JPS625277A - Developing device - Google Patents

Abstract

PURPOSE:To change over a developing device with simple constitution by rotating an image holding body in cleaning condition at the time of changing over from one side developing device to other developing device. CONSTITUTION:When change over is executed from the first developing device 23 from the second developing device 24, and even if the developing device 23 located backward in the rotating direction of a photosensitive drum 2 is separated from the drum 2, the toner of the developing device 23 is stuck on the drum 2 over the section theta1 from contacting positions (a) and (b) of developing devices 23 and 24 to a cleaning position (c). In such condition, when the developing device 24 located forward is contacted in the rotating direction of the drum 2, the toner of the developing device 23 is mixed into the developing device 24. Then, over the distance of a section theta2 or above from the contacting position (a) of the developing device 23 to the contacting point (b) of the developing device 24, clearances S3 and S4 are formed between the magnet roller and the drum 2 of developing devices 23 and 24, the drum 2 is rotated in the cleaning condition and the mixing of the toner is prevented. Consequently, since changeover can be executed without using the positive reverse rotatable driving motor, and the supply of the toner can be stopped without turning the magnet roller, the device can be made simple constructively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing device included in, for example, an electronic copying machine.

[Technical background of the invention and its problems]

Recently, electronic copying machines that are capable of two-color development have become popular. This electronic copying machine has first and second developing devices arranged near the photoreceptor, and for example, the first developing device performs color development and the second developing device performs black development. .

The first and second developing devices each include a developing roller formed by a rotating sleeve surrounding a magnetic roller having a plurality of magnetic poles, and the rotation of the rotating sleeve moves the magnetic brush of the developer to the static surface of the photoreceptor. It is designed to be brought into sliding contact with the electrostatic latent image and developed.

The first and second developing devices are selectively switched and used.

However, conventional methods require a motor capable of forward and reverse rotation as a means for selectively driving the first and second developing devices, and the power of the motor is intermittently applied to the first and second developing devices. It also requires a one-way clutch to transmit the signal, and also requires a drive means to rotate the magnetic roller to cut the magnetic brush of the developing device when it is not in use, resulting in a large number of parts. However, there was the inconvenience of high costs.

[Purpose of the invention]

The present invention has been made in view of the above circumstances.

The purpose of this is to provide a simple configuration for the first and second
It is an object of the present invention to provide a developing device that can selectively switch between two developing devices.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention has the following features.

first and second developing devices located close to a rotatable image carrier; and selectively moving the first and second developing devices in a direction toward and away from the image carrier. a switching means for relatively changing a gap between the two, and at least one developing device located at the rear with respect to the rotational direction of the image carrier to the other developing device located at the front. By causing both the developing devices to be viewed from the image carrier and by rotating the image carrier in a clean state beyond the distance between the two developing devices, a Motors and one-way clutches that can rotate forward and backward.

Alternatively, it is possible to eliminate the need for a means for rotating the magnetic roller for magnetic brush cutting, and to prevent the developer from the previous developing device adhering to the image carrier from getting mixed into the next developing device. This prevents damage to the image carrier when the developing device is attached and detached.

[Embodiments of the invention]

The present invention will be described below with reference to an embodiment shown in the drawings. In the figure, reference numeral 1 denotes a main body of an electronic copying machine, and a photosensitive drum 2 as an image carrier is rotatably provided approximately at the center of the main body 1. As shown in FIG. A charger 3. Developing device 4. Transfer peeling charger 5
&, 5b and a cleaning device 6 are provided.

Further, an original platen glass 7 is provided on the upper surface of the main body 1, and an optical system 8 is provided on the lower side of this original platen glass 7. This optical system 8 includes a lamp 9. It is composed of first to thirtieth reflecting mirrors 10, 11, 12, a lens 65, and a fourth reflecting mirror 66, 67.

Further, first and second paper feed cassettes 24.15 are detachably attached to one side of the main body 1, and the paper sheets p, p in these first and second paper feed cassettes 14.15 are removably attached.
' are taken out one by one by take-out rows 268 and 69.

These taken out sheets P and P' are conveyed along the conveyance path 16, and on this conveyance path 16 there are feed rollers 217h and 17b.
, v Dystrora 18. The above transfer/peel charger 5h
, 5b, a conveyor belt 19, a fixing roller 20, and a discharge row 221 are provided. 22 is a paper discharge tray.

When copying an original, the original placed on the original platen 7 is scanned with light from the lamp 9 of the optical system, and the reflected light is reflected from the first to third reflecting mirrors 10, 11, 12, .
An image is formed on the photosensitive drum 2 via the lens 65 and the fourth and fifth reflecting mirrors 67 . The surface of the photosensitive drum 2 is uniformly charged by a charger 3, and a static latent image is formed by the above image formation. This electrostatic latent image is sent to the developing device 4 by the rotation of the photosensitive drum 2.

As will be described in detail later, the toner is developed with red or black toner and then transferred to the transfer and peeling charger 5&, and sent to the Sb side. On the other hand, at this time, the paper P or P' is fed from the first or second paper feed cassette, and the paper feed roller 217a or 17b is fed to the registration roller 218.
After being sent to the photosensitive drum 2 and aligned, it is transferred to the photosensitive drum 2.

