JPH02282766A - Developing device - Google Patents

Abstract

PURPOSE:To eliminate the difference in history between an image and non-image by providing a 1st developer peeling means which faces a developer carrier and has an electric field generating means, a 2nd developer peeling means which peels the developer on the surface thereof and a charge imparting means to the developer deposited on the developer carrier. CONSTITUTION:The 1st developer peeling means 7 has the electric field generating means and is disposed to face the developer carrier 3. The developer on the developer carrier 3 is attracted by the effect of the electric field of the 1st developer peeling means 7 and is peeled by the potential difference between both. The developer sticking to the rotating 1st developer peeling means 7 is pulled and stripped by the fixedly disposed 2nd developer peeling means 8 to prevent the deposition of the developer on the 1st developer peeling means 7. Further, the charge imparting means 9 disposed backward in the moving direction on the surface of the developer carrier 3 from the 1st developer peeling means 7 applies a triboelectrostatic charge on the developer by the effect of the triboelectrostatic charge or electric field, thereby applying a prescribed quantity of the triboelectrostatic charge to the fresh developer deposited on the developer carrier 3. The difference in the history between the image and the non- image is eliminated in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a developing device, particularly an electrophotographic copying machine, an electrostatic recording machine,
The present invention relates to a developing device using a one-component developer applied to an image forming apparatus such as a magnetic recording machine.

[Prior Art] Conventionally, in a developing method using a -component developer, the toner layer is not brought into direct contact with the electrostatic latent image bearing surface, but the toner is selected on the electrostatic latent image bearing surface by the electric field of the electrostatic latent image. There is a known method for making it fly.

According to this method, not only is the developer not attracted to the non-image area where there is no latent image potential, but also the developer does not come into contact with the non-image area, resulting in good development without any nicks.

In addition, the applicant has previously proposed a developing method different from the above-mentioned method, in which a uniform thin layer of developer is formed on a developer carrier by the magnetic force of a magnetic field generating means, and development is performed opposite to the image area by electrostatic attraction. A method of developing by stretching the agent (
(Japanese Patent Application No. 52-109240), development is carried out by applying a low frequency AC bias voltage as a developing bias voltage to the developer carrier and further changing the distance between the electrostatic latent image surface and the developer carrier over time. (Special application 1986-1992)
108) was proposed.

The above-mentioned developing method in which a thin layer of a one-component developer is disposed opposite to the latent image surface provides extremely excellent effects in terms of development performance, image reproducibility, developer life, and the like.

[Problems to be Solved by the Invention] However, even in the developing method described above, when put into practical use, differences in image density may occur due to differences in the nine image histories. This "image history" means the progress of image and non-image formation on the electrostatic latent image bearing surface of the latent image carrier, and the image density is affected by the development sleeve, which is the developer carrier. This is because there is a problem with the toner coating layer in the developing sleeve.To elaborate on this point, at the development position, the toner in the developing sleeve attracts the electrostatic force by electrostatic attraction in order to develop the image area on the electrostatic latent image bearing surface. It is attracted to the latent image bearing surface and removed from the surface of the developing sleeve, or only a small amount remains.

On the other hand, for non-images, all or most of the toner on the developing sleeve remains on the developing sleeve even at the developing position. As a result, new toner is supplied to the surface of the developing sleeve that has received the image history at the next toner supply, but the previous toner remains on the surface of the developing sleeve that has not received the image history. New toner is not supplied during the primary toner supply. If such a non-image history is repeatedly experienced at the same location, the toner tribo coating at that location on the surface of the developing sleeve may change, which may further cause toner deterioration, surface contamination of the developing sleeve, etc. be.

As a result, due to the difference in history between images and non-images, differences occur in the state of toner on the surface of the developing sleeve, and the developing ability and
This causes a difference in the quality of the final image. This phenomenon is particularly noticeable when copying a large number of originals with black or white band images in the vertical direction.

Further, this difference in image history tends to cause density unevenness in halftone areas, and in extreme cases, there is a problem that characters become thicker or thinner.

The difference in images (particularly halftone images) due to the difference in history between images and non-images as described above varies depending on various conditions. For example, if new toner is insufficiently supplied to the developing sleeve after the image history, if an electrostatic latent image is created at that location again in the first stage, the density of the developed image will decrease. Further, when the amount of coating after the non-image history is reduced, if an electrostatic latent image is formed corresponding to that location in the next stage, the density of the developed image will decrease.

What is the difference in developability due to such a difference in image history?

This problem can be resolved by stripping off all remaining toner on the surface of the developing sleeve after the development position and constantly supplying new toner to the entire surface to form a uniform thin coat layer of a predetermined thickness. be able to.

