JPH0427990A - Image forming device - Google Patents

Abstract

PURPOSE:To form a good image having no surface fogging by providing a returning amount controlling means which controls the returning amount of a developer per unit time discharged from the developer discharging part of a cleaning means to a developer returning means. CONSTITUTION:On the bottom of a cleaning device main body 50, a toner collecting auger 54 as a carrying means to carry toner in the cleaning device main body 50 to a toner discharging part 53 projecting to an outside in order to receive and deliver the toner to a toner returning means 41 as a developer returning means is arranged. Furthermore, on the terminal side in the carrying direction of the toner collecting auger 54, a toner discharging amount adjusting auger 60 is successively set and controls a toner discharged amount to the toner discharging part 53 per unit time. Consequently, even when a collecting amount increases, the developer amount per unit time carried to a developing means is within a certain limitation; therefore, the toner density of the developer in the developing means is always stabilized. Thus, the good image without the surface fogging is formed.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention relates to an image forming apparatus such as a laser printer or an electronic copying machine. The cleaning means is configured to form a developer image and transfer it to an image support, remove developer remaining on the image support after image transfer by a cleaning means, and reuse the developer removed by the cleaning means. The present invention relates to an image forming apparatus having a structure in which the developer is returned to the developing means from the developer discharge section via the developer returning means.

(Prior Art) In recent years, image forming apparatuses in which the developer removed by a cleaning means is returned to the developing means for reuse are extremely economical as the amount of developer consumed is small, and the amount of developer removed by the developing means is extremely economical. They tend to be used frequently because they have the advantage of being easy to maintain, such as reducing the number of times the developer needs to be replenished and eliminating the need to dispose of the developer removed by cleaning means.

Conventionally, this type of image forming apparatus has been configured to return the developer removed by the cleaning means to the developing means as quickly as possible using various developer returning means.

(Problems to be Solved by the Invention) As described above, in the conventional apparatus, during the conveyance process in which the developer removed by the cleaning means is returned to the developing means, the developer is conveyed using the maximum conveying force of the cleaning means. Therefore, when a large amount of developer is temporarily fed into the cleaning means and the developer return means, all of it is transported to the developing means. For this reason, especially in the case of a two-component type developing means,
There was a problem in that the toner density increased significantly, causing blurring in the image.

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to form an image capable of forming a good image without blurring in a recycle type in which the developer removed by the cleaning means is returned to the developing means. The aim is to provide equipment.

[Structure of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a method in which a developer image is once formed on an image carrier by a developing means and then transferred to an image support, After the image transfer, the developer remaining on the image carrier is removed by a cleaning means, and the developer removed by the cleaning means is transferred from the developer discharge part of the cleaning means to the developer return means to the developing means. In the image forming apparatus configured to return the developer to the developer, the image forming apparatus is provided with a return amount regulating means for regulating the amount of developer returned per unit time discharged from the developer discharge part of the cleaning means to the developer return means. .

(Function) In the present invention, the amount of developer returned per unit time to the developer returning means is regulated by the returning amount regulating means provided in the developer discharge portion of the cleaning means.

In this way, the amount of developer sent to the developer returning means is within a certain limit, so even if a large amount of developer temporarily remains on the image carrier and the amount recovered by the cleaning means increases, the amount of developer The amount of developer transferred to the developing means per unit time is also within a certain limit, so that the toner concentration of the developer inside the developing means is always stable. Therefore, it is possible to form a good image without blurring.

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

FIG. 2 shows the configuration of a laser printer as an image forming means, and FIG. 3 shows the configuration of its main parts.

1 in Figure 2 is the printer main body, and this printer main body 1
An image forming means 2 is housed inside.

That is, a drum-shaped photoreceptor 3 as an image carrier is provided in the center of the printer body 1, and around it are a charging device 4, a laser optical system 5 as an exposure device, and a developing device 6. , a transfer device 7, a peeling device 8, a blade type cleaning device 9 serving as cleaning means, and a static eliminator 10 are arranged in this order.

Furthermore, the printer main body 1 includes a photoreceptor 3 and a transfer device Wt7.
An image forming medium transport path 12 is formed passing through the image transfer section 11 between A sheet of paper P as an image forming medium is guided to the image transfer section 11 .

Further, the image transfer section 11 of this image forming medium transport path 12
An aligning roller pair 17 is arranged on the upstream side, and a fixing device 18, a paper ejection roller pair 19, and a second paper ejection roller pair 20 are arranged on the downstream side.

Further, on the upstream side of the aligning roller pair 17, a paper feed roller 21 and a moving roller pair 22, 22 are arranged.

In the image forming operation, the photoreceptor 3 is driven and uniformly charged by the charging device 4, and then the laser optical system 5 exposes the photoreceptor 3 to light corresponding to image number 1. An electrostatic latent image is formed.

Next, the electrostatic latent image on the photoreceptor 3 is transferred to a developing bag Fi1 using a two-component developer consisting of toner t and carrier C.
6 and sent to the image transfer section 11 side as a developer image.

Meanwhile, in synchronization with this developer image forming operation, the paper feed cassette 1
5 through the paper feed roller 21,
Alternatively, the manually fed paper P is aligned with the aligning roller pair 17.
The developer image previously formed on the photoreceptor 3 is transferred onto the paper P by the action of the transfer device 7. Next, the paper P is peeled off from the photoreceptor 3 by the peeling device It8, passes through the image forming medium conveyance path 12, and is sent to the fixed stone device 18. Here, after the developer image is melted onto the paper P, the paper ejection roller pair 19.20
The paper is discharged to the paper discharge tray 23 via the paper discharge tray 23.

Note that after the developer image is transferred onto the paper P, the residual toner t remaining on the photoreceptor 3 is cleaned by the cleaning device 9, and the next copying operation is ready.

The developing device 6 has a configuration as shown in FIG.

That is, this developing device 6 includes a developing mechanism section 30 and a developer stirring section 31.

The developing mechanism section 30 includes an opening 33 of the developing device main body 32.
A developing roller 34 disposed opposite to the developing roller 34 and a sliding contact portion of the developer magnetic brush D' formed on the surface of the developing roller 34 with the photoreceptor 3, that is, provided on the upstream side of the developing section 60. The doctor 35 regulating the thickness of the developer magnetic brush D' and the developer magnetic brush D' formed on the surface of the developing roller 34 provided on the downstream side of the developing section 46 are peeled off and the developer stirring section 31 is removed. It has a sclay/<36 leading to .

Further, the developer agitating section 31 includes a first developer containing section 37 which is formed behind the arrangement section of the developing roller 34;
The second developer stirring bodies 38 and 39 are shown in white.

Further, the developing roller 34 includes a magnetic roll 34a having a plurality of magnetic pole parts (not shown), and a magnetic roll 34a having a plurality of magnetic pole parts (not shown).
and a non-magnetic sleeve 34b that is fitted onto the outside of the sleeve 34a and rotates clockwise in the figure.

A toner receiving section 40 as a developer receiving section is formed at a position facing the developer agitating section 31 of the developing device main body 32, and receives toner t and developer supplied from a toner cartridge tray (not shown). The toner t spilled from the cleaning device 9 is received through a toner return means 41 serving as a return means.

Further, a developer concentration detector 45 for detecting developer concentration is provided at a position facing the scraper 36, and a detection signal from the developer concentration detector 45 causes toner to be transferred from a toner cartridge (not shown). will be replenished.

On the surface of the non-magnetic sleeve 34b, developer particles stand up on the surface of the non-magnetic sleeve 34b due to the lines of magnetic force generated from each magnetic pole portion and are attracted in a brush-like manner to form a developer magnetic brush D'. are sequentially conveyed to the developing section 46 by the rotation of the sleeve 34b, and the toner t in the magnetic brush D' adheres to the electrostatic latent image on the photoreceptor 3 and develops it.

Further, a toner replenishment shaft of a toner cartridge (not shown) is driven by a replenishment signal from the toner concentration detector 45, and the insufficient toner t is replenished as appropriate.

On the other hand, the developer stirring body 3 disposed in the developer storage section 37
The developer is stirred by the 8.39 rotations, and frictional electrification between the toner t and the carrier C can be performed satisfactorily.

Further, the cleaning device 9 has the following configuration.

That is, 50 is a cleaning device main body having an opening in a portion facing the photoreceptor 3, and a cleaning blade 51 is housed within this cleaning device main body 50. The tip of the lower end of the cleaning blade 51 is in pressure contact with the circumferential surface of the photoreceptor 3 .

The remaining toner t adhering to the photoreceptor 3 is then scraped off by the cleaning blade 51.

Further, a recovery blade 52 is disposed below the cleaning blade 51.
The toner t scraped off by the cleaning device is collected into the cleaning device main body 50.

Further, at the bottom of the cleaning device main body 50, a cleaning device main body 5 is provided.
A toner discharge portion 53 protrudes to the outside to receive and transfer the toner t in 0 to a toner return means 41 serving as a developer return means.
(See FIGS. 1 and 4) A toner recovery auger 54 is disposed as a conveyance means for conveying the toner.

