DE102008012582B4 - Developer station for an electrographic printer or copier - Google Patents

Abstract

Developer station for an electrographic printing or copying device, with which charge images of images to be printed which are applied to a charge image carrier are colored with toner, - in which a developer roller (19) which is at an electrical potential is electrically charged toner (6) on the charge image carrier (11) transported over, - in which a transport arrangement for a developer mixture (17) of carrier and toner is provided, - for transporting the developer mixture (17) to the developer roller (19), a magnetic roller (18) with an electrically conductive roller shell (21) and one provides magnetic stator (20) arranged in the interior of the roller sleeve (21), the roller sleeve (21) having an electrically insulating layer on the surface, - which has a charging electrode (23) adjacent to the magnetic roller (18), which acts as an electrode doctor (24) which adjusts the height of the developer mixture (17) and the density of the developer mixture (17) increased and the surface of the developer mixture (17) is electrically charged from the outside before it reaches the developer roller (19), ...

Description

Electrographic printing or copying machines are known, see, for. B. US 6,246,856 B1 or DE 10 2004 059 532 A1 , In such a printing or copying machine are on a charge image carrier, for. B. a photoconductor belt, generated by a character generator charge images of the images to be printed. Subsequently, the charge image carrier is moved past developer stations, one per color. These transport toner to the charge image carrier. According to the charge images on the charge image carrier, the toner transfers to the charge image carrier and colors it. In the next step, the toner images are transferred to a substrate and fixed on it. The exact course of the printing process can US 6,246,856 51 are removed, the contents of which are hereby incorporated into the disclosure.

To develop the charge images, a developer station may be used, as appropriate WO 03/036 393 A2 ( US 2005/0036806 A1 . DE 101 52 982 A1 ) is constructed. From a developer mixture of toner and magnetic carrier takes a first magnetic roller, the inking roller, developer in which the toner is triboelectrically charged. The magnetic roller consists of a rotating roller shell with a magnet stator arranged in the interior, in which magnets are provided, which are polarized differently. Adjacent to the first magnetic roller, there is provided a developer roller or applicator roller which takes in toner from the first magnetic roller due to an electric field existing between the developer roller and the magnetic roller and transports it to the charge image carrier. There goes in a developer gap toner for coloring the charge images on the charge image carrier. The residual toner remaining on the developer roller after the development of the charge images is then cleaned by a cleaning roller from the developer roller. The cleaning roller is realized as a second magnetic roller. This is arranged adjacent to the first magnetic roller and takes over from this developer mixture, forms a mixture carpet and leads it past the developer roller, the residual toner being rubbed off the developer roller by the mixture carpet. The cleaning process is assisted by an existing between cleaning roller and developer roller electric field. From the cleaning roller, the developer falls into the developer supply due to the polarity of the magnets and / or using a doctor blade or by using a further magnet arrangement, on which a developer mixing brush is formed.

The described developer station thus has at least one magnetic roller, the inking roller, which, by virtue of its rotation and by means of a magnet configuration arranged in its interior, brings a defined amount of developer mixture to the developer roller. Driven by the potential difference between the developer mixture and the developer roller, a charged amount of toner is transferred from the developer mixture to the developer roller at the point of contact between the developer mixture and the developer roller. The transferred amount of toner is u. a. depends on the height of the potential difference. The charge in the developer mixture is generated via the inking roller, to which a voltage or current source is connected. While the developer mix is in contact with the inking roll, the charge is transferred from below into the developer mix. By transporting on the inking roller, the charged developer mixture is mixed. Thus, a more or less undefined distribution of the charge takes place in the developer mixture. However, potential or charge differences in the developer mixture are manifested by uneven toner transfer and thus fluctuations in toner quantity on the developer roller.

