JPH02149874A - Developing device - Google Patents

Abstract

PURPOSE:To prevent a ghost image from being formed in a copy image by forming a magnetic brush of a single-component magnetic developer between a developer carrier and a magnetic brush forming means and rubbing the magnetic brush against the developer carrier. CONSTITUTION:The developing device is equipped with a developer container 20 which has an opening part 20a and contains the single-component developer T, the developer carrier 11 which is provided rotatably to the opening part 20 of the developer container 20, and the magnetic brush 13 forming means which forms the magnetic brush of the single-component magnetic developer T with the developer carrier 11 arranged in the developer container 20 nearby opposite the developer carrier 1. Then, the magnetic brush 13 is rubbed against the developer carrier 3. Consequently, the ghost image is prevented from being formed in the copy image.

Description

[Detailed description of the invention] FIELD OF THE INVENTION This invention relates generally to developing ml, and more particularly to, for example.

Used in image forming devices that use electrophotography, electrostatic recording, etc. in the image forming process.

An electrostatic latent image formed in the image forming apparatus.

The present invention relates to a developing device that produces visible images using a one-component magnetic developer.

[As is well known, this type of developing device uses a developing sleeve that is rotatably supported in the opening of the toner hopper to generate electricity such as a one-component magnetic developer contained in the toner hopper. The electrostatic latent image is visualized by holding a developer having a high resistance value and supplying the developer to an image carrier on which an electrostatic latent image is formed.

FIG. 8 shows a general configuration of an image forming apparatus in which a developing device having the above-mentioned configuration is used.

The image forming apparatus shown in FIG. 8 employs an electrophotographic method for the image forming process, and its overall configuration is already well known, but its outline can be explained as follows. It is. That is, in FIG. 8, the cleaner 8
At the same time, the one-component magnetic developer T remaining on the outer peripheral surface of the photoreceptor drum 1, which is rotatable in the direction of arrow A in FIG. After removing the residual charge, the outer circumferential surface of the photoreceptor drum 1 is uniformly charged at a predetermined potential using a negative charger 5. - An electrostatic latent image is formed on the outer circumferential surface of the photoreceptor drum 1 after it has been uniformly charged by the charger 5 by irradiating image exposure 6 from an image exposure irradiation means (not shown). The electrostatic latent image is made into a visible image by the one-component magnetic developer T contained in the developer. That is, the process of visual imaging involves the photosensitive drum 1 and the hopper 2.
By applying a developing bias voltage between the developing sleeve 2 which is rotatably supported in the direction of the arrow in FIG. This is done by attaching the electrostatic latent image on the outer peripheral surface of the photoreceptor drum l. In addition, in the developing sleeve 2, there are four magnetic poles N, as shown in the figure.
A substantially cylindrical magnet 3 equipped with S, , Nz, sz
is permanently installed. The visible image formed on the outer peripheral surface of the photoreceptor drum 1 through the process described above is
The image is transferred onto the transfer material fed into the opposing gap defined by the outer peripheral surface of the photosensitive drum 1 and the transfer charger 7 by the transfer material guide 11 and the transfer material conveying roller 10 . That is, the visible image on the outer peripheral surface of the photosensitive drum 1 is transferred onto the transfer material by corona charging applied from the back side of the transfer material by the transfer charger 7. The transfer material, on which the visible image has been transferred on the outer peripheral surface of the photoreceptor drum 1 through the above-described process, undergoes image fixation in a fixing device (not shown) and is discharged out of the main body of the image forming apparatus.

On the other hand, the one-component magnetic developer T remaining on the outer peripheral surface of the photoreceptor drum 1 is removed by a cleaner 8, and the electric charge remaining on the outer peripheral surface of the photoreceptor drum 1 is removed by a pre-exposure lamp 9. This will prepare the image forming process for the new image formation process.

