provided with the image suspension first electrode, a blocking electrode rollable thereon, an irradiation device and an electrical voltage source that can be connected to the electrodes, characterized in that a connection device (30) for the connection between the electrical voltage source (28) and the blocking electrode (18) is provided, which causes the formation of an electric field in an area within the contact zone between the blocking electrode (18) and the 3ildstoffsuspension (16). Device according to Claim 2, characterized in that the blocking electrode (18) is provided with a flexible, electrically relatively non-conductive surface which is adapted to the shape of the first electrode (10) by means of guide devices (62, 64) in the contact zone, and that the 0 0 9846 / 1.R3R Switch-on device on the first electrode (10) facing away from the barrier electrode (18) between the Guide devices (62, 64) is arranged 4. Device according to claim 2 or 3, characterized in that the blocking electrode (18) has a flexible endless Surface (.20). 5. Device according to claim 4, characterized in that that the endless surface (20) has a cleaning device | i for removing accumulated image suspension (16) is assigned, 6. Device according to one of claims 2 to 5, characterized in that the blocking electrode (18) as a band (58) is trained··- 7. Device according to claim 6, characterized in that the tape is removed from a supply roll (60) and fed to a take-up roll (66) after imaging will. 8. Device according to one of claims 2 to 7, characterized in that * indicates that one of the electrodes (10, 20) has a drive device (M-1) for moving the blocking electrode surface (20) so movable in a predetermined direction relative to the first electrode (10) in rolling contact i3t that the contact zone moves over the image substance suspension (16) provided on the first electrode (10) and each time new parts of the electrode surface (20) form the contact zone. 9. Device according to claim 8, characterized in that daduroh the blocking electrode (18) with a movable with it 009846/1638 - .13 - Bracket (84, 86) '' is provided, which holds the Arischaltungvorrichtung (88) and carries it so that it is within the contact zone is passed over the image material suspension (16) o 10. Device according to one of claims 2 to 9, characterized in that that the voltage acting on the blocking electrode (18) is caused by an alternating current Oorona discharge is produced. 11. Device according to one of claims 2 to 9, characterized in that that the voltage acting on the blocking electrode (18) is caused by a direct current corona discharge is produced. 00 98 467183 8