DE2226021A1 - ELECTROPHOTOGRAPHIC COPY DEVICE - Google Patents

Description

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Description for the registration of

KALLE AKTIENGESELLSCHAFT Wiesbaden-Bieforich

for a patent on “a Electrophotographic copier ~

The present invention relates to an ele & trophotographisches copying machine that a reusable photoconductor "a Aufiadungssta'tion for charging this photoconductor, a Bellefitungsstation to bildtoäMgen exposure of the charged photoconductor, a Ent ^ ickltsngs- station to the development of the photoconductor with Torierteilciien, a ifbertragungsstation for transmitting des TorierbiMes in front of the photoconductor on "a copy carrier ₅ , an inclination station for removing fonei * remaining on the photoconductor and a suction unit with a filter in which the toner.

containing air from ', sucked off the cleaning station and the toner is deposited in the filter, has *

3ÖS8S1 / ÖS8S

BATH ORIGINAL

With known elektrophot ο graph-is before η devices of the described Art, the toner contained in the extracted air is removed from the air flow by labyrinth filters. The toner is lost. Also have such Labyrinth filters increase with the degree of pollution Loss of pressure * The filters are accordingly maintenance-

intense and can only be used once.

It has already been proposed in DOS 2 038 555 to avoid these disadvantages by _{charging the incoming toner T} particles in a corona discharge and depositing them on a surface which is then freed from the toner with the aid of a scraper. To this. Way was a recovery of the toner from the air. which was vacuumed by the cleaning station, allows.,.

However, this device also has some undesirable effects Disadvantages on. The construction of the device is complex and because of the use of sensitive spray wires expensive, the separation performance is not very large. and there is a risk that individual, secluded Toner particles are fused due to local heating caused by a strong discharge.

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The object of the present invention is therefore to provide a copier of the type defined at the outset, in which a A filter is provided which, despite a simple structure that is not susceptible to interference, has a very high separation efficiency and at the same time enables recovery of the deposited toner particles.

According to the invention, this object is achieved by a copier of the type defined at the outset, which is characterized in that the filter is located close behind the cleaning station is arranged that the filter has at least two planar electrodes, which are designed and in the Suction device are arranged that the air flow laden with toner particles between these electrode surfaces and that some electrodes are grounded and others are connected to a high voltage source or are connectable.

It has been shown that with a copier constructed in this way, a very satisfactory cleaning of the toner particles loaded air is made possible. The requirement

a spray discharge is completely avoided with this arrangement and the residual charge is used to clean the air

3 0 9 8 5 1/0998 BAD original

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the toner particles themselves are being exploited. "It must therefore be prevented that the toner particles during their movement from the cleaning station to the one constructed according to the invention The filter device will lose this residual charge, as otherwise the cleaning effect of the electrodes will be considerably weakened.

To completely clean the air sucked out of the cleaning station and also a contamination of the ambient air To prevent the copier with toner particles in the event of a failure of the high voltage, it is according to the invention preferably a mechanical protective filter in the suction device in the air flow direction after the electrodes to arrange. This mechanical protective filter must be replaced from time to time, but its useful life is limited an order of magnitude higher than with known filter devices, since only a remainder of toner particles pass through this mechanical filter must be removed from the air already cleaned by the electrodes.

It is further preferred according to the invention, a stripping device to remove the toner material deposited on the electrodes. This stripping device, which can be actuated from the outside, releases

the deposited toner material from the electrodes,

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309851/0998

whereby the toner material falls into a collecting container .. This not only facilitates the recovery of the toner material, but above all a uniform cleaning characteristic of the electrode plates is achieved; Standard components can be used if the electrodes are arranged as concentric cylinders arranged one inside the other are formed, the axis of which is the main flow direction corresponds to the air. When the cylinders run horizontally Axis are arranged and are slotted along their lowest surface line, the distance can of the deposited toner with the help of several around the Cylinder axis of rotatably arranged brushes, - ■■ ' the wiped toner falling through the slots into a container located under the outermost electrode.

A fixed scraper can be used., when the electrodes are off. consist of several flat, rotatably arranged circular disks with a common center line. "■ - - -

The invention is to be described in greater detail below with reference to exemplary embodiments shown in the figures of the drawing explained. -

Show it:

30 9851/09 9 8

Bathroom original

FIg. 1 is a schematic representation of an electrophotographic Copier with an enlarged toner separation device,

PIg, 2 a further embodiment of a toner separation device _s

Figures 3 and 4 show two examples of a toner deposition device with concentric cylinder electrodes.

