JP2743385B2 - Developing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used for an electrophotographic copying machine capable of forming images of a plurality of colors.

2. Description of the Related Art Conventionally, as a developing device of this type, there is a developing device including a plurality of developing devices using toners of different colors arranged along the rotation direction of a photosensitive drum. As the container, for example, one using a magnetic brush developing method is used. In the case of the above-described developing device, if another developing device is close to the photosensitive drum while one developing device is performing development, the following problem occurs. That is, when the other developing device is located upstream of the developing device in the rotation direction of the photosensitive drum with respect to the developing device, the magnetic brush of the developing device rubs against the electrostatic latent image on the photosensitive drum, so that static electricity is generated. There has been a problem that the electro-latent image is disturbed or toner of a magnetic brush adheres to the photosensitive drum to cause color mixing, thereby deteriorating image quality.

Conversely, if another developing unit is located downstream of the developing unit in the direction of rotation of the photosensitive drum, the magnetic brush of the developing unit disturbs the toner image already developed on the photosensitive drum. Also, there is a problem that toner of the magnetic brush adheres to the photosensitive drum to cause color mixing, which also causes deterioration of image quality.

Therefore, in a developing device having a plurality of developing devices,
Each developing unit can be individually moved to an operating position close to the photosensitive drum, and while one developing unit is performing development,
There is a configuration in which another developing device is separated from the photosensitive drum. That is, as shown in FIG. 9, two developing units 6 arranged vertically near the photosensitive drum 60.
1 and 62.Each of the developing units 61 and 62 has a photosensitive drum 6
It is movably supported in the direction approaching and separating from zero.
The developing devices 61 and 62 are urged by springs 63 and 64 in a direction away from the photosensitive drum 60, and
On the back side of the developing devices 61 and 62, eccentric cams 67 fixed to the drive shafts 65 and 66 so that the eccentric positions rotate 180 degrees differently,
68 are provided respectively. Then, the drive shaft 6
By rotating 5, 66, the back of one of the developing units 61 or 62 is pressed by the tip of the eccentric cams 67, 68, and this developing unit 61 or 62 can be driven to the operating position close to the photosensitive drum 60 It has become.

[Problem to be Solved by the Invention] However, such a conventional technique has the following problems. That is, the eccentric cams 67 and 68 and a mechanism for driving the eccentric cams 67 and 68 must be provided on the back side of the developing devices 61 and 62, and the space on the back side of the developing devices 61 and 62 becomes large, and the mechanism becomes complicated. There is a problem that.

Further, when the developing devices 61 and 62 move to the positions close to the photosensitive drum 60, they do not contact the members on the photosensitive drum 60 side before reaching the stop position. Therefore, the developing device 61,
When the eccentric cams 67 and 68 are pushed by the eccentric cams 67 and 68 to move to the operation position close to the photosensitive drum 60, the leading ends of the developing devices 61 and 62 set the interval between the photosensitive drum 60 and the developing roll. The developer adhered to the developing roll or the like is spilled by the impact and mixed into another developing device to cause color mixing or stain the surrounding area.

As a solution to the above-mentioned problems, a device as shown in FIG. 10 can be considered. That is, a lever 70 that can be manually operated from outside the copying machine is provided, and
A gear 72 is provided on a shaft 71 pivotally supporting 70, and this gear 72 is used as a drive shaft.
The gear 74 is engaged with a gear 74 provided on the gear 73. Cams 76 and 77 for pressing a leaf spring 75 provided on the back surface of the developing device 61 are fixed to the drive shaft 73. The cam 77 is for pressing a developing device (not shown) provided below the developing device 61. As shown in FIG. 11, the lever 70 is provided with a projection 78, and near the lever 70,
The state where the developing device 61 is moved to the operating position by operating the lever 70
A micro switch 79 that is turned on is provided. By doing so, the developing device 61 can be moved manually, thereby simplifying the mechanism and reducing the cost. In the figure, reference numeral 80 denotes a bearing.

Also, as shown in Fig. 12, dial instead of lever
81, and the rotational driving force of this dial 81 is
And to the drive shaft 73 via the belt 84,
It is also conceivable to change the developing device 61 to the operating position.

However, even in these cases, the problem that the developer scatters due to an impact when the developing device collides with a predetermined member when the developing device moves cannot be solved.

Means for Solving the Problems Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and its object is to save space and to provide a developing device. An object of the present invention is to provide a developing device capable of performing a switching operation smoothly and preventing a developer from scattering.

That is, according to the present invention, in a developing device including a plurality of developing devices and each of the developing devices can be individually moved to an operation position close to the image carrier, a setting for setting a gap between the developing devices and the image carrier is provided. A member is provided, and the setting member is provided with a displacement portion for displacing the developing device in a direction of coming into contact with and separating from the image carrier, and the setting member provided in each of the developing devices is pressed against a member on the image carrier side. By rotating the setting member, each developing device is configured to be movable in a direction of coming into contact with and separating from the image carrier.

As the number of the developing devices, for example, two developing devices are used, but the number is not limited thereto, and may be three or more.

As the image carrier, for example, a photoconductor drum is used, but it is not limited to this, and a photoconductor belt or the like may be used as a matter of course.

Further, as the displacement portion, for example, an eccentric portion formed on a rotary plate or the like provided in the developing device so as to have a different distance from the center is used. Further, as the displacement portion, a member in which a setting member is formed in a rotatable disk shape and an eccentric portion whose distance from the center is different from the others in the circumferential direction is used in the setting member.

[Operation] Also, in the present invention, since each developing device is provided with a setting member for setting a gap between the developing device and the image carrier, each setting device provided in each developing device is rotationally driven, so that each of the developing devices is rotated. The operation of contacting and separating the developing device and the image carrier can be performed in a short time, and the switching operation of the developing device can be performed in a short time.

[Embodiments] The present invention will be described below based on the illustrated embodiments.

FIG. 7 shows an electrophotographic copying machine capable of forming images of a plurality of colors to which the developing device according to the present invention can be applied. In FIG. 1, reference numeral 1 denotes a document table glass on which a document (not shown) is placed. The document placed on the document table glass 1 is illuminated by a light source 2 and its reflected light image is composed of a mirror and a lens. The light is projected onto the photosensitive drum 4 by showing a scanning optical system. The surface of the photosensitive drum 4 is uniformly charged in advance by the charger 5 before the image of the document is exposed, and then the image of the document is exposed to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 4 is developed by any one of the developing devices of the developing device 6 according to the present invention. The developing device 6 has two developing units 7 and 8 containing developers of different colors in the illustrated embodiment, and each of the developing units 7 and 8 is individually operated close to the photosensitive drum 4. It is possible to move to the position.
An image developed by any of the developing devices is sent out from a paper feed cassette 9 by a paper feed roll 10 and transferred onto a transfer paper 12 which is conveyed by a registration roll 11 to the surface of the photosensitive drum 4 at a predetermined timing. Transcription corotron 13
Is transferred by the electrification. Then, the transfer paper 12
The toner image transferred by the fixing device 14 is fixed,
It is discharged onto the tray 15. In the figure, reference numeral 16 denotes a cleaner.

By the way, as shown in FIG. 6, the developing units 7 and 8 are arranged at an interval above and below.
Numeral 8 is slidably mounted in slots A and 20 formed in a frame 19 of the copying machine via rods 17 and 18 protruding from the side surface in a direction indicated by an arrow A which comes into contact with and separates from the photosensitive drum 4. ing. Also, on the back side of the developing devices 7 and 8, these developing devices 7 and 8 are provided.
The plate springs 50 and 51 are provided to make the pressure contact with a setting member described later.

As shown in FIG. 4, each of the developing devices 7 and 8 is provided with a developing roll 22 rotatably provided inside the developing device main body 21 and a rotatable provided on the back side of the developing roll 22. The main part is composed of a paddle 24 for supplying a developer 23 composed of toner and a magnetic carrier to the developing roll 22, and a mixer 25 rotatably provided on the back side of the paddle 24 and mixing the developer 23. Have been.

