JP2001282005A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize the internal space of an intermediate transfer drum. SOLUTION: In an image forming device of a type where a toner image is transferred to an intermediate transfer medium after an electrostatic latent image is formed on an image carrier and developed to be the toner image by a developing device, the intermediate transfer medium is a transfer drum 7 having an opening part 20 on its one side surface, and the outer periphery of the drum 7 is supported by at least three turning rollers 21 on one side of the drum 7, and is supported by a center shaft 19 on the other side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate transfer drum in an image forming apparatus using an electrophotographic method, such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art In the above-mentioned image forming apparatus, an electrostatic latent image is formed on an image carrier such as a photoreceptor, and the electrostatic latent image is developed into a toner image by a developing device. Then, the toner image is transferred onto an intermediate transfer medium, and the toner image transferred onto the intermediate transfer medium is transferred onto a transfer material and then fixed.

The types of the intermediate transfer media are classified into two types, a drum and a belt. In the case of the drum, the rotational inertia (inertia) is large, and the resist (color superposition) performance is insensitive to load fluctuations, but the shape is limited to a cylinder, but the layout flexibility is low. In the case of a belt, as opposed to a drum, there is almost no inertial component, so it reacts sensitively to load fluctuations and causes speed fluctuations, so it is practically necessary to add a flywheel mass. On the other hand, the shape as viewed from the front can be set freely, and a space-saving layout is possible.

An object of the present invention is to realize space saving which is a drawback of the system using the intermediate transfer drum. Letter size (8.5 x 11 inches) on intermediate transfer drum
When two images are formed, the drum diameter D is determined as follows: D = (2 × 25.4 × 8.5 + 2 × V × T) / π under the conditions of the process speed V and the sheet interval time T. For example, V = 200 (mm / sec), T = 0.3
In the system of (sec), D = 176 (mm),
The space occupies a very large weight in the entire system. However, what is essentially needed as an intermediate transfer medium is the drum surface layer, and the inside of the drum is substantially dead space.

An object of the present invention is to solve the above-mentioned conventional problems and problems, and to provide an image forming apparatus which can effectively use an internal space of an intermediate transfer drum and save space even when an intermediate transfer drum is used. With the goal.

[0006]

To achieve the above object, an image forming apparatus according to the present invention forms an electrostatic latent image on an image carrier, and converts the electrostatic latent image into a toner image by a developing device. In the image forming apparatus of the type in which a toner image is transferred onto an intermediate transfer medium after development, the intermediate transfer medium is a transfer drum having an opening on one side, and one side of the transfer drum is a transfer drum. Is supported by at least three rotating rollers, and the other side is supported by a central shaft.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram showing an embodiment of the image forming apparatus of the present invention. Although this image forming apparatus is a color electrophotographic printer capable of forming a full-color image with four color toners, the present invention is not limited to this. Applicable to the device.

A photosensitive member 3 is provided in a case body 2 of the image forming apparatus 1. The photoreceptor 3 has a drum-shaped conductive substrate and a photosensitive layer formed on the surface thereof, and is driven to rotate in a direction indicated by an arrow by a driving unit (not shown).
Around the photosensitive member 3, a charging device 4 for uniformly charging the photosensitive member 3 along its rotation direction, an exposure device 5 for forming an electrostatic latent image on the photosensitive member 3, A rotary developing device 6 for developing an electrostatic latent image, an intermediate transfer drum 7 for transferring a single-color toner image formed on the photoconductor 1 and a photoconductor cleaner 8 are provided.
, A secondary transfer roller 9 for transferring the four-color full-color image formed on the intermediate transfer drum 7 onto a recording medium (paper or the like), and fixing the toner image transferred onto the recording medium. A fixing device 10 and a transfer drum cleaner 11 are provided. Reference numeral 12 denotes a paper feed tray for storing a recording medium, and reference numeral 13 denotes a recording medium transport path.

The rotary developing device 6 includes a developing device 6 for yellow.
A developing unit 6C for Y, cyan, a developing unit 6M for magenta, and a developing unit 6K for black are configured to be rotatable, and these developing units 6Y, 6C, 6M, 6K
Only the developing roller of one developing unit can be selectively brought into contact with the photoreceptor 3 for each rotation. A toner cartridge 14 containing the respective toner is connected to each developing unit so as to supply the toner.

The operation of the image forming apparatus having the above configuration will be described. When an image forming signal is input from a computer (not shown), the photosensitive member 3, the developing roller of the developing device 6, and the intermediate transfer drum 7 are driven to rotate, and first, the outer peripheral surface of the photosensitive member 3 is uniformly charged by the charging device 4. The outer peripheral surface of the charged and uniformly charged photoconductor 3 is selectively exposed by the exposure device 5 in accordance with the image information of the first color (for example, yellow) to form a yellow electrostatic latent image. You.

The developing unit 6Y for yellow rotates and the developing roller comes into contact with the photoconductor 3, whereby a toner image of a yellow electrostatic latent image is formed on the photoconductor 3. The toner image formed on the photoconductor 3 is transferred onto the intermediate transfer drum 7. At this time, the secondary transfer roller 9 is separated from the intermediate transfer drum 7. After the toner remaining on the photoreceptor 3 is removed by the photoreceptor cleaner 8, the surface of the photoreceptor 3 is discharged by the discharging means 8A.

