JP5568780B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus, and more particularly, to a developing device using a screw feeder for feeding a developer and an image forming apparatus including the developing device.

  A developing device used in an image forming apparatus such as a printer or a copying machine that forms an image by an electrophotographic method. For example, in a developing device using a two-component developer composed of a toner and a magnetic carrier, the developer is used. The carrier and toner are triboelectrically charged by stirring. The toner is electrostatically attached to the surface of the carrier by frictional charging, and the carrier to which the toner is attached is magnetically attracted to the surface of the developing roller. The magnetically attracted brush-like developer is transported by the rotation of the developing roller, and after the transport amount is regulated by the spike height regulating plate, the electrostatic latent image formed on the surface of the photosensitive drum is developed. .

The developing roller is provided so that a part of the outer periphery is exposed from the developing container, and is rotated in one direction so that the developer sucked on the outer peripheral surface reaches a region facing the surface of the photosensitive drum (developing region). While being conveyed, the remaining developer after being subjected to development is collected in the developing container.
Here, for example, a pair of screw feeders is often used as one that efficiently performs both stirring of the developer and feeding of the developer to the developing roller.

  The first screw shaft of the first screw feeder is provided in the developing container so as to face the developing roller in parallel. The second screw shaft of the second screw feeder is provided in parallel with the first screw shaft. In the developing container, a space between both screw shafts other than a portion where both end portions of both screw shafts face each other is partitioned by a partition wall. That is, both ends of the partition wall are openings that allow the developer to flow between the screw shafts.

  Both screw shafts are rotated by a driving source such as a motor provided outside the developing container, and convey the developer in opposite directions. The transported developer loses its place at the downstream end of each screw shaft and flows into the other screw shaft through the corresponding opening, so that the developer circulates in the developing container. Then, the toner is supplied to the downstream end of the second screw shaft, and the developer is sufficiently stirred while being conveyed by the second screw, and then flows into the first screw shaft side. The developer that has flowed in is fed along the entire length of the developing roller by the first screw shaft.

Since both screw shafts receive power from the drive source, one end portion projects from the developing container. The developer container portion from which the screw shaft protrudes is formed in a cylindrical portion whose inner surface is formed in a cylindrical shape, and the screw shaft portion in the vicinity of the protruding side end portion is rotatably supported by a bearing fixed to the cylindrical portion. Has been.
By the way, with the demand for higher image quality of formed images, the toner particle size tends to be smaller. For this reason, the toner may leak out of the developing container (outside of the developing device) through a very small gap between the bearing and the outer periphery of the screw shaft. In particular, when a bearing is present at the downstream end in the developer flow direction, this problem is significant because the pressure by the developer is high.

  In order to prevent this, conventionally, a seal member is provided in the cylindrical portion closer to the inside of the developing container than the bearing. The sealing member is made of synthetic rubber or the like and has an annular shape. The outer diameter is larger than the inner diameter of the cylindrical portion, and the inner diameter is smaller than the outer diameter of the screw shaft. By pressing the seal member into the cylindrical portion and the screw shaft, the seal member is elastically deformed to strongly adhere the seal member to the cylindrical portion and the screw shaft, thereby ensuring sealing performance.

  However, the toner is melted and solidified by the frictional heat generated by the frictional force between the screw shaft and the seal member, resulting in a large particle size, a part of which is mixed into the developer circulation in the developer container, There has been a situation where the quality of the formed image is reduced. Further, the solidified toner increases the rotational torque of the screw shaft. In particular, since the process speed is increased, it is necessary to feed more toner to the developing roller, so that the rotational speed of the screw shaft is increased, and the melting point of the toner is lowered due to the demand for power saving in the fixing device. This problem has become prominent in certain situations.

  In order to cope with this, in the developing device described in Patent Document 1, a sheet material having a thickness of 100 [μm], which has a donut shape closer to the inside of the developing container than the seal member, is used as a partition member and is not in contact with the screw shaft. In this way, the toner is prevented from entering the seal member. The developing device described in Patent Document 2 has a double seal structure in which a seal member similar to the seal member is further provided closer to the inside of the developer container.

