DE1965460B2 - Photoelectrophoretic imaging method and apparatus - Google Patents

Description

trode is brought, and that between the

first and second electrode during the pictorial The invention relates to a method for photographic Exposure existing electric field 30 electrophoretic imaging in which on the the potential difference thus formed creates an electrically insulating surface of a first, von will. at least two electrodes, at least of which

3. The method according spoke 1, thereby a partially translucent, continuous and indicates that the between the first and uniformly an electrophoretic image material dispenser second electrode during the imagewise 35 sion with therein finely divided particles with the help of a Exposure existing electric field applied by to- coating device and with a additional application of a direct voltage between the second electrode is brought into contact, zwider first and second electrode is generated. see the first and second electrodes

4. The method according spoke 3, thereby ge image substance suspension penetrating electric field indicates that with repeated image generation 40 generated and the image substance suspension through the light gen the transparent electrode is exposed imagewise during the imagewise exposure, as well as existing electric field by renewing how. a device for performing this switch-on experience of the additional DC voltage.

is procreated. One such method in which a conductive

5. Device for carrying out the method 45 injecting electrode, a non-conductive locking element according to one of the preceding claims, trode and light-sensitive particles, dispersed in a non-conductive carrier liquid with a first, a locking electrode surface, between the electrode having a coating electrode , enables the highlighting to apply an image fabric position of excellent images. Most of the poly-suspension layer on this electrode is assigned 50 meren substances, which are used as a barrier layer on one electrode, with a second, on which the first electrode is used, have a specific opposite side of the image substance suspension layer standing from 10 ⁸ to 10 ¹⁵ ohm-cm or more. The arranged electrode, and with a device with a lower resistivity device for image-wise distributed irradiation of 10 ⁸ to 10 ^IZ ohm-cm, for example barite image suspension with activating electro-paper, allow the generation of excellent magnetic radiation while an electrical neter pictures, however, are sensitive to moisture. Maintain the field between the electrodes (their specific resistance changes as a function of the , 15) envisaged 60 image products to be cleaned. Blocking electrodes. layers with higher resistivities and

6. Device according to spoke 5, marked lower sensitivity to moisture are net by an additional device for Er- therefore preferably used. These substances produce a direct voltage between the first specific resistance at 10 Ω · cm or higher and the second electrode (1, 5). 6 _S , for example Mylar and Teflon, lead however

7. The device according to spoke 5 and 6, in addition to an increasing deterioration of the image characterized in that to create a quality, especially when generating several images DC voltage to the coating device with one electrode in quick succession. For the blocking

The electrode layer are therefore many different types of insulation. Are, however, already a device mr generating at turning one and the same electrode multiple images photoelektrophoretischem paths images produced Jn produced rapid succession under encryption, so decreases proposed because of La, dung storage in which at least two electrodes during each image formation, the 5 are provided , of which at least one for an image quality, the higher the specific resistance of the electromagnetic radiation is permeable, wherein is barrier electrode layer. It is believed that one of the electrodes is a barrier electrode and that this is due to an accumulation of undesirable charges, the other electrode is an injection electrode, and is due to the barrier electrode. Example - where a first electrode is designed as a known polymeric material with an electrode rotatable and ^{movable over a range of two-specific resistance of about 10 '3} or th electrode, with IQi'Ohm · cm when used as a roller Blocking electrode devices for generating an electrical layer of iron address this problem. des between the electrodes and with facilities