In the known developer station electrical potentials are thus applied to the inking roller, developer roller and cleaning roller, which support the transport of the developer mixture and the toner by electric field forces. These electrical potentials must be supplied to the rollers. A known solution for generating the electric field forces consists in contacting electrically conductive surfaces of the rollers with high voltage sources. The contact takes place z. B. via sliding contacts, which bear against an electrically conductive axis of the roller. With insufficient conductivity z. B. caused by toner deposition on the roller fails this solution. The internal contacting of rollers for the defined adjustment of their surface potential requires conductive surfaces. As a result, the selection of materials for the production of z. B. inking rollers and cleaning rollers severely limited. This limitation is particularly problematic due to the fact that very poorly conducting materials often have certain physical properties which would be advantageous elsewhere. These include z. B. antiadhesiveness, stability or triboelectric charging behavior. Also uncontrollable toner or other deposits on surfaces of the rollers during operation can reduce the conductivity to the extent that it leads to failure of the developer station.

In US Pat. No. 5,950,057 is a developer station in an electrographic printing apparatus described in which charge images are developed on a charge image carrier with toner with a developer roller. To the toner on the developer roller with a defined electrical potential provided adjacent to the developer roller, an electrode is provided which transports the toner. In this case, the toner layer is to be reloaded continuously on the developer roller. This is achieved by loosening the toner layer in the region of the electrode by means. The toner is supplied to the developer roller through a inking roller, which is realized as a magnetic roller.

US Pat. No. 6,272,305 B1 discloses a developer station for an electrographic printing apparatus having a developer roller and a developer roller coloring agent which may be realized as a belt or roller. The colorant contains a layer of photoreceptors. When the inking agent is electrically charged, regions of different electrical potential are formed, at the boundaries of which differently polarized potentials arise. This makes it possible to remove from a toner supply toner of different potential (negative, positive or equal to 0). The toner layer on the colorant is then subjected to an ion charge process.

Out US 4,876,575 A results in a developer station for a printing device, which prevents the wrong-loaded toner particles are transported with the developer roller. For this purpose, a roll lying at an electrical potential is arranged adjacent to the developer roller, which removes the incorrectly charged toner particles from the developer roller.

The problem to be solved by the invention is to provide a developer station with a inking roller and a developer roller, in which a uniform charging of the developer mixture is achieved.

The problem is solved according to the features of claim 1.

• – eine an einem ersten elektrischen Potential liegende Entwicklerwalze, die elektrisch geladenen Toner an dem Ladungsbildträger vorbei transportiert;
• – eine Transportanordnung für ein Entwicklergemisch aus magnetischem Träger und Toner;
• – die Transportanordnung weist auf – eine Walze, die das Entwicklergemisch an der Entwicklerwalze vorbei bewegt, – benachbart der Walze ein Auflademittel, das die Oberfläche des Entwicklergemischs auf der Walze von außen elektrisch auflädt,
• – die Walze und die Entwicklerwalze sind derart zu einander angeordnet, dass die Entwicklerwalze elektrisch geladenen Toner von der Walze übernimmt.

The developer station for an electrographic printing or copying machine, with which charge images of images to be printed on a charge image carrier are inked with toner, thus has the following components with the following functions:

• A developing roller located at a first electric potential, which transports electrically charged toner past the charge image carrier;
• A transport assembly for a developer mixture of magnetic carrier and toner;
• The transport arrangement comprises a roller which moves the developer mixture past the developer roller, a charging means adjacent to the roller which externally electrically charges the surface of the developer mixture on the roller,
• - The roller and the developer roller are arranged to each other, that the developer roller takes over electrically charged toner from the roller.

Further developments of the invention will become apparent from the dependent claims.

The charging means may be disposed to the roller so as to electrically charge the surface of the developer mixture.

The charging means may be a charging electrode disposed adjacent the surface of the roller across the width thereof so as to be remote from the surface. The charging electrode may be a squeegee (electrode blade) resting against the roller.

The charging electrode can be fixedly arranged to the surface of the roller, but it can also be arranged to be movable to the roller.

In order to avoid a flow of charge, it is expedient if the surface of the roller an electrically insulating layer, for. B. Teflon, ceramic or plastic.

For transporting the developer mixture, the roller can be realized as a magnet roller with a roller shell and a magnet stator arranged in the interior.

