JPH0731250Y2 - Development device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a developing device such as a copying machine or a laser printer for developing an electrostatic latent image formed on a recording medium.

<Prior Art> A copying machine or the like is provided with a developing device for adhering toner composed of a color pigment to an electrostatic latent image for the purpose of visualizing the electrostatic latent image formed on a recording medium such as a photoconductor. ing. Further, a copying machine or the like is provided with a plurality of developing devices each containing toner of each color in order not only to blacken the electrostatic latent image but also to color the electrostatic latent image, and these developing devices are selectively used.

The developing device needs to be controlled so that toner does not adhere to the latent image when it is not used for development. Therefore, conventionally, the development gap (the distance between the recording medium and the developing portion of the developing device) is switched so that the toner is not brought into contact with or conveyed to the developing area facing the recording medium.

However, when the developing gear and the like are switched, the developing conditions are varied and the image density is changed. Particularly, if the developing gears are not accurately positioned, a normal image cannot always be formed.

Further, when a magnetic brush developing system is adopted as the developing device, there is a device that shifts the position of the magnet constituting the developing unit so that the developing brush does not come into contact with the recording medium. If the deviation occurs, not only a change in image density but also a carrier (when a two-component type developer is used) adheres to the recording medium, resulting in a marked deterioration in image quality.

Therefore, the applicant has proposed a technique such as Japanese Patent Application No. 62-222661. That is, this includes a developing roller arranged to face the recording medium, a supply passage for supplying a developer to the developing roller, and a cylindrical shutter having a portion for opening or closing the supply passage. The opening / closing device and the switching means having a spring clutch for switching the opening / closing device between an open state and a closed state are provided. The interval between and is always constant, the developing conditions do not change, and a normal image can always be formed.

<Problems to be solved by the invention> However, in the above configuration, since the input side and the output side of the spring clutch are fixed, if the center axis of the switchgear and the center axis of the spring clutch shift, the switchgear stops. In this state, the rotation driving force is transmitted from the input side to the output side of the spring clutch by the action of the spring inside the clutch, and the stop position for opening and closing the supply passage of the switchgear shifts, especially in the open position. Even if there is no problem because the developer is supplied to the developing unit in the displacement, there is a problem in that the developer is supplied to the developing unit in the positional displacement in the closed state.

In view of the above, the present invention absorbs the swing of the switchgear by the action of the spring inside the clutch and stops the switchgear at a fixed position even if the center axis of the switchgear and the center axis of the spring clutch are slightly displaced. It is an object of the present invention to provide a developing device that can be used.

<Means for Solving the Problems> The developing device according to the present invention includes a developing section (22) arranged to face a recording medium (3), as shown in FIGS. 1 and 2.
In a developing device having a supply passage (29) for supplying a developer to the developing portion and a recovery passage for returning the developer in the developing portion to the supply passage, the supply passage is opened or closed. An opening / closing device (35) that has a portion and is rotatably provided and that opens or closes the supply passage, and a spring clutch (for transmitting a rotational force to the opening / closing device and rotating it in one direction as necessary). 39), a switching device (36) for activating the spring clutch to switch the opening / closing device to an open position or a closed position, and correcting a variation in the stop position of the opening / closing device due to a positional shift between the spring clutch and the opening / closing device. And a stop position correcting means (55) for stopping the developing device.

<Operation> In the above problem solving means, the developer is supplied to the developing roller 22 to develop the electrostatic latent image formed on the photoconductor 3 which is a recording medium, and is removed from the developing roller and collected after the completion of the development. The portion is returned to the developer supply passage 29. As a result, when the development by the developing device becomes unnecessary, the supply of the developer is stopped, the switching means 36 is operated, and the closing plate of the opening / closing device 35 is operated via the spring clutch 39.
38 rotates to close the developer supply passage 29. At this time,
When the rotation center shaft 30 of the closing plate 38 and the center of the coil spring 50 of the spring clutch 39 are displaced, the closing plate
Even when 38 is in a stopped state, the spring clutch 39 may be swung around and the switchgear 35 may not be able to stop at a fixed position.

However, in the present invention, since the stop position correction mechanism 55 is provided, the suspension 59 of the spring clutch 39 can be absorbed by the gap 59 which is a component thereof, and the stop position of the closing plate 38 of the opening / closing device 35 can be made constant.