From the French patent 1 521 727 a photoelectrophoretic imaging method is already known for irradiating the electromagnetic radiation in a vertical distribution by means of a jet method in which two mutually permeable electrodes and one between the electrodes in the form of cylinders are present - Electrodes located suspension are seen from photoelectro, on one of which with the help of a plioretic particle and with an image material suspension with an electrode interacting with the first coating device suspension application therein is applied finely distributed particles, ao is a device for continuous application of at least one of the two electrodes light-permeable suspension layer on this cst electrode, being casual, so that the image to be reproduced by the suspension application device at least two of these electrodes jetted into the image material suspension is rotatable in a holder gerte order sticks can be. During the imaging process, the circumference of which is in each case with the surface, an electrical field is generated between the two electrodes, i.e. the rotatable first electrode is in contact. However, this known method also has the disadvantage already explained above, between itself and the first electrode, of forming a storage space for the suspension,
The present invention is now the task, if the barrier electrode layer were based on a material, a method of the type mentioned at the beginning with a high specific resistance used, with which the production of a plurality and if with such a barrier electrode layer from successive reproductions in rapid succession several images can be generated in quick succession with consistently high image quality. becomes possible.

The inventor has already done this in the case of a method of

DT-OS 1 949 120 a photoelectrophoretic exit mentioned type according to the invention thereby

education method proposed in which the image solves that with the help of a to the coating device

substance suspension to a first, charge carrier injection applied DC voltage to the insulating

rende electrode of two electrodes applied surface of the first electrode one substantially

and in which a uniform electrical charge is applied before the imagewise exposure,

and the generation of the electric field between 40. The method according to the invention has the essential

this first, injecting electrode and a third- borrowed advantage that reproductions with equal

th, in contact with the image substance suspension, good image quality can also be obtained

electrode brought a second electric field that can, if a storage / electrode layer with

same field direction as that of the first, the figure is used - a high specific resistance

Generation effecting electric field is generated. 45 and the reproductions carried out in quick succession.

In this way they can be led on the basis of them alone. It is believed that this

Self-charge to one or the other electrode is achieved by the fact that the coating

migrating image material particles in the image forming device applied DC voltage residual

suspensions that do not contribute to the formation of the image, removes or discharges charges on the blocking electrode.

and even disturb the images to be generated before they are equalized.

actual imaging process from the image material - The method is preferably carried out in such a way that

suspension must be removed. that the surface of the first electrode through the

In DT-OS 1 949 369, the inventor already proposed that the quality of the electrical charge applied to the charging device be increased to a predetermined potential and, in particular, to improve the color of the second electrode and saturation in the production of color images in that the between the first and the second electrophotoelectrophoretic imaging process this electrode during the imagewise exposure to carry out imaging processes in such a way that an electric field is generated between the thus formed potential difference photoelectrophoretic image material suspension. As a result, firstly, the residual charges are removed by the first electrode and at least voltage provided as a carrier for the image generated identically from the suspension 60 on the loading device, and a further electrode is exposed to an activating second wi / d in a single process step, and at the same time a sufficient charge is applied to the blocking electrode between the electrodes, around which the electric field is applied during the exposure-variable electric field Create an injection electrode halfway necessary for Ji's imaging.
Threshold remains. In this case, the procedure thus has an effect

5 ^ 6

going that the accumulation of residual charges is applied to the surface of the barrier electrode, for which purpose

the surface of the barrier electrode is prevented by a coating device 13, which

and that the barrier electrode for generating the image substance suspension to be selected is dimensioned in such a way that

The electric field required for image generation results in a uniform layer thickness. Thieves-

between the barrier electrode and the injecting 5 layering device consists of the rods 14

Electrode by contact with the coating and 15 as well as the pressure rollers 16 and 17. These

The device or elements are attached to a holder 18 via the image suspension. Above

will load. the upper part of the blocking electrode S is formed

According to another embodiment of the invention image material supply 19.

on the surface of the barrier electrode.