Then, the roller may be a inking roller which takes the developer mixture from a developer supply and supplies it to a developer roller. In this embodiment, the charging electrode may be arranged adjacent to the inking roller so that the developer mixture passes between the charging electrode and the inking roller and the surface of the developer mixture is electrically charged by the charging electrode before it reaches the developing roller. Furthermore, it may be appropriate to arrange the charging electrode adjacent to the inking roller and the developer roller such that the developer mixture is no longer mixed on the way to the developer roller. An advantage of this solution is that the developer mixture can only be charged by the charging electrode.

• – Die Ladungseinbringung in das Entwicklergemisch kann an dessen Oberfläche erfolgen; dies hat zur Folge, dass eine geringere Abhängigkeit vom Gemischwiderstand (Ladungen müssen nicht mittels Elektronentransport durch das Entwicklergemisch an die Oberfläche transportiert werden, wo sie für die Einfärbung benötigt werden) und vom Durchmischungsgrad des Entwicklergemischs beim Gemischtransport besteht (geladener Träger muss nicht zwingend körperlich durchgemischt werden, um an die Oberfläche des Gemischs zu gelangen, wo sie für die Einfärbung benötigt werden).
• – Das Entwicklergemisch kann sowohl von der Unterseite als auch von der Oberseite gezielt beladen werden mit dem Ergebnis, dass ein geringerer Platzbedarf bei höherer Beladungsmenge besteht.
• – Durch eine gezielte Erhöhung der Dichte des Entwicklergemischs, z. B. durch eine Rakel, kann der Gemischwiderstand gesenkt und die Ladungseinbringung erhöht werden. Die Ladungseinbringung in das Entwicklergemisch wird gleichmäßiger, wodurch die Qualität gesteigert wird:
• – Durch die Ladungseinbringung an der Oberfläche des Entwicklergemischs gewinnt man eine Unabhängigkeit von Gemischwiderstand und Gemischdurchmischung hinsichtlich der die Einfärbequalität bestimmenden Ladungsverteilung, damit werden Ungleichmäßigkeiten in der Ladungsverteilung vermieden.
• – Bei der Beladung des Entwicklergemischs durch die Oberfläche der Walze können Ungleichmäßigkeiten in der Ladungsverteilung an der Gemischoberfläche durch zusätzliche Ladungseinbringung von oben (z. B. durch die Elektrodenrakel) ausgeglichen werden. Ergebnis ist eine gleichmäßige Ladungsverteilung und bessere Einfärbequalität.
• – Durch eine effiziente Ladungseinbringung kann bei gleich bleibender Beladungs- und damit Einfärbequalität auf zusätzliche Magnetwalzen verzichtet werden; dies führt zu geringeren Kosten und zu Platzersparnis.
• – Die elektrische Kontaktierung drehender Teile beim Stand der Technik ist deutlich aufwändiger als eine Kontaktierung stehender Teile z. B. bei einer Elektrodenrakel.

When using the invention as Einfärbewalze arise z. B. the following advantages:

• - The charge introduction into the developer mixture can take place on its surface; This has the consequence that there is less dependence on the mixture resistance (charges do not have to be transported to the surface by means of electron transport through the developer mixture, where they are needed for the coloration and the degree of mixing of the developer mixture during the mixture transport (charged carrier does not necessarily have to be physically mixed in order to reach the surface of the mixture where it is needed for coloring).
• - The developer mixture can be specifically loaded from the bottom as well as from the top with the result that there is less space required with a higher load.
• - By a targeted increase in the density of the developer mixture, z. B. by a doctor blade, the mixture resistance can be lowered and the charge injection can be increased. The charge introduction into the developer mixture becomes more uniform, which improves the quality:
• - By the charge injection on the surface of the developer mixture to gain independence of mixture resistance and mixture mixing in terms of the inking quality determining charge distribution, thus unevenness in the charge distribution can be avoided.
• When loading the developer mixture through the surface of the roller, unevenness in the charge distribution at the mixture surface can be compensated for by additional charge introduction from above (eg by the electrode blade). The result is a uniform charge distribution and better inking quality.
• - By an efficient charge introduction can be dispensed with additional magnetic rollers with the same loading and thus coloring quality; This leads to lower costs and space savings.
• - The electrical contacting rotating parts in the prior art is much more complex than contacting stationary parts z. B. in an electrode blade.