<Embodiment> An embodiment of the present invention will be described below with reference to FIGS. 1 is a sectional view of an opening / closing device of a developing device according to an embodiment of the present invention, FIG. 2 (a) is a sectional view of a stop position correcting mechanism, FIG. 2 (b) is a side view thereof, and FIG. FIG. 3C is a perspective view showing the engaged state of the coil spring, FIG.
Is a side view showing the appearance of the spring clutch.
Is a sectional view taken along the line AA in FIG. 4D, FIG. 6F is a perspective view of the armature air, FIG. 3 is a perspective view of the opening / closing device, FIG. 4 is a sectional view of the developing tank, and FIG. 5 is an outer wall of the developing tank. FIG. 6 is a front view of the switching means of the unit, and FIG. 6 is a configuration diagram showing an electrophotographic process of the copying machine developing device.

As shown in the figure, the copying machine of the present invention has a photoreceptor 3 as an endless belt-shaped recording medium wound around a pair of drive rollers 1 and 2.
And a plurality of developing tanks 4, 5, 6, 7 arranged close to the photoconductor 3 and capable of switching between a developing position and a non-developing position, and rollers 8, 9, 10 on the side of the one driving roller 1. An endless belt-shaped intermediate transfer member 11 wound around the photosensitive member 3 and in contact with the photoconductor 3, a main charger 12 arranged on the other driving roller 2 side, and the intermediate transfer member
A first transfer charging device 13 disposed on 11, a second transfer charging device 15 disposed on the lower side of the transfer paper 14 conveyed to the intermediate transfer body 11,
Cleaning blade 16 disposed below the photoconductor 3
It is equipped with In FIG. 6, 17 is a paper feeding device, 18 is a fixing device, and 19 is an exposure device. A replenishing tank 20 is arranged above the developing tanks 4 to 7.

Since the developing tanks 4 to 7 have the same structure,
The structure will be described. As shown in FIG. 4, the developing tank 4 is provided with a developing roller 22 as a developing portion rotatably arranged in an opening 21 for transferring toner to the photoconductor 3, and a developing roller 22 rotatably above the developing roller 22. Developer transport roller 23
A first agitating roller 24 for agitating the developer scraped off from the carrying roller 23, and agitating means for agitating the developer from the first agitating roller 24 and supplying it to the developing roller 22. It is arranged between the second stirring roller 25, the developing roller 22, the conveying roller 23, the first stirring roller 24 and the second stirring roller 25, and scrapes off the developer on the conveying roller 23 and conveys it to the first stirring roller 24. The partitioning member 26 is installed inside. Further, the developing tank 4 is internally equipped with a doctor 27 arranged at a constant distance from the developing roller 22 and a toner concentration sensor 28 for detecting the concentration of the developer. Then, in order to collect the developer on the developing roller 22 and the developer on the developing roller 22 by the transport roller 23 and supply the developer to the developing roller 22 again in a circulating manner, between the developing tank 4 and the partition member 26, A recovery passage and a supply passage 29 for supplying the developer to the developing roller 3 are formed at the position where the conveying roller 23 is provided.

The developing roller 22 is fixed to the developing tank 4 and has an outer peripheral portion of each pole.
A developing magnet body 22a having magnets magnetized to N1, N2, N3, S1 and S2, and a cylindrical non-magnetic aluminum body loosely fitted in the developing magnet body 22a and rotatably supported in the developing tank 4. And a body developing sleeve 22b.

The transport roller 23 is also constructed similarly to the developing roller 22. That is, the outer peripheral portion is fixed to the developing tank 4 and the respective poles N1, N2,
Transport magnet body 23 having magnets magnetized in S1, S2, S3
a and a cylindrical non-magnetic material transfer sleeve 23b made of aluminum and loosely fitted in the transfer magnet body 23a and rotatably supported by the developing tank 4.

Each of the first stirring roller 24 and the second stirring roller 25 has a central shaft 30 rotatably supported by the developing tank 4, and a plurality of stirring fins 31 are arranged on the central shaft 30.

