JPH01120591A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To stably feed paper to a photosensitive drum and to eliminate the need for taking the timing for exchange of a transfer guide into special consideration by mounting the transfer guide to a drum cartridge which holds the photosensitive drum. CONSTITUTION:The transfer guide 15b is mounted to the drum cartridge 11. The guide 15b is in contact with a side plate 16 to form gap (g) between the guide and the photosensitive drum 12. The guide 15b is mounted to the cartridge 11 in such a manner and since the guide 15b is integrated to the cartridge 11, the gap (g) can be surely maintained constant in the axial direction of the drum 12 if both ends of the guide 15b are brought into contact with the side plate 16. The paper 31 is thus stably fed to the drum 12. The guide 15b can be exchanged if the guide is exchanged together with the cartridge 1 of the drum 12 and, therefore, the need for taking the timing for exchange of the guide 15b into special consideration is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to electrophotographic devices such as laser beam printers and copying machines.

[Conventional technology]

FIG. 2 is a schematic diagram showing a conventional laser beam printer, and FIG. 3 is a diagram showing a part of the laser beam printer shown in FIG. In the figure, 1 is a main body, 2 is an upper main body, and 3 is a lower main body, and the main body 1 is composed of the upper main body 2 and the lower main body 3. 5 is a drum shaft attached to the upper body 2, 1
1 is a drum cartridge attached to the drum shaft 5, 16 is a side plate of the drum cartridge 11, and 12 is a photosensitive drum held in the drum cartridge 11. By removing the drum shaft 5 from the upper body 2, the drum cartridge 11 and the photosensitive drum are removed. The drum 12 can be removed from the upper body 2. 25 is a laser exposure unit provided on the upper body 2; 21 is a charger provided on the upper body 2; 24;
3 is an erase lamp provided on the upper body 2; 22 is a developer provided on the upper body 2; 35 is a registration roller provided on the upper body 2; 36 is a fixing device provided on the upper body 2;
2 is a paper cassette provided in the lower body 3; 31 is paper stored in the paper cassette 32; 33 is a paper feed roller provided in the lower body 3; 34 is a registration roller provided in the lower body 3; 15a is a paper cassette provided in the lower body 3; A transfer guide 15a is provided on the upstream side of the photosensitive drum 12 in the paper feeding direction.The transfer guide 15a is attached to the lower body 3, and the transfer guide 15a is attached to the side plate 16.
A gap g is formed between the photosensitive drum 12 and the photosensitive drum 12 . Then, when the humidity is high or when the paper 31 that has absorbed moisture is used, the transferred charge is transferred to the paper 31.
In order to prevent printing defects from occurring due to escaping through the transfer guide 15a, the surface of the transfer guide 15a is coated with an insulating coating. 14 is a cleaning blade provided on the downstream side of the photosensitive drum 12 in the paper feeding direction, and 13 is a conveyance coil provided on the downstream side of the photosensitive drum 12 in the paper feeding direction.

In this laser beam printer, when a motor (not shown) is rotated, the photosensitive drum 12, the fixing device 36, the developing device 22, etc. start rotating, and the charger 21 uniformly charges the surface of the photosensitive drum 12. The laser exposure unit 25 forms an electrostatic latent image on the surface of the photosensitive drum 12, and the developing device 22 forms a toner image according to the electrostatic latent image. Further, one sheet of paper 31 stored in the paper cassette 32 is fed by a paper feed roller 33 and sent to registration rollers 34 and 35. Then, the registration rollers 34 and 35 start rotating in synchronization with the exposure by the laser exposure unit 25, and when the registration rollers 34 and 35 feed out the paper 31,
The paper 31 is guided to the transfer guide 15a, and the photosensitive drum 12
, the transfer device 23 applies a transfer charge to the paper 31,
The toner image on the surface of the photosensitive drum 12 is transferred to the paper 31. Thereafter, the paper 31 reaches a fixing device 36, where the toner image is heated and fixed, and is discharged to a paper discharge tray.

On the other hand, the toner remaining on the surface of the photosensitive drum 12 without being transferred is scraped off by the cleaning blade 14, and the electrostatic latent image on the surface of the photosensitive drum 12 is removed by the erase lamp 24.