Further, on the terminal end side of the toner collection auger 54 in the conveying direction,
As shown in FIG. 1, a toner discharge ffi adjustment auger 60 as a return amount regulating means is provided in series, and is configured to limit the amount of toner discharged per unit time to the toner discharge portion 53.

The toner release amount adjusting auger 60 is designed such that the conveyance pitch, the width, depth, and shape of the conveyance groove are such that the toner conveyance amount per unit time is below a certain limit. That is, the conveyance pitch is made smaller, the width of the conveyance groove is made smaller, and the depth is made shallower than that of the toner recovery auger 54. In this embodiment, the amount of toner conveyed per unit time of the toner release amount 31 auger 60 was set to 0.1 g/see.

The amount of residual toner recovered by the laser printer of this example was measured to be around 0.06 g/See per unit time during normal printing. However, a portion of the toner t scraped off by the cleaning blade 51 during printing adheres and accumulates on the inner side surface and upper surface of the toner transport path 63 within the cleaning device main body 50. Moreover, since the accumulated toner t is not conveyed to the toner collection auger 54, the amount thereof may exceed 10 g at maximum.

The toner t accumulated in this way is peeled off from the inner side surface and top surface of the toner transport path 63 due to impact when the printer main body 1 is moved or the cover of the printer main body 1 is opened and closed for paper jam removal, etc., and the toner is collected. The auger 54 transports the toner toward the toner discharge section 53 . If all of these are transferred to the toner discharge port 53 within a short period of time and sent to the developing device 6 via the toner return means 41, the ratio of toner t to developer in the developing device 6 will increase significantly, resulting in the formation of an image. Buri occurs inside.

However, in the present invention, by providing toner release amount adjustment auger 0 in the direction of the toner release part 53 of the toner collection auger 54, a large amount of toner t can be delivered to the toner release part 53 within a short time.
be prevented from being sent to

On the other hand, as shown in FIG. 1, a toner storage space 62 is formed extending from the upper part of the joint part 61 between the toner collection auger 54 and the toner discharge amount adjusting auger 60 to the upper part of the toner discharge port 53. And toner release amount adjustment auger 60
When a larger amount of toner t is sent by the toner collection auger 54 than the amount of toner transported, the toner t that has not been transported and stagnated in the toner storage space 62 is stored. This prevents toner clogging.

Further, the toner return means 41 includes a first connecting portion 65 connected to the toner discharge port 53 of the cleaning device, as shown in FIG.
, a second connecting portion 66 that connects to the developing device 6, and a communication pipe 67 that communicates these connecting portions 65 and 66. A coil spring 69 serving as a toner transfer member whose one end side is fixed to a driving body 68 is housed in the communication pipe 67, and as the coil spring 69 rotates, the toner t discharged from the toner discharge port 53 is transferred to the developing device 6. The developer is returned to the developer storage section 37.

Further, the maximum amount of toner per unit time discharged to the toner return means 41 by the toner discharge IT adjustment auger 60 as a return amount regulating means is determined by the predetermined lifespan of the image carrier when the laser printer is used in a normal state. Good results were obtained within 30 times the average transport amount per unit time within the period.

Further, when the developer weight was 250 g, good results were obtained by keeping the toner t to carrier C ratio within 6%, for example, 12 g. When the toner t exceeded 6%, ground blurring occurred and image defects occurred.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made without changing the gist.

[Effects of the Invention] As described above, the present invention provides an image forming apparatus that is capable of forming good images without blurring in a recyclable type in which the developer removed by the cleaning means is returned to the developing means. It has the effect of making it possible.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional view of the toner discharge port portion of the cleaning device, FIG. 2 is a diagram showing the internal structure of the image forming apparatus, and FIG. 3 is a diagram showing the main parts. FIG. 4 is a perspective view of the toner discharge port of the cleaning device, and FIG. 5 is a schematic diagram of the toner return means. 6...Developing means 1.3...Image carrier, 9...Cleaning means (blade type cleaning device), 41...Developer return means (toner return means) 5゛3...Developer Emission part, 60
... Return amount regulating means, D... Developer.

Claims (1)

[Scope of Claims] A developer image is once formed on an image carrier by a developing means and transferred to an image support, and after the image transfer, the developer remaining on the image carrier is removed by a cleaning means. In an image forming apparatus configured to return the developer removed by the cleaning means to the developing means from the developer discharge section of the cleaning means via the developer return means for reuse, the developer discharge section of the cleaning means returning to the developing means. An image forming apparatus comprising a return amount regulating means for regulating the amount of developer returned per unit time discharged to the developer returning means.