By the way, in the developing device used in the image forming apparatus configured as described above, the one-component magnetic developer T housed in the hopper 20 is transferred to the developing sleeve 2 by the magnetic field generated from the magnet 3. The one-component magnetic developer T is triboelectrically charged by adsorbing it onto the outer circumferential surface and conveying it from the hopper 20 to the photosensitive drum 1. The developing sleeve 2 corresponds to the electrostatic latent image on the outer circumferential surface of the photoreceptor drum l among the one-component magnetic developer T that is adsorbed and carried on the outer circumferential surface of the developing sleeve 2 described above.
The T-layer of magnetic developer on the outer circumferential surface is consumed to convert the electrostatic latent image into a visible image. However, in the one-component magnetic developer T layer adsorbed and supported on the outer circumferential surface of the developing sleeve 2, one component on the outer circumferential surface of the developing sleeve 2 that does not correspond to the electrostatic latent image on the outer circumferential surface of the photoreceptor drum l. The magnetic developer T layer remains as it is without being consumed. In this way, the one-component magnetic developer T layer remaining unconsumed on the outer circumferential surface of the developing sleeve 2 gradually becomes electrically charged as it rubs against the outer circumferential surface of the developing sleeve 2. The potential will rise. On the other hand, in the area on the outer peripheral surface of the developing sleeve 2 where the one-component magnetic developer T layer has been consumed due to the above-mentioned visual imaging, new one-component magnetic developer T is added to the hopper by the magnetic field generated from the magnet 3. 2
The one-component magnetic developer T newly replenished from the hopper 20 is replenished from 0.

Naturally, the charging potential is lower than that in the existing one-component magnetic developer T layer, and therefore, there are parts with different charging potentials in the one-component magnetic developer T layer that is adsorbed and supported on the outer peripheral surface of the same developing sleeve 2. Since this difference in charging potential appears as a difference in development characteristics, a problem arises in that a ghost image as shown in FIG. 9, for example, appears in the copied image. That is, in FIG. 9, a visible image indicated by PI is first formed on the transfer material P that is moving in the direction of the arrow in FIG. 9 (i.e., upward in FIG. 9), and then the transfer material P When a visible image (solid black area) indicated by the symbol Pz is formed after moving by a distance distance, the above-mentioned 4-brown image r+ whose image density is lower than that of the visible image Pz is added to the visible image Pz. East statue PI
' is formed, and the problem arises that :5 and T~ are put away.

Also, 1-Subordinate J1 Go 1: In addition, the said place, image sleeve? 19 consumption on the outer surface! E, 1 layer of one-method, quarter-based magnetic developer remaining in i'' (7) '5f' Due to the high kicking potential, this developer layer 1): between the developing sleeve and the outer solid surface of Z. 111. 1-1, the present depressant T
There is also the problem that it is difficult to remove the layer from the outer peripheral surface of the developing sleeve.
It was invented in order to solve the above-mentioned problems and defects.The purpose is to develop a one-component magnetic developer layer held on the outer circumferential surface of the developing sleeve. By preventing the characteristic 1% from collapsing,
In addition to preventing the occurrence of ghost images on images, the remaining one-component magnetic developer layer is removed from the developing sleeve's outer circumferential surface instead of being consumed during development. It's easy to peel off 1. ζ 17 It's easy to remove the image device, ?) It's in the 7 La, - all - solution, Ushiboo Benitaichi car 01 - step ■-The stated purpose has been achieved with the developing device according to the present invention.To summarize, the present invention has an aperture formed therein, and -component-based magnetic lJ!, a developer container for storing a developer; A magnetic brush is formed between the one-component magnetic developer (1) and (2), which is arranged so as to face the developer container in close proximity to the developer carrier; There is a developing device 1, which is characterized in that: f, the step number is J'L @L, and the magnetic pusher is used to locate the developer carrier in the tank L5. Hereinafter, the implementation of the present invention will be explained with reference to the drawings.
- As shown in the image engraving apparatus, three types of electrophotography and electrostatic recording are used in the process of image engraving. The developing device 4, which is used for converting a latent image into a visible image, is clearly shown in FIG. Image form J& Hitting the atonement carrier in the device Figure 1 Arrow pu'
It is arranged close to the photoreceptor dome 1 which can be rotated freely in the direction.
-1ρru9 In FIG. 1, the developer container or hopper 2
0 contains a one-component magnetic developer T having a high resistive force as a developer. Opening 20 in the area where
a is formed. A developer carrier, that is, a developing sleeve 2 is faced to the opening 20a, and the outer circumferential surface of the developing sleeve 2 can be contacted with the side facing the opening 20a. A layer thickness regulation one-stage tip 1'31/- door 21 which is rotatably supported is installed. The developing sleeve 2 is provided with a developing bias power source (
17) is connected to the switch 7.

