EP0474409B1 - Magnetbürstenentwicklungsgerät - Google Patents

Magnetbürstenentwicklungsgerät Download PDF

Info

Publication number
EP0474409B1
EP0474409B1 EP91307747A EP91307747A EP0474409B1 EP 0474409 B1 EP0474409 B1 EP 0474409B1 EP 91307747 A EP91307747 A EP 91307747A EP 91307747 A EP91307747 A EP 91307747A EP 0474409 B1 EP0474409 B1 EP 0474409B1
Authority
EP
European Patent Office
Prior art keywords
flux density
magnetic
magnetic flux
developer
restriction member
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP91307747A
Other languages
English (en)
French (fr)
Other versions
EP0474409A3 (en
EP0474409A2 (de
Inventor
Kunihiko Sato
Sachio. Hainesu Biriji I-202 Sasaki
Akira Nagahara
Shin C/O Fujitsu Limited Araki
Hideaki Iwasaki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujitsu Ltd
Original Assignee
Fujitsu Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fujitsu Ltd filed Critical Fujitsu Ltd
Priority to EP95102168A priority Critical patent/EP0658826B1/de
Publication of EP0474409A2 publication Critical patent/EP0474409A2/de
Publication of EP0474409A3 publication Critical patent/EP0474409A3/en
Application granted granted Critical
Publication of EP0474409B1 publication Critical patent/EP0474409B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/08—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer
    • G03G15/09—Apparatus for electrographic processes using a charge pattern for developing using a solid developer, e.g. powder developer using magnetic brush
    • G03G15/0921—Details concerning the magnetic brush roller structure, e.g. magnet configuration