The partition member 26 has a surface facing the transport roller 23 and the second stirring roller 25 formed in an arc shape, and each arc surface 32, 3
3 and the rollers 23 and 25 are arranged with a small gap.
However, the gap A between the agitating fin 31 of the second agitating roller 25 and the corresponding arcuate surface 33 of the partitioning member 26 is different from the gap of the conveying roller 23 and is formed to be as large as the thickness of the closing plate 38 described later. Has been done. Further, the wall surface of the developing tank 4 facing the second stirring roller 25 is also formed in an arc shape so as to have the same gap as the above. The partition member 26 is, as shown in FIG.
It is inclined downward from the transport roller 23 to the second stirring roller 25 side. The toner is accommodated in the replenishing tank 20 above the developing tank 1, and is supplied to the vicinity of the first stirring roller 24 according to a command from the toner concentration sensor 28 of the developer, and the first stirring roller 24. The developer mixed and agitated via the toner reaches the second agitating roller 25 along the partition member 26.

In the supply passage 29, a developer inlet 35a is formed between the first stirring roller 24 and the second stirring roller 25 by the developing tank 4 and the partition member 26, and the second stirring roller 25 and the developing roller 22 are connected to each other. A developer outlet 35b is formed between the developing tank 4 and the partition member 26, and the inlet 35a and / or the outlet 35 are formed.
An opening / closing device 35 for controlling the opening / closing of b to supply the developer on the first stirring roller 24 side to the developing roller 22, and a switching means 36 for switching the opening / closing device 35 between an open state and a closed state. Is provided.

As shown in FIGS. 1 and 3, the opening / closing device 35 includes the second stirring roller 25.
Flange 37 rotatably fitted to both ends of the central shaft 30 of
A pair of arc-shaped closing plates 38 fixed to the outer peripheral portion of the flange 37 in a point-symmetrical position about the central axis 30, and a pair of arc-shaped openings 38a formed between the closing plates 38. Composed of.

The switching means 36 includes four spring clutches 39 provided at the end of the central shaft 30 and four spring clutches 39 arranged at equal intervals (90 ° intervals) on the outer peripheral flange 40a of the cylindrical clutch cover 40 of the clutch 39. A plate-shaped armature air 43 releasably engaged with the pawls 41, 42, a solenoid 44 forcibly moving the armature air 43 in the pawl disengagement direction, and a return spring for urging the armature air 43 in the pawl engagement direction. It consists of 45 and.

The spring clutch 39 includes a clutch shaft 46 fitted and fixed to the central shaft 30 and a boss portion 46 a fitted to the clutch shaft 46.
A first hub 47 fitted and fixed to the shaft portion 37a of the flange 37, a second hub 49 connected to the first hub 47 with a stepped tapping screw 48, the second hub 49 and the boss. Coil spring 50 wound between the portion 46a and the spring
The clutch cover 40 is arranged on the outer periphery of the clutch cover 50.

The coil spring 50 has one end 50a engaged with the notch 40a of the clutch cover 40 and the other end 50b fixed to the notch 49a of the second hub 49.

The spring 50 is wound in the direction in which the boss portion 46a is tightened, but by braking the clutch cover 40 (rotation restricted state), the spring 50 is separated from the boss portion 46a, that is, in a loosened state, and the rotational force of the central shaft 30 is reduced. It is a structure that does not transmit.

A central hole 43a of the armature air 43 is loosely fitted to the clutch shaft 46, and a lower end portion 43b of the armature air 43 is fitted and supported on an inner end 51a of a case 51 on an outer wall surface of the solenoid 44. Fixed. A stopper 52 that engages with the claws 41 and 42 of the clutch cover 40 is formed at the center of the upper end of the armature air 43, and the outer surface of the stopper 52 is in contact with the upper end of the case 51. The return spring 45 is interposed between the lower portion of the solenoid case 51 and the lower end portion 43b of the armature air 43.

The first hub 47 is formed with a through hole 54 in which a fixing screw 53 is fitted in a radial direction on the peripheral surface thereof, and the fixing screw 53 is fitted in the through hole 54 and press-contacts with the shaft portion 37a of the flange 37. The flange 37 and the first hub 47 are fixed.

Further, the second hub 49 is rotatably fitted onto the clutch shaft 46, and at the connecting portion between the second hub 49 and the first hub 47, the stop position of the closing plate 38 due to the rotation of the spring clutch 39 is set. A stop position correction mechanism 55 is provided to prevent variations.