JP-A-4-291282 JP 2000-250309 A

  However, in the developing device of Patent Document 1, although the partition member can prevent most of the toner from entering the seal member, the partition member and the screw shaft are not in contact with each other. Enter and eventually reach the seal member. For this reason, the toner melted in the seal member is solidified, and the rotational torque of the screw shaft increases. Further, in the developing device of Patent Document 2, the inflow of toner to the seal member on the side close to the bearing can be blocked by the seal member on the side far from the bearing, but the seal member on the far side is the same as the seal member on the near side. Therefore, the above-mentioned problem due to melting and solidification of the toner also occurs in the far side seal member.

  In view of the above-described problems, the present invention provides a developing device capable of effectively preventing leakage of toner while suppressing melting and solidification of toner due to frictional heat as compared with the prior art, and an image including the developing device. An object is to provide a forming apparatus.

In order to achieve the above object, a developing device according to the present invention has a screw feeder that conveys developer in a developing container to a developing roller by rotation, and drives one end of a screw shaft that constitutes the screw feeder. A developing device having a configuration in which a rotational driving force from a source is projected outward from the developing container, wherein the projecting end of the screw shaft is supported in the developing container, and the bearing Formed with an elastomer material that is closer to the inside of the developing container than the outer periphery of the screw shaft, and prevents the developer from leaking out of the developing container from the gap between the bearing and the screw shaft. A first sealing member that is disposed closer to the inside of the developing container than the first sealing member, and is closely attached to the screw shaft over a predetermined length. A second sealing member formed of a material, in the axial direction of the screw shaft, provided between said first sealing member and the second seal member, the constituent material of the second seal member And a spacer for preventing entrainment between the first seal member and the outer peripheral surface of the screw shaft .

Also, before Symbol fiber material characterized in that it is a felt. Further, the first seal member and the second seal member are provided in a bearing chamber having a cylindrical inner surface and provided with the bearing, and the interior of the developer container through which the developer flows. Is partitioned by a partition wall having a window through which the screw shaft passes, and the second seal member has a cylindrical shape, and the screw is compressed in a state where one end surface thereof is pressed against the partition wall and compressed. It is mounted on a shaft.

Alternatively, the second seal member is formed by implanting fibers on an inner peripheral surface of a cylindrical base material .

Further, the second seal member is coated or impregnated with a fluorine-based lubricant.
In order to achieve the above object, an image forming apparatus according to the present invention includes the developing device described above.

  According to the developing device having the above configuration, the second seal member located closer to the inside of the developing container than the first seal member formed of the elastomer material is formed of the fiber material. The friction force generated between the second seal member and the surface can be made smaller than that of the first seal member. For this reason, it is possible to suppress the frictional heat in the second seal member to be lower than that in the conventional case where the second seal member is formed using the same material as the first seal member formed of synthetic rubber or the like. . As a result, the melting and solidification of the toner can be suppressed as compared with the conventional case. In addition, since the second seal member is wrapped around the screw shaft in a close state over a predetermined length, the toner can be prevented from entering the first seal member, so that the leakage of the toner can be prevented.

1 is a diagram illustrating a schematic configuration of a tandem printer according to an embodiment. It is sectional drawing of the image formation unit which comprises the said tandem type printer. In FIG. 2, it is a part of sectional drawing of the image development unit cut | disconnected along the FF line. (A) is an expanded sectional view of the support structure portion of the second screw shaft, and (b) shows a state before the first seal member and the second seal member are mounted on the second screw shaft. FIG. It is sectional drawing which shows the slide bearing which supports a 2nd screw shaft in the developing device which concerns on a modification, and its vicinity. It is a perspective view of the 2nd seal member concerning a modification.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a fixing device and an image forming apparatus having the same according to the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a tandem printer 10 (hereinafter simply referred to as “printer 10”) according to an embodiment. Although a printer is taken as an example here, the present invention can also be applied to an image forming apparatus such as a copying machine or a facsimile.

  As shown in FIG. 1, the printer 10 includes a transfer belt 14 that is horizontally installed in a housing 12 and travels in the direction of arrow A, and four image forming units 16 </ b> C that are arranged in the travel direction of the transfer belt 14. 16M, 16Y, 16K, primary transfer rollers 18C, 18M, 18Y, 18K provided corresponding to the respective image forming units, and secondary transfer unit 20, and each image forming unit 16C, 16M, 16Y, 16K. This is a so-called intermediate transfer type image forming apparatus in which the formed toner images of the respective color components are once transferred onto the transfer belt 14 and then transferred to the recording sheet S to form a color image.