[Problem that the invention seeks to solve]

However, in such laser beam printers,
If the transfer guide 15a is attached to the lower body 3 at an angle with respect to the surface of the photosensitive drum 12, the transfer guide 15a
One end is in contact with the side plate 16, but the transfer guide 15a
The other end is not in contact with the side plate 16, and the gap g
is not constant in the axial direction of the photosensitive drum 12, and in this case, the paper 31 cannot be stably fed to the photosensitive drum 12. Furthermore, the insulating coating applied to the surface of the transfer guide 15a peels off due to friction with the paper 31, so it is necessary to replace the transfer guide 15a periodically, but it is necessary to take special consideration when replacing the transfer guide 15a. This is troublesome, and there are cases where the user forgets to replace the transfer guide 15a, and in this case, printing defects may occur.

This invention was made to solve the above-mentioned problems, and it is possible to reliably keep the gap between the surface of the photosensitive drum and the transfer guide constant in the axial direction of the photosensitive drum, and to replace the transfer guide. An object of the present invention is to provide an electrophotographic device that does not require special consideration of timing.

[Means for Solving the Problems] In order to achieve this object, the present invention includes a drum cartridge removably attached to the main body, a photosensitive drum held in the drum cartridge, and a drum cartridge attached to the drum cartridge. In an electrophotographic apparatus including a transfer guide provided in contact with a side plate and having a gap between the transfer guide and the photosensitive drum, the transfer guide is attached to the drum cartridge.

[Effect]

In this electrophotographic apparatus, the transfer guide is integrated with the drum cartridge, and if the photosensitive drum is replaced with the drum cartridge, the transfer guide can also be replaced.

[Embodiment] FIG. 1 is a diagram showing a part of a laser beam printer according to the present invention. In this laser beam printer,
A transfer guide 15b is attached to the drum cartridge 11, and the transfer guide 15b is in contact with the side plate 16, so that a gap g is formed between the transfer guide 15b and the photosensitive drum 12.

As described above, in this laser beam printer, the transfer guide 15b is attached to the drum cartridge 11, and the transfer guide 15b is attached to the drum cartridge 11.
Since both ends of the transfer guide 15b are brought into contact with the side plate 16, the gap g can be reliably closed to the photosensitive drum 1.
2 can be kept constant in the axial direction, and the paper 31 can be stably fed to the photosensitive drum 12. Furthermore, the lifespan of the photosensitive drum 12 is shorter than that of the entire laser beam printer, and the photosensitive drum 12 needs to be replaced periodically, for example, when 30,000 sheets have been printed. Transfer guide 1
Since the transfer guide 5b can also be replaced, the transfer guide 15b
There is no need to take special consideration when replacing the transfer guide 15b, so it is not troublesome, and furthermore, there is no need to forget to replace the transfer guide 15b, and printing defects can be reliably prevented.
Also, the lifespan of the insulating coating on the transfer guide 15b is longer than that on the photosensitive drum 1.
The life of the transfer guide 15b is slightly longer than that of the transfer guide 15b.
It is economical to apply an insulating paint with low abrasion resistance to the surface.

In the above embodiments, the case of a laser beam printer has been described, but it is obvious that the present invention can be applied to other electrophotographic apparatuses such as copying machines.

〔Effect of the invention〕

As explained above, in the electrophotographic apparatus according to the present invention, since the transfer guide is integrated with the drum cartridge, when both ends of the transfer guide are brought into contact with the side plates, there is a gap between the surface of the photosensitive drum and the transfer guide. Since the gap can be reliably kept constant in the axial direction of the photosensitive drum, the paper can be stably fed to the photosensitive drum. In addition, if you replace the photosensitive drum with the drum cartridge, you can also replace the transfer guide, so there is no need to take special consideration when replacing the transfer guide, so it is not a hassle, and there is no need to forget about replacing the transfer guide. Therefore, it is possible to reliably prevent printing defects from occurring. As described above, the effects of this invention are remarkable.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a part of a laser beam printer according to the present invention, FIG. 2 is a schematic diagram showing a conventional laser beam printer, and FIG. 3 is a diagram showing a part of the laser beam printer shown in FIG. It's a diagram. 1...Main body, 11...Drum cartridge, 12.
...Photosensitive drum, 15b...Transfer guide, 16...
side plate.゛ゝ--/ Next 2-Figure

Claims (1)

[Claims] 1. A drum cartridge detachably attached to a main body, a photosensitive drum held by the drum cartridge, and a transfer guide provided in contact with a side plate of the drum cartridge and having a gap between the photosensitive drum and the drum cartridge. An electrophotographic apparatus comprising: the transfer guide attached to the drum cartridge.