Conventionally, it has been proposed to use a mechanical scraper blade in contact with the developing sleeve as a method for stripping off the residual toner after development on the developing sleeve and constantly supplying fresh toner. .

However, in the above conventional method using a mechanical scraper blade, the surface of the developing sleeve and the contact portion of the scraper are worn out because the scraper blade strongly rubs the developing sleeve.

As a result of damaging the toner and causing a scrape spring, or locally adding a strong tribo to the toner with a good scrape spring, the image may be
Defects such as black lines and white lines may occur.

The present invention removes residual toner after development on the surface of the developing sleeve, and in the next stage of development, supplies new toner to all of the above surfaces, thereby eliminating the difference in history between images and non-images. The purpose of the present invention is to provide a developing device that solves this problem.

[Means for Solving the Problems] According to the present invention, the above objects include: a developer storage container which partially has an opening and stores a one-component developer; A developing device including a developer carrier that supports and transports the developer on its surface.

a first developer stripping means disposed facing the developer carrier in contact with or not in contact with the developer storage container and provided with an electric field generating means; and a developed image on the surface of the first developer stripping means. a second developer stripping means for stripping off the developer, and the developer carried on the developer carrier is located at a galvanometric position in the moving direction on the surface of the developer carrier than the first developer stripping means. This is achieved by disposing a charge applying means for applying a charge to.

[Function] According to the present invention, the first developer stripping means is provided with an electric field generating means and is disposed opposite to the developer carrier, and the developing agent is developed by the potential difference between the first developer stripping means and the developer carrier. The developer on the developer carrier is attracted to the first developer stripping means by the action of the electric field, and is stripped from the developer carrier. Therefore, even if the first developer stripping means is disposed at a distance from the developer carrier, it will still strip the developer and will not damage the developer carrier. Further, the developer attached to the first developer stripping means which is rotated by the fixedly disposed second developer stripping means is peeled off from the first developer stripping means, and the developer is transferred to the first developer stripping means. prevents the accumulation of Further, a charge applying means disposed in the direction of movement of the surface of the developer carrier than the first developer stripping means applies a triboelectric charge to the developer by triboelectric charging or the action of an electric field. Since a predetermined amount of triboelectric force is applied to the carried new developer, an image with sufficiently high image density and no blur can be obtained, and toner scattering can be prevented.

[Example] Next, the first to eighth examples and the first to fourth comparative examples of the present invention will be described. Among the above embodiments, only the second embodiment carried out regular development, and the other embodiments carried out reversal development.

First, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2 of the accompanying drawings.
This will be explained using figures.

In FIG. 1, l is a hopper serving as a developer storage container containing a one-component developer, and a developing sleeve 3 serving as a developer carrier is rotatably disposed in an opening 2 of the hopper l. It is set up. A magnetic roller 4 is provided concentrically and fixedly within the developing sleeve 3, and a plurality of magnetic poles N1, N2, N, S, -3, S3 are formed parallel to the longitudinal direction of the circumferential surface. ing. A regulating blade 5 as a developer layer thickness regulating means is attached to the hopper L with a gap gl between the developing sleeve 3 and the hopper L,
A photosensitive drum 6, which serves as a latent image carrying means and is rotatably arranged in the direction of the arrow, has a gap fl1g2 with respect to the developing sleeve 3.

Inside the hopper l, an electrode roller 7 serving as a first developer stripping means is disposed opposite to the developing sleeve 3 so as to be rotatable in the direction of arrow B with a gap g3 between the electrode roller 7 and the developing sleeve 3. Grounded.

Further, one end of a scraper blade 8 serving as a second developer stripping means contacts the electrode roller in the forward direction, and the other end of the scraper blade 8 is attached to the hopper l. The scraper blade 8 may be made of polyethylene terephthalate, urethane rubber, silicone rubber, or the like.

Further, a galvanometric current is applied in the rotational direction of the developing sleeve 3 relative to the position facing the electrode roller 7, and a charge is applied to a position facing the magnetic pole N3 of the magnetic roller 4 fixedly disposed within the developing sleeve 3. An elastic blade 9 serving as a means is disposed such that one end thereof contacts the developing sleeve 3 in the forward direction, and an elastic blade 9 is disposed above the contacting end of the upper valve plate 9 so as to face the magnetic pole N1. The magnetic member IO is arranged so as to.

Next, each of the above-mentioned means will be explained in more detail.

First, the electrode roller rough as the first developer stripping means,
It is extremely effective to use electric field action. That is, an electrode roller 7 is provided that moves in close proximity to or in contact with the developing sleeve 3.