As shown in FIGS. 1 and 5, the photosensitive drum 4 and the developing roll 22 of the developing device are provided at both ends of the photosensitive drum 4.
A drum support 26 is provided for setting the distance between the drum support 26 and the drum support 26. The drum support 26 is formed in a disk shape and fixedly provided coaxially with the photosensitive drum 4. The drum support 26 keeps a constant distance between the surface of the photosensitive drum 4 and the developing roll 22 of the developing device by making contact with a part of the developing device described later.

In this embodiment, each developing device is provided with a setting member for setting a gap with the image carrier, and the setting member is provided with a displacement portion for displacing the developing device in a direction of coming into contact with and separating from the image carrier. It is configured. That is, the developing devices 7 and 8
As shown in FIG. 1, eccentric cams 27 and 28 as setting members are provided coaxially with the developing roll 22, and these eccentric cams 27 and 28 are provided with arc-shaped portions 27a, 28a
And portions 27b and 28b protruding toward the photosensitive drum 4 side. On the outer surfaces of the eccentric cams 27 and 28,
Pins 29 and 30 are protruded on the part opposite to b, 28b,
Elongated holes 34 and 35 formed in the arms 32 and 33 of the link member 31 are engaged with these pins 29 and 30.

The link member 31 has arm portions 32 and 33 projecting substantially 180 degrees from the center axis 36.
The central axis 36 of the motor 37 is, as shown in FIG.
It is connected to a crank 39 fixed to 38 via a link 40.

Then, by rotating the motor 37 by a predetermined amount, the link member is connected via the crank 39 and the link 40.
Move 31 up and down. By doing so, the link member
The eccentric cams 27 and 28 provided in the developing devices 7 and 8 are rotated by the pins 29 and 30 engaged with the long holes 34 and 35 of the developing device 31, and the projections 27b and 28b of the eccentric cams 27 and 28 are Drum support 26
, The developing units 7 and 8 can be individually brought into contact with and separated from the photosensitive drum 4.

In the above configuration, in the developing device according to this embodiment, the switching of the developing device is performed as follows. That is, since the developing devices 7 and 8 are pressed toward the photosensitive drum 4 by the plate springs 50 and 51, the eccentric cams 27 and 28 provided in the developing devices 7 and 8 abut against the drum support 26. I have. At that time, the eccentric cams 27 and 28 are, as shown in FIG.
Since the projections 27b and 28b are in contact with the drum support 26 so as to face substantially the same direction, the projection 27b of one eccentric cam 27
Is in contact with the drum support 26, the other eccentric cam 28 has its circular arc portion 28a in contact with the drum support 26. Therefore, the distance from the surface of the drum support 26 to the center of the eccentric cams 27, 28 is larger in the developing device 8 in which the protrusion 28b is in contact with the drum support 26, and the arc portion 27a
However, the developing device 7 in contact with the drum support 26 is smaller. That is, the developing device 7 includes the photosensitive drum 4
Is located at an operation position close to the developing device 8.
Is located at a non-operating position separated from the photosensitive drum 4.

Next, in order to switch the developing device to move the developing device 8 to the operating position and to move the developing device 7 to the non-operating position, the motor 37 is rotated by a predetermined amount so that the link through the crank 39 and the link 40 is performed. The member 31 is moved upward. Then, the eccentric cams 27 and 28 are rotated counterclockwise by the elongated holes 34 and 35 formed in the arm portions 32 and 33 of the link member, and as shown in FIG. Part 27b is drum support 26
And the circular arc portion 28 of the eccentric cam 28.
a is brought into contact with the drum support 26. By doing so, the developing device 7 moves to the non-operation position separated from the photosensitive drum 4 against the elastic force of the leaf spring 50 while the eccentric cam 27 is always in contact with the drum support 26, and Developing device 8 has an eccentric cam 28 which is always a drum support.
In the state of contact with 26, the plate spring 51 moves to the operating position close to the photosensitive drum 4 by the elastic force of the leaf spring 51.