Definitions

  • the present invention relates to a magnetic brush developing apparatus for developing an electrostatic latent image, which is used in an electrophotographic recording apparatus or the like.
  • a developing method applicable to a developing apparatus is a two-component magnetic brush developing method using a toner or a colored powder, and a carrier or a magnetic powder as a developer.
  • the carrier used therein imparts an electrostatic charge to the toner through a triboelectrification or the like thereof, and the toner is held by the electrostatic force for conveyance.
  • the developing roller functions to convey the developer to the developing section and holds the carrier by the magnetic force for conveyance, and thus the magnetic properties of the developing roller have a great influence on the image quality.
  • a developing roller 1 is constituted of a magnet 1b having a plurality of magnetic poles, and a rotational sleeve 1a which rotatably covers the surface of the magnet 1b.
  • the magnet 1b is usually fixed, and a developer 4 is caught on the surface of the rotational sleeve 1a, through the magnetic force exerted by the magnet 1b, and carried to a developing section 9 in which a photosensitive drum 3 confronts the developing roller 1a, through the rotation of the rotational sleeve 1a.
  • the developer restriction member 2 i.e., a blade is arranged opposite to the developing roller 1 (rotational sleeve 1a) to restrict the amount of the developer 4 to be carried to the developing section 9.
  • the amount of the developer 4 passing through the developer restriction member 2 is determined by the interval (a blade gap) between the developing roller 1 and the developer restriction member 2, and the amount by which the developer head has been raised. Accordingly, the amount of the developer 4 which has passed through the developer restriction member 2 is determined by the height of the developer head.
  • the developer head is the height of the developer brush carried on the surface of the sleeve 1a.
  • the image quality is also influenced by the height of the developer head. Namely if the height of the developer is comparatively low and the amount of the developer to be carried to the developing section 9 is thus reduced, sufficient toner for a development is not supplied, which results in a deterioration of the image density. Conversely, if an excessive amount of toner is supplied, the image is unstable.
  • a variation in the height of the developer head may cause an instability of the image and a deterioration of the image quality. Accordingly, to eliminate any unevenness of the image quality, it is necessary to maintain the quantity of developer 4 passing through the blade gap of a constant value.
  • the quantity of the developer 4 passing through the blade gap is determined by the amount by which the developer resting on the developing roller 1 is raised in the developer restriction member facing section 6.
  • the condition of the raising of the developer is determined by the vertical magnetic flux density at a position opposite to the developer restriction member 2 on the developing roller 1, and as a result, the vertical magnetic flux density at the opposing position must be constant.
  • Figure 19 shows the distribution of the vertical component (normal to the sleeve surface) of the magnetic flux density of the conventional developing roller 1.
  • the "vertical component of the magnetic flux density” will be hereinafter referred to as “magnetic flux density”.
  • the peak portion of the magnetic flux density in the magnetic flux density distribution will be designated as.a magnetic pole.
  • This embodiment has five magnetic poles as shown in Fig. 19.
  • the magnetic pole A confronts the photosensitive drum 3, the magnetic poles B, C, and E are mainly used for conveying the developer 4b, and a magnetic pole D is mainly used for applying the developer 4 to the developing roller 1.
  • the developer restriction member facing section 6 is positioned between the magnetic poles B and C.
  • Figure 20 shows, on an enlarged scale, the distribution of the magnetic flux density of the conventional developer restriction member facing section 6.
  • the conventional developing apparatus suffered from a large change in the vertical component of the magnetic flux density on the developing roller 1 in the developer restriction member facing section 6.
  • the parts to be mounted in the developing apparatus have respective mounting precision errors which must be allowed for in the fabrication. Namely, if the mounting precision for the developer restriction member 2 is ⁇ 0.5 degrees, if the precision in the magnetized position for the magnet 1b is ⁇ 3 degrees, if the fixing precision for the magnet 1b ⁇ 0.5 degrees, and if the processing precision of the other parts is ⁇ 1 degree, the position of the developer restriction member 2 relative to the magnetic flux density distribution has a precision as shown by the positional precision range Q.
  • the positional precision range Q is generally within the range of ⁇ 5 degrees of the above-mentioned precision, and becomes 10 degrees in total.
  • the magnetic flux density in the developer restriction member facing section 6 differs depending on the developing apparatus used, due to the large variation in the magnetic flux density within the positional precision range Q.
  • a developing device which includes a developing sleeve provided rotatably at a side of an electrostatic latent image support member, a supply member for supplying developer to the developing sleeve, a bristle height regulating member which confronts an upper portion of the developing sleeve so as to adjust an amount of the developer transported to a developing region and a plurality of magnets provided in the developing sleeve.
  • the magnetic poles of the magnets not only extend in an axial direction of the developing sleeve but are arranged in a circumferential direction of the developing sleeve.
  • the magnetic poles include a weak magnetic pole disposed adjacent to the upper portion of the developing sleeve and two strong magnetic poles between which the weak magnetic pole is interposed. The strong magnetic poles have a polarity different from that of the weak magnetic pole.