It is preferable to arrange the developing sleeve 3 and the movable electrode roller 7 with a distance between them from the following points.

That is, damage to the developing sleeve 3 and the electrode roller can be easily prevented, and torque can be reduced. In addition,
When the developing sleeve 3 and the electrode roller 7 are in contact with each other, the effect of stripping off the developer becomes greater, and there is an advantage that the voltage applied to the electrode roller 7 can be lowered.
In addition to the increased torque, it is necessary to take care to prevent damage to the developing sleeve 3 and the electrode roller. Therefore, in this case, it is preferable to use an elastic roller as the electrode roller 7 in order to prevent damage to the developing sleeve 3 and the electrode roller rough, and it is preferable to provide a leak prevention layer on the surface of the elastic roller.

Further, the electrode roller 7 is particularly effective in reversal development. That is, in one-reversal development, the latent image potential is generally a dark potential VD in a non-image area, a bright potential VL in an image area, and a developing bias Vbia* between vo and vL, as shown in FIG. The developer on the developing sleeve 3 has the same polarity as the latent image, and the contrast potential in the non-image area is V2''VD Vbi
The repulsive electric field generated by 'am acts, and the image area is developed with a contrast potential v1=Vbi□-vL without being developed.

Here, when the electrode roller 7 is grounded, a voltage of Vl+ia* is applied between the developing sleeve 3 and the electrode roller, and a force is exerted to move the developer on the developing sleeve 3 toward the electrode roller 7.

The potential between the developing sleeve 3 and the electrode roller 7 (Vbt--0
) is larger than the potential between the latent image and the developing sleeve 3 (V-VL). Therefore, if the gap fll1g3 between the developing sleeve 3 and the electrode roller 7 and the gap g2 between the photosensitive tram 6 and the developing sleeve 3 are made the same as shown in FIG. 1, the electric field E between the developing sleeve 3 and the electrode roller 7! is larger than the electric field E2 between the photosensitive tram 6 and the developing sleeve 3, and the developer on the developing sleeve 3, which has received a non-image history, can be stripped off more than when the image history was developed in the developing section. Therefore, the history of images and non-images can be resolved. In this manner, in the case of reversal development, it is possible to ground the electrode roller 7, which eliminates the need for means for applying voltage to the electrode roller 7, thereby improving safety and reducing costs.

The electric field E1 here refers to the DC component of the developing bias applied to the developing sleeve 3 as Vbiag, and the DCQ component of the bias applied to the electrode roller 7 as Vbia.

When, (Vb=a=Vbia*□) 7g3
f) In this case, since the electrode roller 7 is grounded, Vbia*2=0, and El=Vbt-/
It becomes g'l.

The electric field E2 is (Vb, , -V, .g-)/g2 when Visage is the latent image potential in the image area, and since Image=VL when t1 is satisfied, (E
2=Vbra--VL)/g3.

Further, if the means for regulating the gap g3 between the developing sleeve 3 and the electrode roller 7 and the means for regulating the gap g2 between the photosensitive tram 6 and the developing sleeve 3 are used together, the structure is simple and the cost is low.

Further, it is preferable that the electric field E1 at the closest position l between the electrode roller 7 and the developing sleeve 3 be greater than the electric field E2 at the closest position between the developing sleeve 3 and the photosensitive drum 6. Note that when the developing sleeve 3 and the electrode roller 7 are brought into contact with each other via the developer, the electric field E2 becomes extremely large, and a greater developer stripping effect is achieved.

With this configuration, the electrode roller 7 can strip off the developer on the developing sleeve 3 that has received a non-image history more than the developer that is developed in the developing section due to the image history, so it is possible to use any developer. However, it is possible to eliminate the history of images and non-images. That is, it has the advantage that any developer can be used without being limited by the type of developer.

Next, the moving direction of the electrode roller 7 will be explained.

The direction of movement of the electrode roller can be either forward direction or counter direction with respect to the conveying direction of the developer on the developing sleeve 3, but when moving it in the forward direction, the machine speed is lower than when moving it in the counter direction. Although the electrical developer stripping effect is somewhat inferior, the electrical stripping effect is sufficient, and it can be used suitably in that it can easily prevent clogging, spillage, etc. of the developer.

On the other hand, when the electrode roller 7 is moved in the counter direction, the mechanical developer stripping effect is slightly advantageous.
Although it can also serve as a means for suitably supplying the developer to the developing sleeve 3, in order to actually apply it, it is necessary to take measures to prevent clogging, spillage, etc. of the developer.

