JPH07117805B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus in which a plurality of developing devices are arranged around an image bearing member such as a photosensitive drum, and particularly to a main body portion having an upper frame and a lower frame. The present invention relates to an image forming apparatus capable of being divided into two.

2. Description of the Related Art Recently, an image forming apparatus such as an electrophotographic copying apparatus is required to have various functions, so that not only the conventional black toner copying but also the red, blue, green and other color toner copying are possible. To be done.

Some of these machines make copies of each color by exchanging the developing device of each color, but recently, an automatic double-sided and multiple copying system has become possible, and toner of different colors has entered the copying machine. Two or more developing devices are provided so that copying of different colors can be performed by a simple button operation on the operation unit, and multicolor copying can be easily performed on one copy sheet.

FIG. 4 shows an example of a two-color electrophotographic copying machine.

That is, the copying apparatus includes a main body 1 including an upper frame 2 and a lower frame 3 which can be opened and closed via a hinge 4.

The main body 1 is provided with an original placing glass 5, and an original 6 placed on the original placing glass 5 is illuminated by a lamp 7 and its optical image is constituted by reflecting mirrors 8 to 13 and a lens 14. The optical system is guided to the photosensitive drum 15. In this case, the lamp 7 and the mirrors 8, 9 and 10 scan along the document 6 at a predetermined speed in the arrow direction. On the other hand, the surface of the photosensitive drum 15 is also uniformly charged by the charger 16 and then rotated in the direction of the arrow, so that an electrostatic image corresponding to the original image is sequentially formed on the surface of the photosensitive drum 15. Around the photosensitive drum 15, a color developing device 17 containing color toner (for example, red, blue, etc.) and a black developing device 18 containing black toner are arranged. These developing devices 17 and 18 are movable in the direction of the arrow and are formed so as to approach the photosensitive drum 15 and visualize the electrostatic image on the photosensitive drum 15 according to a desired color image.

This visualized electrostatic image is transferred to the transfer paper 21 by the transfer charger 19.
After being transferred to, the photosensitive drum 15 is sent to the cleaner 20, the residual toner is removed, and the process proceeds to the next step.

The transfer paper 21 is stacked on the cassette 22 and sent to the roller pair 24 by the paper feed roller 23. When a plurality of rollers 24 are fed with the transfer papers 21 stacked on top of each other, the transfer paper 21
Only separate and register rollers via guide plates 25, 26
Send to 27.

The register roller 27 is provided with the transfer image 21 and the visible image on the photosensitive drum 15.
The transfer paper 21 is fed to the surface of the photosensitive drum 15 at the timing when the two coincide with each other.

When the image of the transfer paper 21 is transferred as described above, it is separated from the surface of the photosensitive drum 15 by the separation charging device 28 and is sent to the fixing device 30 via the conveying unit 29. Then, after being fixed as a permanent image by the fixing device 30, it is sent to the first discharge roller 31 and discharged onto the tray 32.

The problem to be solved by the invention is that, in the copying apparatus having the above-described structure, in order to maintain a good developing state, each developing device is brought into a state of being close to the photosensitive drum at least during the developing operation, and the developing roller of the developing device is The space between the photosensitive drum surface and the photosensitive drum surface was extremely small.

Therefore, unless the photosensitive drum or the developing device is exchanged in a state where they are separated from each other so that they do not contact each other, there is a problem in that both are damaged by the contact.

In order to meet the demand for space saving, that is, for downsizing of the copying apparatus, such a problem is caused in such a manner that one developing device is close to the photosensitive drum while the other developing device is separated from the photosensitive drum. In the copying apparatus, since one of the developing devices is always close to the photosensitive drum, it is inevitable that the photosensitive drum or the photosensitive drum is damaged due to contact when the developing device is replaced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to avoid mutual contact between an image carrier such as a photosensitive drum or a developing device, and replace these members without damage. In particular, it is to provide an image forming apparatus of a two-division system.

Means for Solving the Problems In order to achieve the above object, an image forming apparatus according to the present invention includes an image carrier that carries an electrostatic image, and a first image developing device that develops the electrostatic image on the image carrier. An image forming apparatus having a first developing device and a second developing device and capable of being opened and closed by a first frame and a second frame, the image carrying device being attachable to and detachable from the first frame along a generatrix direction of the image carrying body. A first developing device and a second developing device on the second frame, and the second developing device is separated from the image carrier and the first developing device by opening the first frame and the second frame. .

Embodiment Hereinafter, the present invention will be described with reference to FIGS. 1 to 3 showing an embodiment embodied in an electrophotographic copying apparatus.

In this embodiment, the photosensitive drum 101, which is an image carrier, is attached to the upper frame 2, which is the first frame. The upper frame 2 is provided with a color developing device 102, which is a first developing device accommodating toners of colors such as red and blue, in the vicinity of the photosensitive drum 101, and the lower frame 3, which is the second frame, is exposed to light. A black developing device 103, which is a second developing device accommodating black toner, is attached in the vicinity of the drum 101.

