EP1156390A2 - Apparatus for developing an electrostatic image - Google Patents

Abstract

The photocopying machine for developing an electrostatic image has a photo-conducting drum (12) with a magnetic brush in contact with the photo-conducting drum. The magnetic brush deposits a mixture of toner and hard-magnetic toner particles on the photo-conducting drum. An Independent claim is made for a support for a toner unit (10) with a support bar and a sliding bar that engages in the support bar. The sliding bar is shaped so that is holds the toner unit and a pair of mounting pins are used to mount the toner unit in relation to the sliding bar and a mounting member that brings the toner unit into register steadiness using the mounting pins.

Description

The present invention relates to an apparatus for electrostatic image development and in particular a device in which a magnetic brush with a photoconductor drum cooperates.

Development devices and methods using a magnetic brush to place toner on the photoconductor have been known for years. Development devices and methods using a magnetic brush which has hard magnetic carrier particles are in US 4,473,029 and US 4,546,060. The devices disclosed in these patents feature a rotating housing that is made with a mixture of hard magnetic Carrier particles and toner coated, a rotating magnetic core with a variety of magnetic poles, which are arranged within the housing, and a thin, flat, photoconductive film. The rotating magnetic core brings the hard magnetic Carrier particles on the surface of the case, resulting in increased movement and increased Contact of the toner with the photoconductive film ensures.

The two-component dry developer composition disclosed in US 4,546,060 includes charged toner particles and magnetic carrier particles opposite charge comprising (a) a magnetic material which has hard magnetic properties, such as that of a coercivity of at least 30 mT are marked and (b) an induced magnetic moment of at least 200 mC / kg if they are in a field of 100 mT Gauss. As in This patent describes the developer in connection with a magnetic application element related, which has a rotatable magnetic core and an outer includes non-magnetizable housing for developing electrostatic images. If hard magnetic carrier particles are used and these a number of magnetic fields, which start from the rotating core application element, are exposed, rotate and the particles roll over in each new field and are thus transformed into magnetic fields Alignment moves. Any flipping is also a consequence of both the magnetic moment of the particles as well as the coercivity of the magnetic Material from a rapid jump of each particle in the circumferential direction against the Direction of movement of the rotating core accompanied. The observed result is that the Developer of US 4,546,060 with no problems and with a fast flow rate around it Housing flow while the core rotates in the opposite direction and thus quickly transfers fresh toner to the photoconductor and high-performance copying and printing applications.

Previous uses for hard magnetic carrier particles saw a flexible one Photoconductor in the form of a thin, flat film. Flexible photoconductor or Photoconductor films have several important advantages for fast photocopiers. In a typical The device is the photoconductor film under slight tension with a series of rollers positioned. The film has an inherent compliance that allows it To respond to changes in the thickness of the magnetic brush.

Photoconductor drums are state of the art, but are not yet included Magnetic brushes that have hard magnetic carrier particles have been used. The The reason that photoconductors have not been used is largely because they are are much stronger than film photoconductors and the increasing thickness of the magnetic brush Surface of the drum. Conversely, a decreasing thickness of the Magnetic brush cause insufficient contact with the photoconductor and thus too lead to poor image development.

The invention is accordingly based on the object of an improved device to create an electrostatic image.

This object is achieved by the features of claim 1.

In one embodiment of the invention, an apparatus for developing a electrostatic image a photoconductor drum and a magnetic brush holding the photoconductor touched and has a mixture of toner and hard magnetic carrier particles.

According to a further embodiment of the invention, a toner unit comprises one Support rail, a slide rail that lies in the support rail, the slide rail so is adapted to receive the toner unit, a pair of dowel pins, the Slide rail positioned the toner unit in relation to the dowel pins and one Actuator that aligns the toner unit with the dowel pins.

The invention is more preferred below with reference to the drawings Embodiments described.

Fig. 1

eine Seitenansicht einer erfindungsgemäßen Entwicklervorrichtung einschließlich einer Querschnittsansicht einer erfindungsgemäßen Tonereinheit,

Fig. 2

eine vergrößerte Ansicht einer erfindungsgemäßen Entwicklungszone,

Fig. 3

eine vergrößerte Ansicht einer Entwicklungszone mit einem Rückstaubereich,

Fig. 4

eine auseinandergezogene perspektivische Ansicht der Tonereinheit aus Fig. 1,

Fig. 5

eine auseinandergezogene perspektivische Ansicht der Tonereinheit aus Fig. 1 von deren entgegengesetztem Ende aus gesehen,