  • US Patent No. 4,825,241 discloses an electrostatic latent image developing apparatus including a rotatable developing sleeve, multiple fixed magnets in the developing sleeve and a brush height regulating member positioned opposite one of the multiple magnets is magnetised so that the region corresponding to 80% plus of the peak value of magnetic force has a spread which subtends an angle of 20° or more at the exterior surface of the developing sleeve.
  • the difference in the magnetic flux density causes a variation in the amount of the developer 4 to be carried to the developing section, which has a large affect on the image quality. Accordingly, many different problems arise such as a remarkable difference in the image density depending on the developing apparatus used, a solid, a thin line, missing out of half toning dots, and the adherence of the carrier to the photosensitive body.
  • An object of the invention is to overcome the conventional disadvantages and to provide a magnetic brush developing apparatus which prevents unevenness in the image quality resulting from a substitution of different developing apparatus, thus leading to an improvement in the image quality, and which has a wider assembly precision range enabling an easy installment of the apparatus.
  • a magnetic brush developing apparatus comprising: a development container for containing a developer; a developing roller including a shaft and, a magnet stationarily located in said development container and having a plurality of magnetic poles at points on its circumference; a rotational sleeve arranged so as to cover the outer circumference of said magnet and rotatably driven to carry the developer of said development container; and a developer restriction member arranged opposite to said rotational sleeve to restrict the amount of the developer carried by said rotational sleeve; wherein at the position facing said developer restriction member, and in its vicinity, there is formed a uniform magnetic flux density section having a magnetic flux density whose radial component is uniform to a predetermined tolerance on the periphery of the said rotational sleeve; and characterised in that two of said magnetic poles are positioned so that a distance between said two magnetic poles is such that magnetic flux a) flows from one magnetic pole toward the other magnetic pole and b) flows toward inner
  • said uniform magnetic density section may include a distribution of a magnetic flux density having a vertical component which is substantially uniform in a wider range than that of any of a precision in a magnetized position for said magnet, a precision in a mounting of said magnet to said developing apparatus, and a precision in a mounting of said developer restriction member to said developing apparatus.
  • said uniform magnetic flux density section may include a distribution of a magnetic flux density having a vertical component which is substantially uniform in a wider range than that of a precision of a relative mounting position of said uniform magnetic flux density section and of said developer restriction member.
  • said uniform magnetic flux density sections may be provided on both sides of said developer restriction member facing position, to thus extend by an angle of at least 3 degrees, preferably at least 5 degrees, more preferably at least 10 degrees, in terms of the rotational angle of said rotational sleeve.
  • said uniform magnetic flux density section may have a vertical magnetic flux density within the range of ⁇ 20%, preferably ⁇ 15%, more preferably ⁇ 10% with respect to the preset value for said developer restriction member facing position.
  • Figure 17 shows the variation in the developer head based on the magnetic flux density distribution of the developer restriction member facing section 6.
  • Fig. 17(a) shows the state of the developer head in the developer restriction member facing section 6 in accordance with the present invention.
  • the magnetic flux density has a substantially uniform vertical component in the developer restriction facing section 6, so that the condition of raising of the head in this section is substantially uniform.
  • Fig. 17(b) shows the state of the developer head in the developer restriction facing section 6 of the prior art.
  • the vertical component of the magnetic flux density is changed in the developer restriction member facing section 6, which causes the variation in the state of the head raising in this section.
  • the variation in the amount of the developer 4 influences the image quality, resulting in a different image quality depending on the developing apparatus used.
  • a constant uniform image quality can be obtained in an individual developing apparatus, effectively resulting in an improvement in the image quality and a reduction of the processing precision of the parts.
  • the magnetic flux density in the developer restriction member facing section may thus be almost unchanged even though the relative mounting position diverges between the magnetic flux density distribution and the developer restriction member, thereby rendering the supply of the developer uniform among different developing devices.
  • a uniform image quality may be obtained without unevenness, leading to an improvement in the image quality, and a developing apparatus having a wider processing and assembly precision range can be obtained.
  • Figure 1 shows an electrophotographic printer.
  • the present invention is widely applicable to not only printers but also copying machines and the like.
  • reference numeral 3 denotes a photosensitive drum rotatable around a shaft thereof
  • 11 denotes a preelectrostatic charger for electrifying the photosensitive drum
  • 12 represents a light exposure device for exposing the photosensitive drum 3 by a scanned laser beam, to form an electrostatic latent image on the surface of the photosensitive drum 3.
  • reference numeral 10 represents a magnetic brush developing apparatus for developing the electrostatic latent image formed on the photosensitive drum 3, to form a toner image
  • 13 designates a transfer device for transferring the toner image onto a printing sheet
  • 14 designates a cleaner for removing residual toner on the surface of the photosensitive drum 3
  • 15 shows a fixing roller for thermally fixing the toner image onto the sheet.
  • Figure 2 shows the developing apparatus 10.
  • a two component developer 4 Contained within a development container 7 is a two component developer 4 composed of a toner 4a, a colored powder, and a carrier 4b, i.e., a magnetic powder.
  • the toner 4a is supplied into the development container 7 from a toner hopper 21 provided on the upper portion through a toner supply roller 22.