A further explanation of the above-mentioned 1.7 planting is as follows. Also, the developing sleeve 2 is made of stainless steel such as aluminum whose surface is oxidized.
Alternatively, a non-magnetic osmanthus is made of four materials to form a substantially rounded shape with an outer diameter of L 6 mm, and four wires (which are rotatably supported by the hopper 20 in the direction of the arrow in Fig. 1) are used. ing.

The outer peripheral surface of the developing sleeve 2 is sandblasted using No. 40-600 amorphous abrasive grains.

The inside of the developing sleeve 2 is provided with four magnetic poles N1, $1, NZ, 52 as shown in the figure 131.
A magnet 3 having a 1-shaped shape is fixedly interposed. By rotating the developing sleeve 2 in the direction of the arrow R in FIG. The outer circumferential surface of the sleeve 2 is brought together.
1', and by this thick rubbing, the component system magnetic development T%: 11. By being negatively charged, the developing sleeve 2 is made to have a tripo (thickness charge) on the component thread magnetic developer. By the magnetic force generated from 3, the 2-component base magnet (1-component base magnet (1)) housed in the hopper 2e is drawn and held in one rotation, and the core is 1. Holding 1-9 of one component, y?--magnetic l;, image agent ``I---outside hopper 20.''
・〕・ 1. :l na-).

According to the first embodiment of the present invention, in the hopper 20,
A magnetic brush forming means, that is, a shaft member 12 made of a magnetic material is disposed so as to be close to and face the outer circumferential surface of the developing sleeve 2 . The shaft member 12 has an opposing gap defined by the outer peripheral surface of the shaft member 12 and the outer peripheral surface of the developing sleeve 2 by a magnetic field generated from the magnetic pole Sz of the magnet 3 between the shaft member 12 and the outer peripheral surface of the developing sleeve 2. A magnetic brush 13 is formed by the carrier 17 (shown in FIG. 3) present in the area and the one-component magnetic developer T. The shaft member 12 causes the magnetic brush 13 to rub against the same surface on the outside of the developing sleeve 2, thereby removing the one-component magnetic developer T layer remaining unconsumed on the outer peripheral surface of the developing sleeve 2. It is designed to peel off and remove. In this embodiment, the shaft member 12 has an outer diameter of, for example, 8.
mm is used, and the shaft member 1
The distance between the outer circumferential surface of the developing sleeve 2 and the outer circumferential surface of the developing sleeve 2 is set and maintained at 0.3 mm to 2 mm.

In this embodiment, the carrier 1 shown in FIG.
For example, magnetic powder made of ferrite, iron, or the like is used as the material 7. The carrier 17 is used together with the one-component magnetic developer T as a necessary material to form the magnetic brush 13 having the shape shown in FIG. 2, and is used in a developing process such as the so-called magnetic brush developing method. It is different from the carrier provided when executing. The carrier 17 exists only in the opposing gap defined by the outer circumferential surface of the shaft member 12 and the outer circumferential surface of the developing sleeve 2, and does not exist in areas other than the opposing gap. .

