JP3122134B2 - Method and apparatus for applying toner to an electrostatic image - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to the development of electrostatic images, in particular, different toners,
For example, the present invention relates to a developing device and a method useful for developing a series of images with toners of different colors.

Background Art U.S. Patent No. 4,928, issued May 22, 1990 to Yamada,
No. 146 shows an example of some known devices for developing a series of electrostatic images supported on an image bearing drum at one development position with toners of different colors. No. 3,797,930 issued to Tanaka et al. On Mar. 17, 1974; U.S. Pat. No. 4,275,134 issued to Knechte on June 23, 1981; March 1
Zwaldo's U.S. Patent 4,728,
No. 983 was also referenced.

Four consecutive developing units are moved to the developing position one by one. Each unit develops the image at the development position, but when instructed to apply a different color toner to the next image, the corresponding other unit is replaced by that development position. A series of units are juxtaposed and are moved linearly so that the units to be used are at the development position. When one developing unit is aligned with the developing position, the cam rotates to push the entire unit, that is, the developing device, to the developing position in a direction orthogonal to the direction of movement of the series of units.
In other documents, the developing unit is arranged on a rotating support,
It discloses a configuration that can be sequentially rotated via a development position.

Such a conventional device has the advantage of utilizing only one development position to apply four different colors of toner to the electrostatic image. This makes it possible to use developing units of a size and number that make it impossible to place them around a relatively small image bearing drum. Therefore, a relatively small image bearing drum can be used for developing a multicolor image. The ability to use small drums has advantages such as reduced cost, reduced device size, and convenience in cartridge type deployments.

Prior art structures require two movements for each developer unit. That is, the four developing units are integrally moved linearly in one direction to the developing position, and the developing units facing the developing position are moved in a direction orthogonal to the direction of the linear movement so as to approach the image bearing drum. The unit is moved with respect to the remaining developing units. In order to achieve the latter movement, all the developing units need to be mounted so as to be movable relative to each other, and a moving mechanism for each developing unit is required to move each developing unit. In addition, the moving mechanism must not only be driven at an appropriate timing, but also must be sufficiently powered to completely move the developing unit.

U.S. Pat. No. 4,922,302 issued to Hill et al. On May 1, 1990; U.S. Pat. No. 4,884,109 issued to Hill et al. On Nov. 1, 1989; Hill et al. Issued on Jan. 10, 1989. U.S. Pat.No. 4,797,704 discloses a developing unit with an applicator having a rotating magnetic core and a stationary non-magnetic sleeve for moving the mixed developer around by rotation of the core through a developing position. ing. A rotatable paddle for mixing and supplying the developer to the applicator is disposed directly below the applicator, and the rotation of the paddle supplies the developer to the applicator. Toner is periodically supplied to the mixed developer from a toner supply portion of the unit. New toner is supplied by rearranging the developing unit.

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a method and apparatus for developing a series of electrostatic images with toners of different colors in a simple design.

These and other objects include a developing unit that includes an applicator for supplying developer to an electrostatic image, the applicator being movable toward a developing position relative to the remaining developing units. Achieved by providing.

According to a preferred embodiment, the invention is incorporated in a developing device in which such a plurality of developing units are fixed to one another and are moved linearly in order to sequentially align each unit at a developing position. The applicator of the developing unit aligned with the developing position is moved to the developing position with respect to the remaining developing units to facilitate development of the electrostatic image.

With this arrangement, the moving means does not need to move the entire developing unit, so that the energy to achieve this purpose is significantly reduced. The developer units themselves are fixed to each other and have many advantages in design and reliability (this advantage is described in further detail with respect to the preferred embodiment below). Accurate positioning of the applicator relative to the surface carrying the electrostatic image can be achieved.

According to yet another preferred embodiment, the applicator is accurately positioned on the imaging member by a pair of pins fixed to the imaging member, said pins being fixed to the applicator. A pair of holes fit to control relative lateral and rotational movement. Rollers on both ends of the applicator define the spacing between the applicator and the imaging member.

BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed description of the preferred embodiments of the present invention, reference is made to the accompanying drawings.