  • the toner used in this embodiment is made of styrene acrylic series or polyester series resin and has an average particle diameter of 11 to 12 ⁇ m.
  • the carrier which is a resin-coated magnetic material such as magnetite or ferrite has an average particle diameter of about 100 ⁇ m.
  • a saturation magnetization of the carrier is 80 emu/g.
  • Reference numeral 23 stands for a stirring device for stirring the developer within the development container 7, to produce an electrostatic charge therein.
  • 24 signifies a flow restriction member for returning the developer 4 held back by a developer restriction member 2, to the stirring device 23, and 25 signifies a toner density sensor for detecting a toner density in the developer 4 through a measurement of a permeability of the developer 4, to thereby determine the toner replenishment timing.
  • the development container 7 has at its left end portion an opening which defines a developing section 9 for developing the surface of the photosensitive drum 3, in which there is provided a developing roller 1 constituted of a cylindrical magnet 1b made of a magnetized magnetic material, and, a tubular rotational sleeve 1a rotatably driven and arranged so as to cover the surface of the magnet 1b.
  • the magnet 1b is made of ferrite and has a shaft made of a non-magnetic material such as aluminum alloy, for example.
  • the rotational sleeve 1a is made of the non-magnetic material such as aluminum alloy, for example.
  • Figure 3 is a perspective view showing the partially cut-away developing roller 1.
  • the magnet 1b shown in Fig. 3 includes a plurality of radially alternately magnetized lines (five lines).
  • a developer restriction member or blade 2 made of a non-magnetized material is rigidly fixed to the development container 7 so as to be parallel to the axial direction of the rotational sleeve 1a.
  • a predetermined small gap (1.0 mm in this embodiment)
  • the height of the developer 4 (the height of the head) carried by the rotation of the rotational sleeve 1a is restricted to a predetermined value by the developer restriction member 2.
  • Figure 4 shows a distribution of the magnetic flux density, in which reference numeral 6 denotes a developer restriction member facing section arranged opposite to the developer restriction member 2.
  • a magnetic pole A is an N pole confronting the photosensitive drum 3.
  • Magnetic poles B, C, and E are mainly utilized to carry the developer 4, and a magnetic pole D is mainly used to apply the developer 4 to the developing roller 1. Further, the magnetic poles E and D have the same polarity, and therebetween the developer is removed from the developing roller 1. Further, the developer 4 that has been removed is stirred by the stirring device 23 for re-use.
  • That magnetic flux density lying between 80 to 90 gauss is suitable to obtain a satisfactory image in the apparatus of this embodiment, the magnitude of which may be appropriately selected depending on the properties of the apparatus.
  • the uniform magnetic flux density section Z is made to extend across 10 degrees or more and is 20 degrees in total at both sides of the developer restriction member facing the position 6a therebetween.
  • the parts mounted in the apparatus have respective mounting precisions (errors permissible in the manufacture) and the like. Accordingly, when the mounting precision of the developer restriction member 2 is ⁇ 0.5 degrees, the magnetized positional precision of the magnet 1b is ⁇ 3 degrees, the fixing precision of the magnet 1b is ⁇ 0.5 degrees, and the processing precision of the other parts is ⁇ 1 degree, the position of the developer restriction member 2 relative to the magnetic flux density distribution of the developing roller 1 includes a precision shown by a positional precision range Q.
  • the uniform magnetic flux density section Z is formed so as to be substantially double the range Q in this embodiment.
  • Figure 6 is a graph showing the relationship between the relative positional variation of the developer restriction member 2 with respect to the magnetic flux density distribution of the developing roller 1, and the printing density (developing density).
  • Figure 7 shows the + or - direction of the graph. The variation in the relative position of the developer restriction member with respect to the magnetic flux density distribution of the magnet, toward the directions as shown in the drawing, are designated by + and -, respectively.
  • FIG. 6 shows the apparatus of this embodiment, and a broken line shows the conventional apparatus.
  • this embodiment apparatus is subjected to very little change in the printing density regardless of the position of the developer restriction member 2 within the positional precision range Q.
  • each developing apparatus can present a similar uniform image quality within a predetermined range, with respect to the image density, fogging, skip, carrier adhesion and the like.
  • Figure 8 shows the angle range for the uniform magnetic flux density section Z of the developing roller used in the developing apparatus, and the ratio of the developing apparatus by which a satisfactory printing can be obtained when the variation range of the magnetic flux density is changed.
  • the image density of a 4 mm square solid of an output image was judged to be satisfactory at 1.2 or over.
  • o means that the ratio (good ratio of the apparatus) of the developing apparatus at which a satisfactory printing can be obtained is approximately 100%
  • o means that the ratio (good ratio of the apparatus) of the developing apparatus at which a satisfactory printing can be obtained is 80% or more
  • ⁇ signifies that the ratio (good ratio of the apparatus) of the developing apparatus at which a satisfactory printing can be obtained is 60% or more
  • x signifies that the ratio (good ratio of the apparatus) of the apparatus at which a satisfactory printing can be obtained is 50% or less.
  • the developing apparatus using a developing roller having a uniform magnetic flux density section Z with a wider angle range, and having a narrower variation angle of the magnetic flux density within the foregoing angle range, is able to obtain a satisfactory printing with a 1.2 or more image density.
  • the good ratio of the apparatus was almost 100%, which is ideal result.
