DE1472993B2 - MAGNETIC ROLLER FOR ELECTROPHOTOGRAPHIC PURPOSES - Google Patents

Description

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education images with a developer mix, the coating, ζ. B. from known thermosetting Gießmas toner powder and magnetizable particles contains, sen or with a thin, non-magnetizable characterized by a roller jacket, consisting of metal foil, to prevent the dropping of the draft distributed over the circumference of the roller, essentially winder powder during the magnetically non-excited borrowed axis-parallel extending soft magnetic 5 state of the roll shell to promote, table pole pieces, which are separated from each other by non-ma- The connection of the tubular jacket with seignetisch Separating strips are separated, and an inner drive shaft is generally not made within The exciter system located in the roll shell, half of the roll shell, since the exciter is present here distributed over the circumference of the roller, located in the system, but preferably at the ends essential axis-parallel extending period of the roller, z. B. by capsule-like connecting element magnets, the excitation system with the mente.

Roll shell rotate around a common axis that is inside said tubular

-and in its angular position with respect to the Walzenman- roll shell located cylindrical exciters-

tel can be adjusted. system consists in principle of one, also several

The invention is explained in more detail as follows: 15 rare permanent magnets, which are

The magnetic roller according to the invention consists in dividing, extending axially parallel and such

Principle of two parts, a roll shell and direction of magnetization, that magnetic poles

a pathogen system. The roll shell is rohrför- pointing outwards to the roll shell. At the

mig designed and has several permanent magnets within this turn

Shell lying cylindrically shaped Erre- 20 be attached to a soft magnetic core,

gersystem a common axis around which both suitable metallic permanent magnet materials

Systems can turn. Roller shell and exciter are z. B. Iron - Cobalt - Vanadium, Copper -

system unite to form the ent-nickel-cobalt according to the invention. As examples of oxidic per-

'' winder roller. '' Magnetic materials are barium and co-

The roll shell is split into individual pole shoes called the baltf harvest. ^: . divides, which are essentially axially parallel over the entire circumference of the circumference facing the roll shell. The number of pole pieces magnetic poles should be at most equal to the number of which played no critical role, but should preferably be mentioned pole pieces. Equal number is prior to choosing an even number. The pole pieces close. Between the individual magnetic poles are by non-magnetic separating strips voneihan- '30 are gaps that have a high magnetic of the separated, so that the tubular roller resistance have, that is, they exist z. B. from a jacket alternating from pole piece - separating strips - non-magnetic or a non-magnetizable pole piece - separating strips - etc. builds up. The Aus material. More detailed embodiments are further expansion of the pole shoes in the radial direction is also described below.

if not critical. This will depend on the 35 The excitation system rotates around the roller version of the excitation system, which is located within the sheath common axis. The material connection Roll shell is located and of the required training of the excitation system and the roll shell with Roll diameter. their respective drive shafts must be designed so

The pole pieces consist of soft magnetic that the excitation system in its rotation opposite

Material that is the same or different to the roll shell only for the duration of the action

exciting magnetic field is magnetized and can have speed and direction of rotation,

after the excitation magnetic field has disappeared, this is known to be technically feasible, for example

only a small remanence "magnetization retains, through a combination of thru-axles, which from-

Materials that are suitable for this are, for. B. are driven separately from each other. Is now in

Soft iron, cobalt, nickel or the well-known Heus- 45 result of a certain setting of the excitation system

alloys. stems a magnetic pole opposite the roll shell

The separating strips are preferably a material of the excitation system exactly below a pole piece

rial with low magnetic permeability, the roll shell, this magnetic pole generates a

z. B. are suitable numerous metals, such as aluminum, magnetization of the pole piece, creating a

Brass, among other things, as well as thermoplastic and thermosetting 5 ° magnetic field that forms over the roller surface

Plastics. However, air can also extend out from the dividing strips. This allows the magrietisable

contain. In this case, of course, the particle of the developer mixture must be extracted

Penetration of magnetizable particles of discovery. These form a so-called magnetic brush,

winding mixture is prevented in the separating strips, whereby in a known way the developer, otherwise they cancel their separating effect 55 powder on the surface of the material to be developed

would. education image can lead. If the pathogen is now

- The connection of the magnetic separating strip system is twisted in relation to the roll shell, and and the pole shoes are twisted to one another to a fixed position, although in the extreme case so far that the whole magnet tube can be connected by mechanical means. Pole of the excitation system exactly opposite the non-elements at the roll ends, such as hoops etc., 60 magnetic separating strips of the roll shell are located or grounded by gluing, or through end flanges, occurs outside of the roll shell. njir one more follow. These construction elements consist of an expediently negligible magnetic field, since they are practically made of non-magnetic material, so that they do not influence the field lines emanating from the magnetic poles. Because of the almost always prevalent poles. In this position, between the remaining remanence of the pole shoe material, there is a regersystem and the roll shell, therefore, no release is shown to be advantageous, and the outer surface of the winder mix is attracted. , ^■:; · ■ roller jacket with a thin smooth plastic between the two extreme cases mentioned]