There are various ways to prevent clogging, spillage, etc. of the developer.1 For example, as shown in FIG. If the area where the developer on the sleeve 3 and the developer on the electrode roller come together and are peeled off is D, then by arranging the opening C above the area, the developer can be peeled off and removed in the area by the action of gravity. Since the developer can be prevented from moving to the opening C, clogging and spilling of the developer can be prevented, and even if a barrier or step is provided between the area and the opening C, A similar effect can be obtained. Alternatively, the developer peeled off and removed from the developing sleeve 3 in the area may be forcibly moved into the hopper 1 by a conveyance means such as a conveyance screw or a packet roller.

Next, the scraper blade 8 as a second developer stripping means
I will explain about it.

By providing the scraper blade 8 that peels off and removes the developer held on the electrode roller 7, the developer on the developing sleeve 3 can be effectively scraped off by the electrode roller 7. Without this, the TL electrode roller would rub against the developing sleeve 3 while holding a large amount of developer, making it impossible to remove the developer on the developing sleeve 3 sufficiently. It is not necessary for this scraper blade 8 to completely strip off the developer held by the electrode roller 7, and even if the electrode roller 7 holds some developer, the developer on the developing sleeve 3 The scraper plate 8 can be set quite roughly. As the scraper plate 8, mechanical means, ? Although there are tE gas means, magnetic means, etc., it is preferable to use a flade as a mechanical means because of its simple structure and low cost. As the blade member, for example, elastic members such as urethane rubber, silicone rubber, and styrene-butadiene rubber, and flexible members such as polyethylene terephthalate, polyethylene, and thin metal plates can be suitably used. The scraper plate 8 may be in contact with the electrode roller 7 in either a counter direction or a forward direction.

Note that the scraper blade 8 may be non-contact. For example, the electrode roller 7 can be
Since it is not necessary to completely strip off the developer held by the electrode roller 7, the tolerance range for the setting of the scraper blade 8 is wide. (It can be done quite roughly). Further, even if scratches occur on the scraper blade 8 and the electrode roller rough due to durability, the developer on the developing sleeve 3 can be sufficiently removed.

Next, the moving speed of the electrode roller will be explained.

If a developing system in which the developing sleeve 3 rotates, the electrode roller 7 is arranged with a gap between the developing sleeve 3 and the electrode roller 7 moving in the forward direction, the electrode roller 7 and the developing sleeve 3 may be moved in the forward direction. There is an appropriate range for the peripheral speed ratio, and the present invention is not limited to this range.
100% is preferable, and 30 to 10% is more preferable.

If the circumferential speed ratio is small, that is, the relative speed of the electrode roller rough is slow, the image history elimination effect is reduced, and if the circumferential speed ratio is large, that is, the relative speed of the electrode roller rough is high, the torque becomes large and image unevenness is likely to occur. Electrode roller 7 here
The circumferential speed ratio of the developing sleeve 3 is Va/V, eX 100 (%), where the moving speed of the electrode roller 7 is vE and the moving speed of the developing sleeve 3 is v1e. In addition, in the case of a circumferential speed ratio of 100%, the gear configuration can be set to the WJ width, which has the effect of lowering the cost.

As mentioned above, the residual developer on the developing sleeve 3 is stripped off by the electrode roller 7, and the state of the residual visual agent on the developing sleeve 3 is made uniform, and then a new one is used. Although it was possible to eliminate the difference in image history by supplying fresh developer to the developer, the following problems sometimes occurred.

That is, after most or all of the developer on the developing sleeve 3 is once stripped off by the electrode roller 7, fresh developer is newly supplied.

This occurs because the newly supplied developer is subjected to development without being given sufficient triboelectricity.

There were problems such as (1) somewhat low image density, (2) background fog, and (3) developer scattering. In particular, in a developing device with a small and simple configuration, the area (time) in which the newly supplied developer comes into contact with the developing sleeve 3 is reduced, so the above problem becomes more noticeable.

In order to solve these problems, it is necessary to place the developer on the downstream side of the electrode roller in the direction of conveyance of the developer on the developing sleeve 3, and on the upstream side of the regulating means for regulating the thickness of the developer coat layer. A charge applying means for applying electric charge may be provided.

As the above-mentioned four charging means, a method of imparting an electric charge to the developer by frictional charging, a method of charging the developer by an electric field, a method of injecting an electric charge into the developer by an electric field, etc. can be applied. To explain a method using frictional charging, for example, a method in which a frictional charging member such as an elastic blade, a fur brush, or an elastic roller is rubbed against the developing sleeve 3 can be applied to a wide range of developers. Among these, it is preferable to use an elastic blade because of its simple structure and low cost.