  • the good ratio of the apparatus was 80% or more, and for the developing apparatus using a developing roller having an angle range of ⁇ 3 degrees and the variation range of the magnetic flux density of ⁇ 20%, the good ratio of the apparatus was 60% or more.
  • the good ratio of the apparatus was 50% or less, which is unusable in practice.
  • the good ratio of the apparatus was not less than 60%.
  • the uniform magnetic flux density section Z should be formed to extend by 3 degrees, preferably by 5 degrees, more preferably 10 degrees in terms of angle range on both sides of the developer restriction member facing section 6 therebetween, more preferably, a 5 degrees angle range or more, most preferably a 10 degrees angle range or more.
  • the vertical magnetic flux density of the uniform magnetic flux density section Z should lie within a range of ⁇ 20%, preferably ⁇ 15%, more preferably ⁇ 10% with respect to the preset value at the developer restriction member facing section 6.
  • an electromagnet 30 is arranged surrounding a magnet raw material 1c.
  • a coil (not shown) of the electromagnet 30 is then energized to exert a magnetic force on the electromagnet 30, to thereby magnetize the magnet raw material 1c to form a magnet 1b.
  • the range of the angular position of each magnetic pole is determined by the angular positional arrangement of the electromagnet 30, and the magnitude of the magnetic flux density of each magnetic pole is determined by the current supplied to the coil of the electromagnet 30.
  • Figure 10 shows a developing roller of another embodiment in accordance with the present invention.
  • the magnet 1b has a shaft having planes to which magnets are attached, and through an appropriate magnetic flux density and the angle arrangement, a satisfactory distribution of the magnetic flux density can be obtained.
  • Figure 11 shows the relationship between the positions of the developer restriction member or blade 2 and the two magnetic poles B and C located on the circumference of the developing roller 1 and between these magnetic poles B and C.
  • There are two methods of forming the uniform magnetic flux density section Z one being attained by a balance control between the two magnetic poles B and C located between these magnetic poles B and C, and the other being attained by providing a new magnetic pole C′ in the vicinity of the developer restriction member (blade) 2.
  • Fig. 12(a) shows a structure of the developing roller and Fig. 12(b) shows the vertical component of the magnetic flux density distribution on the rotational sleeve 1a of the developing roller 1.
  • the developing roller 1 comprises the rotational sleeve 1a and the magnet 1b.
  • An isotropic ferrite magnet is used as a material of the magnet 1b.
  • Figure,12(b) shows the results of the measurements of the magnetic flux density distribution on the rotational sleeve 1a. The positions of the magnetic poles B and C are shown at the bottom of the drawing.
  • the abscissa indicates an angle ⁇ .
  • the flat portion is located at a zero line of the magnetic flux density, but if the strength of magnetization of one of the magnetic poles B and C is smaller than that of the other, or if the width of one is narrower than that of the other, the flat portion is not located at the zero line. For example, if the width of the magnetic pole C (N-pole) is narrower, the amount of the magnetic flux around the magnetic pole B (S-pole) is increased, and therefore, the flat portion is moved to the side of N-pole, and thus a uniform magnetic flux density section Z is formed at the side of N-pole, as shown in Fig. 13(c).
  • a uniform magnetic flux density section (flat portion) Z can be advantageously formed if the angle ⁇ 0 (Fig. 12(a)) between the center lines of the two magnetic poles B and C is not less than three times the average width of these magnetic poles B and C, and if the width of one of the magnetic poles B and C is smaller (not more than 80%) than that of the other, or the magnetic flux density of one is smaller than that of the other.
  • a method (not claimed herein) of forming a uniform magnetic flux density section Z by providing a new magnetic pole C′ will now be described with reference to Fig. 14.
  • a new magnetic pole C′ is arranged between the two magnetic poles B and C and opposite the developer restriction member or blade 2.
  • the distance between the magnetic poles B and C′ is a little bit shorter than the distance between the magnetic poles C′ and C.
  • the width of the magnetic pole C′ is about one half that of the magnetic pole B or C and the strength of magnetization of the magnetic pole C′ is about 5 to 50% that of the magnetic pole B or C.
  • Figure 14(b) shows a distribution of magnetic flux density of this magnetic pole C′ on the rotational sleeve 1a.
  • the distribution of magnetic flux density between the magnetic poles B and C is represented as a combination of both, and thus a uniform magnetic flux density section Z is formed, as shown in Fig. 14(c).
  • a uniform magnetic flux density section (flat portion) Z can be advantageously formed by providing a new magnetic pole C′, the width of which is about a half that of the magnetic pole B or C and a strength of magnetization thereof is about 5 to 50% of that of the magnetic pole B or C, at a position between the developer restriction member or blade 2 and the two magnetic poles B and C.
  • the angle ⁇ , (Fig. 12(a)) between the center lines of the two magnetic poles B and C is not less than twice the average width of these magnetic poles B and C.
  • Figures 15 and 16 show a distribution of the magnetic flux density in the above-mentioned embodiments (1) and (2), respectively.
  • the strength of magnetization of the magnetic poles A, B, C, D and E is the same, but the width thereof is changed as follows. Also the positions of these magnetic poles A, B, C, D and E are set as follows.
  • the strength of magnetization and the width of the magnetic poles A, B, C, C′, D and E are set as follows. Also the positions of these magnetic poles are set as follows.
  • the present invention is not confined to the above embodiments.
  • an appropriate magnetic flux density for example, 80 to 90 gauss
  • the image quality among the apparatuses can be made largely uniform compared to the conventional apparatuses.
  • the above angle may be made at least 3 degrees or more on both sides thereof, and 6 degrees or more in total, to obtain a better effect.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Brush Developing In Electrophotography (AREA)

