DE2333877A1 - DEVICE FOR DEVELOPING AN ELECTROSTATIC LATENT IMAGE - Google Patents

Description

Patent attorneys

Dr. Ing.Walter Abitz

Dr. Dieter F. fvlorf 2333877

Qr. Hans-A. Browns

8 Munich ob, PicnzöiUUöTStr. 28 ■ »^ J ₁ Qi 1973

■■■ ".. ■ 2239

ITEK CORPORATION

IO Maguire Road, Lexington, Massachusetts, V. St. A. Device for extracting an electrostatic latent image

The invention relates to an electrophotographic Apparatus, particularly an improved apparatus for developing electrophotographic express dem, toi the solid developer jr.ater.ial on latent electrostatic Images is applied to the surface of an insulating layer »

Eci the 'usual' processes that elctrcphctoerarhie a conductive pad with red hotconductive on it insulate the layer in a hurry, because the surface is initially uniformly electrostatic is charged and then the charged surface with a pattern of a cuetivierencen electrcrafnetischen

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Radiation, such as a light pattern, is illuminated »Das ■ Radiation pattern selectively moves into the illuminated zones Electrostatic charges on the photoconductive surface, creating an electrostatic latent image in the non-illuminated areas. This electrostatic latent image can then be developed into a visible image be opposed by being finely divided charged electroscopic marking particles, in general referred to as "toner" on the surface of the photoconductive insulating layer. Developed toner images can be melted onto the insulating layer or transferred to another carrier, such as plain paper and melted there. -

Provide solid electrophotographic developer substances generally two-component systems consisting of finely distributed Toner particles and, on the other hand, larger and coarser ones Träp.erperlen exist. Toner particles and Ti army pearls are chosen or modified to be triboelectric are uneven, so that each of the two tribes is triboelectric generated charges are caused during the development process. In addition, the components are selected so that the toner with triboelectric Charges are provided whose signs are opposite to that of the electrostatic charge pattern to be developed. ^ Lie toner particles, thus adhere to the toner particles vreren their opposite electrostatic. Charge and due to van der Aals forces until it is mechanically be shaken and by the opposite and stronger electrostatic charges towards d3r Trap developing insulating surface.

At a. Prior art type of development apparatus utilizes a conveyor belt that attaches magnetic developer material to a photoconductive roller

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with an electrostatic egg on it brings. -That's a kind of magnetic development •Brush. For other devices for solid developer substances if you apply the fiozbrush development, pressure development and dust cloud development *

The most common method of developing; electrostatic latent images with such two-component development. substances is known as "cascade development" tknow. Eei normal cascade development, the developer is guided so that he under the action of gravity over the surface carrying the electrostatic charge flows in order to bring about the image development, characteristic toner-charged Carrier pearls flow over the photoconductive surface and meet with it, the toner is removed from the carrier pearls stripped and placed on the plate surface according to the pattern of the latent electrostatic thereon Image deposited,

In the usual downward cascade development, the image-bearing photoconductive surface and the flow of two-component developer material move in the same direction are no longer in electrostatic equilibrium, have a second important effect, which is the removal of unneeded toner from the substrate or the unimaged areas on the plate surface; this process is often called "rinsing". .described., net. , .- "..._ ■■■ -." - -. "■ -". ' - -..-. -.- -

It is true that one can use the downward rKa'skaden development method generally address as useful, but occur ..

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numerous significant difficulties and / or limitations that have not yet been eliminated. There are numerous modifications to the cascade downward development process made in order to eliminate the disadvantages mentioned, for example the following has been tried: ■ "" ■ ".

Many cascade developing devices have electrical bias developing electrodes that are stationary metal sheets held close to and parallel to the surface of xerographic plates have been used, which were electrically connected to the metal base of the plate. The development electrodes serve to change the field configuration of the electrostatic image to change and the field in the space above large fully filled Reinforce cargo areas. The reproduction of high-quality uniformly tinted and large, all-over black Areas can be improved significantly as a result. On the other hand, developing electrodes cause other difficulties for example "blocking", which means a gradual build-up of developer on the electrode surface. This has a negative effect on the effectiveness of the electrode and, if it occurs very strongly, even the The passage of further developers through the development zone must be blocked. In extreme cases it can be sensitive Photoconductor surface can be scratched by developer substance.