The stop position correction mechanism 55 is formed on the first hub 47 with a plurality of tapping screw fitting holes 56 formed in the same direction as the central shaft 30, and on the second hub 49 so as to face the fitting holes 56. Screw hole 57
And the stepped tapping screw 48 that is loosely fitted in the fitting hole 56 and screwed into the screw hole 57, and the stepped tapping screw 48.
And a gap 59 formed between the large diameter portion 48a and the fitting hole 56.

Further, the second hub 49 is formed with a projecting piece 60 projecting in the radial direction of the central shaft 30 corresponding to the position of the closing plate 38,
A closing plate position detecting switch 61 that is turned on by the projecting piece 60 is provided in the developing tank 4.

Further, a drive gear 63 to which a rotational force is transmitted is fixed to an end portion of the central shaft 30 opposite to the spring clutch 39, and rotates the stirring roller 25 in a fixed direction.

The copying operation in the above configuration will be described.

When the copy switch is turned on, the photoconductor 3 is moved to the arrow b in FIG.
It rotates at a constant peripheral speed like. Then, after being charged by the main charger 12 and exposed, the developing tank 4 is placed in a developing attitude according to the purpose.
The brush of the developer is brought into contact with the photoconductor 3 for development. In addition,
When the photoconductor 3 is not developed, the ears of the developing tanks 4 to 7 are opened / closed.
Therefore, it is not formed on the developing roller 22.

The developed toner image moves in the direction of arrow b and is transferred to the transfer intermediate 11 by the first transfer charger 13. After that, it is transferred onto the transfer paper from the direction of the arrow by the second transfer charger 15 and then fixed.

When the developing tank 4 is used for development, it is necessary to open the passage 29 for supplying the developer to the developing roller 22. Therefore, various rollers also rotate in accordance with the rotation of the developing roller 22 (rotation of the sleeve).

Then, according to the rotation of the second stirring roller 25, the rotational force of the central shaft 30 is transmitted to the closing plate 38 via the spring clutch 39. That is, the solenoid 44 is energized and the armature air
The upper end of 43 is attracted to the solenoid 44 side and moves in the claw detachment direction. This allows the upper end stopper of the armature air 43 to be
The engagement between 52 and the claw 41 is released. Then, the spring 50 tightens the boss portion 46a of the central shaft 30 according to the rotation of the central shaft 30, and the rotational force thereof is transmitted from the second hub 49, the first hub 47 to the flange 37, and the closing plate 38 rotates. .

After that, when the solenoid 44 is de-energized, the armature air 43
Is released from the solenoid 44, and the return spring 45 moves the upper end of the armature air 43 in the pawl engaging direction, so that the stopper 52 engages with the next pawl 42. Then, by the engaging operation, the spring 50 is loosened, the rotational force of the central shaft 30 is not transmitted to the first and second hubs 47, 49, and the rotation of the closing plate 38 is stopped. That is, the closing plate 38 is rotationally controlled so as to rotate by 90 ° and stop. When the closing plate 38 rotates by 90 ° and stops, the openings 38a between the closing plates 38 face the inlet 35a and the outlet 35b of the developer passage as shown in FIG. 4, and open the passage. . Therefore, the developer is supplied to the developing roller 22 while being stirred by the rotation of the second stirring roller 25, and is used for development.

In this case, while the developer is being supplied to the developing roller 22, the detection portion of the sensor 28 for detecting the toner concentration is in the developing tank 1.
Being positioned inside, the toner density is detected. In response to this detection output, toner is replenished from the replenishing tank 20 into the developing tank 1. Further, since the protrusion 60 of the clutch cover 40 corresponds to press the operating portion of the detection switch 61,
The detection switch 61 informs the control unit of the copying machine main body that the closing plate 38 opens the passage and is in the developing state.

As described above, the developer is supplied to the developing roller 22, and after the development is completed, it is sent to the conveying roller 23 according to the rotation of the developing roller 22, and is further conveyed upward by the conveying roller 23, and the partition member 26. Then, it is circulated and supplied again to the second stirring roller 25.