Claims (12)

  1. Magnetbürsten-Entwicklungsgerät, mit
       einem Entwicklungsbehälter zur Aufnahme eines Entwicklers (4),
       einer Entwicklungsrolle mit einer Welle und
       einem Magneten (1b), der stationär in dem Entwicklungsbehälter (7) angeordnet ist und eine Vielzahl von Magnetpolen an Stellen seines Umfangs besitzt,
       einer Drehhülse (1a), die so angeordnet ist, daß sie den Außenumfang des Magneten (1b) überdeckt und drehbar angetrieben wird, um den Entwickler (4) des Entwicklerbehälters (7) mitzunehmen, und
       einem Entwickler-Begrenzungsteil (2), welches gegenüber der Drehhülse (1a) angeordnet ist, um die Menge des Entwicklers (4) zu begrenzen, die durch die Drehhülse (1a) mitgeführt wird,
       wobei bei der Position (6a), die zu dem Entwickler-Begrenzungsteil (2) hinweist und in dessen Nähe (6) gelegen ist, ein Abschnitt (Z) mit einheitlicher magnetischer Flußdichte ausgebildet ist, deren radiale Komponente innerhalb einer vorbestimmten Toleranz am Umfang der Drehhülse (1a) einheitlich ist, dadurch gekennzeichnet, daß zwei der Magnetpole so positioniert sind, daß ein Abstand zwischen den zwei Magnetpolen so bemessen ist, daß der Magnetfluß a) von einem Magnetpol zu dem anderen Magnetpol verläuft und b) zu inneren Magnetpolen hin verläuft, die auf einer Seite der Welle gelegen sind, wobei die Magnetflüsse von jedem der zwei Magnetpole wechselseitig abgeglichen sind, um einen flachen Abschnitt dazwischen als Abschnitt mit einheitlicher magnetischer Flulßdichte auszubilden und wobei die zwei der Magnetpole voneinander verschieden sind.
  2. Magnetbürsten-Entwicklungsgerät nach Anspruch 1, bei dem der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte eine Verteilung der magnetischen Flußdichte aufweist, deren senkrecht zur Hülse (1a) verlaufende Komponente in einem weiteren Bereich im wesentlichen einheitlich ist als derjenige irgendeiner Magnetisierungs Lagepräzision für den Magneten (1b), einer Befestigungspräzision des Magneten (1b) an dem Entwicklerbehälter (7) und einer Befestigungspräzision des Entwickler-Begrenzungsteiles (2) an dem Entwicklerbehälter (7).
  3. Magnetbürsten-Entwicklungsgerät nach Anspruch 1, bei dem der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte eine magnetische Flußdichteverteilung aufweist, deren senkrecht zur Hülse (1a) verlaufende Komponente in einem weiteren Bereich im wesentlichen einheitlich ist als derjenige einer relativen Befestigungsposition-Präzision zwischen dem Abschnitt (Z) mit einheitlicher magnetischer Flußdichte und dem Entwickler-Begrenzungsteil (2).
  4. Magnetbürsten-Entwicklungsgerät nach irgendeinem der Ansprüche 1 bis 3, bei dem die Abschnitte (Z) mit einheitlicher magnetischer Flußdichte auf beiden Seiten einer Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, dazwischen angeordnet sind, so daß sie sich über einen Winkel von wenigstens 10 Grad in Form eines Drehwinkels der Drehhülse (1a) erstrecken.
  5. Magnetbürsten-Entwicklungsgerät nach irgendeinem der vorhergehenden Ansprüche, bei dem der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte eine senkrecht zur Hülse (1a) verlaufende magnetische Flußdichte hat, die innerhalb des Bereiches von ± 10% hinsichtlicvh eines Voreinstellwertes für die Stelle (6a), die zu dem EntwicklerBegrenzungsteil hinweist, liegt.
  6. Magnetbürsten-Entwicklungsgerät nach irgendeinem der Ansprüche 1 bis 4, bei dem der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte auf beiden Seiten der Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, dazwischen vorgesehen ist, so daß er sich über einen Winkel von wenigstens 3 Grad in Form eines Drehwinkels der Drehhülse (1a) erstreckt, und wobei die Abschnitte (Z) mit einheitlicher magnetischer Flußdichte eine senkrecht zur Hülse (1a) verlaufende magnetische Flußdichte besitzen, die innerhalb des Bereiches von ± 20% hinsichtlich eines Voreinstellwertes für die Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, liegt.