5 6

namely the maximum training and the practical and developed development skills

table complete disappearance of the outer magnetic field of the magnetic circuit

des, all intermediate stages can be implemented. This can be the excitation system - pole piece - developer mixture -

by turning the exciter system and roller pole shoe exciter system.

Sheath take place at angles that are smaller than the 5 Fig. 1 and 2 show the cross section of a Angle between the two extreme positions. exemplary embodiment of the erfindungsge-Die Strength of the magnetic field and thus the strength of the magnetic roller at which the magnetic talker The attraction of the developer mixture and thus the supply as a whole can be switched on and off, the hardness of the magnetic brush can therefore continuously A b b. 3 illustrates another embodiment of FIG or discontinuously up to a maximum of one magnetic roller according to the invention in which the are created. . excitation as a whole switched on and off and additional

The width of the non-magnetic separating strips Hch the excitation of the pole pieces in a fixed wind-

between the pole pieces of the roll shell can be interrupted periodically in the kelbereich. A b b. 4th

wide limits. The width and 5 show examples of training specifically

Amount of the attracted developer mixture, 15 of which is the pathogen system.

Distribution along the circumference of the roller shell, in Fig. 1 the magnetic roller consists of a and thus affects the hardness of the magnetic brush. The even number of pole pieces 1 to Ic made of soft iron, The width of the dividing strips only has to be so large that the width of the dividing strips 2 to 2 c is not magnetic resistance is greater than the magnetic material separated from each other and the gnetic resistance of the field between two ao by means known per se, not shown » Pole shoes retained developer mixture. Since z. B. end flanges, are combined to form a pipe, this a high proportion of a ferromagnetic excitation system located inside the pipe Material contains, this condition is already in consists of a magnetizable core 3 on which a width of the separating strips met, which is only slightly larger than the same number of permanent magnets 4 to 4 c is than the diameter that is fixed in the developer, how pole pieces are present. The Permisch contained ferromagnetic particles. Manentmagnete are magnetized so that each

If the width of the separating strips is relatively small, poles N and S are facing the pole pieces and the magnetic field lines predominantly on the adjacent poles have different polarities. Separating strips from adjacent areas from the pole to Sc between the perma shoes, so that the field strength in these end magnets should have a very high magnetic range is much greater than in the middle of the pole resistance, that is, they consist of non-magnetic shoes. In this case, therefore, a relatively tical material is created. The excitation system is an independently hard magnetic brush, the density of which fluctuates around the circumference of the roller or depending on the rotation of the pole pieces. If, however, the width of the common axis 3 α rotatable. The means for the separation strip, which is relatively large, are the field strength- 35 storage of the excitation system and for mutual differences between the center and the areas of the pole pieces adjoining the rotation of the excitation system and pole pieces, as well as the drive means are known, so that theirs are much smaller, so that a softer magnetic reproduction in Fig. 1 as well as in the following brushes with practically the same density along the whale formations can be dispensed with,
zen size is formed. 4 ° In A b b. 1 there is a perma-

The separating strips between the pole pieces can be magnetized. There between two pole pieces

in a radial or in an inclined Rieh- high magnetic resistance in the form of the non-

extension. In the first case, the magnetic separator strip 2 consists of the roller, close

formed magnetic brush mirror-symmetrical with respect to the magnetic field lines over the outer space of the

on each by the axis of rotation of the magnet roller 45 magnet roller, so that developer mixture - attracted

and the center of the pole pieces or the center of the will. To illustrate this, Fig. 1 shows some

Separating strip laid level. In the second case, these field lines 6 are shown in their basic course

Symmetry does not exist, since then the field strength represents. '.'. '.'. ■ ..... '■

of the pole pieces to the In A b b adjacent to each pole piece. 2 is the same magnetic roller, the two separating strips are different. As a result, the 50 is as in Fig. 1 with the difference that the stiffness or the hardness of the magnetic brush held by such a permanent magnet against a separating strip 2 counter roller is asymmetrical. The ones at the northern poles of the Permanentz. B. larger in the direction of rotation than in the opposing direction magnets 4 exiting. Field lines 6 α now run. This fact may make itself special. In the interior of the pole shoes 1, the neighboring south winding problems have a beneficial effect. , 55 poles, so that the pole pieces in the outer space of the Ma -.- For the above-described field shaping gnetwalze generate no field and thus no EntWirkung the separation strips are put into it _(most linewidth wicklergemisch., ......