Urethane rubber, silicone rubber,
A member having elasticity such as styrene butadiene rubber, a member having flexibility such as polyethylene terephthalate, polyethylene, or a thin metal plate can be suitably used. It does not matter whether the above-mentioned tolade contacts the developing sleeve 3 in the counter direction or in the forward direction.Furthermore, when a magnetic developer is used, there is a method using the action of a magnetic field as a charge imparting means. 6 For example, a fixing member such as magnetic trude is arranged with a gap maintained between it and the developing sleeve 3, and the developer is rubbed by the conveying force of the developer and the restraint force by the magnetic field, thereby triboelectrically charging the developer by frictional electrification. A method of imparting electric charge can be preferably applied.

Similar effects can be obtained by using a rotating member instead of the fixed member. As a simple charge applying means, an alternating magnetic field generating means is provided in the developing sleeve 3, and by rotating the ears of the developer of the developing sleeve 3F, the developer is rubbed against the developing sleeve 3, and by frictional charging. In a method of imparting a triboelectric charge to the developer, or in a developing device in which the developing sleeve 3 is arranged to rotate, a magnetic field generating means is fixedly disposed inside the developing sleeve 3 between the 'Itc pole low top and the rough plate 5. (In this case, the strength of the magnetic field generating means is preferably 500 G or more as the magnetic flux density on the developing sleeve 3.) However, these two methods are compared with others. However, since the charge imparting effect is somewhat inferior, it is preferable to use it in combination with other means.

Next, we will explain the method of charging the developer using an electric field as the four charging means.
As is known in the art, a method of arranging an electrode with a gap between it and the developing sleeve 3 and applying an alternating electric field to charge the developer can be applied. A method of arranging an electrode roller and charging the developer using direct fi, an electric field, an alternating electric field, or both can be applied.

Next, as an example of a method of injecting charge into the developer using an electric field as a charge imparting effect, a side electrode is placed close to the developing sleeve 3 and in contact with the developer, and a voltage is applied to this needle electrode. There is a method of directly applying voltage to the developer. In this case, the volume resistance of the developer is preferably IQIOΩ·C11 or less.

Next, the operation of the apparatus of this embodiment will be explained using FIG.

When the developing sleeve 3 receives a driving force from a driving source (not shown) and rotates in the direction of arrow E, the developer is restrained on the developing sleeve 3 by supporting forces such as magnetic force and electrostatic force. It is conveyed in the direction of arrow E by the rotation of , and is coated in a constant layer thickness by the regulating plate 5 . This applied developer is applied to the photosensitive drum 6 on the surface facing the photosensitive drum 6.
The latent image pattern is transferred to the latent image surface by electrostatically jumping or elongating the gap g2 in accordance with the upper latent image pattern, and is subjected to development. The residual developer on the developing sleeve 3 after being developed and the developer remaining on the developing sleeve 3 without being developed are completely or mostly removed by the electrode roller rough, and the amount of residual developer on the developing sleeve 3 is reduced. are almost the same in both cases. Thereafter, new developer is supplied onto both areas of the developing sleeve 3 from within the hopper 1 in the same manner.

The supplied developer is rubbed by the developing sleeve 3 and the elastic blade 9 to be given a sufficient triboelectric charge, and then the thickness of the developer layer is similarly regulated by the regulating blade 5 on both sides and used for development.

In this way, since the history of one image and non-image is resolved, it is subjected to development, so an image with no difference in image history can be obtained, and the developer on the sleeve has sufficient triboelectric charge, so the image density can be improved. A sufficiently high fog-free image can be obtained and toner scattering can be prevented.

On the other hand, the developer on the electrode roller 7 is conveyed in the direction of arrow B by the rotation of the electrode roller 7, and the developer on the scraper blade 8
It is peeled off and removed. The electrode roller 7 holding the small amount of developer that has been peeled off and removed effectively peels off and removes the developer on the developing sleeve 3 by the action of an electric field on the opposing surface of the developing sleeve 3 .

Next, an example of an experiment conducted using the apparatus of this embodiment will be explained.

In this experimental example, the dark potential VD is -700V and the bright potential is VD.
L is set to -130V and the frequency to developing sleeve 3 is 1800H.
z, an alternating electric field with an amplitude of 1600 V was applied, and a DC bias of -480 V was superimposed.