Another attempt to improve cascade development is described in U.S. Patent 3,611,992 (Lyles), according to which the cascade development device is designed so that the xerography drum is rotated in a direction opposite to that of the cascade developer. This type of development is common as "Aüfwärts" cascade

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development. However, this procedure only has insignificant successes can be achieved because the surface of the photoconductive drum is very smooth and not is suitable, the effects of gravity influencing the developer to change significantly, and because the developer in some way after going through a short Entry zone seeks to fly away from the drum so that the drum does not touch the developer for most of its fall path leading back into a container,

Although extensive investigations have been made are to use the classic cascade development method improve, serious problems could not be solved.

The main problem is that of the use of gravity alone, because of that fact the area was the points at which the developer material of the xerography drum ' supplied and withdrawn from it, is considerably narrowed, i. e. the feed must be near the highest Place of the drum. Methods according to which a longer contact time between the electrostatic images and the developer should have at the. Cascade development has so far found little application. Most important, however, is the lack of control over the important parameters of the cascade development process, If only gravity controls the flow of developer particles.

Recent studies on the cascade development hal-en y shown that there are certain Steuerparareter. These can be classified into three main categories: Cl) defective properties, such as toner and carrier measurements and distributions, ratios of the frictional electrical charge, adhesive forces between toner and carrier,

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concentration etc .; (2) dynamic parameters such as carrier density , Carrier tangential velocity ,, Trä pe rraci al velocity , Carrier angular velocity, etc .; and (3) design parameters such as development time, length Development range, preload heights, etc. usual cascade development one can see the traveled developer properties monitor well. V.'if you also have some control over the construction and dynamic Parameters in normal cascade development can be>, if this is limited to a control outside of the latent electrostatic image, the probability is nonetheless a development event, i.e. the trapping of a toner particle by the electrostatic latent image, largely dependent on the ability to defrost and dynamic parameters of the developer at the control electrostatic image. In order to fully control the development process, it is therefore necessary to some control over these parameters at the, latent to be able to exert electrostatic images.

The preferred embodiment. the invention can be refer to as a mechanically operated cascade processor for xerography. This includes a moving one Conveyor belt> that is close to and parallel to a section moving the photoconductive insulating surface; the drum is often a glass-like one Selenium drum. Dair.it will be a development scene between deir. Tape and the insulating surface. An elctrrskopischer Carrier pearl and toner particle developer is introduced at the top (inlet) end of these teeth and after Execution of the development occurs the developer ar. Practitioner the end. The tape is in the longitudinal direction bi-2 £ ssn, so c-λλ es . the shape of the phctcleiter-dan Isolierfluche ar.z ^ r.asren capable, ater is preferably semi-rigid in the transverse direction,

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so that it has a constant distance from the drum surface over its entire width.

It can be seen that this mechanically operated cascade processor gave the designer of a copier new freedom in terms of width. Limitations that have hitherto faced cascade development equipment, including the choice of the points at which the developer could be introduced and the placement of the device itself avoided or reduced because the flow of the developer is only partially dependent on the effects of gravity. For example, the developer no longer needs the the top of a xerography drum introduced to because the found can be routed around other sections of the drum. This allows the tape to wrap around sections of the Trornmelmantels are performed outside of the areas lie, a-n which gravity has its maximum effect on the sirrom of the developer substance, and / or the actual The length of the development zone can be increased. Furthermore, the effective length of the development zone can be thanks increased turbulence. All these · factors lead to-the development of xerographic Images can be taken at a higher speed, so that the number of copies per minute can be enlarged or a corresponding development speed with smaller xerography tubules can be achieved, resulting in lighter, more compactly built. Copy machines can lead. -. - '