As described above, the developing devices 7 and 8 are constantly pressed against the drum support 26 via the eccentric cams 27 and 28, and the eccentric cams 27 and 28 are rotated, whereby the eccentric cams 27 and 28 of the developing devices 7 and 8 are rotated.
Is always in contact with the drum support 26, and the developing device 7,
8 can be individually moved to the operation position close to the photosensitive drum 4, so that when the developing device is moved to the operation position, it does not collide with the member on the photosensitive drum 4 side, and the impact thereof causes the developing device Of the developer can be prevented from spilling. Further, there is no need to provide an eccentric cam or a mechanism for rotating the eccentric cam on the rear side of the developing devices 7 and 8,
An eccentric cam and a mechanism for driving the eccentric cam may be provided on the side surface of the developing device having a sufficient space, so that the apparatus can be reduced in space and size.

FIG. 8 shows a reference example of the present invention.
In this reference example, the displacement unit is not provided on the developing device side, but is provided on the setting member side. That is, as shown in FIG. 8, a projection 26a is provided on a part of the drum support 26 as the setting member, and the tip of the projection 26a has a radius larger than that of the circular arc of radius R. It has an arc shape having an R, and both sides thereof are gently inclined from the tip and continue to the arc portion 26b. A gear 43 is fixed to the rotating shaft 42 of the drum support 26, and the gear 43 is meshed with a drive gear 45 fixed to a motor 44. Further, on both sides of the developing devices 7 and 8, disc-shaped tracking rolls 46 and 47 are provided rotatably coaxially with the developing roll 22,
These tracking rolls 46, 47
To come into contact with.

Then, the drum support 26 is rotationally driven by a motor 44 via a drive gear 45 and a gear 43, so that the tracking roll of one of the developing devices comes into contact with the protrusion 26a of the drum support 26, and this developing device is The developing device is moved to a non-operating position separated from the photosensitive drum 4 and the tracking roll of the other developing device abuts against the arc portion 26b of the drum support 26, so that the developing device is moved to the operating position close to the photosensitive drum 4. It is designed to be moved. Even in this case, since the tracking roll of the developing device moves while always in contact with the drum support, it is possible to prevent the developer from spilling when the developing device moves to the operating position. In this reference example, since the drum support 26 only needs to be rotated, the drive mechanism can be further simplified, and further space saving and cost reduction can be achieved. Other configurations and operations are the same as those of the above-described embodiment, and the description thereof will be omitted.

[Effects of the Invention] The present invention has the above-described structure and operation. In addition to saving space, the switching operation of the developing device can be performed smoothly, and the scattering of the developer can be prevented. Can be.

[Brief description of the drawings]

1 and 2 are side views showing different states of an embodiment of the developing device according to the present invention, FIG. 3 is a front view showing a mechanism for switching the developing device, and FIG. FIG. 5 is a plan view showing a photosensitive drum and a developing device, FIG. 6 is a perspective view showing a supporting structure of the developing device, and FIG. 7 is an electronic device to which a developing device according to the present invention can be applied. FIG. 8 is a schematic front view showing a reference example of the present invention, FIG. 9 is a schematic view showing a conventional developing device, FIG.
FIG. 11 is a perspective view of a main part showing a proposal example, FIG. 11 is a perspective view showing a main part of the proposal example, and FIG. 12 is a perspective view of a main part showing another proposal example. [Description of symbols] 7, 8 Developing device 26 Drum support (setting member) 27, 28 Eccentric cam 27b, 28b Projection 50, 51 Plate spring

Claims (1)

(57) [Claims] 1. A developing device comprising a plurality of developing devices, wherein each developing device can be individually moved to an operation position close to an image carrier, and a setting member for setting a gap between each developing device and the image carrier. The setting member is provided with a displacement section for displacing the developing device in a direction of coming and going from the image carrier, and the setting member provided in each of the developing devices is pressed against the member on the image carrier side and pressed. A developing device characterized in that each of the developing devices can be moved in a direction of coming into contact with and separating from the image carrier by rotating a contact setting member.