The present inventor disposed the shaft member 12 in the hopper 20 so as to face and be close to the outer peripheral surface of the developing sleeve 2, and the carrier 17 and the one-component magnetic developer T are magnetized by the magnetic field generated from the magnetic pole Sl of the magnet 3. forming a brush 13 and sliding the magnetic brush 13 on the outer circumferential surface of the developing sleeve 2 to peel off the unconsumed one-component magnetic developer T layer remaining on the outer circumferential surface of the developing sleeve 2; The background to devising a method for removing it is as follows.

That is, the one-component magnetic developer T adsorbed and supported on the outer peripheral surface of the developing sleeve 2 has a magnetic pole S of the magnet 3.
A magnetic force IF Z due to z and a force IF 3 due to a mirror image force are acting, and the magnetic force IFz and the mirror image are created. Here, mz is the magnetic moment applied to the one-component magnetic developer T, a is the particle size of the one-component magnetic developer T, and Q is the charge per particle of the one-component magnetic developer T. It is quantity. On the other hand, the rotational force per carrier 17 is expressed by torque: mIX Hl, and this torque: m1lX
The rotational angular acceleration of the carrier 17 caused by HI can be expressed as m11 x H1/I +.

Here, II is the moment of inertia that acts on each carrier 17, and the inertia moment is (ρ: density of the carrier 17, rl: the carrier 1
7 radius), when the carrier 17 and the one-component magnetic developer T collide on the outer peripheral surface of the developing sleeve 2, the carrier 17 attracts the one-component magnetic developer T and moves. try to make it happen. At this time, the force F1 acting on each one-component magnetic developer T is as follows.

F + = Mz (ml + X H1) / I
＋, Kokote.

Mz is the mass of one component of the one-component magnetic developer T. The force F acting on each one-component magnetic developer T, and the magnetic force F due to the magnetic pole SZ of the magnet 3 mentioned above.
If the relationship F, cosθ>FZ +F317) is established between Z and the force F3 due to the mirror image force,
It is possible to peel and remove the unconsumed one-component magnetic developer T layer adsorbed and supported on the outer circumferential surface of the developing sleeve 2 from the outer circumferential surface of the developing sleeve 2. The value of COS θ is clear with reference to FIG. Here, if the shaft member 12 is placed so as to face a portion of the outer circumferential surface of the developing sleeve 2 that corresponds to the peak of the magnetic pole Sl of the magnet 3, the shaft member 12 is placed opposite the hopper. θ, and as described above <1.
The magnetic brush 13 formed by the magnetic brush 13 brushes the outer circumferential surface of the developing sleeve 2 at the portion including the portion W t,”!-4.

First, since there is a point in the magnetic brush 13 where the magnetic force F7=o (~B-1-=o), there is a point where the magnetic force F7=o (1'F,=O). p I Q 05θ described in
If the relationship Fl cos>Fl is established between F3 and F3, the unconsumed one-component magnetic developer which has been rejected will be attached to the outer circumferential surface of the developing sleeve 2. The r layer is peeled off and removed from the outer peripheral surface of the developing sleeve 2.
The inventor conducted an experiment in order to realize a theoretically possible 1-Rem theory. In this experiment, a one-component magnetic developer (T) with an average particle size of 84 m, 50 parts of magnetrodeite, and 10 parts of styrene acrylic resin was added to the one-component magnetic developer T.
Adopt l developer 1. Ta. The developer T has a density of 1.4 g/em', a saturation enhancement power of l5esu/g, and a charge of -465 μme/g. It was mg. Furthermore, the image force F1 acting per particle divided into the one-component magnetic developer T is F3 and 4. O/a yn passed away L. As early as rear 17, average grain R120p, m,
Saturation magnetic force I'', 65e 51,1/g, density 2
．． A carrier of 5 g/ern' was used. Said carrier 1
The force F1 acting on each piece of 7 is F=6.09
When solving st>F3 and finding the count of -H, FW>731
．． 6 Gauss is obtained i,, in this experiment,
Using magnetic poles S2 of 0 gauss, 800 gauss, and 850 gauss, and setting the magnetic pole 3z of 1-1 above 750 gauss to 1 (1), a strange result can be obtained. As is clear from the explanation 17.), the first embodiment according to the present invention 1. ．． If it enters, the outer circumferential surface of the 4′ sleeve-b 2 that appears in the beak hem 20, one facing each other, and the proximity one @′υ
← Due to the magnetic field generated by part 11 (12 is arranged, - magnetic pole S2 of segment 3) 5. By making the shape 1&L, Mla, and r sash 13 cover the outer circumferential surface 1.' of the developing sleeve 2, the unconsumed unconsumed material remaining on the outer circumferential surface of the developing sleeve 2 is removed. - It is possible to peel off and remove one layer of component-based magnetic developer, which may cause a ghost image to be formed on the copied image.)
It is now possible to have the luxury of 11-.