The charge brought on is only used to that which is on the "light-sensitive" particles in the following

Barrier electrode can be understood in successive steps every description of every particle,

to compensate for the remaining charge after the initial binding to the injecting one

rend the electrical field required for image generation electrode from this under the influence of an electrical

by means of a span applied between the electrodes, when an activating field acts

generated. For this purpose, the electromagnetic radiation between the electromagnetic radiation is first migrated. The picture

voltage applied to both electrodes switched off pulp suspension can also be a sensitizer

and then to neutralize the residual charges on and / or a binder for the pigment particles

the surface of the barrier electrode contain a DC chip, the binder at least partially

connected to the coating device, ao be soluble in the carrier liquid of the suspension

This DC voltage is then used by the coating.

processing device is switched off again and that for the while the blocking or image forming electrode 5

Image generation required electric field through the surface of the injecting electrode 1

the next time the voltage is applied between the blocking, switch 7 is closed,

electrode and the injecting electrode generated, as a result of the voltage source 8 on the image material

As a further advantage of the suspension 4 according to the invention, an electric field is generated. Of the

Driving it has been shown that the formation of spots on the core of the barrier electrode is connected to earth. the

on the image suspension layer during the on- pigment suspension is carried out with a projection

Bring to the barrier electrode surface avoided device exposed from a light source 21,

will. 30 consists of a see-through image 22 and an optical system 23.

A device for carrying out the invention. A color slide is used as a see-through image, according to the method with a first, a blocking elec- While the imaging roller over the surface Electrode surface having an electrode to which one of the NESA electrodes is guided, becomes an image material coating device to apply an image suspension from the supply 19 evenly onto the substance suspension layer assigned to the electrode 35 applied to the surface of the image generation electrode, is, with a second, on which the first electrode at the same time is connected by the connection of those facing away Side of the image suspension layer tension on the coating rod 14 the electrically arranged Electrode, and with a device tric field for image generation on the surface of the for the image-wise distributed irradiation of the image substance-injecting electrode and for the neutralization of the suspension with activating electromagnetic 4 ° residual charges on the surface of the barrier electrode Radiation while creating an electric field between. The exposure causes them to migrate initially the electrodes is maintained, is bound to the injecting electrode 1 and characterized in that a device for applying then irradiated particles through the carrier liquid a DC voltage to the coating device so that it is applied to the surface of the image generation is provided. 45 supply electrode 5 can adhere and on the upper

The invention is in the following closer to the palm of the injecting electrode a picture back-

of the figures shown in the drawing, which corresponds to the original image 22,

ben. It shows in Fig. 2 is a front view of the device

F i g. 1 shows the section through an embodiment for carrying out the method according to the invention

a device for carrying out the invention 50. The coating device 13, consisting of

according to the method, and from holder 18, coating rod 14 and pressure

F i g. FIG. 2 is a front view of the FIG. 1 roller 17 brings the image suspension 4 to the upper positions Contraption. surface of the blocking electrode 5. The injecting elec-

In Fig. 1 is a transparent electrode 1, electrode 1 consists of the conductive base 2 and which consists of an optically transparent glass 2 and 55 of the tin oxide layer 3 and is under the barrier element thereon applied thin and transparent trode 5 arranged between the coating layer 3 consists of tin oxide. Such a glass rod 14 and the injecting NESA electrode 1 are covered with a plate is referred to as a Nesa glass plate. This is an electrical connection via the already In the following, the electrode is described as the injecting elec- tric voltage source 8 and the switch 7. trode called. Near the injecting electrode 1 60 The injecting electrode should preferably be off a rotatable electrode 5 is arranged, whose conductive an optically transparent material such. B. Glass able core 11 consist with a layer of a non-conductive, which is coated with a conductive material such as. B. Barrier electrode materials 12 is coated. These elec- tin oxide, copper, copper iodide, gold or the like coated trode is fan following also as locking or picture is in order to achieve optimal results. Other generating electrode designated. A thin layer 4 65 suitable materials including many semiconductors such as the image suspension, which is made from remotely distributed, light- raw cellophane, which is not normally used as a conductor sensitive particles dispersed in a non- can be viewed, however, an intake of injected conductive carrier liquid, is as a coating on charge carriers of the appropriate polarity under the