FIG. 1 is a front view of a part of a color printer in which many parts are omitted for simplifying the drawing.

FIG. 2 is a partial front view of the developing device of the printer shown in FIG. 1 in which many parts are omitted to simplify the drawing and a small number of parts are changed to change the drawing.

FIG. 3 is an illustration of FIG. 2 with parts omitted for simplicity of the drawing.
3 is a right side view of a part of the developing device shown in FIG.

FIG. 4 is a front view similar to FIG. 1 showing a modified structure of some parts.

FIG. 5 is a perspective view of a portion of the apparatus shown in FIGS. 1 and 2, illustrating another structure for positioning an applicator with respect to the imaging member.

 FIG. 6 is an enlarged view of a part of the apparatus shown in FIG.

7 and 8 are front views of the part shown in FIG. 5 with some parts omitted for simplicity of the drawing.

FIG. 9 is a perspective view of the positioning pin shown in FIGS. 5 and 6.

10 and 11 are drawings including a cross-sectional view of the hole 114, and are left side views of a part of the positioning pin 110 of the cooperative structure.

 FIG. 12 is a rear view of the pin 111 and a cross-sectional view of the hole 115.

FIG. 13 is a front view similar to FIG. 7, showing another sealing structure for the applicator 71 as shown in FIG.

FIG. 14 is a front view similar to FIG. 7, showing a gear for a driving body for the applicator 71 as shown in FIG.

FIG. 15 is a front view showing a preferred lifter mechanism having the structure shown in FIG. 5. BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 1, an electrostatic color printer 1 is, as is well known in the art, It includes a photoconductive drum 2 mounted to rotate past a series of locations to create a plurality of color toner images on the transport roller 3 or on a receiving sheet supported by the transport roller 3. More specifically, the drum 2 is uniformly charged at the charging station 6,
An exposure station, for example, a laser exposure station 5
Exposes a series of electrostatic images. This electrostatic image is developed by a developing device 4 that supplies each successive image with a different color toner to form a series of different color toner images. The continuous toner image is transported in register with the surface associated with transport roller 3 to produce a plurality of color images. The surface associated with the roller 3 may be either the surface of the transport roller 3 or the outer surface of a receiving sheet fixed to the surface of the transport roller 3. If a plurality of color images are formed directly on the surface of the transport roller, the image formed on the transport roller will be transferred to the receiving sheet at a position away from the photoconductive drum by means not shown. . On the other hand, if images of a plurality of colors are formed on the surface of the receiving sheet supported by the roller 3, the sheet will be separated from the roller 3 and from the drum 2 by means (not shown).

The photoconductive drum 2 is made very small, the circumference of which is substantially smaller than one image. Small photoconductive drum 2
Can be easily replaced, for example, as a part of the processing cartridge including the charging station 6 and the cleaning station 8. It also contributes to a reduction in the size and cost of the printer 1. However, if the photoconductive drum is small, it is geometrically difficult to apply different color toners to a continuous electrostatic image. In the printer 1 of the present invention, only one developing position 9 is used around the drum 2 as in the above-described prior art, while a series of four developing units 10, 20, 30, 40 are used.
Are sequentially moved with respect to the developing position to color each of the electrostatic images through different developing units, thereby solving the above-described problem.

According to FIG. 1, all of the developing units 10, 20, 30, 40 are fixed to a carriage 50 which is movable in the lateral direction. The carriage 50 is supported on a guide rail so as to be movable linearly in the horizontal direction below the drum 2. The carriage 50 is driven by a motor 52 via a metal drive tape 53 whose part 54 is connected to the carriage 50.

In FIG. 1, among the plurality of developing units, the developing unit
10 is aligned with the developing position 9. Preferably, the carriage 50 has a start position to the left of the position shown in FIG. 1 and moves to the position shown in FIG. 1 to develop a first electrostatic image. When the electrostatic image is colored with toner, the carriage 50 moves again to align the next developing unit 20 with the developing position 9 to color the second electrostatic image with toner. Similarly, units 30 and 40 are sequentially aligned with development position 9 to color the third and fourth electrostatic images with toner. Thereafter, the carriage 50 returns to the start position.