The above processing is repeated for the second, third, and fourth colors of the image forming signal, and the latent image formation, development, and transfer by one rotation of the photosensitive member 3 and the intermediate transfer drum 7 are repeated. Four color toner images corresponding to the contents of the image forming signals are superposed and transferred on the intermediate transfer drum 7. Then, at the timing when this full-color image reaches the secondary transfer roller 9, a recording medium (transfer paper) is supplied from the transport path 13 to the secondary transfer roller 9, and at this time, the secondary transfer roller 9 is transferred to the intermediate transfer drum 7. While being pressed, the secondary transfer voltage is applied, and the full-color toner image on the intermediate transfer drum 7 is transferred onto the recording medium. The toner image transferred onto the recording medium is heated and pressed by the fixing device 10 and fixed. The toner remaining on the intermediate transfer drum 7 is removed by the transfer drum cleaner 11.

Next, the features of the present invention will be described with reference to FIGS. 2A is an exploded perspective view around the intermediate transfer drum 7 in FIG. 1, and FIG. 2B is an assembled perspective view.

In FIG. 1, each component disposed in the case body 2 is detachable from the front side (the front side in FIG. 1). As shown in FIG. 2, the intermediate transfer drum 7 is rotatably mounted between the front frame 15 and the rear frame 16. A fixed shaft 17 protrudes from the rear frame 16, and a bearing 19 is attached to the fixed shaft 17. An opening 20 is formed in the front frame 15, and three rotating rollers 21 are provided around the opening 20. The intermediate transfer drum 7 is inserted through the opening 20 of the front frame 15, and the rear side of the intermediate transfer drum 7 is fitted and supported by a bearing 19 (center shaft).
The outer peripheral surface of the front side of the intermediate transfer drum 7 is supported by at least three rotating rollers 21.

An opening 20 is formed on the front side of the intermediate transfer drum 7, and the opening 20 is formed through the opening 20.
The waste toner tank 22 is inserted into the inside. A fitting recess 23 is formed on the rear side of the waste toner tank 22 so as to fit with the fixed shaft 17. A handle 24 is attached to the outer peripheral surface on the front side, and the handle 24 is provided with an engagement protrusion 25. I have. On the rear side of the waste toner tank 22, the fitting recess 23 is fitted to the fixed shaft 17, and on the front side, the engaging projection 25 is engaged with the engaging hole 26 of the front frame 15, whereby the waste toner tank 22 is The intermediate transfer drum 7 is fixed between the front frame 15 and the rear frame 16 and rotates around the waste toner tank 22.

The waste toner in the transfer drum cleaner 11 is
The toner is conveyed into the photoconductor cleaner 8 by the waste toner pipe 27 (FIG. 1). A drive gear 2 is provided below the photoreceptor cleaner 8.
9, a toner transport mechanism 32 including a toner transport auger 30 and a waste toner pipe 31 is mounted, and the waste toner pipe 31 is connected to a toner discharge pipe 33 inside the waste toner tank 22. The toner discharge pipe 33 is fixed to an inner wall of the waste toner tank 22 by a fitting 34.

The capacity of the waste toner tank 22 has a sufficient margin with respect to the preset number of replacements of the intermediate transfer drum 7.
It is set so that it is only necessary to discard. Needless to say, a full detection sensor may be provided in the waste toner tank 22 to notify that the waste toner tank 22 is to be discarded by itself.

According to the present embodiment, the rear side of the intermediate transfer drum 7 is fitted and supported by the bearing 19, and the outer peripheral surface of the front side of the intermediate transfer drum 7 is supported by three rotating rollers 21. With this configuration, a large-capacity waste toner tank 22 can be accommodated in the intermediate transfer drum 7 from the front side thereof, and the space can be saved by that much. Further, when the waste toner is directly stored in the intermediate transfer drum 7, the drum speed fluctuates due to toner resistance, bias, and the like in the drum. However, according to the present embodiment, the waste toner tank 22 Can prevent this because of the fixed state. Further, when the waste toner is directly stored in the intermediate transfer drum 7, if the toner becomes full before the drum is replaced, it is necessary to replace even a usable drum. According to the embodiment, only the waste toner tank 22 can be replaced.

FIG. 3 is an exploded perspective view showing another embodiment of the present invention. Note that the same components as those of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

This embodiment is an example in which a control device 37 is provided on the intermediate transfer drum 7 instead of the waste toner tank. That is, a printed circuit board 3 such as a power supply circuit board and a control circuit board
6 is attached to a support plate 35, and a handle 24 having an engagement projection 25 is
6 is stored in the intermediate transfer drum 7.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made. For example, in the above-described embodiment, the waste toner tank 22 or the control device 37 is housed in the intermediate transfer drum 7, but the toner cartridge 14 for development shown in FIG. 1 may be housed.

[0022]

As is apparent from the above description, according to the present invention, since the structure which allows the internal space of the intermediate transfer drum to be used effectively, the space can be saved even when the intermediate transfer drum is used. Can be. Further, when the waste toner tank is stored in this space, the operation of replacing the waste toner tank can be reduced, and the operability can be improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing one embodiment of an image forming apparatus of the present invention.

FIG. 2A is an exploded perspective view around an intermediate transfer drum of FIG. 1, and FIG. 2B is an assembled perspective view of the same.

FIG. 3 is an exploded perspective view showing another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 3 photoconductor 6 developing device 7 intermediate transfer drum 19 central shaft (bearing) 20 opening 21 rotating roller 22 waste toner tank 37 control device

Claims (3)

[Claims] An image forming apparatus that forms an electrostatic latent image on an image carrier, develops the electrostatic latent image into a toner image by a developing device, and then transfers the toner image onto an intermediate transfer medium. The intermediate transfer medium is a transfer drum having an opening on one side, one side of the transfer drum supporting the outer periphery of the transfer drum with at least three rotating rollers, and the other side having a central shaft. An image forming apparatus, wherein the image forming apparatus is supported by: 2. An image forming apparatus according to claim 1, wherein a waste toner tank is fixedly provided in said transfer drum. 3. The image forming apparatus according to claim 1, wherein a control device is provided in the transfer drum in a fixed state.