It is sent between the peeling charger 51 and sb.

The original image on the photosensitive drum 2 is transferred to this paper P (P') by the action of the transfer charger 5a.

After that, the action of the peeling charger 5b begins.

It is peeled off from the photosensitive drum 2 and sent to the fixing roller 20 via the conveyor belt 19. Here, the image is paper p(p'
) is fixed on the paper output tray 22 via the paper output row 221.
The paper will be ejected.

Next, the developing device 4 will be described in detail.

This developing device 4 is composed of first and second developing units 23 and 24 located at the top and bottom. A developing roller 2 is provided in the first and second developing devices 23 and 24, respectively.
5.26 is provided.

As shown in FIG. 1, these developing devices n-225 and 26 are constituted by a magnet roller 27 having a plurality of magnetic pole parts and a rotary sleeve 28 that is fitted onto the magnet row 222.

Further, toner 29 as a red developer is stored in the first developing device 23, and black toner 30 is stored in the second developing device 24. These first and second
The developing units 23 and 24 can be alternately moved toward and away from the photosensitive drum 2 by a switching mechanism to be described later.゛As shown in Figs. 2 to 6, the above switching mechanism
A pair of bins 31, 32 and 33, 34 are respectively provided on one side in the longitudinal direction corresponding to the 70-ant side frame 60 of the duplicating machine main body 1 of the second developing units 23, 24, while protruding inwardly; The rotating shaft ends 27m, 27h of each of the magnet rollers 21 and the bins 35 and 36 are provided protruding from the other side in the longitudinal direction corresponding to the rear side frame (not shown). 33 and rotating shaft 27
a2 and 27m are respectively fitted into guides 37.38 and 39.40 fixed to the front side 7 frame 60 and the rear side 7 frame (not shown).

The respective bins 32 and 34 and bins 35 and 36 are mounted on the 70-tont side frame 60s? and a link 41 rotatably and movably attached to each elongated hole 61 of the rear frame (not shown) via a guide bushie '62 in a locked state as shown by way of example in FIGS. 3 and 4. 42 and links 43 and 44 respectively, the first and second developing units 23 have a spigot structure.
．． 24 can move movably close to and away from the photosensitive drum 2. Further, each of the links, for example the link 42, has a daruma groove portion 4jlL,
The guide bushy 62 is movably fitted into the daruma groove 42&, and the biasing force of the spring 63 causes the guide bushy 62 to move toward the left side.
That is, the first and second developing devices 23 and 24 are urged in a direction against the photosensitive drum 2. Furthermore, a link 4 that moves the first developer 023
1.43 is.

A link 42, which is connected to the shaft 47 via a lever 45, 46, while movable the second developer 24;
．． 44 are connected to shafts 50 via levers 48.49, these shafts 41.50 are connected to guide arms 5
It engages with the cam 53 via 1 and 52. This cam 5
3 is a reduction gear 54 as shown in FIGS. 5 and 6.
．． 55, the drive motor 56 rotates the guide arm 51.
, 52m and alternately forcefully push them down with the convex portions 53b, thereby reciprocating the shafts 4'l and 50 to alternately expose the first and second developing units 23, 24 to light. It is switched so as to press against the drum 2 side. Further, the cam 53 rotates in one direction, and when the initial position is detected by the switch 57, the cam 53 is moved to the first or second position.
The position of the protrusion 53b for switching between the developing devices 23 and 24 can be selected.

That is, the first and second developing devices 23 and 24 described above
To explain the driving state of #g2, as shown in FIG.
The developing device 24 is pushed down by the guide arm 52 by the convex portion 53b of the cam 53.

A thrust force is transmitted from the lever 48 to the link 42 to the bin 34, and the bin 33 is pressed against the guide 38. At this time,
The stroke SA of the bottle 33 is larger than the stroke BA1 of the link 42 (SA<8A'), so that the second developing device 24 is always pressed against the photosensitive drum 2 by the biasing force of the spring 63. It looks like this. Conversely, in the first developing device 23, the cam 53 and the guide arm 51 are pushed up, and the lever 45-link 41-pin 3
2 and the thrust force is transmitted to move in the direction away from the photosensitive drum 2, and at this time also, the stroke S of the link 41
The bin 320 stroke 8B becomes larger with respect to R' (
si<SB'), and as shown in FIG. 5, the height of the convex portion 53b of the cam 53 is
) If the length of lever 46 (49) is set to , then the movement stroke of link 4 J (42) will be .

This also makes it easier to set up links.

By the way, as shown in FIGS. 3 and 4, K.

For example, when the link 42 is on the right side, that is, when the second developing device 24 is away from the photosensitive drum 2, the guide push crystal 62 and the link 42 are in contact with each other at the end of the long hole 42 & of the link a2o, and the link 42 and the link 42 are integrally moved on the right side. and the gap δ that occurs at this time.

is different from the gap δ, ~a4 shown in Figures 7 to 9)
, even when the link 42 is at the leftmost position, the frame 60
A margin is provided so that it does not come into contact with the elongated hole 61 and become stretched.