The developing unit 10 includes an applicator 11, for example, a paddle 12
And an auger 13. This mixing device is disposed in a developing chamber 14 that contains a mixture of hard magnetic carrier particles and insulating toner particles. The toner chamber 15 stores the supplied toner. The toner is
The toner is supplied from the toner chamber 15 to the developing chamber 14 by the toner supply roller 16.

The manufacture and operation of each developing unit is described in U.S. Pat.
This is the same as the developing unit described in US Pat. No. 4,797,704.
In operation, the rotation of paddle 12 and auger 13 causes the developing chamber
Mixing of the developer within 14 and raising the surface level of the developer is performed, thereby allowing the developer to access the magnetic field of the applicator 11. As fully described in the above-mentioned patents, the applicator 11 comprises a rotatable magnetic core 17 and a stationary sleeve 18. The magnetic carrier particles carry the developer to the developing position 9 while moving on the outer periphery of the sleeve 18 as the core 17 rotates. The developing material is moved by rotating the core 17 at substantially the same speed as when the electrostatic image on the rotating drum 2 moves, thereby performing high-quality development of the electrostatic image.

The developing units 20, 30, and 40 have basically the same structure as the above-described developing unit 10, but it should be noted that the toner chamber 15 of the developing unit 40 is larger than the other toner chambers 15. The developing unit 40 contains a black toner that is used more frequently than the color toners in the units 10, 20, and 30. Units 10, 20, 30 may have cyan, magenta, and yellow toners, or may contain high-intensity color toners, for example, red, blue, and yellow, respectively, for full color reproduction. .

The developing device 4 including the developing units 10, 20, 30, and 40
A small, precise spacing between the sleeve 18 of the applicator 11 and the drum 2 is required. In FIG. 1, this spacing is achieved by providing a total of four rollers 60 at each corner of the applicator 11 of the unit 10. Each roller 60
When the developing unit 10 is pressed against the drum 2 as shown in FIG.
Are precisely positioned so that there is a precise spacing between them.

In the above-described prior art, each developing unit is sequentially aligned with a developing position. After or when it is aligned, this developing unit is moved towards the developing position relative to the other developing units and engages the drum 2. In order to move the developing units engaged with the drum 2, it is necessary that each of the developing units is relatively movable with respect to each other. In order to relatively move each of the developing units in this way, a driving means such as a rotatable cam is provided for each of the developing units. The driving means, together with the driving means for aligning and moving the developing unit to the developing position 9, must be adjusted in timing. This has been described above.

However, in the developing device 4 shown in FIG.
By fixing the developing units 10, 20, 30, 40 to one another, this prior art device is substantially improved.
As each developing unit aligns with developing position 9, applicator 11 in the developing unit aligned with developing position 9
Moves relatively toward the drum 2 with respect to the remaining developing units to bring the roller 60 into contact with the drum 2.

To this end, the applicator 11 is mounted together with the rollers 60 on an applicator block 71 to form an applicator assembly. The applicator block 71 has an opening 72 to which the applicator 11 is attached.
Having. Opening 72 is larger than applicator 11 to allow developer from chamber 14 to move around sleeve 18 during development of the electrostatic image. The applicator block 71 is attached to the side wall by mounting means 77 so that the block 71 can be restrictedly moved in the vertical direction.
It is freely mounted on 75 and 76. Block 71
The side wall of is freely fitted into the side walls 75 and 76 so that the block 71 can perform side and tilting movements.
A pair of lifters 80 are rotatably attached to both ends of the applicator block 71, and loosely attached to both ends of the developing unit 10. A similar lifter 80 is provided in the units 20, 30, and 40.

Under the carriage 50, just below each lifter 80
There are 83. The engagement pin 83 includes a sleeve 84, a pin core 85 mounted in the sleeve 84, and a spring 86 in the sleeve 84 for urging the pin core 85 downward. The pin implanted in the pin core 85 and the slot formed in the sleeve 84 prevent the pin core 85 from dropping out of the sleeve 84 due to the pin engaging with the slot. A pair of inclined portions or wedge members 90 are rotatably fixed to the base of the printer via pivots 91 and are aligned with the front and rear engagement pins 83, respectively.