  7. Magnetbürsten-Entwicklungsgerät nach irgendeinem der Ansprüche 1 bis 3, bei dem der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte auf beiden Seiten der Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, dazwischen so angeordnet ist, daß er sich über einen Winkel von wenigstens 3 Grad in Form eines Drehwinkels der Drehhülse (1a) erstreckt, und bei dem der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte eine senkrecht zur Hülse (1a) verlaufende magnetische Flußdichte besitzt, die innerhalb des Bereiches von ± 10% hinsichtlich eines Voreinstellwertes für die Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, liegt.
  8. Magnetbürsten-Entwicklungsgerät nach irgendeinem der Ansprüche 1 bis 3, bei dem der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte auf beiden Seiten der Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, dazwischen angeordnet ist, so daß er sich über einen Winkel von wenigstens 10 Grad in Form eines Drehwinkels der Drehhülse (1a) erstreckt, und daß der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte eine senkrecht zur Hülse (1a) verlaufende magnetische Flußdichte besitzt, die innerhalb des Bereiches von ± 20% hinsichtlich eines Voreinstellwertes für die Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, liegt.
  9. Magnetbürsten-Entwicklungsgerät nach irgendeinem der Ansprüche 1 bis 3, bei dem der Abschnitt (Z) mit der einheitlichen magnetischen Flußdichte auf beiden Seiten der Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, dazwischen so angeordnet ist, daß er sich über einen Winkel von wenigstens 5 Grad in Form eines Drehwinkels der Drehhülse (1a) erstreckt, und bei dem der Abschnitt (Z) mit einheitlicher magnetischer Flußdichte eine senkrecht zur Hülse (1a) verlaufende magnetische Flußdichte besitzt, die innerhalb des Bereiches von ± 10% hnsichtlich eines Voreinstellwertes für die Stelle (6a), die zu dem Entwickler-Begrenzungsteil hinweist, liegt.
  10. Magnetbürsten-Entwicklungsgerät nach irgendeinem der vorhergehenden Ansprüche, bei dem das Entwickler-Begrenzungsteil (2) zwischen zwei (B, C) der Vielzahl der Magnetpole angeordnet ist, wobei ein Winkel (ϑo) zwischen den Mittellinien der zwei Magnetpole (B,C) nicht kleiner ist als dreimal die mittlere Weite der zwei Magnetpole (B,C) und wobei eine Weite des einen der zwei Magnetpole (B,C) kleiner ist als diejenige des anderen.
  11. Magnetbürsten-Entwicklungsgerät nach irgendeinem der vorhergehenden Ansprüche, bei dem das Entwickler-Begrenzungsteil (2) zwischen zwei (B,C) der Vielzahl der Magnetpole angeordnet ist, wobei ein Winkel (ϑo) zwischen den Mittellinien der zwei Magnetpole (B,C) nicht kleiner ist als dreimal ein Mittelwert der Weite der zwei Magnetpole (B,C) und wobei die magnetische Flußdichte von einem kleiner ist als diejenige des anderen.
  12. Magnetbürsten-Entwicklungsgerät nach irgendeinem der vorhergehenden Ansprüche, bei dem das Entwickler-Begrenzungsteil (2) zwischen zwei (B,C) der Vielzahl der Magnetpole angeordnet ist, wobei ein Winkel (ϑo) zwischen den Mittellinien der zwei Magnetpole (B,C) nicht kleiner ist als zweimal eine mittlere Weite der zwei Magnetpole (b,C), und bei dem ein weiterer Magnetpol (C′), dessen Weite ca. die Hälfte von derjenigen des Magnetpols (B oder C) beträgt und der eine Magnetisierungsstärke von ca. 5 bis 50% von derjenigen des Magnetpols (B oder C) besitzt, an einer Stelle zwischen den zwei Magnetpolen (B,C) vorgesehen ist.
EP91307747A 1990-09-03 1991-08-22 Magnetbürstenentwicklungsgerät Expired - Lifetime EP0474409B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP95102168A EP0658826B1 (de) 1990-09-03 1991-08-22 Entwicklungsgerät mit magnetischer Bürste

