JPS6180179A - Image forming device - Google Patents

Abstract

PURPOSE:To remove the developer sticking to parts except an image forming region and to prevent the deterioration in functions owing to sticking of the developer by disposing blades to the parts outer than the width of transfer paper at both ends in the axial direction of an image carrying body in the position just before the transfer of a visible image. CONSTITUTION:A pair of the blades 40 for scraping away the developer sticking to the parts except the image region at both ends of a photosensitive drum 1 are provided. The blades 40 and the drum 1 are positioned in such a relation that the blades contact under pressure with the surface of the drum 1 in the parts outer than the width of the paper so as not to destruct the visible image formed on the drum 1 by the blades 40. As a result, the unnecessary developer sticking to the outside peripheral surface of the drum is scraped off, the deterioration in the functions of various devices owing to the staining as a result of the sticking of the developer to paper and the jumping in of the scattering developer is prevented. The sticking of the unnecessary developer to the drum 1 itself is obviated and the deterioration of the drum is prevented.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an image forming apparatus, and particularly to an image forming apparatus that can prevent developer from adhering to areas other than the image forming area of an image bearing member. It is related to.

[Prior art]

Generally, a developing device provided in an image forming apparatus such as an electrophotographic copying machine is configured as shown in FIG.

That is, the developing device 2 is a photosensitive drum 1 which is an image carrier.
It has a casing 4 that forms a developer storage section 3 in the lower part of which is disposed near the developer storage section 3. A stirring member 5 is provided.

Above the stirring member 5 and closer to the photoreceptor drum 1, a developing sleeve 6 made of a non-magnetic material such as aluminum and rotating in the direction of the arrow is connected to the circumferential surface of the developing sleeve 6 and the photoreceptor drum 1. A magnetic body 7 having a plurality of N and S magnetic poles alternately arranged on the surface in the circumferential direction is arranged inside the developing sleeve 6 so as to be rotatable in the direction of the arrow. It is set up.

The N-3 magnetic pole of the magnetic body 7 is usually 500 to 15
It is magnetized to a magnetic flux density of 0.00 Gauss.

A regulating blade 8 is provided on the front side of the developing sleeve 6 in the rotational direction with respect to the photoreceptor drum 1, and is spaced apart from the outer peripheral surface of the developing sleeve 6 by a predetermined distance. The predetermined interval can be changed depending on the type of developer (two-component developer).

Furthermore, a scraper 9 that is in contact with the outer circumferential surface of the developing sleeve 6 is disposed further forward in the rotational direction of the developing sleeve 6 than the developing area A.

A hopper 1 for toner particles T is provided in the upper part of the casing 4.
0, and a supply roller 11 having a concave portion on its surface for dropping toner particles T into the developer reservoir 3 is provided at the lower opening of the impeller 10.

Note that 12 is connected to the developing sleeve 6 via a protective resistor 13.
It is a bias power supply that applies bias voltage to DC, AC, or a combination of DC and AC.

In the developing device 2 configured as described above, so-called spikes of developer are formed on the surface by the magnets in the developing sleeve 6, and these spikes are formed when the photosensitive drum 1 is supplied. The electrostatic latent image is developed on the surface of the photosensitive drum 1, and as shown in FIG. 4, the developers 3a and 3b at both ends of the developing sleeve 6 are Because it is not vertically magnetized,
The developer is not sufficiently attached compared to the central portion which is vertically properly magnetized.

The developers 3a and 3b at both ends (portions that do not affect the electrostatic latent image corresponding to the image) do not contribute in any way to the formation of a visible image in the image forming area of the photoreceptor drum 1. Due to the weak magnetic force of the magnet, it adheres to areas outside the visible image area during development, staining the transfer paper (paper) and other materials, and scattering particles may fly into various devices and cause functional deterioration. Moreover, if the adhered developer continues to adhere to the photoreceptor drum 1, it has a disadvantage that the photoreceptor drum 1 is adversely affected.

[Purpose of invention]

This invention eliminates the drawbacks of the conventional methods as described above, and removes the developer that adheres to areas other than the image forming area of the photoreceptor drum, thereby preventing unnecessary developer from scattering onto members such as the transfer pole. to prevent these other parts from becoming dirty or deteriorating, and further,
An object of the present invention is to provide an image forming apparatus that can also prevent deterioration of a photoreceptor drum caused by unnecessary developer adhering to the photoreceptor drum.