Allow the influence of an electric field, can be applied to the barrier electrode

can also be used. The better conductive layer thickness is generally between about

Genetic substances, however, allow a better charge trend - 0.025 mm and about 0.15 mm, preferably at

and prevent possible charge accumulation- 0.1 mm. The respective coating rod is such

gene on the electrode that applied between the electrode 5 that he is on the barrier electrode surface

could weaken the generated electric field. Which, when touched, transmits a tension that the

The barrier electrode, on the other hand, is selected to prevent charge accumulation on the barrier electrode layer

neutralizes the injection of electrons into the photosensitive and that required for image formation

Pigment particles prevented or largely from electric field on the image suspension in contact, when the particles reach their surface. generated area of the two electrodes. Typical

The core of the barrier electrode generally consists of usable coating rods are rods made of conductive

made of a material with a high level of electrically conductive glass, made of conductive rubber and wire-woven

speed. Typical conductive materials are conductive rubber, celt sticks, known as Meyer spreading sticks

Metallioles made of steel, aluminum, copper or brass.

sing. However, if a material of low conductivity is used, a special electrical adjustment must be made, preferably the distance between the back of the barrier electrode layer and the electrode contact is less than 0.25 mm. A special barrier electrode with these values results in a better image overlay, although it is not absolutely necessary to provide a solution and, in the case of a multicolor process, a better one, however, improves the results of the image generation but more color separation. This improvement will be considerable. In general, the high field strength at the image material suspension should be returned to the electrode layer made of a material with a specific one of these small distances. Resistance of about 10 ⁸ ohm cm or more to serve to further explain the method, preferably values are in the range of the following examples. Proportions and percentages about IO "to 10" ohm cm. Favorable barrier electrodes relate to weight, unless otherwise materials are, for example, baryta paper, one with in one indicated. In this case, four different image substance gelatin solution suspended in barium sulfate are coated in a device of the type shown in FIG. 1 dargenes paper, polyvinyl fluoride and polyurethane. It put kind of used. The injecting electrode can, however, also contain other substances with the desired resistance. Typi- 30 earth is laid. The blocking electrode consists of a conductive hard rubber core of about 5 cm diameter coated with cellulose acetate, paper, polystyrene, polytetrafluoroethylene and polymer. which is covered with a tedlar layer. To the ethylene terephthalate. The barrier electrode layer can be designed as a special replaceable layer during the image exposure, a negative voltage of about 3000 volts, which is applied to the barrier electrode with mechanical fastening. The exposure takes place with a photographic element or in a similar way easily visible see-through image at a light intensity of approximately solidify and is thus kept in a simple manner. 19,370 lux. The image suspension consists of about The layer can also be used as part of the electrode 7 parts by weight of pigment particles, which are approximately trode themselves and are dispersed on the electrode 100 parts by weight of mineral oil. Glued, drawn on or sprayed onto the surface 40 Examples 1 and 2 will be used as a coating rod. Wire-wound metal rod is used, in the case of the above-described image generation games 3 and 4 a conductive rubber roller. The image steps are carried out repeatedly and the barrier substance suspension is cleaned on the surface of the barrier electrode in each case, but not discharged in front of the respective electrode with a thickness of about 0.08 mm in the image generation step Approximately 0.1 mm in the accompanying drop in image quality with increasing numbers of play 3 and 4 applied to the images generated. This deterioration has its own

Cause in the accumulation of undesirable electro- Example I static charges on the surface of the barrier electrode. For this reason, a voltage is applied to 50. A three-substance mixture is produced by

the coating device is switched on, which is dispersed in equal proportions of a cyan pigment