  Each of the image forming units 16C, 16M, 16Y, and 16K includes charging units 24C, 24M, 24Y, and 24K arranged around the photosensitive drums 22C, 22M, 22Y, and 22K that are image carriers, and a developing unit. 26C, 26M, 26Y, and 26K. An exposure unit 28 is arranged below the image forming units 20C,..., 20K, and light-modulated laser beams LB are emitted toward the respective photosensitive drums 22C,. The surfaces of the photosensitive drums 22C,..., 22K rotated in the direction of arrow B are uniformly charged by the charging units 24C,. A latent image is formed, and the electrostatic latent image is developed into a toner image by the developing units 16C,. Each of the developing units 16C,..., 16K is sensitive to toners of C (cyan), M (magenta), Y (yellow), and K (black) corresponding to the light modulation color component of the laser light. Supplied to body drums 22C,.

The toner images formed on the photosensitive drums 22C,..., 22K travel by receiving the action of an electric field generated between the primary transfer rollers 18C,..., 18K and the photosensitive drums 22C,. The images are sequentially transferred onto the transfer belt 14.
On the other hand, the recording sheet S fed from the paper feed cassette 30 by the pickup roller 32 is moved to the secondary transfer unit 20 by the registration roller 34 in accordance with the timing when the toner image on the transfer belt 14 reaches the secondary transfer unit 20. It is conveyed. The secondary transfer unit 20 transfers the toner image superimposed on the transfer belt 14 onto the recording sheet S.

The toner image on the recording sheet S is fixed by the fixing device 36 and then discharged to the paper discharge tray 40 by the discharge roller 38.
FIG. 2 is a sectional view of the image forming unit. Note that each of the four image forming units 16C, 16M, 16Y, and 16K provided for each color has the same configuration. Therefore, in the following description and the drawings used for this, C, M, Y , K is omitted.

As described above, the image forming unit 16 has the charging unit 24 and the developing unit 26 arranged around the photosensitive drum 22.
The developing unit 26 is a unit type developing device. The developing unit 26 includes a developing container 42 for storing a two-component developer (hereinafter simply referred to as “developer”, not shown in FIG. 2) composed of toner and a magnetic carrier.

  The developing unit 26 also includes a developing roller 44 provided so that a part of the outer periphery is exposed from the developing container 42. As will be described later, the carrier that has been agitated and frictionally charged and has the toner adhered thereto is magnetically attracted to the surface of the developing roller 44. The magnetically attracted developer in brush form (not shown) is conveyed by the developing roller 42 rotating in the direction of arrow E, and the conveyance amount is regulated by the head height regulating plate 46 in the middle, and then the photosensitive drum. The electrostatic latent image formed on the surface of the photosensitive drum 22 is developed by being transported to a region (development region) facing the surface of the photosensitive drum 22. The remaining developer after being subjected to development is collected in the developing container 42 by the rotating developing roller 44.

  The developing unit 26 includes a first screw feeder 48 and a second screw feeder 50 for stirring the developer and transporting the developer to the developing roller 44. The first screw shaft 52 constituting the first screw feeder 48 is provided in parallel with the developing roller 44, and the second screw shaft 54 constituting the second screw feeder 50 is connected to the first screw shaft 52. It is provided in parallel.

In FIG. 2, a part of a sectional view of the developing unit 26 cut along the F / F line passing through the axis of the first screw shaft 52 and the axis of the second screw shaft 54 is shown in FIG.
As described above, the developer D is stored in the developing container 42.
In the developing container 42, a first screw shaft 52 and a second screw shaft 54 are provided in parallel. The inside of the developing container 42 is partitioned (partitioned) by a partition wall 58 provided with an opening 56 left at a portion where the end portions of the first and second screw shafts 52 and 54 face each other. In addition, the opening part is opened also in the part which the other end part part which does not appear in FIG. 3 of both the screw shafts 52 and 54 opposes (that is, it is not partitioned off by the partition wall 58).