As the carriage 50 is moved from left to right as viewed in FIG. 1, each engagement pin 83 engages a corresponding wedge member 90 as the developing unit 10 is aligned with the developing position 9. The engagement between the engagement pin 83 and the wedge member 90 causes the core 85 to be displaced upward against the force of the spring 86. Then, the spring 86 presses the top of the sleeve 84 against the lifter 80 and pushes the lifter 80 upward against the applicator block 71. Thus, the applicator block 71 is urged until the roller 60 contacts the drum 2 and positions the applicator 11 at a development position that is precisely spaced from the drum 2.

After developing the first electrostatic image by the developing unit 10, the motor 52 is operated to drive the carriage 50 further rightward. By the action of gravity and the two rollers 60, the applicator block 71 and the lifter 80 are pressed downward toward their original positions. This movement is facilitated by a cantilevered spring (not shown) that biases applicator block 71 downward against spring 86. The motor 52 is used to move the applicator 21 of the developing unit 20 to the exposure position 9 and the corresponding engagement pin 94 to move the applicator 21 to an appropriate position to color the second electrostatic image. The carriage is driven to the right until it engages member 90. This process is repeated for each of the developing units 30 and 40 such that the applicators 31 and 41 move in response to the engagement of the wedge members 90 with the engagement pins 95 and 96.

If any inconsistency occurs in the developing unit 10,
The free mounting of the block 71 between the side walls 75 and 76 and the rotatable mounting of the applicator block 71 on the lifter 80 allow the application while maintaining the precise spacing controlled by the rollers 60 on the surface of the drum 2. The tab block 71 performs a certain amount of tilting and lateral displacement with respect to the applicators 11, 21, 31, and 41.

The motor 52 reversely rotates after all four electrostatic images have been colored to move the cartridge 50 to its original position to the left. Developing unit 1 during its return movement
In order to avoid interference between 0, 20, 30, 40 and the drum 2, the wedge member 90 is engaged with engagement pins 83, 94,
It is pivoted out of the passage 95 (see FIG. 3).

Alternatively, the wedge member 90 may be made symmetrical so that the set of images is colored on the return movement. This requires exposing all other sets of images in the reverse order of the other sets of images. Variations of the exposure sequence in an electrostatic printer can be achieved with programming designs well known to those skilled in the art.

FIG. 2 shows some advantages of moving only the applicator with respect to the remaining units in order to finally position the applicator with respect to the drum at the development position 9. This applicator 11 has a rotatable magnetic core that must be driven during development. Typically, it is 10 per minute
It is driven at a rotational speed from 00 to 1300. The paddle 12 is driven at a low speed, for example, 50 to 300 revolutions per minute. Auger 13
Is usually engaged with the gear within the unit itself. The toner supply roller 16 is rotated several times when supplying toner by a program or command from a toner monitor or pixel count of the printer. Such a development unit typically has three separate connections to one or more drive means for rotating these components. See, for example, the aforementioned U.S. Pat. No. 4,797,704.

An alternative to separate the drive means is to engage the component within each developer unit with a clutch operable for optional engagement of the toner supply roller. This method of interlocking with components complicates each developer unit excessively, and in particular requires substantial gear reduction.

However, if the entire developer unit is moved relative to the other developer units for final positioning of the applicator, each of the moving developer unit drive couplers must absorb that motion. Moving only this applicator means that only one coupler for each developer unit is complicated.

This is shown in FIG. The applicator 11 has a drive shaft 45 for driving the rotatable magnetic core 17 (see FIG. 1). The drive shaft 45 is connected via a universal joint 46 that is freely fitted in a connecting wall 79. It is connected to a gearbox or gearbox 61. When the roller 60 comes into contact with the drum 2, the applicator block 71 is inclined with respect to the side walls 75 and 76. The universal joint 46 has a block 71 in which the wedge member 90 and the engaging pin 83
Must absorb the tilting and vertical movement of the block 71 when pushed up by the engagement (see FIG. 1).
However, since the developing units 10, 20, 30, 40 are fixed to each other (except for the applicator assembly), the driving connection between the paddle such as the paddle 12 and the supply roller such as the supply roller 16 is inexpensive. It is made as a simple fixed connection. For example, the shaft 47 for driving the supply roller 16 does not require the use of a universal joint, does not need to be freely fitted to the wall 79, and is provided with a gear box 61 via the wall 79 from each developing unit. Extends to Similarly, (Developing unit
Only shaft 40 (shown in FIG. 2) is connected to gearbox 61 via a similarly fixed joint. The gearbox 61 is driven by one motor 62 and includes a clutch on the shaft 47 of each supply roller 16 to control the supply of toner by program or command.