and shape of the separating strips on the outer jacket- ". The transition from that drawn in Fig. 1; area of the roll shell is decisive, while the width of the excitation system and pole pieces corresponds to the in. and the shape of the separating strips on the inner jacket- 60 Fig. 2 drawn can be useful automatically ,, area has a much lower impact on the z. B. from the movement of the latent image and exercise the hardness of the magnetic brush. The low recording medium can be controlled, whereby The cross-section of the separating strip can therefore largely be used to carry out the required twisting Known mechanical, hydraulic, pneumatic, selected according to manufacturing-related aspects will. It is only necessary to ensure that magnetic or electromagnetic means are used Resistance of the separating strips over their ge. B. in sheet-shaped recorded expansion is noticeably greater than the ma- nagement means, during the development process, Magnetic resistance of the two neighboring poles - those in A b b. Maintain 1 drawn position,

while the developer renewal between the development of two recording media by temporary Setting the in A b b. 2 drawn position is made.

The magnetic roller according to the invention according to A b b. 3 besides the renewal of the whole of the developer mixture attracted to the roller by switching off the excitation additionally the ongoing renewal of the developer mixture during the development process. This magnetic roller is suitable therefore especially for the development of latent electrostatic images on tape-shaped recording media indefinite length. Similar to A b b. 1 and 2 is the magnetic roller according to Fig. 3 off Soft iron pole pieces 7, between which there are separating strips 8 made of non-magnetic material. The permanent magnets 9 have a rectangular cross-section, so that they are easy and inexpensive to manufacture. The spaces 10 are not magnetizable. The "magnetized parallel to one edge of their cross-section Permanent magnets 9 are thus on a magnetizable core 11 of polygonal cross-section attached so that the magnetic poles point outwards, and that, progressing along the circumference of the roller, Alternate north and south poles.

As with the magnetic roller in A b b. 1 or 2 is also the case in A b b. 3 drawn magnetic roller the excitation system, consisting of the core 11 and the permanent magnets 9, can be rotated against the pole shoes, so that the permanent magnets during the development process the pole pieces 7 and for Purpose of the developer renewal the separating strips 8 can be compared. On part of the Circumference is a magnetic short circuit between the permanent magnets 9 and the pole shoes 7 in the form a cylindrically bent sheet 12 made of highly permeable material inserted that is not with rotates with the pole pieces and the excitation system, but is fixed in place. The magnetic Field lines 15 a, which emerge from the magnetic poles in the area of the sheet metal 12, go through the sheet metal 12 to the neighboring poles, so that the pole shoes in the area of the plate 12 are not excited. Through this takes place during the rotation of the magnet roller, a constant renewal of that held by the magnet roller Developer mix instead of by the pole pieces that move past the short-circuit plate 12 drop the developer mix at 13 and pick up new developer mix at 14, when they leave the area of the short-circuit plate. In A b b. 3 are for sketching the field distribution in the area where there is attraction of the developer mixture, some magnetic ones Field lines 15 are shown schematically.

If the excitation system consists of several permanent magnets of suitable dimensions, the opposite the cores 3 or 11 of A b b. 1 or 3

ίο individually pushed forwards and backwards in the direction of rotation of the roller can be, without short-circuit plate 12 during operation of the magnetic roller a spatially fixed angular range of the roller circumference can be kept permanently unexcited.

This can be done, for example, in that each permanent magnet when it enters the mentioned angular range by moving against or in the direction of rotation of the roller in one of the A b b. 2 corresponding position is brought to the roll shell, in which it remains until it is in the course of Rotation of the roller leaves the aforementioned angular range again, where it enters that of Fig. 1 corresponding Position is moved back. The required movements can be made with known engineering Devices are easily mastered.

The in A b b. 1 and 3 shown excitation systems can be simplified and cheaper by every second permanent magnet is replaced by a soft magnetic body of the same shape.

In A b b. 4 is a further embodiment specifically of the excitation system of one according to the invention Magnet roller shown. It consists of a magnetizable core 16, over which a tube 17 is made Permanent magnet material is pushed, which is magnetized in the radial direction, so that, over the Evenly distributed circumference, there is an even number of magnetic poles of alternating polarity. The tube 17 can also be made up of a suitable number of permanent magnetic rings in a row be replaced with appropriate magnetization.

Another embodiment of the excitation system is shown in A b b. 5. In this case the excitation system exists from a permanent magnetic rod 18 of suitable length, which in the specified manner on The circumference is magnetized. The magnetic field lines in the interior of the magnetic rod essentially run in the circumferential direction. Some of these field lines 19 are shown for clarity.

1 sheet of drawings

209508/340

Claims (2)

dive and attract it magnetically. Due to the patent claims: The rotation of the rollers brings the mixture up to the surface to be developed. at 1. Rotating magnetic roller for developing such previously known magnetic rollers, of charge images with a developer mixture, 5 if they have permanent magnets, it prepares the toner powder and magnetizable particles difficulty containing the depletion of the developer, characterized by a mixture of toner powder during the development roller jacket, consisting of compensate for the Walzenum- process, as without complicated and Catch distributed, essentially parallel to the axis failure-prone additional devices, z. B. Stripping extending magnetically soft pole pieces, always the same magnetically excited tears, which adhere to the magnet roller from each other by non-magnetic particles, whereby Separating strips are separated, and within λ insufficient mixing of the entire Entde The exciter system located in the roller jacket, the winder supply and the enrichment of the carrier particles consisting of distributed over the roller circumference, can take place with toner. substantially axially parallel extending 15 This disadvantage can with electrically excited Ma permanent magnets, whereby the excitation system gnetwalzen be avoided, since with these there is the possibility with the roller shell to a common possibility, the entire excitation during or Rotate axis and its angular position opposite between two development processes, or the Erüber the roll shell can be adjusted. excitation of individual magnetic poles during a part ' 2. Magnetic roller according to claim 1, characterized by periodically switching off their rotation. However is indicates that the excitation system essentially also uses electrically excited magnetic walls from axially parallel on the lateral surface zen associated with disadvantages: The production of the a soft magnetic core arranged rollers is cumbersome and expensive, which is especially with Rod-shaped permanent magnet consists. the usual long magnetic rollers into the 3. Magnetic roller according to claim 1, characterized in that weight falls. The supply of the excitation current must indicates that the excitation system is essentially carried out via slip rings or a collector borrowed from one on the lateral surface to become one; this can very easily give rise to malfunctions magnetically arranged soft magnetic core. The ohmic losses in the magnet wounded, permanent magnetic tube. lungs cause a 4. Magnetic roller according to claim 1, characterized by 3 ° and under certain circumstances very harmful heating indicates that the excitation system essentially causes sticking of the developer mixture, borrowed from a circumferentially magnetized Finally, the electrically energized for operation The permanent magnetic tube or roller has its own power supply unit, required, whose space requirements and heat generation 5. Magnetic roller according to one of claims 1 35 ment the desirable compact structure of to 4, characterized in that the number of developing devices opposes. the pole pieces are even and equal to the number of Furthermore, a stationary magnetic magnetic pole is already known is. brush one in the vicinity of the upper surface line 6. Magnetic roller according to one of claims 1 horizontally lying, rotating, non-magnetic to 4, characterized in that the number 40 tubes with a rough surface by the effect of the rod-shaped permanent magnets is less one inside the non-magnetic pipe roals the number of pole pieces. animal permanent magnet roller and one between 7. Magnet roller according to one of claims 1 of the permanent magnet roller and the non-magnetic 5, characterized in that between the table tube fixedly arranged, cylindrical, to the roll shell and the excitation system via 45 upwardly open, magnetic shielding generate a certain angular range around the rota. The non-magnetic tube plunges into you tion axis a highly permeable, in a certain container with developer and transports a geten Position of fixable material concentric to the certain amount of developer to the magnetic brush and the same surface of the excitation system is arranged. - early a certain amount of developer from the Ma- 50 brush back into the developer container, which constantly a small part of the magnetic brush educational developer is renewed. This device ■ v - · ■■ - has the major disadvantage that the speed . ability, with. the magnetic brush over the The invention relates to a device for developing recording media strokes, always the same winding of charge images, a mixture of the feed speed of the recording media being magnetizable carrier particles and toner pulver, while it is often expedient to convert one of these by means of a speed different from a permanent magnetic one to adjust ..
Excitation system and a whale enveloping it. Another disadvantage is that it is only partial zenmantel existing roller to which the latent image 60 renewal of the magnetic brush, whereby this in the carrying hat is worn. The magnetic development of highly opaque copies quickly excites of the roll shell can be poor here between zero. and a maximum value can be regulated or fixed at will. It was the object of the invention to roller that has the aforementioned advantages of Magnetic rollers are already known that combine axially permanent and electrical excitation, without having a number of permanent magnets or the disadvantages associated with them.
Have electrically excited magnetic poles and the subject of the present invention is a a storage container with developer mixture rotating magnetic roller for developing la-