Fig. 6

eine Seitenansicht der erfindungsgemäßen Tonereinheitträgeranordnung,

Fig. 7

eine perspektivische Ansicht der Trägeranordnung aus Fig. 6,

Fig. 8

eine Ansicht einer seitlichen Draufsicht auf eine Gleitschiene, die in der Trägeranordnung aus Fig. 6 angeordnet ist,

Fig. 9

eine perspektivische Ansicht der Trägeranordnung aus Fig. 6 von dem entgegengesetzten Ende, zu dem in Fig. 7 dargestellten Ende,

Fig. 10

eine Seitenansicht der Trägeranordnung aus Fig. 6 mit der Tonereinheit aus Fig. 1 registerhaltig mit einer Fotoleitertrommel ausgerichtet,

Fig. 11

eine vergrößerte Ansicht eines Passlaufreifens und eines Passstiftes in einem nicht-registerhaltigen Zustand, und

Fig. 12

eine vergrößerte Ansicht eines Passlaufreifens und eines Passstiftes in einem registerhaltigen Zustand.

The drawings show:

Fig. 1

2 shows a side view of a developer device according to the invention, including a cross-sectional view of a toner unit according to the invention,

Fig. 2

2 shows an enlarged view of a development zone according to the invention,

Fig. 3

an enlarged view of a development zone with a backflow area,

Fig. 4

FIG. 2 shows an exploded perspective view of the toner unit from FIG. 1,

Fig. 5

1 is an exploded perspective view of the toner unit of FIG. 1 seen from the opposite end thereof;

Fig. 6

a side view of the toner unit carrier assembly according to the invention,

Fig. 7

6 shows a perspective view of the carrier arrangement from FIG. 6,

Fig. 8

6 shows a view from the side of a top view of a slide rail which is arranged in the carrier arrangement from FIG. 6,

Fig. 9

6 shows a perspective view of the carrier arrangement from FIG. 6 from the opposite end to the end shown in FIG. 7,

Fig. 10

6 shows a side view of the carrier arrangement from FIG. 6 with the toner unit from FIG. 1 in register with a photoconductor drum,

Fig. 11

an enlarged view of a tread tire and a dowel pin in a non-register state, and

Fig. 12

an enlarged view of a tread tire and a dowel pin in a registered state.

Various embodiments of the invention are shown in Figures 1-12 are not drawn to scale, and in which the parts in the different Views have the same reference numerals. In Fig. 1 is a toner unit according to the invention 10, which comprises a photoconductor drum 12 and a magnetic brush 14, which a mixture of toner and hard magnetic carrier particles in contact with the outer Surface of the photoconductor drum 12 brings. The magnetic brush 14 comprises a housing 16, preferably made of non-magnetizable material and a core 18 which is rotating Has a variety of magnetic poles. The photoconductor drum 12 rotates in the Direction indicated by arrow 20, the sleeve 16 rotates in the direction indicated by arrow 22, and core 18 rotates in the direction indicated by arrow 24.

The toner unit 10 and the photoconductor drum 12 are attached to the frame 28, each as needed for a special copier or printer application Printer is designed. The toner unit 10 comprises a sleeve 16, a collecting basin 30, four screws 32, which are rotatably mounted in the catch basin 30, one Transport roller 34, which is arranged above the screws 32 next to the sleeve 16, and a Filling unit 36, which has a fixed perforated tube 38 and a filling brush 40 within tube 38 which rotates in the direction indicated by arrow 42. The padding unit 36 directs toner into the toner / carrier particle mixture according to the Information from a toner concentration monitor 44 to determine the weight ratio of Toners and carrier particles, e.g. Maintain 1/10. Some of these parts can ever be added or removed after the specific application. The additional Mixing through the four-screw system improves mixing and uniformity Toner distribution across the entire image width. The toner concentration gradients are preferably minimized and represent only a few percent.

When used, the mixture of hard magnetic carrier particles and toner covers the Snails 32 to a level that is approximately the level of the bottom of the Transport roller 34 corresponds. The screws 32 include a variety of angled paddles 46 which are attached to the shafts 48. The mixers mix them Carrier particles and the toners to create friction charge and homogeneity and around a generally equal level of toner / carrier particle mixture in the To create catch basin 30. The transport roller 34 rotates in the direction of the arrow 50 indicated direction and lifts the mixture from the collecting basin 30 to the sleeve 16.

FIG. 2 shows an enlarged view of the gap area from FIG. 1, which shows where the toner / carrier particle mixture 52 surrounding the sleeve 16, the photoconductor drum touched. The flow of the toner / carrier particle mixture 52 has a thickness T and touches the drum 12 over a length L. The flow shown in Fig. 2 is very high desirable.