After that, when the development of the photoconductor 3 is completed and the development by such a developing device becomes unnecessary, the control for stopping the supply of the developer is executed. For this reason, the solenoid 44 is energized to release the engagement between the tip of the armature air 43 and the claws 41 and 42, and then driven to the non-energized state. As a result, the closing plate 38 is rotated by 90 ° and stopped via the spring clutch 39, so that the closing plate 38 enters the inlet 35a and the outlet 35b of the developer supply passage.
Will be closed.

As a result, the developer is no longer supplied to the developing roller 22 and the developing state is set. Further, in order to inform the control section of the copying machine main body of this state, the detection switch 61 is in an inoperative state.

In such an opening / closing operation of the closing plate 38, when the rotation center shaft 30 of the closing plate 38 and the center of the coil spring 50 are deviated, even if the closing plate 38 is in a stopped state, The portion is in pressure contact with the boss portion 46a, and the rotational force may be transmitted from the input side of the spring clutch 39 to the second hub 49 side.

However, in the present invention, a gap 59 is formed between the stepped tapping screw 48 connecting the first hub 47 and the second hub 49 and the fitting hole 56 of the first hub 47. Therefore, the gap 59 can absorb the suspension of the spring clutch 39 and the closing plate 38.
Can stop at a fixed position.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

For example, although the developing roller 22 and the conveying roller 23 are arranged in the vertical direction in the above embodiment, the present invention is not limited to this and the present invention can be applied to a case where they are arranged in the horizontal direction.

Further, the arrangement order of the plurality of magnetic poles of the magnet body is not limited to the above embodiment. Further, the photoconductor 3 is not limited to the belt-shaped one as in the above embodiment, but may be a drum-shaped one. Further, the number of developing tanks is not limited to plural, and one developing tank may be applied. Further, by adding a configuration in which the closing angle by the closing plate in the above embodiment is made larger than the opening angle by the opening portion, the outflow of the developer to the developing roller due to the variation of the rotation stop position of the closing plate is completely prevented. You may do it.

<Effect of device> As is apparent from the above description, according to the present invention, since the stop position correction mechanism is provided, even if the center axis of the switchgear and the center axis of the spring clutch are slightly deviated, the spring inside the clutch is If the opening and closing of the opening and closing device is absorbed by the action and the opening and closing device can be stopped at a fixed position, an excellent effect can be obtained.

[Brief description of drawings]

1 is a sectional view of an opening / closing device of a developing device according to an embodiment of the present invention, FIG. 2 (a) is a sectional view of a stop position correcting mechanism, FIG. 2 (b) is a side view thereof, and FIG. (c) is a perspective view showing the engaged state of the coil spring, (d) is a side view showing the outer appearance of the spring clutch, (e) is a sectional view taken along the line AA in (d) of FIG. f) is a perspective view of the armature air, FIG. 3 is a perspective view of the opening / closing device, FIG. 4 is a sectional view of the developing tank, FIG. 5 is a front view of the switching means of the outer wall of the developing tank, and FIG. 6 is a copying machine. It is a block diagram which shows the electrophotographic process of a developing device. 1,2: drive roller, 3: photoconductor, 4: developing tank, 22: developing roller, 22a: developing magnet body, 22b: developing sleeve, 23: transport roller, 23a: transport magnet body, 23b: transport sleeve,
35: Switchgear, 36: Switching means, 37: Flange, 37a: Shaft part, 3
8: Blocking plate, 39: Spring clutch, 40: Clutch cover, 43: Armature air, 44: Solenoid, 45: Spring, 47: First hub, 48: Tapping screw, 49: Second hub, 56: Fitting hole, 59: Gap.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 64-15771 (JP, A) Actual opening 55-38311 (JP, U) Actual opening 60-110341 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A developing section arranged to face a recording medium,
In a developing device having a supply passage for supplying a developer to the developing section and a recovery passage for returning the developer in the developing section to the supply passage, the supply passage has a portion for opening or closing the supply passage. And a rotatably provided opening / closing means for opening or closing the supply passage, a spring clutch for transmitting a rotative force to the opening / closing means to rotate the unidirectional direction as necessary, and actuating the spring clutch. Switching means for switching the opening / closing means to an open position or a closed position, and a stop position correcting means for correcting variations in the stop position of the opening / closing means due to a positional shift between the spring clutch and the opening / closing means. A developing device characterized by the above.