The one in Pig. I illustrated electrophotographic Copier, a photoconductor drum 1 in a charging station 2 is uniformly charged electrostatically. In an exposure station 3, the charged 'photoconductor' layer exposed imagewise and the resulting charge image is in a development station 4 with toner particles developed »The toner image located on the drum 1 is transferred to a transfer station 5 Transfer copy recording material such as paper.

In a cleaning station, generally designated 7, remaining toner is removed from the surface of the Photoconductor 1 removed. "For this purpose it is in a housing 8 a rotatable roller brush 9 with a long-haired pile arranged. This brush roller 9 can be set in rotation in the direction of the arrow against the photoconductor circulation.

309851/0998

BATH ORIGINAL

With the help of a cross-flow fan 10, which is the same Width as the drum 12 has, air is in the area of the Cleaning station 7 sucked into the housing 8. This provides a simple air flow with a low pressure loss. This air takes the toner particles wiped off by the brush 8 with it and guides them into the one explained in more detail below Separation station 11.

A special filter is located in the housing 8 in the area of the separation station. This filter has a plurality of circular electrode plates 12 which are arranged with a common center slot and substantially at the same distance from each other. ₃ The total width also corresponds to the drum width. The air flow thus has essentially the same width transversely to the direction of flow on the way from the photoconductor via the cleaning brush, the filter, the cross-flow fan and the safety filter. The electrode plates 12 are alternately connected to earth potential and a high voltage source (-6000 V). The electrode plates of the deposition station are as close as possible to the cleaning brush 8.

The electrode plates 12 sit on a common axis and can be driven by a motor (not shown) in FIG

3 0 9 8 5 1/0 9 9 8

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In the direction of arrow 13 or in the opposite direction. In addition, there is a scraper 14 on each of the toner-receiving electrode plates, which extends from the axis of rotation of the disks to their circumference. The toner that collects on this scraper Ik can fall into a vessel located under the actual separator. The toner 16 accumulating there can be reused if desired.

To catch the last bit of toner in the air and to be sure that In the event of a failure of the high voltage, no toner gets into the ambient air, a protective filter 17 is provided provided on the exhaust side of the fan 10.

The brush 9 removes all of the toner particles remaining on the photoconductor 1 as it rotates. Of the Air flow generated by the fan 10 removes these particles from the brush and guides them between the electrode plates 12. Since the electrode plates are arranged in the immediate vicinity of the brush,

the toner particles could not discharge. the . positive residual charge of the toner particles causes them to be attracted to those plates that are attached to the

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negative pole of the high voltage source IB. · »- After these electrode plates separate the toner particles» By the rotation of the plates 12, the separated particles are picked up by the wiper 14 and fall into the receptacle 15 Into the visual filter 17. Completely purified air then emerges from this », ¹

In the Vorriehtang shown in Pig »2, the protective filter 17 is arranged in front of the fan 10. Bie ■ electrodes ■ '■'. ■! Flatten 12 -have in this "trap in weseKtXiehen rechteefeige shape and the electrode cleaner .Can 14" in the horizontal direction ,, be moved as indicated by the arrow 19th The toner material falls into the receptacle 15 *

In the case of the separators II shown in FIGS. 3 and 4 the electrodes 12 are designed as concentric cylinders.

The in -Pig ·. .Ausführiingsior-ia shown in Figure 3 are arranged, these cylinders standing, that is, their common axis extends vertically ■ .. to be purified, loaded with toner air passes in the direction of the arrow 20 into the separator * The individual cylinders 12 are connected to high voltage and, to earth potential »

BAO ORIGINAL

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The toner that comes out of the airflow to the cylinder-shaped Electrodes 12 has been deposited, is removed with the aid of an electrode cleaner 14 rotating around the cylinder axis. The scraped off toner falls into the floor Section 15 of the flasctienförraigen separating station 11. The outer cylinder jacket of this separation station 11 has an annular protective filter 17, on which the last remainder of the toner is separated from the air »

The separation station 11, which is shown in Fig. 4, corresponds to that shown in Pig with regard to the electrode structure. In this case, however, the electrodes are arranged with a common cylinder axis running horizontally. In addition, the electrodes are along their lowest surface line provided with a slot .21. In this case, the scraper 14 conveys deposited toner from the electrodes up to the slot 21. The separated toner falls through the slots 21 into the collecting container 15. In this case, can the protective filter covers the entire face of the separation

station 11 on the downstream side include, like it is shown in FIG.

