JPH04198966A - Image forming device - Google Patents

Abstract

PURPOSE:To form a satisfactory toner image and to prevent the scattering of toner by separating a development part from a developer stirring part and connecting them by the use of a developer circulating means. CONSTITUTION:The developer stirring part 34 is arranged in the space of the side of an upper paper feeding tray 31, and the development part 13 in an image formation part and the stirring part 34 are connected with each other by a developer circulating device 35. Therefore, a sufficient amount of carrier can be used in order to sufficiently electrify used toner and the carrier and the toner can be supplied for the development after being mixed and stirred sufficiently. Thus, a satisfactory toner image can be formed, and the scattering of toner can also be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic image forming apparatus such as a copying machine or a printer.

[Conventional technology]

In general, an electrophotographic image forming apparatus uniformly charges the surface of an electrostatic latent image carrier such as a photoreceptor drum, and forms an electrostatic latent image by exposing image information to the charged area from an optical system. death,
The latent image is developed into a visible image by a developing device, and the visible image is transferred to a transferred transfer material and fixed.

As developing devices for developing the electrostatic latent image, there are known developing devices that use a one-component developer made of toner, and ones that use a two-component developer that includes toner and carrier.

In a developing device that uses a two-component developer, before the toner is subjected to development, the toner and carrier are mixed in a developer stirring section to triboelectrically charge the toner, and the toner is transferred together with the carrier onto the developing roll of the developing section. The material is supplied and conveyed to the development area by rotation of the roll.

If there is a toner charging defect, not only the development cannot be performed satisfactorily, but also the improperly charging toner scatters from the developing device to the surroundings, causing problems such as contaminating the inside of the image forming device and contaminating the transfer material.

[Problem to be solved by the invention]

Today, as image forming apparatuses become faster, toner consumption is increasing.However, contrary to this increase in toner consumption, as image forming apparatuses today are required to be smaller and more compact, developing Devices themselves tend to become smaller and more compact, and as a result, the amount of carrier that can be used in one developing device is naturally limited.As a result, toner cannot be sufficiently charged, resulting in the toner scattering. This is one of the causes of such problems.

Therefore, the present invention makes it possible to use a sufficient amount of carrier to sufficiently charge the toner used, and to mix the carrier and toner sufficiently so that a good toner image can be formed and toner scattering can be prevented. An object of the present invention is to provide an image forming apparatus that can perform development after stirring.

[Means to solve the problem]

In accordance with the above object, the present inventor provides an image forming apparatus characterized in that a developing section and a developer stirring section in a developing device are separated, and the developing section and the developer stirring section are connected by a developer circulation means. It is something.

[Function] According to the image forming apparatus of the present invention, the toner and carrier are sufficiently mixed and stirred in the developer stirring section, and the thus mixed and stirred developer is supplied to the developing section by the developer circulation means, where the electrostatic charge is removed. The developer used to develop the latent image is circulated so that the remaining developer is returned to the developer stirring section by the developer circulation means.

Toner is supplied to the developer stirring section.

〔Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of a copying machine that is an embodiment of the present invention, and FIG. 2 shows a developing section, a developer stirring section, and a developer connecting the copying machine when viewed from the rear side. The layout of the circulation device is shown.

This copying machine is comprised of an image forming section 1 in an upper stage and a paper feeding section 3 provided below.

The image forming section 1 includes a photoreceptor drum 11 in the center, and a charger 12 and an inter-image eraser 1 around the photoreceptor drum 11.
7a, a developing section 13, a transfer charger 14, a separation charger 15, a cleaner 16, and an eraser 17 are arranged in this order.

An optical system I8 is provided above the photosensitive drum 11.
Furthermore, a document placement glass 18a is provided above it.

On the upstream side of the transfer charger 14 (on the left side in FIG. 1), a manual paper feed tray 19, a manual paper feed roller 20, a paper separation roller 21, and a timing roller 22 are sequentially provided.

On the downstream side (right side in FIG. 1) of the separation charger 15, a transfer paper conveying belt 23, a fixing roller 24, a paper discharge roller 25, and a paper discharge tray 26 are provided in this order.

The paper feed section 3 includes paper feed trays 31 and 32 arranged in upper and lower stages.

Each paper feed tray can be moved in and out of the paper feed section 3 from the front side of the paper feed section 3 by means of a guide device (not shown).

The paper feed tray 31 is provided with a paper feed roller 311 and a separation roller 312, and the paper feed tray 32 is provided with a paper feed roller 321 and a separation roller 322.

A paper push-up plate 31a is provided in the paper feed tray 31, and a paper push-up plate 32a is provided in the paper feed tray 32, and these paper push-up plates operate when the tray is inserted into a predetermined position in the paper feed section 3. It is pushed up by a push-up plate drive device (not shown), which is known in the art, and brings the topmost sheet of paper placed on the push-up plate into contact with the paper feed roller.

A paper passage 33 is provided on the side of the two-stage tray 3L32 and continues to an intermediate roller 333 that guides the paper to the timing roller 22 of the image forming section 1.
31 and 332 are provided sequentially from bottom to top.