With reference to embodiments, which are illustrated in the figures, the invention will be further explained.

Show it

1 a known developer station showing the flow of the developer mixture;

2 a first embodiment of the invention for the realization of a Einfärbewalze.

1 shows a developer station ES in principle accordingly WO 03/036 393 A2 ( US 2005/0036806 A1 ) WO 03/036 393 A2 is hereby incorporated into the disclosure. From a supply 1 Developer mixture, which consists of carrier and toner (hereinafter developer 4 called), by a dredger 2 developer 4 taken and a coloring roller 3 fed. The developer 4 is shown schematically, wherein the carrier 5 dashed lines and the toner 6 dotted. The inking roller 3 is realized as a magnetic roller and consists of a rotating roller shell 7 and a stator 8th with magnets 9 , which are poled so that the developer is transported in the direction of rotation. The inking roller 3 transports the developer 4 to a developer roller 10 , which is realized as a jump roller in a development according to the jump principle. The developer roller 10 takes over from the inking roller 3 toner 6 and transports this to a charge image carrier 11 , z. B. a photoconductor belt, over. toner 6 goes according to the charge images on the charge image carrier 11 above. The on the developer roller 10 remaining toner, hereinafter residual toner 12 called, is from a cleaning roller 13 cleaned; this is constructed as a magnetic roller with a magnetic stator 14 and magnets 15 internally. Because developers 16 from the inking roller 3 partly to the cleaning roller 13 (the rest of the developer falls into the developer's stock 1 back), forms on the cleaning roller 13 a mixture brush, the rotation of the cleaning roller 13 at the developer roller 10 passes by and the residual toner 12 cleans. From the cleaning roller 13 drops the residual toner 12 into the developer's stock 1 back.

2 shows the application of the invention to that part of the developer station ES where the developer mix 17 from the inking roller 18 to the developer roller 19 is transported. This is the coloring roller 18 used, which is realized as a magnetic roller. To a magnetic stator 20 rotates a roll shell 21 that the developer mix 17 to the developer roller 19 transported. The developer roller 19 is z. B. at an electrical potential of z. B. 0 V to 500 V and z. B. be realized as a tribo-jump roller. The developer roller 19 takes over from the inking roller 18 from the developer mix 17 toner 22 and transports it to a charge image carrier (in 2 not shown) over. To the transition of the toner 22 from the developer mix 17 to the developer roller 19 To influence, electric field forces are generated, which are the transition to the developer roller 19 promote. This is the developer mix 17 electrically charged such that the transition of the toner to the developer roller 19 is supported. The charge of the developer mix 17 is primarily by a charging agent 23 reaches that adjacent to the inking roller 18 is arranged. The charging agent 23 can as a charging electrode 24 be realized, the adjacent and spaced from the inking roller 18 is arranged. The charging electrode 24 may be a squeegee at which an electrical potential of z. B. -2000 V ... 0 V is present. Through the squeegee 24 can then the height of the mixture flow to the developer roller 19 and the developer mix 17 be compacted, thereby increasing the electrical conductivity in this area and thus the efficiency of the charge injection. As charging electrode 24 Alternatively, an electrode of a different shape may be used, but it must be suitable for the developer mixture 17 to charge electrically. The advantage of the arrangement of the charging electrode 24 lies in particular in the fact that the developer mix 17 can be charged at its surface to the desired electrical potential, z. To the specified -2000 V ... 0 V. The location of the charging electrode 24 can preferably be chosen so that the developer mixture 17 in the direction of movement of the inking roller 18 seen then no longer mixed. In addition, the inking roller 18 be placed in a conventional manner to an electrical potential, for. B. to -2000 V ... 0 V in the embodiment of 2 ,

The developer mix 17 can via the charging electrode 24 only be charged from the top. To drain the charge from the developer mixture 17 in the inking roller 18 it is expedient to avoid the roll cover 21 the inking roller 18 to be provided with an electrically insulating layer, for. B. with Teflon. In addition, the coloring roller can also 18 namely its shell 21 be charged in the usual way, for. B. to a potential of -2000 V ... 0 V.