As shown in FIG. 2, the developing units 10, 20, 30, 40
It is configured as one component, and is detachable as one unit with respect to the carriage 50. The wall between adjacent developing units acts as one wall common to these adjacent developing units. This has many advantages in cost, weight, space, and simplicity, but because the black toner consumption tends to be significantly different from the toner consumption in the other three units, the development unit 40 for black toner Is separate from the other three developing units.
Desirably, it is exchangeable. In this manner, one or all of the developing units may be configured to be detachable separately. In this case, the one wall between the adjacent developing units is not a common wall between the adjacent developing units, and the carriage 50 has a structure necessary for accommodating each of the separately removable developing units. Will be prepared. This is what is shown in FIG. 1, in which each developing unit 1
Reference numerals 0, 20, and 30 denote one detachable developing unit that contains, for example, cyan, magenta or yellow toner. The developing unit 40 containing the black toner has its own separate wall and is separately removable.

Each applicator assembly, including the applicator block and applicator, accounts for only a small portion of the weight of the entire developing unit, including the developer. by this,
The spring 86 that produces the force to move the applicator assembly into engagement with the drum 2 is of a suitable moderate strength. However, wedge member 90 is used with engagement pin 83 to raise the applicator assembly, which requires the entire developer unit to be moved for eventual lateral positioning. If the developing unit were configured according to the prior art, it would be used to raise the entire unit. In this case, the spring 86 must generate a large biasing force. In any case, since the wedge member 90 has an advantage of utilizing the energy from the motor 52 for the lateral movement of the developing unit, it is conventionally required separately for the movement (as shown in FIG. 15). The existing driving device can be omitted. Thus, the concept of the wedge member 90 and the engagement pin 83 can be used in the structures shown in all the drawings as well as in prior art structures. However, this concept is particularly useful for the structure shown in the accompanying figures because the corresponding applicator assembly is light in weight relative to the overall weight of each developing unit.

FIG. 4 shows another embodiment in which an applicator block 71 is pivotally mounted between a pivot 79 and a stop lug 78. Further, in FIG. 4, another configuration is adopted for positioning the applicator 11 with respect to the drum 2. The abbreviator 11 (and each of the other applicators) has a disk 19 mounted concentrically with a magnetic core drive shaft 45 (see FIG. 1). This disc 19 engages a pair of shafts 64 at each end of the drum 2. A roller 65 is mounted on the shaft 64 and is pressed toward the drum 2 by means (not shown). The rollers 64 roll in contact with the drum 2 and constitute permanent means for engaging the disc 19 when the applicator block 71 is pushed laterally. The pivot 79 must be a relatively loose pivot consisting of a short pin and a substantially large hole, thereby adjusting for slight misalignment of the position of the block 71 in response to contact of the disk 19 and the rollers 65. be able to.
Shaft 64 and rollers 65 are not part of the developing device, but are part of the printer and / or drum structure.

5 to 15 show another preferred embodiment for positioning the applicator 11 with respect to the drum 2. FIG. At the same time, block 71 and side wall 75, which can be used in the embodiment of FIG.
And 76 are also shown. Referring to FIGS. 5 to 7, the applicator block 71 includes:
It is movably arranged between the walls 75, 76, 109, 120. Felt pads 107 and 108 completely surrounding block 71 so that the developer does not escape around block 71.
Form a labyrinth seal. A felt pad 107 is attached to the walls 75, 76, 109, 120, and a felt pad 108 is attached to the block 71 (as best shown with respect to walls 75 and 76 in FIG. 5). The felt pads 107 and 108 prevent the toner from escaping around the block 71 and prevent the applicator 11 from moving over its entire range when the applicator 11 is placed in the operating position with respect to the drum 2. Wall 7 while allowing
The block 71 is frictionally held between 5,76,109 and 120.