FIG. 3 shows an undesired flow of the toner / carrier particle mixture 52, thereby creating a back pressure area 54. It is believed that a Backflow area 54 arises when the flow of the toner / carrier particle mixture 52 increases is the amount that flows through the gap between the sleeve 16 and the roller 12 can. The backflow area can interfere with image development on the drum 12 cause and also damage the surface of the drum 12. The backwater area 54 is not passive because the rotating core 18 tends to reduce the mass of material in the To back pressure area 54 with active force in the gap.

According to one embodiment of the invention, the development of a backflow area bypassed. In Fig. 1 it can be seen how the register position of the housing 16 to the drum 12 is controlled by a pair of dowel pins 56 on each side of the drum 12 are attached. The drum 12 includes a shaft 58 which is in a pair of bearings 60 is attached, which in turn are attached to the frame 28. The toner unit 10 includes a pair of registration fittings 62 on each end into which the pins 56 fit. According to In a preferred embodiment of the invention, the toner unit 10 is in register fixed with the pins 56, whereby they during the operation of the drum 12 and Magnetic brush 14 is immobilized. The one shown in Fig. 1 Registration fitting 62 is largely hidden behind the toner unit 10. A better reproduction can be found in FIG. 12.

According to a further embodiment of the invention, the centers of rotation lie of the core 18 and the sleeve 16 not one above the other, but the Centers of rotation of the core 18 in relation to the center of rotation of the sleeve 16 towards the drum 12 (eccentric), forming an area 64 in which the Inner surface of the sleeve 16 is closest to the outer surface of the core 18 (slightly below the point at which drum 14 and sleeve 16 are closest. On Dosing element 66 is arranged opposite the area 64, in which the sleeve 16 on farthest from the core 18. The dosing element 66 doses a predetermined one Thickness of the toner / carrier particle mixture on the sleeve 16. The magnetic field on the Toner / carrier particle mixture is applied, is weakest at this point, so that it's not fully compressed. The thickness of the mixture decreases as it is guided around the housing to the drum 12. Therefore, every change in the Thickness decreases with the thickness of the mixture, creating a more precise thickness T. According to a preferred embodiment, an imaginary line runs from the area 64 to the dosing element 66 horizontally, and the two elements lie at a 180 ° angle to each other (one element at 9 o'clock and the other at 3 o'clock Position).

4 and 5 show exploded views of the toner unit 10 of FIG opposite ends for additional detail and the relationship between the Represent components.

The rotating magnetic core 18 can lose eddy current in the photoconductor drum 12 cause. A combination of a relatively fine magnetic pole frequency (e.g. a 14-pole Arrangement with about 4 cm [1.6 inch] diameter) and relatively thin wall of 4 to 8 mm for the photoconductor drum 12 reduces the eddy current losses that arise. About that also minimizes the choice of material for a relatively hard aluminum (T3 or T6) Drum wall the conductivity of the wall and thus the eddy current losses.

According to a further embodiment of the invention, the dosing element 66 is on both Winged ends 67 which the flow of the toner / carrier particle mixture in the Reduce near the ends of the photoconductor drum 12. The river this way too reduce, prevents damage to the ends of the development zone due to the edge effects that locally increase the flow. Further Reductions in the formation of backwater areas at the ends of the development zone are achieved by small permanent magnets on the dosing elements 66 on the Position of the wing 67 can be arranged.

A DC bias is applied to the sleeve 16 to apply an electric field generate that brings the toner onto the surface of the photoconductor drum 12. A AC bias can also be used to control the rate of development and thus also to improve the level and consistency of the image quality. In Full area development systems will create an electrical bias between the Base layer of the photoconductor and the sleeve of the developer unit applied. Becomes a High frequency or high voltage (e.g. 1000 to 2000 Hertz and 500 to 1500 volts effective voltage) signal is added to the constant bias, the Development rate increased significantly.

6 to 12 is a carrier arrangement 100 according to an embodiment of the Invention shown, which is used together with the toner unit 10 (Figs. 1 and 10) can be used to precisely register the toner unit with the photoconductor drum 12 (Fig. 1 and 10). The carrier arrangement 100 compensates for displacements of the Photoconductor drum 12 out. As shown in FIGS. 6 to 9, the carrier unit comprises a support rail 102 and a slide rail 104 formed by the three rods 106, 108 and 110 is held and led. The support rail is fixed with a structure, e.g. the Frame 28 of Fig. 1 connected. As best seen in Figure 8, the Slide rail 104 two horizontally elongated holes 132 that the outer Pick up rods 106 and 110 and a slightly oversized hole 134. The middle pole 108 restricts the movement of the slide rail 104 in the longitudinal direction while it allows the slide rail to move laterally along the rod 108. The two outside lying bars 106 and 110 serve to maintain the flatness of the Slide rail 104.