Most importantly, the control of the dynamic Parameters on the electrostatic latent image can, veil the developer between two moving surfaces flj & t, namely between the moving Fand and the

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photoconductive, insulating surface, because of the development zone surrounding moving boundaries, the turbulence is significantly higher than if they were just through Gravity flow of the developer is caused. Increased turbulence · in the development zone, however, means Better separation of carrier and toner, which means more activated toner near the photoconductive surface becomes available for development, which increases development efficiency. Activated toner is through the mechanical Shaking generated in the developing zone and that it makes it easier for the "latent image to overcome the electrostatic and van der Waals forces, which hold the toner particles on the carrier beads. An increased turbulence also leads to a more uniform one Development within the entire development zone and also avoids the directional effects that often ta. encountered the known cascade developing devices are.

Increased turbulence is seen in the developing device described herein achieved by changing the tape speed and direction to include all speed vectors of the one flowing through the development zone Change developer. For a specified developer throughput, the average tangential velocity the carrier in the zone can be lowered by moving the belt in the opposite direction, whereby the the average carrier density in the zone is increased; the average Decrease carrier density by driving the belt in advance so that the average tangential speed That is, the carrier density, i.e. the number of carrier beads per unit volume the development zone, can be controlled by adjusting the direction and speed of the belt

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Furthermore, the average tangential velocity of the carriers, which is normally entirely dependent on the Gravity is influenced, can be controlled by changing the speed and direction of travel of the belt «The Indeed, tape movement affects all components of the carrier speed,

Radial and angular velocities are increased because of "reflection" from carriers on the belt. That is particularly noteworthy in the event that the tape is moved in the opposite direction.

It has been found that there is a particular advantage in moving the belt in a direction which is opposite to the direction of gravity acting on the carrier beads, i.e. in the "opposite" direction. In this mode of operation, the tangential speed of the carrier can be reduced, thereby reducing their natural Tendency to accelerate their movement and to move away from the drum surface, · is overcome. Through this There is of course an improvement in development and better rinsing because the carrier and toner are within the entire development zone for a much longer period effective period of time remain in the vicinity of the photoconductor. Since the carrier density can be increased, a corresponding reduction in the mass throughput is possible, resulting in less friction between Trorir.elfläche and toner, makes the machine run more smoothly, and extends the life of the developer. In addition, the turbulence of Carrier and toner particularly increased, because the opposite direction of the movement of the fenders creates this instesondere vertical curl Confers angular velocity components.

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The risk of loosening is also eliminated or substantially reduced mechanically by the inventive method operated cascade developing device. This is because (1) in the developing zone, a much higher one Turbulence occurs and (2) both walls of the development zone are in motion.

The overall result of the novel control of cascade development parameters in the development zone provided in the mechanical cascade development device described herein, is a quieter operation of the machine, better operational safety ι better quality development and higher development speeds or instead constant development speeds at smaller ones and more compactly built photoconductive drums, the machine can be quieter because of lower mass throughputs of Developer material can be applied and it is more reliable because of blocking and similar difficulties be avoided. A qualitatively better development is achieved because of the higher turbulence, and a higher one optical density in the image areas and better rinsing in the underground areas result and also to avoid it of directional effects. Finally, higher development speeds can be achieved, or one can instead, ir.it smaller at constant speed Drums work because the increased turbulence increases the likelihood increases that a development occurs because the developer practically over the entire development zone is held in the vicinity of the photoconductor and v / eil the Development zone actually or effectively extended can be.