As shown in FIG. 7, each of the felt pads 107, 108 has a surface that slides on the wall 75, 76, 109, 120 or the side wall of the block 71. This sliding surface has a block 71
Coated with polytetrafluoroethylene or similar low surface tack material to facilitate the movement of the pad and reduce wear on the pads 107,108.
The pads 107 and 108 may be made of a foam material instead of the felt material.

FIG. 13 replaces pads 107 and 108 with bellows 130,
Another embodiment is shown in which the bellows 130 extends completely around the applicator block 71 as well as the pads 107,108. Bellows 130 is made of a suitable rubber, plastic, or cardboard bellows material and is adhesively secured to both applicator block 71 and side walls 75, 76, 109, 120.

Accurate positioning of the applicator with respect to drum 2
In the embodiment shown in FIGS. 5 to 15, a pair of pins 110 and 111 fixed to the drum 2, a pair of rollers 112 and 11.3 fixed to the applicator 11, A pair of holes 114 and 115 in the fixed block
And have achieved.

When the abricator block 71 is moved upward by the lifter 80 (see FIG. 1), the pins 110 and 111 each have a hole.
Enter 114, 115. The pins 110, 111 are shown in detail in FIGS. Each pin has a conical tip 121 and a cylindrical section 1
And a washer 122 sliding on a cylindrical portion 128.
And a spring 123. The spring 123 has a washer 122
And a housing or cartridge 129 of the drum 2 to which the pins 110 and 111 are fixed. Grooves are formed in the cylindrical portion 128 of each pin to prevent the washer 122 from slipping off the tip 121. Pin 11
0 and 111 are mounted in such a way that they are exactly aligned with each other and with the axis of rotation of the drum 2. As shown in the preferred embodiment, they are oriented vertically and the drum 2
Has a development position at the bottom.

Hole 114 has a circular cross section and is sized to fit into the cylindrical portion of pin 110. As shown in FIG.
Wall is of minimum thickness and does not constrain the direction of pin 110,
Consequently, the positioning device is not excessively restrained. This allows the pin 110 to tilt relative to the top of the block 71.

The hole 115 is a slot whose major axis is parallel to the axis of rotation of the drum 2, and whose crossing direction (short axis direction) is dimensioned to fit the cylindrical portion of the pin 111. FIG.
As shown in FIG. 5, unlike hole 114, hole 115 has a side wall with sufficient depth to control the direction of pin 111 with respect to its wall. The holes 114 and 115 are centered on the rotation axis of the rotatable magnetic core 17 (see FIG. 1). Therefore, when the pin enters the hole, the axis of rotation of the drum 2 and the axis of rotation of the core 17 are parallel. Rollers 112, 113 extend above applicator block 71 and have an applicator 11 having a rotation axis spaced directly above the rotation axis of rotatable magnetic core 17.
Is mounted on the end face part. Thus, as shown in FIG. 8, all of the main fittings are vertically aligned.

FIG. 5 illustrates reference axes x, y, and z for explaining the positioning of the applicator 11 with respect to the drum 2.
This z axis is parallel to the rotation axis of the drum 2. The z-axis is perpendicular to the z-axis in a plane including the rotation axis of the drum 2 and the developing position. In the embodiment of FIG. 5, this X axis is in the vertical direction. The y-axis is orthogonal to the x-axis and the y-axis.

When the lifter 80 pushes the block 71 upward, the roller
Pins 110, 111 enter corresponding holes 114, 115, respectively, until 112, 113 engages drum 2. In this regard, the pin
110 and a hole 114 into which the applicator 11 is inserted allow linear movement of the applicator 11 in the y-axis direction and the z-axis direction.
And the hole 115 into which it is inserted allows only its rotation about the x-axis. The engagement between the drum 2 and the rollers 112, 113 establishes the distance between the applicator 11 and the drum 2,
That is, the linear position of the applicator 11 in the x-axis direction and the rotational position around the y-axis are established. Rotation about the z-axis is established by the pin 111 and the hole 115 into which it is inserted (see FIG. 12). The drum 2 and the core rotation drive shaft 45 are parallel.

