JPH0785186B2 - Development device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a developing device provided in, for example, an electronic copying machine.

[Technical background of the invention and its problems]

Recently, electronic copying machines capable of two-color development have been widely used. In this electronic copying machine, first and second developing devices are arranged in the vicinity of the photoconductor, 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 externally fitting a magnet roller having a plurality of magnetic pole portions with a rotating sleeve, and the rotation of the rotating sleeve causes the magnetic brush of the developer to move onto the photosensitive member. The latent image is slidably contacted with the latent image and developed.

The first and second developing devices are selectively switched for use.

However, in the prior art, a motor capable of rotating in the forward and reverse directions is required as a means for selectively driving the first and second developing devices, and its power is intermittently supplied to the first and second developing devices. Requires a one-way clutch for effective transmission, and a drive means for rotating the magnet roller in order to cut the magnetic brush of the developing device in an unused state, resulting in a large number of parts. However, there was an inconvenience that the cost became high.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object thereof is to provide a developing device capable of selectively switching between the first and second developing devices with a simple structure. It is the one we are trying to provide.

[Outline of Invention]

In order to achieve the above object, the present invention provides a first image bearing member which rotates in a predetermined direction, and a first color developer which is arranged to face the image bearing member at a first position. A developing device, first supporting means for supporting both sides of the first developing device in the longitudinal direction, and biasing the first developing device toward the image carrier; A second developing device having a second color developer different from the first color and facing the image carrier at a second position downstream in the rotation direction of the image carrier; Second supporting means different from the first supporting means for supporting both ends of the second developing device in the longitudinal direction and biasing the first developing device toward the image carrier; By moving the first support means, the first developing device is brought close to the image carrier to perform the development and the image bearing position. The image is moved to a position away from the body where development is not performed, and the second support means is moved to move the second developing device close to the image carrier to perform development and the image. A moving unit that moves away from the carrier to a position where development is not performed, and the moving unit moves the second developing device from a state where development is performed using the first developing device. When the developing device is switched to a developing state, the first developing device is moved from a position close to the image carrier to a position separated from the image carrier,
While the portion of the image carrier facing the first position rotates at least until facing the second position,
Both the first and second developing devices are made to stand by at a position separated from the image carrier, and at least a portion of the image carrier facing the first position faces at least the second position. After the rotation, the first and second supporting means are moved so as to move the second developing device away from the image carrier to a position close to the image carrier. It is what

Example of 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 bearing member is rotatably provided at a substantially central portion of the main body 1. Around the photosensitive drum 2, a charger 3, a developing device 4, and a transfer peeling charger are arranged along the rotation direction.
5a, 5b and a cleaning device 6 are provided. A document table 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 the document table glass 7. The optical system 8 includes a lamp 9, first to third reflecting mirrors 10, 11 and 12, a lens 65 and a fourth reflecting mirror.
It is composed of 68,67. Further, the first and second sheet feeding cassettes 14, 1 are detachably attached to one side portion of the main body 1.
5 is attached to the first and second paper feed cassettes 14,
The paper P, P'in the paper 15 is taken out one by one by the take-out rollers 68, 69. This taken out paper P, P ′
Are conveyed along the conveying path 16, and on the conveying path 16, the feed rollers 17a and 17b, the registration roller 18, the transfer and peeling charges 5a and 5b, the conveying belt 19, the fixing roller 20 and the discharging roller 21 are arranged. Has been done. 22 is a paper ejection tray.