The photosensitive drum 6 has a diameter of 80 mg*, the developing sleeve 3 has a diameter of 32 mm, and the diameter of the developing sleeve 3 is 8 mm. g2:1
00 grs, the gap g3 between the developing sleeve 3 and the electrode roller 7 is 300 gta, and the circumferential speed of the photosensitive drum 6 is 2.
]1 am/sec, the circumferential speed of the developing sleeve 3 is 211 am
/sec, the peripheral speed ratio of the electrode roller 7 and the developing sleeve 3 is set to 0.2 to 1.5, and a black band image (image history part) and a white band image (non-image history part) are formed in the advancing direction, After copying 30 sheets, we formed a single character image and a halftone image, and examined whether there was a difference in the images due to the history difference between images and non-images.We found that the peripheral speed ratio between the developing sleeve 3 and the electrode roller 7 was 0
．． In case 2, although there was a slight difference in image density in the halftone image, it was at an acceptable level, and there was almost no difference in the character image. When the circumferential velocity ratio was 0.3 or more, there was no difference at all in the halftone image, or even if there was a slight difference, it was not noticeable, and the image was good. However, when the circumferential speed ratio was set to 1.5, although it had the effect of eliminating the history difference between images and non-images, image unevenness occurred when several dozen sheets were subsequently subjected to a durability test. When the circumferential speed ratio is set to 1.5, it is necessary to take measures to reduce the torque and to provide means for preventing image unevenness by increasing the outer diameter of the electrode roller rough. These above images are
The image density was sufficiently high and there was no fog. In addition, in the durability test of several dozen sheets, there was no toner scattering and the results were good.

Note that in this embodiment, since the electrode roller 7 is used while being grounded, there is no need for a special means for applying voltage to the electrode roller, which also has the effect of improving safety and reducing costs. Table 1 shows an example of the circumferential speed ratio of 0.4, representing the results from the north.

Next, a comparison between this embodiment and other devices will be explained. Note that the first comparative example is an attempt made by the present applicant, and although it is not a conventional device, it is compared in order to explain the present invention.

(First Comparative Example) As shown in FIG. 3, this comparative example shows a case where the elastic plate 9 and magnetic member 10 of this example are not provided. Other conditions were the same as in the first example, and images were formed with no difference in image history as shown in Table 1.
Although the image density is at an acceptable level, the image density is somewhat low.
There were some images with some fogging. It should be noted that this was also at an acceptable level, and due to durability, the amount of toner scattering was slightly higher than in the first example.

(Second Comparative Example) In this comparative example, as shown in FIG.
A conventional device without the scraper plate 8, elastic blade 9, and magnetic member 10 was used.

Other conditions were the same as in the first example, and image formation was performed in the same manner as in the first example. As shown in Table 1, in the conventional apparatus, there was a noticeable difference in image density due to the difference in image history, and a difference in character images. was also noticeable, making the image difficult to see.

In one comparative example, in the conventional device, the image density was higher in the image history area than in the non-image history area, and the characters were thicker.

(Third Comparative Example) This comparative example is as shown in FIG.
and a scraper blade 81 A conventional device was used in which the elastic blade 9 and the magnetic member 10 were not provided, and a scraper 11, which is a mechanical removal means, was provided instead. When images were formed under the same conditions as in the first example, the difference in image history was almost eliminated as shown in Table 1, but the developing sleeve 3 was worn out due to durability, and the surface shape of the developing sleeve 3 The image quality will change due to the change in image quality, and in low temperature and low humidity environments (15
(°C 110%), uneven images may occur, and the scraper may wear out, resulting in poor scraping springs and black lines and self-streaks on the image. Furthermore, when the developer on the developing sleeve 3 is peeled off and removed using a scraper, the scraped developer is retained and the developer is prevented from agglomerating. There was a slight difference in density in the halftone image without a window.

(Fourth Comparative Example) In this comparative example, as shown in FIG. 6, an apparatus without the elastic blade 9, magnetic member 10, and scraper plate 8 of this example was used. When one image was formed under the same conditions as in the first example, the difference in image history was remarkable as shown in Table 1, and the image was difficult to see. At this time, the electrode roller 7 continued to hold a large amount of developer. Namely.

This is considered to be because the electrode roller 7 was still holding too much developer, so that the electrode roller 7 could not sufficiently strip off the developer that had received the image history on the developing sleeve 3.

Next, a second embodiment of the present invention will be described using FIG. 7. The same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

In this embodiment, the present invention is applied to a copying machine that performs regular development, and since a negatively charged photoreceptor is used, a positively charged developer is used as the developer, and the developer is transferred to the developing sleeve 3. Frequency: 1800Hz, vibration@
This embodiment differs from the first embodiment in that -:100V DC is superimposed on the 160Ov alternating electric field, and -AOOV DC bias is applied to the electrode roller 7. When images were formed using the stirrup of this example in the same manner as in the first example, similar effects were obtained as shown in Table 1.

Next, a third embodiment of the present invention will be described using FIG. 8. The same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

This embodiment differs in that a rotary brush t2 is rotatably fixed to the hopper 1 instead of the elastic plate 9 and magnetic member 1 of the first embodiment as charge applying means. As the rotating brush, both magnetic and non-magnetic members can be used. For example, the magnetic member is a magnetic roller (which may hold magnetic particles on the surface), and the non-magnetic member is a fur brush, a metal flange, etc. I can do it. Other conditions were the same as in the first example, and image formation was carried out.
As shown in Figure 1, the same effects as in the first example were obtained.

Next, a fourth embodiment of the present invention will be described using FIG. 9. The same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

This embodiment differs in that a magnetic blade 13 is fixed to the hopper l while maintaining a distance from the developing sleeve 3 instead of the elastic plate 9 and magnetic member 10 of the first embodiment as a charge applying means. is substantially opposed to the magnetic pole N3 of the magnet roller 4 in the developing sleeve 3. Other conditions were the same as in the first example, and image formation was carried out.
As shown in Example 1, the same effects as in the first example were obtained. In this embodiment, the same effect can be obtained even if the magnetic plate is arranged parallel to the developing sleeve 3 as shown at 13 degrees in FIG.

Next, a fifth embodiment of the present invention will be described using FIG. 1O.

The same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

This embodiment is different in that an auxiliary electrode roller 14 as an electric field generating means is rotatably fixed to the hopper l instead of the elastic flade 9 and magnetic member lO of the first embodiment as a charge applying means; An alternating electric field is applied to the electrode roller 14. Other conditions were the same as in the first example and image formation was carried out. As shown in Table 1, the same effects as in the first example were obtained. In this embodiment, even if an auxiliary electrode 14° is provided instead of the auxiliary electrode roller, similar effects can be obtained.

Next, a sixth embodiment of the present invention will be described using FIG. 11.

The same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

In this embodiment, instead of the elastic plate 9 and the magnetic member 10 of the first embodiment as charge applying means, a needle electrode 15 as an electric field generating means is arranged so as to be in contact with the toner on the developing sleeve 3. Also, as a developer, volume resistivity or 10aQ
The difference is that a non-magnetic developer of C1 is used and a non-magnetic developing sleeve is used instead of the developing sleeve 3 having a magnet roller 4 disposed inside. When image formation was carried out under the same conditions as in the first example, the same effects as in the first example were obtained as shown in Table 1.

Next, a seventh embodiment of the present invention will be described using FIG. 12.

The same reference numerals are given to the same parts as in the first embodiment, and the explanation thereof will be omitted.

This embodiment uses an elastic electrode roller 1 whose surface is coated with an insulating film instead of the electrode roller rough of the first embodiment as the first developer stripping means.
The elastic electrode roller 16 is different from the developing sleeve 3 in that it is disposed in contact with the developing sleeve 3, and the elastic electrode roller 16 rotates in a counter direction, that is, in the force direction of arrow B' in the figure. When image formation was carried out under the same conditions as in the first example, the same effects as in the first example were obtained as shown in Table 1.

Finally, an eighth embodiment of the present invention will be described using FIGS. 13 and 14. Regarding the parts common to the first to seventh embodiments, I? The symbol ir- is given and the explanation is omitted.

This embodiment differs in that the first developer stripping means is arranged above the opening C of the hopper rather than the area where the developer on the developing sleeve 3 is to be stripped. In this embodiment, the same effect as in the other embodiments is obtained, and furthermore, the developer peeled off from the developing sleeve 3 moves downward according to the action of gravity and the conveying force of the electrode roller 7 or the elastic electrode roller 16. Because of the movement, the developer does not clog the opening C between the developing sleeve 3 and the hopper 1, and the developer does not spill out from the opening C. The developer that has moved downward is stirred and mixed by a stirring means (not shown), then pumped up, conveyed onto the electrode roller 7 or the elastic electrode roller 16, and then supplied and conveyed to the developing sleeve 3.

In addition, in the above-mentioned embodiment, the case where the scraper blade 8 is brought into contact with the electrode roller rough in the forward direction has been explained, but the scraper blade 8 may be brought into contact with the counter in one direction, and the scraper blade 8 Instead, an electrode roller, magnetic roller, etc. may be used.