  When the second screw shaft 54 is rotated, the developer D is conveyed in the direction of the arrow G along the axis. The developer D conveyed by the second screw shaft 54 is blocked by the partition wall 60 of the developing container 42 and flows into the first screw shaft 52 side through the opening 56. The developer D that has flowed in is conveyed in the direction of arrow J along the axis of the first screw shaft 52 that is rotated. As a result, the developer is supplied to the surface of the developing roller 44 (not shown in FIG. 3) arranged in parallel with the first screw shaft 52. Note that new toner is supplied to the end of the second screw shaft 54 corresponding to the other opening not shown in FIG. 3 to supplement the toner consumed by the development. The replenished toner is conveyed while being agitated by the rotating second screw shaft 54 and is supplied to the developing roller 44 in a sufficiently charged state while reaching the opening 56.

Since the first screw shaft 52 and the second screw shaft 54 receive the power required for the rotation, one end portion projects from the developing container 42 to the outside.
The protruding end portion of the first screw shaft 52 is provided with a gear unit 62 in which two gears are arranged in the axial direction. The gear unit 62 is generally cylindrical and has a first spur gear 64 and a second spur gear 66 formed on the outer periphery thereof. The end of the gear unit 62 has a reduced diameter, and the reduced diameter portion 62A is inserted into a boss hole 70 formed in the cover plate 68 that covers the side end of the developing container 42 and is rotatably supported. ing.

A spur gear 72 is provided at the protruding end portion of the second screw shaft 54, and the spur gear 72 meshes with the second spur gear 66.
When power is transmitted from a motor (not shown) via a power transmission mechanism (not shown) and the first spur gear 64 is rotated, the first screw shaft 52 and the second spur gear 66 are rotated. As the second spur gear 66 rotates, the spur gear 72 meshed with the second spur gear 66 rotates and the second screw shaft 54 rotates.

  The end portions of the first screw shaft 52 and the second screw shaft 54 protruding from the developing container 42 are supported by the developing container 42 via bearings in order to smoothly receive the power from the power transmission mechanism. Since the screw shaft support structure by the bearing is the same for both screw shafts 52 and 54, the support structure for the second screw shaft 54 will be described as a representative.

FIG. 4A shows an enlarged cross-sectional view of the support structure portion of the second screw shaft 54. FIG. 4B shows a state before a first seal member 84 and a second seal member 86 to be described later are attached to the second screw shaft 54. In addition, in FIG. 4 (a), (b), illustration of the spur gear 72 is abbreviate | omitted.
The developing container 42 has a bearing chamber 74 having a cylindrical inner surface. The bearing chamber 74 and the inside 76 of the developing container 42 in which the developer D flows are partitioned by a partition wall 60 having a window 78 through which the second screw shaft 54 passes.

The slide bearing 80 that supports the second screw shaft 54 is a sleeve bearing having a flange portion 82, and is made of polyacetal, fluororesin, nylon, or other synthetic resin. Incidentally, the dynamic friction coefficient of the fluororesin is 0.15 to 0.25.
The slide bearing 80 is integrally provided with a first seal member 84. The first seal member is made of synthetic rubber, EPDM (ethylene propylene rubber), silicon rubber, fluorine rubber, or other elastomer material. Among these, in particular, tetrafluoroethylene resin (PTFE) is preferable because it is excellent in high temperature resistance and wear characteristics. The first seal member 84 has a ring shape, the radial direction, the outer half is formed in a flat plate shape, and the inner half is formed in a tapered shape (hereinafter, the inner half is referred to as a “tapered portion”). " The portion formed in the flat plate shape is integrally fixed to the slide bearing 80 at the time of insert molding of the slide bearing 80. In addition, the hollow part shown by 80A made into the cylindrical shape is what is called meat stealing (meat removal) for preventing the generation | occurrence | production of the sink mark which arises in the case of shaping | molding.

  Before being attached to the second screw shaft 54, the inner diameter (tapered portion inner diameter) of the first seal member 84 is smaller than the diameter of the second screw shaft 54 (the straight portion thereof). When the slide bearing 80 is attached to the second screw shaft 54, the first seal member 84 is press-fitted into the second screw shaft 54, and the tapered portion is elastically deformed radially outward and spreads. 4A, the inner surface of the tapered portion is in close contact with the outer periphery of the second screw shaft 54. Here, the inner periphery of the sliding bearing 80 for the developer (toner) and the second screw shaft 54 The entry into the gap between the outer periphery and the developer (toner) is prevented from leaking out of the developer container 42. The slide bearing 80 is press-fitted into the bearing chamber 74, and the outer peripheral surface of the slide bearing 80 and the inner peripheral surface of the bearing chamber 74 are in close contact with each other. Never leak into.