A developer stirring section 34 is arranged in the empty space on the side of the upper paper feed tray 31, and the developer stirring section 34
3 and this stirring section 34 are connected to each other by a developer circulation device 35.

As shown in FIG. 2, the upper paper feed tray 31 accommodates transfer paper P1, and the lower paper feed tray 32 accommodates transfer paper P2.

As shown in FIG. 3, the developing section 13 includes a casing 131, and a developing roller 132 in the form of a sleeve is rotatably supported in a portion of the casing 131 that includes an opening 131a.

A magnet body 133 is fixedly arranged inside the developing roller 132 .

This magnet body has developer holding magnetic poles Nl, S3. Nz,S
2, N3 and S4, and a developer separation magnetic pole N4.

The developing roller 132 faces the photosensitive drum 11 from the casing opening 131a and forms a developing area 130.

A height regulating member 136 is provided above the developing roller 132, and behind the developing roller 132, a developing side supply roller 134 in the form of a screw and a developer discharge roller 13 are provided.
5 are arranged in two rows, upper and lower.

The developing roller 132 and the discharge roller 135 are rotated clockwise in FIG. 3 by a driving means (not shown), and the upper supply roller 134 is rotationally driven counterclockwise in FIG. 3 by a driving means (not shown).

The upper and lower rollers 134 and 135 are driven to rotate by receiving a driving force from the direction indicated by the white arrow A in FIG. 2 (from the front side of the image forming section 1).

The developer material containing toner and carrier in the developing section 13 is conveyed in the direction of arrow B from the back side to the front side of the image forming section 1 as shown in FIG. 2 by the rotation of the supply roller 134. , a part of it is supplied to the developing roller 132. The developer that has reached the front side of the image forming section is then conveyed in the direction of arrow C from the front side to the back side of the image forming section by the rotation of the lower discharge roller 135, as shown in FIG. .

The developer supplied onto the developing roller 132 is conveyed to the developing area 130 by the rotation of the roller, with the amount of conveyance being regulated by the height regulating member 136, where the electrostatic latent on the photoreceptor drum 11 is regulated. After the image is developed, the remaining developer is returned into the casing 131 by the separating magnetic pole N4.

The details of the developer stirring section 34 on the paper feed tray 31 are shown in FIG.
(Stirring section perspective view) and FIG. 5 (Stirring section sectional view).

As shown in FIGS. 4 and 5, the developer stirring section 34 has a casing 341, in which a mixing stirring member 342 is rotatably supported.

The member 342 is rotationally driven in the direction of the arrow in FIG. 4 by a motor 344 via a joint 343.

As shown in FIG. 5, this member 342 includes a mixing stirring blade 342a and an axial transport blade 342b that transports the developer in the direction of the rotation axis of the member.

The developer supplied from the developer inlet 353a of the casing 341 is mixed and agitated by the rotation of the member 342 while heading toward the developer outlet 351a, where it is discharged.

A toner replenishment port 36 is attached to the rear of the casing 341, and new toner in the hopper is supplied into the casing 341 from the toner replenishment port 362 by a screw 361 turned by a drive means (not shown). There is.

353a, 351a and 3 indicated by dotted lines in FIG.
6a indicates the height positions of the developer inlet, developer outlet, and toner hopper connection port 36a in the casing 341, respectively.

The bottom of the casing 341 and the developer inlet 351a
An ATDC sensor S for detecting the toner concentration is provided near the.

Note that the developer solution used contains a sufficient amount of carrier to charge the toner satisfactorily, and this developer solution is also stored in the stirring section 34 in advance.

As shown in FIG. 2, the developer circulation device 35 that connects the developing section 13 and the developer agitating section 34 includes a developer outlet 351a of the developer agitating section casing 341 and a developer inlet 134a of the developing section 13. A flexible screw 352 fitted in a flexible tube 35L1 that connects the developer inlet 353a of the developer stirring unit casing and the developer outlet of the developer unit 13 135a, and a flexible conveying screw 354 disposed within the tube.

These tubes and their internal transport screws are of sufficient length to allow the paper feed tray 31 to be pulled out from the paper feed section 3 for paper replenishment or replacement.

The rotation shaft of the transport screw 3520 in the outgoing tube 351 is connected to the shaft of the upper supply roller 134 of the developing section 13, and rotates as the roller 134 rotates. Further, the rotating shaft of the conveying screw 354 in the return tube 353 is connected to the shaft of the developer discharging roller 135 of the developing section 13, and rotates as the roller 1350 rotates.

According to the copying machine described above, first, in the image forming section l, the photoreceptor drum 11 is rotated counterclockwise in the figure, and the surface of the photoreceptor drum is uniformly charged by the charging charger 12.

An image corresponding to the original on the original platen glass 18a is exposed from the optical system 18 to the thus obtained charged area, and the drum II
An electrostatic latent image is formed thereon. Continuing with the inter-image eraser 17
Erase processing can be performed using a.