FIG. 5 shows a developing device according to a second embodiment of the present invention. In this embodiment, as a magnetic shield forming means, a -1 magnet shaft member 14 is used in place of the shaft member 12 made of a magnetic material used in the first embodiment (r). The opposing gap defined by the outer circumferential surface of the developing sleeve 2 and the outer circumferential surface of the magnet shaft member 14 is set to 0.3 mm to 2 mm. The carrier 17 forming the brush 13 is the magnetic brapa.
When it comes off from the developing sleeve 13 and moves from the developing sleeve 2 to the photosensitive drum 1 to the cleaner 8 (shown in FIG. The creases of the one-component magnetic phenomenon agent 1 remaining on the surface are visible, resulting in the appearance of black streaks in the copied image 1. Also, when the carrier 17 gets stuck inside the transfer V charger 7, cracking occurs, resulting in so-called white spots on each image, and furthermore, the transfer material There were also problems such as fogging due to the 1- and 0-4- finishes. Therefore, in this example, Magne 11. + By arranging the shaft member 14, the
7. To prevent the above-mentioned problem (7) from occurring;
It is (a).

FIG. 6 shows a third embodiment 1ζ of the present invention (sub) developing device). In this embodiment, refer to FIG. 6 1. hand! In order to make it clear, the shaft member 12 formed of the central abrasion NP is rotatably provided in the direction marked -h in FIG. It is provided in such a way that its tip ends are in contact with each other; in the configuration shown in 6.12, by rotating the shaft part 12 and 2-, the shaft part 1/- bar 15 is used to rotate the part part 12. The one-component magnetic developer T adhering to the outer circumferential surface is scraped off, and the carrier 17 and one-component magnetic developer T are thereby scraped off and the one-component magnetic developer T adhering to the outer peripheral surface is scraped off. As the magnetic developer T is stirred, the peeling and removal effect of the unconsumed one-component magnetic developer T layer adsorbed and supported on the outer peripheral surface of the developing sleeve 2 becomes even more pronounced. This makes it possible to prevent ghost images from appearing in copied images.

FIG. 7 shows a developing device according to a fourth embodiment of the present invention. In this embodiment, as is clear with reference to FIG. It was decided to connect the That is, when a high voltage is applied between the shaft member 12 and the developing sleeve 2, for example, when the one-component magnetic developer T is negatively charged, the shaft member 12 is applied to the high voltage power supply 16. Developing sleeve 2
Set something that has positive polarity relative to. The high voltage power source 16 may be either a DC high voltage power source or an AC high voltage power source, or a high voltage power source that supplies pulsating high voltage may be selected. On the other hand, the developing sleeve 2 also has a developing bias voltage. Therefore, if the high voltage power source 16 is an AC high voltage power source, the frequency of the AC voltage of the power source is set to be the same frequency as the AC voltage component of the developing bias voltage,
Furthermore, by shifting the phase by half a period, it is possible to increase the potential difference between the developing sleeve 2 and the shaft member 12.