In the attached drawings show:

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Fig. 1 is a schematic representation of a cascade development prior art operating xerographic copier;

2 shows a schematic section through an embodiment of a developing device according to the invention;

3 shows a schematic partial section through another embodiment of a developing device according to FIG the invention;

Figure H is a perspective view of a portion of a movable belt used in the developing device according to the invention,

Fig. 1 illustrates a typical xerographic copier according to the prior art with cascade developing device. A xerographic drum 1 with a conductive Metal substructure, for example made of aluminum, carries a layer of photoconductive insulating on its outside Material, usually made of vitreous selenium, the drum 1 rotates around its axis, namely according to Fig. in the same direction as gravity on the carrier and toner, i.e. in the "down" direction. On the surface a uniform electrostatic charge is generated on the drum 1 by means of a corona charger. the uniformly charged drum 1 then goes to an exposure station 5, where the charged photoconductor is illuminated with a light pattern that is the one to be reproduced Original represents; this discharges the areas of the charged photoconductive surface that are exposed to

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Light are applied. There are other methods of creating latent electrostatic images insulating surfaces known; they can be used instead of the method mentioned. More details about suitable photoconductive elements, chargers and exposure devices can be found in the United States patents, among others 3,277,957, 3,312,548, 3,552,848, 3,566,108, 3,598,991, 3,612,864, 3,615,128, 3,628,786.

The development of the electrostatic latent image is carried out with a conventional cascade developer 6, the one Has a number of elements which are surrounded by a housing 7. A conveyor system consists of a belt 10 that is guided over two drive rollers 11 and 12. The belt carries cup 13. The electroscopic developer is running out a container 15 in the cups 13 up to a point in the upper region of the drum 1, where it is emptied onto the feed surface 17. When the developer drops down over the drum, disconnect the toner particles are removed from the carrier beads and are deposited on the drum surface according to the surface on it electrostatic latent image to form a visible toner image. The unused developer substance is moved from the guide surface 19 into the storage container 15 headed back. A voltage-applied development electrode 21 is located at a small distance from the Drum surface opposite to the full surface coverage to improve.

It can be seen that such a cascade development is largely relies on the action of gravity to direct the flow of developer substance over the electrostatic latent image, and there is very little control over dynamic parameters. The only moving surface

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in the development zone is the photoconductive drum and such drums are generally smooth Surfaces that only slightly influence the flow of developer substance caused by gravity. Since one relies so much on the action of gravity, the choice of setting of the developing device is one considerably restricted.

After the electrostatic image has been developed, the toner image is taken from the surface of the drum 1 the copier, usually transferred to paper. The toner transfer and fusing station 25 generally shows a paper web, delivery, take-up and guide rollers for the web, a corona charger and a Heater. Details about these sub-devices can be found, for example, in US Patents 3,584,195, 3 642 362, 3 647 292. A cleaning brush 27 follows the toner transfer and melting station Removes toner from the surface of the drum 1.

The charging, exposure, transfer, melting and Cleaning facilities should be representative of the equipment commonly used. But many can do it too other systems in conjunction with the mechanically operated xerographic device described herein Cascade development can be used.

Fig. 2 shows schematically in section an embodiment of a mechanically operated xerographic cascade developer According to the invention, a housing 30 surrounds the various individual organs and holds any powder dust generated together. The xerographic developing agent 32 is discharged from the container portion 34 of the developing device of FIG a bucket conveyor 36 made of belt 38 with attached

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th cups 40 promoted to a greater height. The tape 38 is placed over a drive cylinder 42 driven by a motor 4 and a guide cylinder 44. At the upper end of the cup conveyor 36, the developer substance falls out of the cups 40 via an adjustable one Guide plate 46 into a feed funnel 48. The funnel 48 emits the developer substance from its opening 50 the end; the opening can be adjusted to control the throughput.

The developing material emerging from the feed hopper 48 enters a development zone formed between the surface of the xerography drum 5 2 and the movable belt 54. The belt 54 is an endless loop which is guided over the drive cylinder 56 and guide cylinders 58 and 60 driven by the motor 57, so that the entire belt consists of three entangled sections. In the first section extending from the cylinder 56 to the cylinder 58, the belt runs at a small distance from and parallel to the drum 52, but in the opposite direction. After the belt has circled the cylinder 58, it moves away from the drum 5 2 and runs to the cylinder 60, from where it returns to the cylinder 5 6 in the third section. The developing substance emerging from the development zone, which is formed between the tray 5 2 and the movable belt 54, is guided back into the container 34 by a semicircular deflector 6 9.