In the above embodiment, only the front side mechanism was shown, but the mechanism and operation of the rear side are the same, and the explanation thereof will be omitted.

On the other hand, when the first or second developing device 23, 24 is pressed against the photosensitive drum 2, the links 41, 42, 43, 44 move to the left, as shown in FIGS. 2 and 3. pin 31 or 33. of the first or second developing device 23.24. The rotating shafts 27a and 27m are the guides 37~
40, the movement of the guide push crystal 62 also stops at that point, but the links 41 to 44 tend to move further to the left, and thereafter.

The guide push crystal 62 is pushed toward the photosensitive drum 2 by the biasing force of the spring 63.
A gap a, δ4 is created between the edges and the links 41 and 42, so that the first and second developing units 23, 24 are selectively guided only by the biasing force of the spring 63 from both longitudinal ends of the developing units 23, 24. 37 to 4o, the guide 37
~40. The tab allows accurate positioning with respect to the photosensitive drum 2.

In this way, although FIG. 7 shows the copying state by the 20th developing device 24, and FIG. 8 shows the copying state by the first developing device 23, if the developing device is not used, Magnet roller 27 and photosensitive drum 2 of each developing device
A gap S1 or S is relatively formed between the two, so that a non-contact state can be maintained.

Furthermore, FIG. 9 shows the first and second developing units 23, 24.
A gap S8. S,
This figure shows the state in which . That is, after the photosensitive drum 2 stops, the first developing device 23 to the second developing device 24
Even if the first developing device 23 located at the rear with respect to the rotational direction of the photosensitive drum 20 is moved away, the toner 29 of the #g1 developing device 23 remains on the photosensitive drum 2.
Since it is adhered over the section 01 from the contact positions a and b of the second developing unit 23 and the second developing unit 24 to the cleaning position C, the adhesive remains in the forward direction with respect to the rotational direction of the photosensitive drum 2. When the second developing device 24 located in the
4, and at least a distance equal to or longer than section 03 from the contact position a of the first developer 23 to the contact position a of the second developer 24. ! 4 is kept in a non-contact state while the photosensitive drum 2 is rotated. Note that in this case, in reality, the photosensitive drum 2
The rotation range is 1 section 0. It's normal to make more than half a turn, or more than one turn. The above operation is not necessary when switching from the second developing device 24 to the first developing device 23.

Therefore, the first and second developing units 23 and 24 can be selectively operated without requiring a drive motor capable of forward and reverse rotation, a one-way clutch, etc.
The toner 29 can be removed without rotating the magnet roller 21.
Alternatively, the supply of 30 can be stopped, and the structure can be significantly simplified.

Note that the present invention is not limited to the above embodiment,
Of course, various modifications can be made within the scope of the gist.

〔Effect of the invention〕

As described above, the present invention selectively moves the first and second developing devices by a moving means, brings one of the developing devices close to the image carrier, and moves the other one away from the image carrier. This is because the first and 82nd developing units are operated by selectively connecting and disconnecting them to the drive means for their movement.

The first and second developing devices can be selectively operated without requiring a motor capable of forward and reverse rotation, a one-way clutch, etc. as a driving means as in the past, and the magnetic brush of the developer can be cut. magnet row 2
Since there is no need for a driving means, the structure can be significantly simplified and costs can be reduced. Furthermore, when switching between the first and second developing units, both developing units are separated from the image carrier, and the image carrier is rotated in a cleaning state over a predetermined range. It is possible to prevent the previous toner adhering to the toner from getting mixed into the next developing device, and the developing device can be easily attached and detached, and the image bearing member is not damaged.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the developing device according to the present invention applied to an electronic copying machine, FIG. 2 is a configuration diagram showing a switching means for the developing device, and FIGS. 3 and 4 are a schematic diagram of the developing device. FIGS. 5 and 6 are block diagrams showing the driving means of the developing device, and FIGS. 7 and 8 are schematic explanatory diagrams of main parts showing the developing state. , FIG. 9 is a schematic explanatory diagram of main parts showing a state in which the developing device is separated from the image carrier at the time of switching. 2... Photosensitive drum (image carrier), 4... Developing device. 6...Cleaning device, 23.24...Developing device. 27... Magnet roller, 47.50... Shaft, 53... Cam, s6. ,, drive motor, 81~S
4... Gap, 0. ．． 0. ...section, a, b...contact position, C...cleaning position. Applicant's representative Patent attorney Takehiko Suzue Figure 3 Figure 4 Procedure amendment, Eh 6'lk8・-a7a

Claims (1)

[Claims] first and second developing devices located close to a rotatable image carrier; and selectively moving the first and second developing devices in a direction toward and away from the image carrier. switching means for relatively changing the gap between the two, and at least when switching from one developing device located at the rear to the other developing device located at the front with respect to the rotational direction of the image carrier, A developing device characterized in that both developing devices are separated from an image carrier, and the image carrier is rotated in a cleaning state by a distance greater than the distance between both developing devices.