In the example of 2 becomes the developer mix 17 Negatively charged, this is the transition of the toner 22 to the developer roller 19 due to the positive potential on the developer roller 19 reached. The path of the toner to the developer roller 19 shows 2 , The developer mix 17 The carrier and toner is removed from the inking roller 18 from a developer supply or mixer for the developer mix 17 taken. The inking roller realized as a magnetic roller 18 pulls the developer mix 17 at and by their rotation in the direction of the arrow becomes the developer mix 17 to the developer roller 19 emotional. This will be the developer mix 17 at the charging electrode 24 , z. As a doctor, transported past, the developer mixture 17 is electrically charged, negative in the embodiment. However, also is a positive charge of the developer mix 17 possible with correspondingly generated charge images on the charge image carrier. The inking roller 18 then move the developer mix 17 on the developer roller 19 over, leaving the toner 22 on the developer roller 19 can go over. The carrier and a residue of toner eventually falls z. For example, back to the Developer Inventory. The developer roller 19 can then accept the acquired toner 22 to develop the charge images to the charge image carrier; the course of this development process can z. B. WO 03/036 393 A2 ( US 2005/0036806 A1 ).

LIST OF REFERENCE NUMBERS

IT

developer station

1

Developers stock

2

Developers excavators

3

inking

4

developer

5

carrier

6

toner

7

rolling shell

8th

stator

9

magnet

10

developer roller

11

Charge image carrier

12

Waste toner

13

cleaning roller

14

magnetic stator

15

magnet

16

developer

17

developer mixture

18

inking

19

developer roller

20

magnetic stator

21

rolling shell

22

toner

23

charging means

24

electrodes squeegee

Claims (6)

Developer station for an electrographic printing or copying device, with which charge images of images to be printed on a charge image carrier are colored with toner, in which a developer roller lying at an electrical potential (US Pat. 19 ) electrically charged toner ( 6 ) on the charge image carrier ( 11 ) transported by, at which a transport arrangement for a developer mix ( 17 ) of carrier and toner is provided, - for transporting the developer mixture ( 17 ) to the developer roller ( 19 ) a magnetic roller ( 18 ) with an electrically conductive roll shell ( 21 ) and one inside the roll shell ( 21 ) arranged magnetic stator ( 20 ), wherein the roller sleeve ( 21 ) has on the surface an electrically insulating layer, - which adjacent to the magnetic roller ( 18 ) a charging electrode ( 23 ), which is used as an electrode blade ( 24 ), which determines the height of the developer mix ( 17 ) and the density of the developer mixture ( 17 ) and the surface of the developer mixture ( 17 ) electrically charged from the outside before this to the developer roller ( 19 ), - in which the magnetic roller ( 18 ) and the developer roller ( 19 ) are arranged to one another such that a transition of electrically charged toner ( 6 ) from the magnetic roller ( 18 ) to the developer roller ( 19 ) he follows. Developer station according to Claim 1, in which the charging electrode ( 23 ) so adjacent to the inking roller ( 18 ) and the developer roller ( 19 ), that the developer mixture ( 17 ) on the way to the developer roller ( 19 ) is no longer mixed. A developer station according to claim 1 or 2, wherein the developer mixture ( 17 ) exclusively through the charging electrode ( 23 ) is charged. Developer station according to one of claims 1 to 3, wherein the charging electrode ( 23 ) is fixed. Developer station according to one of Claims 1 to 4, in which the charging electrode ( 23 ) adjacent the magnetic roller ( 18 ) is arranged over the width thereof. Developer station according to one of the preceding claims, in which the magnetic roller ( 18 ) is a inking roll containing the developer mix ( 17 ) from a developer supply ( 1 ) and the developer roller ( 19 ) feeds.

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