The electrostatic latent image is developed into a toner image by the developing section 13 and transferred to a transfer paper sent to a transfer charger 14 by the charger.

After the toner image has been transferred, the transfer paper is separated from the drum 11 by the separation charger 15, conveyed to the fixing roller 24 by the conveyance heald 23, where the toner image is fixed, and then discharged onto the paper discharge tray 26 by the paper discharge roller 25. be done.

The transfer paper is conveyed to the transfer section where the transfer charger 14 is located as follows.

In the case of manual paper feed, the transfer paper is placed on the manual feed tray 19, and the paper feed roller 20 moves the transfer paper to the timing roller 2.
2 and is sent onto the charger 14.

In the case of automatic paper feeding, the transfer paper stored in either of the paper feed trays 31 and 32 set in the paper feed section 3 is pulled out by a paper feed roller, and the transfer paper is pulled out one by one from the paper passage path 33 by a separating roller at a timing. It is fed to rollers 22 and from there onto charger 14 .

In any case, the timing roller 22 is the photosensitive drum l.
The transfer paper is sent to the transfer section in synchronization with the toner image on the paper.

After the toner image is transferred from the drum II to the transfer paper,
Toner remaining on the drum is scraped off by a blade of cleaner 16. Also, the residual charge is the eraser 1
It is erased by 7.

During operation of such a copying machine, the stirring rotating member 342 is rotated in the developer stirring section 34 disposed in the upper paper feed tray 3I, so that the developer side of the stirring section is sufficiently mixed and stirred, and the toner is sufficiently charged. Developing side discharge port 351a
from there to the tube 351.

The developer sent to the tube 351 is supplied to the developer inlet 134a of the developing section 13 by the rotation of the conveying screw 352 in the tube, enters the developing section 13 from here, and is fed to the upper supply roller 134 of the developing section. 2nd by rotation
A portion of the developing roller 132 is conveyed in the direction of arrow C in the figure.
is supplied to

The developer that has reached the end of the supply roller 134 returns in the direction of arrow C in FIG.

The developer returned into the tube 353 is transferred to the developer stirring section 34 by the rotation of the conveying screw 354 inside the tube.
from here to the developer inlet 353a of the casing 3.
41 and mixed and stirred again. At this time, the toner concentration is detected by the ATDC sensor S in the stirring section 34, and if the toner concentration is low, the toner hopper 36
Toner is replenished into the casing 341 from the toner.

Thus, the toner to be rendered visible in the electrostatic latent image is mixed with a sufficient amount of carrier contained in the stirring section 34, and
The toner is supplied in a sufficiently charged state to the developing section 13, where it is subjected to development. Therefore, the problem of uncharged toner or insufficient charging due to lack of carrier is solved, and problems such as poor development and toner scattering are solved.

Note that the present invention is not limited to the above embodiments,
It can also be implemented in various other ways.

For example, the developer stirring section 34 may be provided not in the empty space of the paper feed tray but in another empty space in the image forming section 1, and as shown by the two-dot chain line in FIG. In order to easily perform maintenance, this agitation unit is installed inside the case externally attached to the image forming unit l, or below the paper feed tray and paper output tray, etc. 34 and the developing section 13 may be connected by a circulation device such as a developer circulation device 35.

[Effects of the Invention] As explained above, according to the image forming apparatus of the present invention, the developing section and the developer agitating section of the developing device are separated and connected by the developer circulation means, so that the toner used can be reduced. A sufficient amount of carrier can be used to sufficiently charge the toner, and after the carrier and toner are sufficiently mixed and stirred, a good toner image can be formed by development, and scattering of the toner can also be prevented.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention. FIG. 1 is a schematic diagram of the overall configuration of the embodiment, and FIG. 2 shows the copying machine shown in FIG. Figure 3 is a sectional view of the developing unit, Figure 4 is a perspective view of the developer stirring unit, and Figure 5 is a diagram explaining the arrangement of the developer stirring unit and the developer circulation device that connects these parts. FIG. 3 is a cross-sectional view of the agent stirring section. ■...Image forming section 11...Photosensitive drum 13...Developing section 132...Developing roller 134...Developer supply roller 135...Developer discharge roller 31, 32...Paper feeding Tray 34...Developer stirring section 341...Developer mixing and stirring member 35...Developer circulation device 351.353...Flexible tube 352.354...Flexible conveyance screw 36...・
Toner hopper Fig. 1 1... Image forming section 11... Photosensitive drum 13... Developing section 31, 32... Paper feed tray 36... Toner hopper Fig. 3 13... Developing section 132...・Developing roller 134...Developer supply row 5 135...Developer discharge port-ra

Claims (2)

[Claims] (1) An image forming apparatus characterized in that a developing section and a developer stirring section in a developing device are separated, and the developing section and the developer stirring section are connected by a developer circulating means. (2) The image forming apparatus according to claim 1, further comprising a paper feed tray that can be taken in and out of the apparatus from a peripheral side of the apparatus, and wherein the developer stirring section is arranged in an empty space of the paper feed tray.