The movable, 3and 54 is made of silicone rubber or another flexible material. In the preferred shown Embodiment, the belt 54 is equipped with stiffeners 62, which lead transversely through the belt and made it semi-rigid in the width direction. The Ver-

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Stiffeners serve to stretch the tape over its entire width to be kept at a constant distance from the drum 52. If necessary, the ends of the stiffening rods 62 can be inserted into a drive ring attached to the end of the drum for a suitable drive to ensure the tape.

To maintain a constant throughput of developer substance from the funnel 48, the opening 50 set to a predetermined width and the developer substance can the funnel 4 8 just up to Fill overflow. The overflowing developer is caught in a return chute that comes from the parts 61 and 62 is formed. Baffles 64 set the speed of the developing substance flowing back down, so that there is no unnecessary powder dust in the container 34 is formed.

The disc 68 can be moved toward or away from the downwardly moving length of the conveyor belt 38 and acts as a tensioning element for the belt 38. The baffle plate 66 serves as a further seal for the container part 34 the developing device 36 to "hold" all of the toner particles therein.

An important feature of the invention is that the ribbon moves during development. The tape exercises on the developer substance has a much greater effect than the photoconductive surface. That's because the tape comes with a rough surface can be provided while the photoconductor is smooth and also because the developer substance tends to separate from the surface of the photoconductive drum under the action of centrifugal forces

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to remove «In this respect, the belt holds the developer substance together and guides the developer falling from the drum back onto the drum surface. Will If the belt moves in the opposite direction, this also increases the average tangential speed of the wearer.

Increased turbulence is created by the moving part or belt, which changes significantly in size and size Direction of the velocity vectors of the carrier beads caused by gravity through the development zone hike down. The carrier beads become random rather than directional forced in almost all carrier speed vectors have practically the same size and direction. The increased turbulence has a greater number of vehicle collisions per unit volume of the development zone for Consequence, thereby loosening a greater number of toner particles and increasing the likelihood of a development event occurring is enlarged "

The belt can be moved forwards or backwards whether the photoconductive drum is stationary or moving in an "upwards ¹¹ " or "downwards" direction. In this specification, "forwards" means the direction of the action of gravity on the developer substance and " Backward "means the direction opposite to the direction of the action of gravity. For both forward and backward movement, the belt should have a linear speed of at least 2.5 cm / sec (1 inch per second) so that a significant effect can be achieved. Preferably the tape is moved at a linear forward or reverse speed between about 12.5 and 100 cm / sec (5 to HO inches per second).

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In the majority of cases, of course, the drum will move and movement is particularly beneficial of the belt within the limits given above, which are at the same time about 0.5 to 4 times the linear speed the drum surface for forward and Reverse and for upward and downward direction of the Drum movement.

The movable member or belt preferably has a distance from the photoconductive surface which is between the three times and ten times the beam diameter. For most of the commercial xerographic developers this distance is between about 0.8 and 3.8 mm (0.030 and 0.150 inches).

3 shows, in a schematic cross-sectional image, a further embodiment of the invention Developing device. This developing device is shown in the drawing in conjunction with a drum which rotates in a downward direction about a central shaft 72 is used. A piece of zinc oxide paper 7 3 with a The electrostatic image thereon is just moving into the development zone of the development device 74 a. The paper 73 can be attached to the drum 71 with releasable clips or in some other conventional manner.

The developing device 74 has, for example Outer housing 75 made of sheet iron. The strip 76 shown corresponds to that in connection with FIG. 2 and to be described below in connection with FIG. The belt 76 runs around the drive cylinder 77 driven by motor 90 and around guide cylinders 78 and 79; it moves in the same

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Direction as the surface of the drum 71. Spacer 80 serve to keep the band 76 at a constant distance from the guide plate 81.

The developing device 74 further includes a conveyor belt 82 which is laid so that it passes vertically over the guide cylinder 83 and the cylinder 8k which is driven by a motor 91 and cooperates with the belt 76 so that an elevator for developing substance 85 is formed, which is stored in the storage room 86. Spacers 87 are attached to the belt 8 2, which hold the belt at the intended distance from the developer belt 76 in the vertical lift part of the device. Behind the other side of the lift belt 8 2 there is a guide 88, which is also used to maintain the correct distance in serves the elevator section. The developer 85 collects at the top of the elevator section and enters the feed section 89 of the development zone formed between the drum 71 and the belt 76. Since the belt 76 carries the developer substance with it, the development scene can be expanded further than would be possible with a conventional cascade development system which relies solely on conveying the developer substance by gravity. As can be seen from Fig. 3, the developer belt 7 6 supports the effect of gravity in the vertically downwardly extending sections of the development scene and replaces it in the horizontal or vertically upwardly extending sections,

Figure 4 is a partial perspective view of a tape suitable for use in the development apparatus of the invention. The band 100 can be made of silicone rubber or other flexible material, for example

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Polyurethane or even metal. The strip material should of course be preferred from a triboelectric point of view be compatible with the development material. The band 100 shows a relatively thin surface with a sawtooth shape shaped base 103, which gives it strength in addition to flexibility in the longitudinal direction. Cylindrical Bars 102 run across the width of the belt 100 through the reinforcement parts 103 and stiffen it Tape in the transverse direction, in the illustrated embodiment the tape itself is non-conductive and has conductive areas 104 attached to it at regular intervals are. But you can also conduct the whole band in a leading manner. In any case, the tape can be used as a development electrode serve, i.e. it can strengthen the coverage of fully filled areas or, in the other case, the Hold back underground.

The effect of the belt is increased by roughening the surface of the belt. You can use knurled surfaces, rib patterns, Use knap surfaces and the like. Roughened surfaces are particularly low Belt speed preferred.

A mechanically operated electrophotographic cascade developing machine as shown in Fig. 2 was used to obtain experimental data. An 8 inch soaked aluminum drum with an Electrofax zinc oxide sheet attached was used as the photoconductor. A cast silicone rubber band was used, reinforced by steel rods approximately 3.8 mm (0.150 inch) in diameter, evenly spaced 9.5 mm (3/8 inches) and passed through the band,

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This tape corresponds to the tape shown in Fig. 4, except that it was completely dielectric. The width of the tape was 22.9 cm (9 inches) giving a development area of 21.6 mm (8 1/2 inches) on the sheet. A development zone with an arc length of 90 ° was formed; the upper end of the zone had an elevation of 60 ° above the horizontal, so that the zone had both normal and reverse cascade development. The distance between the belt and the photoconductor surface was consistently 2.0 mm (0.080 inches). Hunt Chemical 50-25 negative-working electroscopic developer was introduced into the development zone at a rate of about 30 grams per inch per second. The Electrofax sheets were uniformly charged to a negative potential of about 400 V and contact printing methods were used to form an electrostatic latent image of a bar copy on the sheet.

In a series of tests designed to demonstrate the effectiveness of the tape, the charged and exposed ones were made Zinc oxide sheets stopped in the development zone and developer was allowed through for two seconds flow the zone. If both tape and drum are connected. were held, there was a vigorous development only over an arc length of about 20 ° at the upper end of the zone. That one might expect a cascade designer working in free fall because of what the wearer assumed horizontal moment that would cause the wearer to follow a parabolic path extending from the photoconductor surface distant. Very weak, uneven development, which was assigned to the irregularities of the ribbon surface was found in the remaining area of the development sheet. If the experiment was carried out at a speed of 51 cm / sec (20 inches per second)

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running downward, a similar result resulted strong development at the upper end of the zone and a weak but steady development in the rest of the zone, which has a tendency towards laminar flow indicated with centrifugal action which caused the carrier to remain mainly on the belt surface. Was trying at the same speed running backwards, there was a strong development over the full 90 ° arc length of the development zone, the upper 20 ° being more developed at the edge. These "experiments show that both directions of tape travel improve development and that when the tape is reversed, the carrier density and carrier speeds changed dramatically over the greater part of the zone, increasing the frequency of developmental events.

Another series of Tests carried out with the photoconductor running at a linear velocity of 38 cm / sec (15 inches per second) was rotated through the development zone. The tape was fed at a speed of 76 cm / sec (30 inches per second) moved forward or backward. The optical density in the drawing area was in reflection measured. When running forward, an optical density of 0.9 was achieved, which corresponded to a development time of 0.1 sec. When running backwards, an optical density of 1.4 could be achieved.

Further attempts were made with different speeds of the photoconductor and with the belt running backwards employed at twice the photoconductor speed. Optical density curves in the drawing area in reflection, plotted against development time showed that

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the more the reverse, the more advantageous it is Development time decreases.

A series of tests was carried out with the same equipment, but one was 12.7 cm Reduced drum used. To compensate for the influence of the smaller drum, the development zone was added extended to an arc length of 120 °. The drum was rotated at 25, U cm / sec (10 inches per second) and that Tape moved backward at 50.8 cm / sec (20 inches per second) resulted in optical densities equal to those appeared equivalent that could be achieved with the larger drum.

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Claims (1)

3rd July 1973 Patents s ρ back e: Apparatus for developing an electrostatic latent image on the surface of an insulating Layer with the help of a developer substance, characterized by a) a movable member (54) which, in addition to at least part of the surface of said, the electrostatic latent image-bearing layer (5 2) is arranged to be between organ (54) and layer (52) to define a development zone having an inlet and an outlet for developing substance possesses and the width between said organ (54) and said surface (5 2) so large is that developer substance can flow through the development zone, b) a drive device for the movable member (54) to move between the member (54) and the insulating Surface (5 2) increased turbulence in the development zone when the developer substance flows through to generate, and c) means for introducing developing agent into the inlet of the developing zone. 2, device according to claim 1, characterized in that the movable member (54) at a short distance, practical - 23 309883/1 366 parallel to at least part of the surface of the electrostatic latent image bearing layer (52) is arranged. 3, device according to claim 1 or 2, characterized in, that the developer substance is an electroscopic developer with a mixture of carrier beads and represents toner particles. 4. Device according to one of claims 1 to 3, characterized in that the movable member (54) is a belt represents. 5. Device according to one of claims 1 to 4, characterized in that the drive device is the organ to move in the forward direction at a linear velocity of at least 12.7 cm / sec (5 inches per second). 6. Device according to one of claims 1 to 4, characterized in that the drive device is the organ to move backwards at a linear velocity of at least 12.7 cm / sec (5 inches per second). 7, device according to one of claims 1 to 6, characterized - 24 309883/1366 indicates that the movable organ has a distance from the insulating surface which is between about 3 times and about 10 times the carrier bead diameter, so that developer substance through the development zone can flow. 8. Device according to one of claims 1 to 7, characterized characterized in that the insulating surface is drum-shaped and comprises a photoconductive insulating material adhered to a conductive base. 9. Device according to one of claims 1 to 8, characterized characterized in that said member is made of silicone rubber. 10. The device according to claim 9, characterized in that that through the band (51) transversely extending stiffening rods (62) are drawn, which the band in the transverse direction stiffen and also serve to provide an even To bring about spacing of the belt from the photoconductive insulating surface. 11. The device according to claim 10, characterized in that the photoconductive insulating Tronurel (52) in Downward direction is moved. 12. Device according to one of claims 1 to 11, characterized - 25 - 309883/1366 characterized in that said organ (54) with a roughened surface is provided. 13. Device according to one of claims 1 to 12, characterized by additional storage container devices for storing an electroscopic developer. Device according to claim 13, characterized by additional Conveyors that carry the electroscopic developer from the reservoir to the entrance transport to the development zone. ν - 26 - 309883/1366 L e r s e i t e