A spring 123 for urging the washer 122 and the drum cartridge 129 apart is a spring 86 for urging the lifter 80 upward.
The bias is weaker. When the engagement pin 83 is moved to the ground and the spring 86 does not push the lifter 80 upward, the applicator block 71 pushes downward by the force of the spring 123 that urges the washer 122 downward, and the drum 2 The rollers 112, 113 are moved away from the
, So that the next developing unit can be moved to a position where the carriage 50 is aligned with the developing position 9.

The pins 110, 111 are mounted on the same structure on which the drum is mounted. As shown in FIG. 11, if the drum 2 is enclosed in the cartridge 129 so that the drum 2 can be easily replaced when worn, the pins 110,
111 must be fixed to the wall of the cartridge 129 with respect to the axis of rotation of the drum 2 at the time of manufacture of the cartridge 129, and must be accurately positioned. This is shown schematically in FIG. One of the most important dimensions for the operation of the developing device is
The distance between the applicator 11 and the drum 2 is
It should be noted that it is maintained by direct contact between 13 and the drum rim itself. The accuracy of this distance depends on the roller relative to the applicator 11.
It depends on the positioning accuracy of 112,113. Rollers 112, 1
13 can be attached to the applicator 11 as part of its manufacturing process, thereby ensuring this important spacing. FIG. 8 shows that the applicator 11 has rollers 112 and 113.
(FIG. 8 shows only the roller 112).

Other positioning means, namely pins 110, 111 and corresponding holes 114, 115, are also important for spacing the applicator and drum. For example, if the applicator is tilted about the x-axis with respect to the drum, that is, if the axis of rotation of the drum 2 is not parallel to the drive shaft 45 of the magnetic core, the applicator will be compared to its ends. The middle part is close to the drum 2. Also, when rotated about the z-axis, the spacing between the drum 2 and the applicator 11 is also affected because the flat portion of the applicator faces the drum 2.

In the embodiment of FIG. 1, the drive shaft 45 of the rotatable magnetic core 17 extends along the same axis through a universal joint 46 to a gearbox 61. As shown in FIGS. 5 and 6, such an extension of the drive shaft 45 will encounter either of the pins 110,111. This problem has been addressed in at least two ways. First, the block 71 is located substantially above the drive shaft 45 so that the drive shaft 45 extends therewith and the holes 114, 115 are located above the drive shaft 45.

The second solution is shown in FIGS. 5 and 14. Referring to FIG. 14, the rotatable magnetic core 17 is driven by a gear 117 fixed to its drive shaft 45, and the gear 117 is driven by a drive shaft 145 via a gear 118 fixed to it. I do. This allows the shaft 145 to be displaced from the pin 110 as shown in FIG.

FIG. 15 shows a preferred lifter 80 that can be used with a very accurate positioning mechanism as shown in FIGS.
For highest accuracy, the block 71 must be free with respect to certain rotational and linear movements with respect to all three axes. According to FIG. 15, the softer 80 has a rod 180 to which a stationary ball 181 is fixed at its end. The ball 181 fits into a peripheral socket in the socket member 182 to form a ball joint that allows free angular movement of the socket member 182. The top of the socket member 182 is smooth and flat, and slides on the bottom surface of the block 71. Lifter 80 is a separate drive cam that engages with engagement pin 83
It is moved upward in response to the rotation of 200. Block 7
1 can be freely adjusted in both rotational and linear directions with respect to three axes (FIG. 5) when the socket member 182 and the block 71 are in sliding contact on their respective flat surfaces.

As shown in FIG. 15, the block 71 is brought into precise contact with the drum 2 using the positioning means shown in FIGS. The pins 110 and 111 are omitted from FIG. 15 for simplicity of the drawing, but the roller 112 is shown engaged with the drum 2. Block 71 is adjusted to be slightly to the right as permitted by ball 181 and socket member 182, and to be slightly inclined with respect to side walls 75 and 76. Preferably, a separately driven cam 200 is used to move the lifter 80 upward.
This is because the movement of the pins 110, 111 before retraction is prevented by the holes 114, 115.