The distance between the electrodes is 11: s in the figures shown Examples on the order of 5 to 50 mm “The

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The voltage at the electrodes is preferably in the range between −3 kV and −15 kV if the photoconductor is charged negatively. The air speed in the area of the electrodes should be in the order of magnitude of 0.5 to 3.0 m / sec. With a separation station designed in this way, it was easily possible to separate 93 % of the toner contained in the air stream.

When choosing the electrode spacing, the following must be observed. The distance between the essentially flat electrodes should be chosen so large that flashovers at the operating voltage (for example at -6 kV) can be safely avoided. In doing so, the flashover voltage that is found in the one in question must be used

Distance for a "tip-plate" system in air results. Namely, if toner deposits on the electrode,

the surface becomes quite inhomogeneous and one can therefore no longer benefit from the higher flashover voltage of the system Go out "plate-plate" * While therefore in the case of a voltage of 5 kV an electrode spacing of 10 mm is certainly sufficient should be worked with a distance of 30 to 40 mm in the case of a voltage of 10 kV. These

Numbers are of course from the humidity and depending on the air pressure.

BATH ORIGINAL

3Ü9851 / Ü998

Claims (10)

Pat ent a η sayings \ j> Electrophotographic copier that a) a reusable photoconductor, b) a charging station for uniform electrostatic Charging this photoconductor, c) an exposure station for imagewise exposure of the charged photoconductor, d) a development station for developing the photoconductor with toner particles, e) a transfer station for transferring the toner image from the photoconductor to a copy carrier, f) a cleaning station for removing toner remaining on the photoconductor, g) a suction device with a filter in which air containing toner is sucked out of the cleaning station and the Toner is deposited in the filter, characterized in that h) the filter is arranged close behind the cleaning station is, i) that the filter is at least two planar one another has opposing electrodes which are formed ao and arranged in the suction device that 30985 1/0998 the air flow between them, laden with toner particles is passed through, and k) that the electrodes are connected or can be connected to a high voltage source or ground potential. 2. Copier according to claim 1, characterized in that the electrodes are substantially equidistant from one another and are locally alternately connected to one and the other pole of the high-voltage source. 3. Copier according to claim 1, characterized in that in the suction device according to the air flow direction a mechanical protective filter is placed on the electrodes, 4. Copier according to one of claims 1 b, 3 _S , characterized in that a Abstreifvorrichtung.zur removal of the deposited toner material is provided from the electrodes. 5. Copier according to one of claims 1 to 4, characterized characterized in that the electrodes are designed as cylinders arranged concentrically one inside the other, the axis of which corresponds to the main flow direction of the air. 309851/0998 6. Copier according to claim 4 and 5, characterized in that that the cylinders are arranged with a horizontal axis, that they are arranged along their lowest surface line are slotted that the scraper has a plurality of brushes which are rotatably arranged about the cylinder axis and the cylindrical electrodes touch along the surface line and that under the outermost electrode a container is provided for collecting the separated toner falling through the slits. 7. Copier according to one of claims 1 to 4, characterized in that the electrodes consist of several circular disks with a common center point that these
Circular disks are rotatably arranged and that fixed scrapers for the rotating circular disk-shaped
Electrodes are provided. 8. Copier according to one of claims 1 to 4, characterized in that the electrodes consist of several in parallel
arranged substantially rectangular plates exist. 9. Copier according to one of claims 1 to 8, characterized in that -the cleaning station consists essentially of a rotatable brush roller that this
Brush roller and electrodes close together in one 309851/0998 common housing is arranged, which has two openings, one of which is close to the one to be cleaned Photoconductor is arranged and of which the second is in communication with a suction fan. 10. Copier according to claim 7 or 8, characterized in that the suction device has a cross-flow fan and that the width of the cross-flow fan and the width of the filter are substantially the width of the photoconductor correspond. 3Ü985 1 / Ü998