A second seal member 86 having a cylindrical shape is attached to the second screw shaft 54 at a position closer to the inside of the developing container 42 than the first seal member 84. The second seal member 86 is made of felt that is a fiber material.
The inner diameter of the second seal member 86 before being attached to the second screw shaft 54 is smaller than the outer diameter (of the straight portion) of the second screw shaft 54. The difference between the inner diameter and the outer diameter is that the inner peripheral surface of the second seal member 86 presses the outer peripheral surface of the second screw shaft 54 in a state where the second seal member 86 is press-fitted into the second screw shaft 54. The pressure is set in a range that is smaller than the pressing force with which the first seal member 84 presses the outer peripheral surface of the second screw shaft 54.

The outer diameter of the second seal member 86 is slightly larger than the inner diameter of the bearing chamber 74.
Prior to the slide bearing 80, the second seal member 86 is fitted into the second screw shaft 54 and mounted. Next, the sliding bearing 80 is press-fitted onto the second screw shaft 54 until the flange portion 82 comes into contact with the peripheral edge 74A of the opening portion of the bearing chamber 74.

  Here, when the length excluding the flange portion 82 of the slide bearing 80 is L1, the length of the second seal member 86 before mounting is L2, and the depth of the bearing chamber 74 is L3, L2 <(L3-L1 ) Is satisfied. Therefore, the second seal member 86 is compressed between the end surface of the sliding bearing 80 and the inner wall of the bearing chamber 74 in the state where the press-fitting of the sliding bearing 80 is completed (mounted state).

  In the press-fitting completion state (attached state), the second seal member 86 is circularly attached to the second screw shaft 54 over a predetermined length. Here, if the length in the axial direction of the second screw shaft 54 of the second seal member 86 in the mounted state is too short, the sealability of the developer (toner) cannot be secured. The depth of the chamber 74 and the length of the second screw shaft 54 are unnecessarily increased, leading to an increase in the size of the entire developing device. Therefore. The predetermined length is preferably a minimum necessary length that can ensure the sealability of the developer (toner) by the second seal member 86. This length can be easily obtained by experiments or the like.

  Since the second seal member 86 having the above configuration is in close contact with the outer periphery of the second screw shaft 54 and the surface of the partition wall 60, the developer (toner) can reach the first seal member 84. As long as it can be prevented. Accordingly, since the frictional force generated between the second screw shaft 54 and the second screw shaft 54 is large, toner melting in the first seal member 84 that generates a large amount of heat can be prevented.

Further, since the second seal member 86 is made of a fiber material (for example, the dynamic friction coefficient of the felt is 0.2 to 0.3), the elastomer material (for example, the dynamic friction coefficient of the synthetic rubber is 0.00). The dynamic friction coefficient is smaller than that of the first seal member 84 made of the first seal member 84, and the force by which the second seal member 86 presses the outer periphery of the second screw shaft 54 as described above is the first seal member. The force of the member 86 pressing the outer periphery of the second screw shaft 54 is smaller. Therefore, the frictional force generated between the second screw shaft 54 and the second screw shaft 54 during the rotation of the second screw shaft 54 is smaller in the second seal member 86 than in the first seal member 84. Accordingly, the generated frictional heat is lower in the second seal member 86 than in the first seal member 84. As a result, compared with the case where the second seal member is made of the same elastomer material as that of the first seal member (Patent Document 2), it is possible to suppress melting and solidification of the toner generated in the second seal member. It becomes possible.
(Modification 1)
FIG. 5 shows a cross-sectional view of a sliding bearing 80 that supports the second screw shaft 54 and its vicinity in the developing device according to the first modification.