Therefore, when copying a document, the document placed on the document table 7 is scanned with light from the lamp 9 of the optical system, and the reflected light is reflected by the first to third reflecting mirrors 10, 11, 12, Lens 6
An image is formed on the photosensitive drum 2 via the fifth, fourth and fifth reflection mirrors 67. The surface of the photosensitive drum 2 is uniformly charged by the charger 3, and an electrostatic 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, is developed with red or black toner as described later, and is then sent to the transfer and peeling chargers 5a, 5b side. . On the other hand, at this time, the paper P or P'is fed from the first or second paper feed cassette and is sent to the registration roller 18 by the feed roller 17a or 17b to be aligned and then transferred to the photosensitive drum 2.
It is sent between the peeling chargers 5a and 5b. This paper P
The original image on the photosensitive drum 2 is transferred to (P ') by the action of the transfer charger 5a.
By the action of 5b, it is separated from the photosensitive drum 2 and sent to the fixing roller 20 via the conveyor belt 19. Here, the image is defined on the paper P (P ') and is discharged to the paper discharge tray 22 via the paper discharge roller 21.

Next, the developing device 4 will be described in detail. The developing device 4 includes first and second developing devices 23, 24 located at the upper and lower sides.
It is composed by. The first and second developing devices
Developing rollers 25 and 26 are respectively provided in 23 and 24. These developing rollers 25 and 26 are a magnet roller 27 having a plurality of magnetic pole portions as shown in FIG.
It is constituted by a rotary sleeve 28 which is fitted onto 27. Further, the toner 29 as a red developer is contained in the first developing device 23, and the black toner 30 is contained in the second developing device 24. The first and second developing units 23 and 24 can be alternately moved in a direction in which they come in contact with and separate from the photosensitive drum 2 by a switching mechanism described later.

As shown in FIGS. 2 to 6, the switching mechanism includes a first switching mechanism.
And a pair of pins 31, 3 on one side in the longitudinal direction corresponding to the front side frame 60 of the copying machine main body 1 of the second developing devices 23, 24.
2 and 33, 34 are respectively provided inwardly projecting, while the rotary shaft end portions 27a, 27a of the respective magnet rollers 27 and the pins 35, are provided on the other side portion in the longitudinal direction corresponding to the rear side frame (not shown). Guides 37 and 38 fixed to the front side frame 60 and a rear side frame (not shown) are provided with the respective pins 31 and 33 and the rotating shafts 27a and 27a.
And 39, 40 respectively, and the pins 32 and 34 and the pins 35 and 36 are fitted in the long holes 61 of the front frame 60 and the rear frame (not shown).
In the engaged state as shown in FIGS. 3 and 4 by way of example, the links 31 and 42 and the links 43 and 44, which are rotatably and movably mounted via the guide bush 62, are fitted to the respective links. As a spigot structure, the first and second developing units 23 and 24 can be movably approached to the photosensitive drum 2 in a direction of contacting and separating from each other. Also,
Each of the links, for example the link 42, has a Dharma groove 42a.
The guide bush 62 is movably fitted in the Dharma groove portion 42a, and is leftward by the urging force of the spring 63, that is, the first and second portions with respect to the photosensitive drum 2.
The developing devices 23 and 24 are urged in the direction in which they are pressed.
Further, links 41 and 43 for moving the first developing device 23.
Is connected to the shaft 47 via levers 45 and 46, while links 42 and 44 that move the second developing device 24.
Is connected to a shaft 50 via levers 48 and 49, and these shafts 47 and 50 are connected to a cam 53 via guide arms 51 and 52.
Is engaged with. As shown in FIGS. 5 and 6, the cam 53 is rotated by a drive motor 56 via reduction gears 54, 55, and the rollers 51a, 52a of the guide arms 51, 52 are engaged with the cam groove 53a. The shafts 47 and 50 are reciprocally moved to alternately press the first and second developing units 23 and 24 toward the photosensitive drum 2 side by pressing them together with the protrusions 53b. It is a switch. Further, the cam 53 rotates in one direction, the initial position is detected by the switch 57, and the first or second developing unit 23, 2 is detected.
The position of the convex portion 53b for switching 4 can be selected.