Roll-up ring with the barrier electrode layer or ment material from the alpha-form, metal-free phthalic

the one on the surface of the roller electrode in front of ancyanine, a magenta colored pigment

which substance stands, in general the value of a barium salt of l- (4'-methyl-5'-chloro-2'-sulfone-

connected voltage from the respective Vorrich- 55 acid) azobenzene-2-hydroxy-3-naphthenic acid and one

management and the desired results. It was yellow pigment from 1,2,5,6-di (C, C'-diphenyl) -

the voltages of 2000 volts and up to 7000 volts thioazole anthraquinone. As a carrier liquid

Connected to the coating device, mineral oil can be used. The ternary mixture is called

However, other voltage values can also be used to apply the coating, and the images produced with it

if they do not show any harmful effect. 60 are fully colored and correspond to the original

Operating voltage values are preferably in the transparent image, rich from about 4500 to about 5500 volts The use

iete coating device should at least more example Π ils a role for the distribution of the image suspension

include the barrier electrode. The number of the 65 A three-substance mixture is produced by dis-

The roles used, however, depend on the persion of the same proportions of the cyan pigment

iweck the respective imaging device converts 3,3'-methoxy-4,4'-diphenyl-bis (1 "-azo-2" -hy-

"" ^Ji is and with what strength the suspension is droxy-3 "-NaphthanÜid) of the magenta-colored pie-

ment substance from a calcium dye of l- (2'-azonaphthalene-l'-sulfonic acid) -2-naphthol, and the yellow pigment N-2 "-pyridyl, -8,13-dioxodinaphtho- (2, 1-6; 2 ', 3'-d-furan-6-carboxamide). Mineral oil is used as the carrier fluid. The three-substance mixture is used for image generation in the manner described above and results in fully colored images, which correspond to the original transparency.

Example! III

Seven parts by weight of the metal-free phthalocyanine described in Example 1 are with one hundred Parts of mineral oil mixed together. The obtained one-substance mixture is applied to a NESA electrode as a layer

10

applied and used in the manner described above for image formation. The result is a cyan color Image on white background.

Example IV

An image suspension is prepared from equal proportions of l - ^ '- chloro-S'-EthyW-sulfonic acid) -azobenzene-2-hydroxy-3-naphthenic acid, of the alpha form of metal-free phthalocyanine and of the yellow pigment mentioned in Example 2. as Liquid a kerosene fraction is used. The result is a fully colored picture, similar to the colored Corresponds to the original transparency.

1 sheet of drawings

Claims (2)

(14,15) and to generate a direct voltage "". ... - / wipe the first and the second electrode claims; ^ 15) a common device is provided 1. Method of photoelectrophoretic imaging is. “., *,;» »Hw
generation, in which on the electrically insulating 5 8 Vomchtung after emem the
Surface of a first, of at least two to 7, characterized by ^
Electrodes, of which at least a partial device (M. {f), "
is permeable, continuously and evenly wire-wound ^Met f ^st j * ^ f ™ · _An ... , an electrophoretic image suspension with 9. Vomchwng according to one of the speech 5 therein finely distributed particles with the help of a range to 7, characterized in that the Beschichschict tungsvornchtung applied and with a tungsvorchrung (14, 15) from at least one two electrode ω Contact is made, there is a conductive glass rod between the first and the second electrode 10 an elek to 7 penetrating the image suspension, characterized in that the! Coating Tric field generated and the image suspension 15 device device (M, 15) from at least one through the translucent electrode image-wise conductive rubber roller be-.tent is exposed, characterized Π. From one of the-Ap ^ uAe 5 that with the help of one to the coating device to 10, characterized in that the first DC voltage applied to the insulating electrode (5) from a rotatable roller shape rende surface of the first electrode consists of an in 20 electrode. substantially uniform electrical charge 12. Device according to one of Claims 5 is applied to 11, characterized in that the 2. The method according to claim 1, characterized in that the surface of the first electrode (5) applied image substance is characterized in that the surface of the first electrode layer has a thickness between 0.025 and ^{15 mm and} preferably 0.1 mm via the coating device , applied electric charge to a predetermined potential with respect to the second elec-