As shown in FIG. 5, in the first modification, a spacer 88 is provided between the first seal member 84 and the second seal member 86. The spacer 88 has a ring shape made of a synthetic resin. When the second seal member 86 is frayed due to friction with the second screw shaft 54, the spacer portion is moved to the first seal member 84. It is intended to prevent entrainment.
A small gap is provided between the inner peripheral surface of the spacer 88 and the outer peripheral surface of the second screw shaft 54 so as not to allow the above-mentioned flaws to pass.
(Modification 2)
FIG. 6 is a perspective view of the second seal member used in the second modification. As shown in FIG. 6, the second seal member 90 according to the modified example 2 has an overall cylindrical shape, similar to the second seal member 86 described above.

The second seal member 90 is made of a flocking material obtained by flocking synthetic resin fibers 94 on the inner surface of a cylindrical base material 92. For example, the second seal member 90 is formed by applying an adhesive with a uniform thickness on one surface of a synthetic resin sheet serving as the base material 92, and implanting countless synthetic resin fibers in the applied adhesive. A product obtained by curing the adhesive is cut into a tape shape, the tape is rolled into a ring shape, and both ends are fixed with an adhesive. For example, an acrylic fiber can be used as the synthetic resin fiber. In this case, the flocking density can be 2000 [lines / 25 mm ² ]. Nylon fibers can also be used as synthetic resin fibers.

Since the second seal member 90 having the above-described configuration is also made of a fiber material in the portions (contact portions) that are in contact with the outer circumferences of the first and second screw shafts 52 and 54, the first seal member is made of an elastomer material. The frictional force generated during rotation of the screw shafts 52 and 54 is smaller than 84, and the same effect as the above-described second seal member 86 (FIG. 4) can be obtained.
As described above, the present invention has been described based on the embodiment and the modified examples. However, the present invention is not limited to the above-described one, and for example, the following forms may be adopted.

  (1) Further, in order to reduce the frictional force, the second seal member 86 made of felt and the second seal member 90 made of flocking material may be coated or impregnated. For example, the dynamic friction coefficient of the felt itself is 0.2 to 0.3 as described above, but when this is impregnated with a fluorine-based lubricant, the dynamic friction coefficient can be reduced to 0.1.

(2) In the above embodiment, the first seal member integrated with the bearing is used. However, the first seal member is not limited to this, and may be a seal member independent of the bearing.
(3) In the above embodiment, a slide bearing is used as the bearing of the screw shaft. However, the present invention is not limited to this, and a rolling bearing may be used.

  The developing device according to the present invention can be suitably used as a developing device used in an image forming apparatus that forms an image by an electrophotographic method such as a printer or a copier.

26 Developing Unit 42 Developing Container 44 Developing Roller 48 First Screw Feeder 50 Second Screw Feeder 52 First Screw Shaft 54 Second Screw Shaft 80 Slide Bearing 84 First Seal Member 86, 90 Second Seal Member

Claims (6)

A screw feeder that conveys the developer in the developer container to the developing roller by rotation;
A developing device having a configuration in which one end of a screw shaft constituting the screw feeder is protruded to the outside from the developing container in order to receive a rotational driving force from a driving source;
A bearing that pivotally supports the protruding end side of the screw shaft in the developing container;
An elastomer material that is closer to the inside of the developing container than the bearing, is in close contact with the outer periphery of the screw shaft, and prevents the developer from leaking out of the developing container from the gap between the bearing and the screw shaft. A first seal member formed by:
A second seal member that is located closer to the inside of the developing container than the first seal member, and is closely attached to the screw shaft over a predetermined length and formed of a fiber material;
Provided between the first seal member and the second seal member in the axial direction of the screw shaft, and the first seal member and the outer periphery of the screw shaft of the constituent material of the second seal member A spacer to prevent entrainment between the surface,
A developing device comprising: The developing device according to claim 1 , wherein the fiber material is felt. The first seal member and the second seal member are provided in a bearing chamber having a cylindrical inner surface and provided with the bearing, and the bearing chamber and the inside of the developing container through which the developer flows. The second seal member has a cylindrical shape, and one end surface of the second seal member is pressed against the partition wall and compressed with the partition wall having a window through which the screw shaft passes. The developing device according to claim 2 , wherein the developing device is attached. The developing device according to claim 1 , wherein the second seal member is formed by implanting fibers on an inner peripheral surface of a cylindrical base material. An apparatus according to any one of claims 1-4, characterized in that the fluorine-based lubricant is applied or impregnated to the second seal member. An image forming apparatus wherein a developing device according to any one of claims 1-5.

Images