Therefore, the unconsumed one-component magnetic developer T adsorbed and supported on the outer circumferential surface of the developing sleeve 2 is easily drawn toward the shaft member 12, and the effect of preventing ghost image generation is improved. In addition, in order to prevent leakage between the developing sleeve 2 and the shaft member 12, the carrier F used in this example is an insulating magnetic material made of ferrite or iron powder coated with styrene acrylic resin or fluororesin. Body powder is used.

In the experiment mentioned above, when a magnetic powder carrier coated with Teflon resin was used for a styrene-acrylic resin-based negative one-component magnetic developer, Teflon was more strongly negatively charged than styrene-acrylic. I understand. Due to this fact, the negative charge amount of the one-component magnetic developer T is caused by the friction generated between the magnetic brush 13 and the one-component magnetic developer T that is attracted and supported on the outer peripheral surface of the developing sleeve 2. is reduced, the above-mentioned mirror image force is reduced, and the one-component magnetic developer T is easily peeled off and removed from the outer peripheral surface of the developing sleeve 2, thereby preventing the above-mentioned ghost image from occurring. A comparison of magnetic powder formed into a spherical shape and amorphous magnetic powder revealed that the magnetic powder formed into a spherical shape had a more pronounced effect. . The reason for this is that when the magnetic powder is formed into a spherical shape, each individual magnetic powder rotates more easily in the magnetic brush, and the one-component magnetic developer is conveyed from the developing sleeve 2 through the magnetic brush. It is thought that this is because it has the effect of

11 Standing J As explained above, according to the present invention, the magnetic brush forming means is disposed in the developer container so as to be close to the developer carrier and face the developer carrier, and A magnetic brush made of a one-component magnetic developer is formed between the developer carrier and the magnetic brush forming means, and the developer carrier is rubbed with the FA by the magnetic brush, so that the outer periphery of the developer carrier By preventing differences in the development characteristics of the one-component magnetic developer layer that is adsorbed and supported on the surface, ghost images are prevented from occurring in the copied image, and the developer is not consumed on the outer peripheral surface of the developer carrier. It is possible to provide a developing device that can easily peel off the remaining one-component magnetic developer layer from the outer circumferential surface of the developer carrier.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a developing device according to a first embodiment of the present invention. FIG. 2 is a partially enlarged vertical sectional view of the developing device according to the first embodiment of the present invention. FIG. 3 is a partially enlarged vertical sectional view showing the structure of the magnetic brush in the developing device according to the first embodiment of the present invention. FIG. 4 shows development according to the first embodiment of the present invention:! It is an explanatory view of the operation in the device. FIG. 5 is a partially enlarged longitudinal sectional view of a developing shoe according to a second embodiment of the present invention. FIG. 6 is a partially enlarged vertical sectional view of a developing device according to a third embodiment of the present invention. FIG. 7 is a partially enlarged vertical sectional view of a developing device a according to a fourth embodiment of the present invention. FIG. 8 is a schematic diagram of an image forming apparatus using a conventional developing device. FIG. 9 is an explanatory diagram of a ghost image formed in an image forming apparatus using a conventional developing device. 20, Hopper 0a 2 open 1 part T knee component magnetic developer 1: Photosensitive drum 2: Developing sleeve 12.14: Shaft member 13: a1 air brush 15: Scraper 16: High voltage power supply Figure 4 Figure 8 Figure 9

Claims (1)

[Claims] 1) a developer container having an opening and accommodating a one-component magnetic developer, and an opening of the developer container;
a developer carrier provided rotatably; and a developer carrier disposed in the developer container so as to be close to and face the developer carrier. A developing device comprising a magnetic brush forming means for forming a magnetic brush of the one-component magnetic developer between the developing device and the developing device, the developing device comprising: a magnetic brush forming means for forming a magnetic brush of the one-component magnetic developer, and the developer carrying member is rubbed by the magnetic brush.