6 to 9, the slide rail 104 is attached to the side plate 116. A Eccentric shaft 112 is driven by an electric servomotor 114, is between two parts of the side plate 116 attached and provides the device for positioning the Slide rail 104 ready in relation to the photoconductor drum 12. The electric one Actuator 114 is fixedly attached to the same support structure as the support rail 102 Eccentric shaft 112 comprises an eccentric bearing 113. A load arm 122 is also on the Side plate 116 attached and is about a vertical axis Lift arm pivot point 124 pivoted. The position of the eccentric shaft 112 is determined by the Use of two solid-state microswitches 126 and one eccentric positioning coupling 118 controlled.

The eccentric shaft 112 will move from a parked position to an employed position rotated, it presses against a determined eccentric locking plate 120, which on the Side plate 116 is attached. The movement pushes the slide rail 104 into its position Position (see FIG. 6), as indicated by arrow 142. While the slide rail 104 in their is brought into position, hits the load arm 122, which on the side plate 116th is attached to the toner unit 10 (Figs. 1 and 10) and is deflected, one Spring force is created, the toner unit 10 in register with the dowel pins 56th aligns (Fig. 1 and 10). The determined eccentric locking plate 120 causes one Force so that the eccentric shaft 112 is not rotated away when the device is in the position.

6 to 9 is a positive vertical lifting force by using reached two angled pressure blocks 128, which are attached to the load arm 122 and a mating angled wedge 130 attached to the toner unit 10 (see FIG. 1 and 10) is attached. The pressure blocks 128 fit through a pair of windows that are in the Side plate 116 are provided. 10, an angled pressure block 136 is at Bottom of the toner unit 10 attached and a mating pressure plate 138 is on Frame of the machine, e.g. the frame 28 of FIG. 1 attached. The angled one Pressure block 136 and the corresponding pressure block 138 create an additional one vertical lifting force. The net force is directed up and down on the drum 12, as indicated by arrow 140 in FIG. 1. As shown in Figs. 11 and 12, the Registration fittings 62 attached to each end of the toner unit 10 preferably pointed notches 63, and the dowel pins 56 are in the notches 63 recorded when the toner unit is moved in the direction of arrow 140. The Force that holds the toner unit 10 in position may exceed approximately 450 N and lie in a particular embodiment at approximately 700 N.

The slide rail 104 includes a track 105 in which the toner unit 10 while in the Apparatus is inserted, lies and is guided until all electrical and mechanical Interfaces are connected. The slide rail 104 and the track 105 serve the To place the toner unit 10 in relation to the pins 56 exactly, so that when the Eccentric shaft 12 is activated, the dowel pins 56 are received in the notches 63.

List of reference numbers

10th

Toner unit

12th

Photoconductor drum

14

Magnetic brush

16

Sleeve

18th

core

20th

arrow

22

arrow

24th

arrow

28

frame

30th

Catch basin

32

Snails

34

Transport roller

36

Replenishment unit

38

perforated tube

40

Refill brush

42

arrow

44

Toner concentration monitor

46

angled paddle

48

wave

50

arrow

52

Toner / carrier particle mixture

54

Backflow area

56

Dowel pins

58

wave

60

Bearing pair

62

Registration fitting

63

Notch

64

Area

66

Dosing element

67

wing

100

Carrier arrangement

102

Support rail

104

Slide rail

105

track

106, 108, 110

Poles

112

Eccentric shaft

113

Eccentric bearing

114

Servomotor

116

Side plate

118

Eccentric positioning coupling

120

Eccentric locking plate

122

Low load

124

Load arm pivot point

126

Solid state microswitch

128

Pressure pad

130

angled wedge

132

elongated holes

134

oversized holes

136

Pressure console

138

Pressure plate

140

arrow

142

arrow

Claims (2)

Device for developing an electrostatic image (10) with a photoconductor drum (12) and a magnetic brush (14) in contact with the photoconductor drum,
characterized in that
the magnetic brush (14) applies a mixture (52) of toner and hard magnetic carrier particles to the photoconductor drum (12) Carrier for a toner unit (10) with
a support rail (102);
a slide rail (104) lying in the support rail (102), the slide rail (104) being adapted to receive the toner unit (10); a pair of dowel pins (56), the slide rail (104) positioning the toner unit (10) relative to the dowel pins (56); and
an actuator (114) which brings the toner unit (10) into register with the dowel pins (56).

Images