In addition, although an example is shown in which the electrode roller 7 is arranged at a position facing the magnetic poles of the magnetic roller 4, it is preferable that the electrode roller 7 is placed opposite between the poles because the effect of stripping off the developer is large, and it is more preferable that the electrode roller 7 is placed opposite the magnetic pole of the magnetic roller 4. .

Further, as the developer layer thickness regulating means, a regulating plate using magnetic cutting is shown as an example, but an elastic blade may also be used.

Furthermore, an insulating member may be provided on the surface of the electrode roller or the developing sleeve in order to prevent leakage between the electrode roller and the developing sleeve. In the above embodiments, a cylindrical sleeve was used as the developer carrier, or an elastic belt roller or the like may be used, and a cylindrical electrode roller was used as the electric field generating means. Needless to say, a belt or the like may be used.

Furthermore, although an example has been described in which a direct current is superimposed on an alternating electric field as a developing bias, the present invention can also be applied to a case where only a direct current electric field is used as a developing bias. In addition, the developer on the developer carrier is not in contact with the latent image carrier, and electrostatically jumps or Nakafi, J! I! Although an example has been described in which development is carried out by moving the latent image holding means, the invention can also be applied to a case in which development is carried out by bringing the developer of the developer carrier into sliding contact with the latent image holding means.

(Below↑゛margin) [Advantageous Effects of the Invention 1 According to the present invention, the first developer stripping means is equipped with an electric field generating means, so that it can be disposed at a distance from the developing sleeve. Since an elastic body is used when making sliding contact with the developing sleeve, there is no damage to the surface of the developing sleeve.
Moreover, due to the action of the electric field, it is possible to obtain a greater peeling effect than in the past.

Further, the first developer stripping means is rotatably disposed, and a second developer stripping means is provided on the surface of the first developer stripping means. Since the first developer stripping means is provided, the developer does not adhere to the surface of the first developer stripping means, and as a result, it is possible to maintain a high stripping effect. Moreover, since sufficient triboelectricity can be applied to the developer by the charge applying means, the developer newly carried on the developing sleeve will not suffer from insufficient triboelectricity. Therefore, even during long-term use, the present invention can provide images with no fog and uniform image density, and in particular can clearly reproduce halftone images and character images.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of the device according to the first embodiment of the present invention, FIG. 2 is a diagram illustrating the latent image potential of the device according to the first embodiment of the present invention, and FIG.
The figure is a vertical cross-sectional view of a first comparative example device of the present invention, FIG. 4 is a vertical cross-sectional view of a second comparative example device of the present invention, and FIG. 5 is a vertical cross-sectional view of a third comparative example device of the present invention. 6 is a vertical cross-sectional view of a fourth comparative example device of the present invention, FIG. 7 is a vertical cross-sectional view of a second example device of the present invention, and FIG. 8 is a vertical cross-sectional view of a third example device of the present invention. FIG. 9 is a vertical cross-sectional view of a device according to a fourth embodiment of the present invention, FIG. 10 is a vertical cross-sectional view of a device according to a fifth embodiment of the present invention, and FIG. 11 is a vertical cross-sectional view of a device according to a sixth embodiment of the present invention. FIG. 12 is a longitudinal cross-sectional view of a device according to a seventh embodiment of the present invention, and FIGS. 13 and 14 are longitudinal cross-sectional views of a device according to an eighth embodiment of the present invention. 1-・・・・・・・・・・Developer storage container (hopper)
2......Opening 3...Developer carrier (developing sleeve) 7......No. 1. Developer stripping means (
Electrode roller) 8...Second developer stripping means (scraper parallelade)

Claims (4)

[Claims] (1) A developer storage container that partially has an opening and stores a one-component developer, and a developer carrier that is disposed in the opening and carries and transports the developer on its surface. A developing device comprising: a first developer stripping means disposed facing the developer carrier in contact with or not in contact with the developer carrier in the developer storage container, and comprising an electric field generating means; and a second developer stripping means for stripping off the developer on the surface of the developer stripping means, the developer is placed at a galvanometric position in the moving direction on the surface of the developer carrier than the first developer stripping means. A developing device comprising: a charge applying means for applying a charge to a developer carried on a carrier. (2) The developing device according to claim 1, wherein the charge applying means is a member that slides on the surface of the developer carrier and applies a charge to the developer by frictional charging. (3) According to claim (1), the charge applying means is an electric field means disposed facing the developer carrier without contact with the developer carrier and having a predetermined potential difference between it and the developer carrier. developing device. (4) Claim (4) wherein the electric field generating means is disposed at a position where it comes into contact with the developer carried on the developer carrier.
The developing device according to 3).