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP23390690 1990-09-03
JP233906/90 1990-09-03

Related Child Applications (1)

Application Number Title Priority Date Filing Date
EP95102168.2 Division-Into 1991-08-22

Publications (3)

Publication Number Publication Date
EP0474409A2 EP0474409A2 (de) 1992-03-11
EP0474409A3 EP0474409A3 (en) 1992-08-26
EP0474409B1 true EP0474409B1 (de) 1995-10-25

Family

ID=16962441

Family Applications (2)

Application Number Title Priority Date Filing Date
EP91307747A Expired - Lifetime EP0474409B1 (de) 1990-09-03 1991-08-22 Magnetbürstenentwicklungsgerät
EP95102168A Expired - Lifetime EP0658826B1 (de) 1990-09-03 1991-08-22 Entwicklungsgerät mit magnetischer Bürste

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP95102168A Expired - Lifetime EP0658826B1 (de) 1990-09-03 1991-08-22 Entwicklungsgerät mit magnetischer Bürste

Country Status (3)

Country Link
EP (2) EP0474409B1 (de)
KR (1) KR950001827B1 (de)
DE (2) DE69124120T2 (de)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2046634B (en) * 1979-02-02 1983-09-28 Canon Kk Magnetic brush developer
JPS5821772A (ja) * 1981-07-31 1983-02-08 Konishiroku Photo Ind Co Ltd 静電潜像現像装置
US4800412A (en) * 1985-03-22 1989-01-24 Minolta Camera Kabushiki Kaisha Apparatus for developing electrostatic latent images
JPH07107618B2 (ja) * 1986-05-15 1995-11-15 ミノルタ株式会社 現像装置
JPS6324268A (ja) * 1986-07-16 1988-02-01 Minolta Camera Co Ltd 現像装置
JPH01154182A (ja) * 1987-12-11 1989-06-16 Minolta Camera Co Ltd 現像装置

Also Published As

Publication number Publication date
EP0474409A3 (en) 1992-08-26
DE69114089T2 (de) 1996-04-04
KR950001827B1 (ko) 1995-03-03
DE69124120D1 (de) 1997-02-20
KR920007427A (ko) 1992-04-28
DE69124120T2 (de) 1997-04-17
EP0474409A2 (de) 1992-03-11
EP0658826B1 (de) 1997-01-08
DE69114089D1 (de) 1995-11-30
EP0658826A1 (de) 1995-06-21

Similar Documents

Publication Publication Date Title
US7120379B2 (en) Electrographic development method and apparatus
US6081684A (en) Method and apparatus for image forming capable of performing an improved circulation of developer
JPH03251882A (ja) 現像装置
US9442428B2 (en) Developing apparatus
US4660505A (en) Developing apparatus
JP2002251072A (ja) 現像ローラ及びその製造方法、現像装置並びに画像形成装置
US5424489A (en) Magnetic brush developing apparatus
EP0474409B1 (de) Magnetbürstenentwicklungsgerät
US5396026A (en) Magnetic brush developing apparatus
JP2725686B2 (ja) 磁気ブラシ現像装置
JP2822476B2 (ja) 現像装置
JPS648821B2 (de)
JPS604194Y2 (ja) 現像装置
JPH0644082Y2 (ja) マグネットロ−ル
JPH0336573A (ja) 現像装置
JPS61200563A (ja) 現像装置
JPH0990758A (ja) 現像装置
JPH01219778A (ja) 現像装置
JPH04240675A (ja) 現像装置
JPH02110483A (ja) 現像磁極の調整方法および磁界分布の測定方法
JPS63201674A (ja) 現像装置
JPH0990761A (ja) マグネットロール
JPH0337689A (ja) 現像装置
JPH08339124A (ja) マグネットロール
JPS5948375B2 (ja) 磁気現像方式における磁力調整方法

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE GB IT

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): DE GB IT

17P Request for examination filed

Effective date: 19921016

17Q First examination report despatched

Effective date: 19940407

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE GB IT

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRE;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.SCRIBED TIME-LIMIT

Effective date: 19951025

XX Miscellaneous (additional remarks)

Free format text: TEILANMELDUNG 95102168.2 EINGEREICHT AM 22/08/91.

REF Corresponds to:

Ref document number: 69114089

Country of ref document: DE

Date of ref document: 19951130

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

REG Reference to a national code

Ref country code: GB

Ref legal event code: 732E

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20100728

Year of fee payment: 20

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20100818

Year of fee payment: 20

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 69114089

Country of ref document: DE

REG Reference to a national code

Ref country code: DE

Ref legal event code: R071

Ref document number: 69114089

Country of ref document: DE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20110821

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF EXPIRATION OF PROTECTION

Effective date: 20110823