The color developing device 102 is provided with a developing roller 104 composed of a non-magnetic sleeve having a magnet inside, and is detachably attached to the upper frame 2 via a rail 105 along the generatrix direction of the photoconductor drum 101 via the rail 105. It is installed.

The rail 105 has a rotation center shaft 106 at one end and an urging spring 107 attached to the other end, and is configured to move counterclockwise in the drawing by the urging spring 107. In addition, the moving distance of the rail 105 is such that the rail 105 is stopped at approximately the center.
The developing sleeve 104 and the photosensitive drum 10 of the color developing device 102, which are regulated by abutting on the rail 108, and thus are attached to the rail 105.
The distance from 1 is set to a predetermined value.

The black developing device 103 has a developing roller 109 composed of a non-magnetic sleeve having a magnet inside, and has a rotation center shaft 110 in the central portion, and is swingable via the rotation center shaft 110. Is attached to the lower frame 3.

In the black developing device 103, a biasing means 111 is attached to the slope wall portion 103a facing the developing roller 109 and the rotation center shaft 110.
The biasing means 111 comprises a leaf spring 112 and an eccentric cam 113, and when the eccentric cam 113 comes into contact with one end 112a of the leaf spring 112,
The black developing device 103 is biased toward the photosensitive drum 101 side, and the developing roller 10
9 is brought close to the photosensitive drum 101, and black toner is developed (FIG. 2).

If copying with color toner is selected, the eccentric cam
113 is separated from one end 112a of the leaf spring 112 and rotates, and the other end 112b
Abut. At this time, the black developing device 103 rotates counterclockwise as shown in FIG. 3, and its upper portion abuts the color developing device 102, exposing the color developing device 102 against the biasing force of the spring 107. Rotate to the drum 101 side. By this rotation, the color developing device 1
The developing roller 104 of 02 is close to the photosensitive drum 101 and can develop color toner.

According to this embodiment, the cleaner 114 and the charger 115 are integrally formed with the photosensitive drum 101, form an image forming kit, and are attached to the upper frame 2.

In the copying apparatus having the above structure, when the main body 1 is opened, that is, the upper frame 2 is rotated upward with respect to the lower frame 3, the color developing device 102 is released from the biasing force of the biasing means 111. Therefore, the action of the spring 107 causes the photosensitive drum 101
Away from.

Therefore, the photosensitive drum 101 is a cleaner 1 that forms a kit.
14, together with the charger 115, it can be attached to and detached from the upper frame 2 without contacting the color developing device 102, and neither the color developing device 102 nor the photosensitive drum 101 is damaged.

The color developing device 102 can also be attached / detached to / from the upper frame 2 by being inserted / removed along the rail 105 without coming into contact with the photosensitive drum 101.

Further, since the black developing device 103 is attached to the lower frame 3, it is largely separated from the photosensitive drum 101 attached to the upper frame 2. Therefore, the attachment / detachment is easy, and the contact between the photosensitive drum 101 and the color developing device 102 is surely avoided.

In the above description, the device provided with two developing devices has been described, but the present invention is not limited to this.
It is also applicable to an image forming apparatus having a plurality of developing devices.

As described above, according to the present invention, the image carrier is provided in the first frame, the first developing device is detachably provided along the generatrix direction of the image carrier, and the second developing device is provided in the second frame. Since the second developing device is separated from the image carrier and the first developing device by opening the first frame and the second frame, replacement of the image carrier and the developing device becomes extremely easy and damage is caused. Will not occur. Moreover, it is possible to meet the demand for space saving.

Further, with the above configuration, it is possible to provide a small-sized image forming apparatus which simplifies handling and improves durability and operability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment in which an image forming apparatus according to the present invention is embodied in an electrophotographic copying apparatus, showing a state in which a main body is opened. FIG. 2 is a cross-sectional view showing the development of the apparatus of FIG. 1 with black toner. FIG. 3 is a cross-sectional view showing developing with color toner in the apparatus of FIG. FIG. 4 is a sectional view of a conventional electrophotographic copying apparatus. 1: Main body part 2: Upper frame 3: Lower frame 101: Photosensitive drum (image carrier) 102: Color developing device 103: Black developing device

Claims (1)

[Claims] 1. An image carrier for carrying an electrostatic image, and first and second developing devices for developing the electrostatic image on the image carrier, the first frame and the second frame being opened and closed. A possible image forming apparatus, wherein an image carrier is provided in the first frame, a first developing device is detachably attached along a generatrix direction of the image carrier, and a second developing device is provided in the second frame. An image forming apparatus, wherein the second developing device is separated from the image carrier and the first developing device by opening the first frame and the second frame.