[Structure of the invention]

The present invention provides an image forming apparatus that includes at least an image carrier and a developing device that supplies developer to the image carrier to form a visible image. At a position in front of the image bearing member, it contacts a portion at both ends of the image carrier in the axial direction and is outside the width of the transfer paper, and removes the developer supplied from the developing device to that portion. It has a configuration in which a blade is arranged.

[Embodiments of the invention]

Embodiments of the invention shown in the drawings will be described below.

FIG. 1 shows a schematic layout of an electrophotographic copying apparatus as an image forming apparatus, in which an original glass stand 21 is placed on the upper surface of the main body 2o, and the upper surface of the original glass stand 21 is placed on the upper surface of the main body 2o. A platen cover 22 is provided which can be opened and covered.

An exposure lamp 23 is provided inside the upper part of the main body 20 to irradiate light onto the lower surface of the original glass table 21, and the reflected light from the original irradiated by the exposure lamp 23 is transmitted to the exposure section 25 via a group of reflectors 24. A lens group 26 that is movable in the horizontal direction (in the direction of the arrow) is provided, and a drum-shaped photoreceptor drum 1 serving as an image carrier is rotatably provided in the center. A charging device 27 is provided near the top of the photosensitive drum 1 to face it, and in front of the charging device 27 in the rotational direction of the photosensitive drum 1 are an exposing section 25, a developing device 2, a transfer device 28, and a separating device. Device 2
9, a static eliminator 30 and a cleaning device 31 are disposed close to and facing the photoreceptor drum 1, respectively.

A cassette case 32 is provided in an example of the lower part of the interior of the main body 20.
is removably provided, and the cassette case 32
A paper feed roller 33 is provided which comes into contact with the top surface of the uppermost sheet of the stack of paper sheets when the paper is inserted into the paper stack, and between the vicinity of the paper feed roller 33 and the vicinity of the transfer device 28. A paper feed path 34 is provided for conveying the paper in the cassette case 32 to the transfer device 28.

A portion of the guide plate constituting the paper feed path 34 is cut out, and a pair of upper and lower registration rollers 35 are disposed in this cutout portion.

A fixing device 36 is provided on the other side of the inner lower part of the main body 20, and a paper conveyance path 37 is provided between the fixing device 36 and a separating device 29 provided near the photosensitive drum 1. Also, the conveyance path 37 of the fixing device 36
A paper discharge section 38 is provided on the opposite side, and a paper discharge tray 39 is provided outside thereof.

When the copy start key on the operation unit of the electrophotographic copying apparatus configured as described above is turned on, the copying operation is started.
As the photoreceptor drum l starts rotating, the charging device 2
7 is also activated, and the outer circumferential surface of the photosensitive drum 1 is charged.

Meanwhile, along with this, the paper feed roller 33 also starts rotating.
The uppermost sheet of the sheets in the cassette case 32 is conveyed through the sheet feed path 34, and this sheet is transferred to the registration roller 3.
When it reaches 5, it is detected by a detection member (not shown) such as a microswitch and stops at that position.

Further, at the same time that the paper reaches the registration rollers 35, the exposure lamp 23 turns on and illuminates the lower surface of the original glass table 21, and the exposure optical system starts moving, forming an electrostatic latent image corresponding to the original image. It is formed on the circumferential surface of the photoreceptor drum 1.

Thereafter, as the photoreceptor drum 1 rotates, the electrostatic latent image is developed by the developing device 21 to become a toner image, which is positioned opposite to the transfer device 28 .

On the other hand, the paper is conveyed through the paper feed path 34 by the activation of the registration roller 35 to a position facing the transfer device 28, so that the toner image on the outer peripheral surface of the photoreceptor drum 1 is transferred to the paper by the transfer device 28. After being separated by the separating device 29, it is transferred to the fixing device 36 via the conveyance path 37! The paper is generally fed, fixed here, and discharged onto the paper discharge tray 39.

Further, the photosensitive drum 1 is cleaned by the static eliminator 30 and the cleaning device 31, one process is completed, and the photosensitive drum 1 and the charging device 27 stop operating.

Then, the above operation is performed for a set number of sheets.

Developing device 2 of an electrophotographic copying machine configured as described above
A cross-sectional view of the main parts of the developing device 2 is shown in FIG. start rotating in the direction of the arrow.

As a result, a portion of the developer in the developer reservoir 3 starts to move upward due to the magnetic force of the magnet 7, and when it reaches the regulating blade 8, which is a regulating member, the amount passing therethrough is regulated. As described above, since it is magnetized by the magnet 7, its magnetic force forms developer brushes of a predetermined height and amount on the surface of the developing sleeve 6, that is, magnetic brushes.