That is, the driving state of the first and second developing devices 23 and 24 described above will be described. As shown in FIG. 7, the second developing device 24 is pushed down by the guide arm 52 by the convex portion 53b of the cam 53. Then, the thrust is transmitted to the lever 48-link 42-pin 34 and the pin 33 is pressed against the guide 38. At this time, the stroke S of the pin 33 is different from the stroke S _A ′ of the link 42.
_A becomes large (S _A <S _A ′), whereby the second developing device 24 is always pressed against the photosensitive drum 2 side by the urging force of the spring 63. Conversely, the first developing device
23, the guide arm 51 is pushed up by the cam 53, and the thrust is transmitted to the lever 45-link 41-pin 32 to move away from the photosensitive drum 2. At this time as well, the stroke S _B ′ of the link 41 is Against the stroke of pin 32 S _B
Becomes larger (S _B <S _B ′). Further, as shown in FIG. 5, the height of the convex portion 53b of the cam 53 is set to h, and the guide arm 51 (5
When the length of 2) is set to l ₁ and the length of lever 46 (49) is set to l ₂ , the movement stroke of link 41 (42) is Therefore, it becomes easy to set the stroke of the link.

By the way, as shown in FIGS. 3 and 4, for example, when the link 42 is on the right side, that is, when the second developing device 24 is separated from the photosensitive drum 2, the guide bush 62 and the link 42 are linked.
The ends of the long holes 42a of 42 come into contact with each other and move to the right integrally with the link 42, and the gap δ ₀ generated at this time is different from the gaps δ _{1 to} δ ₄ shown in FIGS. 7 to 9. In contrast, even when the link 42 is moved to the leftmost end, a margin is provided so that it does not abut against the elongated hole 61 of the frame 60 and project.
Although only the mechanism on the front side is shown in the above embodiment, the mechanism and the operation on the rear side are the same, and the description thereof will be omitted.

On the other hand, when the first or second developing device 23, 24 is pressed against the photosensitive drum 2, as shown in FIGS. 2 and 3, the links 41, 42, 43, 44 move to the left. The pin 31 or 33 of the first or second developing device 23, 24, the rotary shaft 2
When 7a and 27b come into contact with the guides 37 to 40, the movement of the guide bush 62 also stops at that point, but the movement of the links 41 to 44 tries to move further to the left, and then the urging force of the spring 63 is applied. As a result, the guide bush 62 is pushed toward the photosensitive drum 2 side, and gaps δ ₂ and δ ₄ are generated between the guide bush 62 and the links 41 and 42, which causes the first and second developing units 23 and 24. The spring 63 from both ends in the longitudinal direction.
Is selectively pressed against the guides 37 to 40 only by the urging force of the guides 37 to 40, which enables accurate positioning with respect to the guides 37 to 40, that is, the photosensitive drum 2.

In this way, FIG. 7 shows the copying state by the second developing device 24,
FIG. 8 shows the copying state by the first developing device 23. However, in the developing device which does not use any of them, a gap S is formed between the magnet roller 27 of each developing device and the photosensitive drum 2. ₁ or S ₂ is relatively formed so that the non-contact state can be maintained.

Further, FIG. 9 shows a state in which gaps S ₃ and S ₄ are formed so as to separate the first and second developing units 23 and 24 from the photosensitive drum 2. That is, when the first developing device 23 is switched to the second developing device 24 after the photosensitive drum 2 is stopped, even if the first developing device 23 located rearward with respect to the rotation direction of the photosensitive drum 2 is separated. On the photosensitive drum 2, the toner 29 of the first developing device 23 is transferred to the first developing device 23 and the second developing device 23.
Section θ ₁ from 24 contact positions a and b to cleaning position c
Therefore, when the second developing device 24 located in front of the rotation direction of the photosensitive drum 2 is brought into contact with the toner 29 of the first developing device 23,
Of the first developing device 23 from the contact position a of the first developing device 23 to the contact position b of the second developing device 24 by a distance of θ ₂ or more. The photosensitive drum 2 and the photosensitive drum 2 are both rotated in a non-contact state. In this case, in practice, the rotation range of the photosensitive drum 2 is usually half rotation or more, which is larger than the section θ ₂ , or one rotation or more. The above operation is not required when switching from No. 1 to developing unit 23.

Therefore, the first and second developing units 23 and 24 can be selectively operated without the need for a drive motor that can rotate in the normal and reverse directions, a one-way clutch, and the like, and the magnet roller 27 can be rotated. Without toner 29 or
The supply of 30 can be stopped and the structure can be significantly simplified.

The present invention is not limited to the above-mentioned embodiment,
Of course, various changes can be made within the scope of the gist.

〔The invention's effect〕

As described above, according to the present invention, the first and second developing devices are selectively moved by the moving means, one of the developing devices is brought close to the image carrier, and the other developing device is separated from each other. The movement of the first and second developing devices selectively connects and disconnects them with the driving means to operate them, so that there is no need for a motor, a one-way clutch, etc. capable of rotating in the forward and reverse directions as the driving means as in the prior art. The first and second developing devices can be selectively operated, and
The drive means of the magnet roller for cutting the magnetic brush of the developer is not required, and the structure is remarkably simplified.
Cost can be reduced. Further, since the first and second developing devices are elastically pressed against the image carrier from both sides, there is an effect that the positioning of the first and second developing devices with respect to the image carrier becomes accurate.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram in which an embodiment of a developing device according to the present invention is applied to an electronic copying machine, FIG. 2 is a configuration diagram showing switching means of a developing device, and FIGS. 3 and 4 are developing devices. 5 is a schematic view showing the driving means of the developing device, and FIGS. 7 and 8 are schematic explanatory views showing the developing state. FIG. 9 is a schematic explanatory view of a main part 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, 23,2
4 …… Developer, 27 …… Magnet roller, 47,50 …… Shaft, 53 …… Cam, 56 …… Drive motor, 63 …… Spring, S ₁ , S ₂ … Gap, a, b …… Contact position.

Claims (1)

[Claims] 1. A first member for an image carrier that rotates in a predetermined direction.
And a developer having a first color, which are arranged to face each other at a position of 1) and which is used for development in the vicinity of the image carrier and is separated from the image carrier and is not used for development. A first developing device movable between a first standby position and a first movement for selectively moving the first developing device to the first developing position and the first standby position. And a developing device for developing a second color different from the first color and arranged to face the image carrier at a second position downstream of the first position in the rotation direction of the image carrier. A second movable portion having an agent and movable between a second developing position in which the developing agent is close to the image carrier and is used for development and a second standby position in which the developing agent is separated from the image carrier and is not used for development. And a second developing device for selectively moving the second developing device between the second developing position and the second standby position. Moving means, selecting means for selecting one of the first developing device or the second developing device, and the first developing device when the first developing device is selected by the selecting device. Of the second developing device is driven by the selecting means so as to move the first developing device from the first standby position to the first developing position, and the second developing device is selected by the selecting device. Drive the second moving means to move the second developing device from the second standby position to the second developing position, wherein the selecting device selects the first developing device. When the second developing device is selected from the above state, the first moving means is driven so as to move the first developing device from the first developing position to the first standby position. And then to the first position on the image carrier. The first developing device and the second developing device are made to stand by at the first standby position and at the second standby position, respectively, while the part that has been rotated rotates at least until facing the second position. Maintained in the above state, and after the portion of the image carrier facing the first position is rotated at least until facing the second position, the second developing device is moved to the second standby position. From the state where the second developing device is selected by the selecting device by driving the second moving device so as to move from the second developing device to the second developing position. Drives the second moving device so as to move the second developing device from the second developing position to the second standby position, and then immediately causes the first developing device to move to the first developing device. It will move from the first standby position to the first development position. Developing apparatus is characterized by comprising driving means for driving said first moving means.