The applicator in these embodiments includes a rotatable magnetic core and a stationary shell. Other known applicators, magnetic or non-magnetic, which are in contact with or separate from the drum 2 during operation can also be used. For example, a stationary magnetic core and rotating shell system, typically including an applicator that contacts the drum 2, or a single component non-magnetic coloring device can be used. Accurate positioning of the axis of rotation, such as a contact applicator, with respect to the imaging member is important in this device. This is because, in this device, such positioning determines the pressure at the contact surface and, in particular, the uniformity of the pressure.

1 and 2, the toner supply unit is shown as a developing unit. As a result, when the supply of toner is exhausted, it is necessary to replace the developing unit or replace the toner manually. Another method is to provide another toner supply device on the extended end of each developing unit so that the toner can be replaced without replacing the developing unit. This method is conventional in conventional copiers. Obviously, the toner supply device used for the black toner developing unit 40 is larger than the toner supply devices for the other three developing units.

Although the invention has been described in detail with particular reference to preferred embodiments thereof, it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described above and as defined in the claims. .

(72) Inventor De Seca, Michael Lewis 14450, New York, USA Fairport, Silver Fox Drive 7 (72) Inventor Gaudino, David Matthew 14609, Rochester, Bayview Road, New York, USA 242 (72) Inventor Ribadas, Jerry Eugene, Scregal Road, Webster, New York 14580, New York, USA 1484 (72) Inventor MacDougall, David Richard, 14450, Fairport, Thornfield Way, New York, USA 23 (72) Inventor Riderick, James Gerrard, Crossfield Road, 449, Rochester, New York, USA 449 (56) References JP-A-2-205864 (JP, A) JP-A-63-118172 (JP, A) JP-A-4-69680 (JP, A) JP-A-50-81343 (JP, A) JP-A-56-75670 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/08 G03G 15/01

Claims (2)

(57) [Claims] 1. A developing device for applying a toner of a different color to an electrostatic image carried on an image forming member when the image forming member passes one developing position, wherein each of the toners has a specific color. And a plurality of developing units to which the applicator assembly is movably mounted, means for fixing the plurality of developing units to each other, and the plurality of developing units as one single unit. Means for sequentially moving a developing unit along a trajectory that aligns with the developing position; and moving the applicator assembly in any of the developing units that are aligned with the developing position to the developing position. An inclined portion provided at a position facing the developing position along the developing unit; and as one of the developing units is aligned with the developing position, the developing unit is moved to the inclined portion. And an assembly moving means having means for moving the corresponding applicator assembly to the developing position in response to the engagement. The unit comprises a wedge member on which the developing unit rides as it is sequentially moved to a position opposed to the developing position. The wedge member faces the track and allows a first position allowing each developing unit to climb up. The developing unit is movable as a single unit along the trajectory so as to face the image forming member.
The developing unit is reciprocally driven in a second direction opposite to the first direction. When the developing unit is driven as a single unit in the second direction, the wedge member is moved to the second position. A developing device further comprising means for moving the developing device. 2. The developing device according to claim 1, wherein the applicator assembly of the developing device is positioned at the developing position with respect to a surface of the image forming member which is curved at least in the developing position. The applicator assembly and the surface, the z-axis parallel to the center of rotation of the image forming member, and the x-axis parallel to the line connecting the development position and the center of rotation of the image forming member A positioning mechanism for positioning the core and the y-axis perpendicular to the z-axis and the x-axis relative to three axes perpendicular to each other is further provided, and the positioning mechanism is fixed to the surface. A first positioning member, fixed to the applicator assembly, but movable with the applicator assembly, engaging the first positioning member to move the applicator assembly to the z-axis Position parallel to the core A second positioning member that determines, together are fixed to the applicator assembly,
A rotational position of the surface and the applicator assembly about the y-axis in engagement with the surface and the x position;
And a third positioning member for controlling a position in a linear direction along the axis.