Then, as the developing sleeve 6 rotates, the magnetic brush reaches the developing area A with the photosensitive drum 1, and development is performed with or without contact.

The magnetic brush after development that has passed through the development area A rotates together with the development sleeve 6 and reaches the scraper 9, where it is scraped off from the development sleeve 6 and falls into the developer storage section 3. In this way, the development is performed one by one. Development is performed in area A, and the developer after development falls into the developer reservoir 3 by the scraper 9 and is stirred by the stirring member 5 within the developer reservoir 3, so that the developer supplied to the development area A is The components of the agent are always uniform, and therefore high development performance can always be maintained.

The N-3 poles of the magnetic body 7 are sequentially opposed to the surface portion of the photoreceptor drum l corresponding to the paper width, and are evenly distributed over the surface portion of the photoreceptor drum l corresponding to the paper width. The magnetic force is distributed uniformly, thereby making it possible to form uniform spikes of developer.

However, as in the conventional device shown in FIG. 4, the developers 3a and 3b at both ends of the developer tray are absorbed in a state where the spikes become lower in sequence, and the developers 3a and 3b in these parts are absorbed during development. However, the first problem is that it scatters or adheres to the photoreceptor drum 1, staining the paper, the transfer device 28 or the separation device 29, and deteriorating the functions of each device. As shown in detail in FIGS. 2 and 3, when the developer adheres to both ends of the photoreceptor drum 1 (portions other than the image area), the device according to the present invention shown in the figure A pair of blades 40 are provided for scraping.

The positional relationship between the blade 40 and the photoreceptor drum 1 is such that the blade 40 is positioned outside the paper width so as not to destroy the visible image formed on the photoreceptor drum 1 as shown in FIG. The photoreceptor drum 1 is brought into pressure contact with the surface of the photoreceptor drum 1.

Furthermore, in order to reuse the scraped developer, the blade 40 shown in this embodiment is provided on the inner wall of the casing 4 of the developing device, but the blade 40 does not need to be provided on the casing 4 to face the photoreceptor drum. Of course, it may also be installed in another location where it will not be moved.

The material of the blade 40 is urethane rubber, and since the blade 40 itself has a certain degree of strength, there is no need to use any special attachment members when attaching it to the casing 4. Even if the visible image 1 is abraded due to rotation, the abrasion powder will not become dirt.

〔Effect of the invention〕

By configuring the present invention as described above, unnecessary developer adhering to the outer peripheral surface of the image carrier is scraped off, thereby preventing the developer from adhering to the paper and causing stains, or There is no possibility that scattered objects will fly into various devices such as transfer devices and cause functional deterioration in them.
Furthermore, some of them have excellent effects such as preventing unnecessary developer from adhering to the photoreceptor drum itself and thus having no adverse effect on the photoreceptor drum.

[Brief explanation of the drawing]

FIG. 1 is a schematic layout diagram showing an image forming apparatus according to the present invention, FIGS. 2 and 3 are schematic layout diagrams showing the relationship among the photosensitive drum, developing sleeve, magnet body, etc., and FIGS. 4 and 5 are FIG. 2 is a schematic diagram showing the relationship among a conventional photosensitive drum, a developing sleeve, a magnet, and the like. A...Development area D-, 3a, 3b...Developer 1...
Photosensitive drum 2...Developing device 3...Developer storage section 4...Casing 5...Agitation member 6...Development sleeve 7 ...Magnet 8 ...Regulation blade 9 ...Scraper 10 ...Hopper 11 ...Supply roller 12 ...Bias Power supply 13... Protective resistor 20... Body 21... Original glass stand 22... Platen cover 23... Exposure lamp 24... ... Reflector group 25 ... Exposure blade 26 ... Lens group 27 ... Charging device 28 ... Transfer device 29 ... Separation Device 30... Static eliminator 31... Cleaning device 32... Cassette case 33... Paper feed roller 34... Paper feed path 35. ...Registration roller 36...Fixing device 37...Transport path 38...Paper output unit 39...Paper output tray 40... ...Blade Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] In an image forming apparatus including at least an image bearing member and a developing device that supplies developer to the image bearing member to form a visible image, a position in front of a position where the visible image is transferred to transfer paper is , a blade is disposed at both ends of the image carrier in the axial direction and in contact with a portion outside the width of the transfer paper to remove the developer supplied from the developing device. An image forming apparatus characterized by: