JPH06110312A - Image forming device - Google Patents

Abstract

PURPOSE:To provide a small-sized image forming device having a simple structure and capable of obtaining a precise image of high image quality. CONSTITUTION:The device is provided with a latent image holding body 1 which is moved while holding the electrostatic latent image on its surface, a magnetic field forming means 2 enclosed in the latent image holding body 1, forming a magnetic field on at least the part of the surface of the latent image holding body 1 where magnetic developer is directly supplied and attracting, restraining and holding the magnetic developer 10 on the surface of the latent image holding body 1 by a magnetic field to supply the developer onto the surface of the latent image holding body 1, an electrostatically charging means arranged at a position opposite the surface of the electrostatic latent image holding body 1 at a prescribed interval, an electric power supply 6 by which an alternating field is formed between the electrostatic charging member 5 and the latent image holding body 1 and the magnetic developer 10 which is attracted, restrained and held on the surface of the latent image holding body 1 by the magnetic field of the magnetic field forming means 2 and carried in a prescribed space is vibrated in the space to be electrostatically charged on the latent image holding body 1, and developer recovering means 7, 8 and 9 for recovering the magnetic developer 10 sticking to the non-image part of the electrostatic latent image on the surface of the latent image holding body 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus applicable to printers, copying machines, facsimiles and the like.

[0002]

2. Description of the Related Art Conventionally, as image forming methods, there are a cascade developing method, a touchdown developing method, a jumping developing method and the like.

Various improvements have been added to all of these for the purpose of improving the reproducibility and sharpness of images.

A developer supplying member (hereinafter, referred to as a developer carrying member) for carrying and supplying a developer has been arranged facing the latent image holding body at a constant interval. Development is carried out by applying an appropriate developing bias voltage between the carrier and the latent image carrier.
As shown in Japanese Patent Publication No. 63-42256, an AC jumping developing method in which an AC bias is superimposed on a DC bias has been put into practical use.

In this conventional AC jumping developing method, due to the alternating current component of the developing bias applied between the developer carrying member and the latent image holding member, the developer carrying member and the latent image holding member are opposed to each other in the developing section. An AC electric field is formed, and by this AC electric field, the developer carried on the developer carrying body reciprocates between the developer carrying body and the latent image holding body, and by this reciprocating movement, the electrostatic latent image The image portion of the electrostatic latent image is attempted to be precisely developed by sequentially adhering to the image portion.

[0006]

However, the conventional AC
In the jumping developing method, a developer carrier is used, a developer layer is formed on the developer carrier, the developer is charged on the developer carrier, and the developer is charged from this charged developer layer by AC jumping. Since it is moved to the latent image carrier, it is necessary that the thickness of the developer layer is uniform in order to perform uniform charging, and the potential corresponding to the light and darkness of the image portion on the surface of the latent image carrier. The thickness of the developer layer is required to be uniform in order to move the developer accurately in accordance with the change. Therefore, in order to perform faithful development, an extremely uniform developer layer on the developer carrier. However, there is a problem in that it is indispensable to form the structure, and a process and a precise control mechanism are necessary to achieve this.

Further, in the conventional AC jumping developing method using the developer carrying member, as shown in FIG.
For example, with respect to a solid image, the hole portion 1 of the developer layer 103 generated by moving from the developer layer 103 to the latent image holding member 102 side.
06 is a mechanism for, when re-attaching the developer on the developer layer 103, this re-attachment causes the developer 100 to be attached in a layered manner by the blade 107, so that only the hole portion 106 is completely filled with the hole portion 106. A large amount of the developer cannot be reattached, and even after the developer layer 103 is reattached, it remains as a hysteresis hole 104, and the developer layer thickness becomes thin at the hysteresis hole 104 portion. There is a problem of a sleeve ghost phenomenon in which the amount of the developer in the image portion that has undergone the movement becomes insufficient, the insufficient portion 105 occurs, and the insufficient portion 105 appears as an afterimage of the previous image in the current image.

Further, since the developer carrying member is electrically conductive, the charged electric charge of the developer carried on the developer carrying member and conveyed easily leaks through the developer carrying member during the carrying process by the developer carrying member. .

The developer loses its charge due to such a leak, and the charge of the developer becomes insufficient at the stage of being used for development, or the charge becomes nonuniform. Not achieved as set, the developing performance is reduced.

The leakage of the charged electric charges becomes more remarkable as the environmental humidity becomes higher, and the charging performance on the developer carrying member is greatly affected by the environment and the stability is lacking.

Further, the supply of the developer to the latent image carrier by the developer carrier and the developing action are limited to a very short time when the developer carrier faces the latent image carrier, so that the developing efficiency is improved. Is bad, and it is difficult to cope with recent speedups.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming method and an image forming apparatus which solve the above problems and have a simple structure, a small size and a high quality image with high precision.

[0013]

In order to solve the above-mentioned problems, an image forming apparatus of the present invention includes a latent image holding member that holds an electrostatic latent image on its surface and moves, and a latent image holding member. A magnetic field is formed in at least a portion of the latent image carrier that is directly supplied to the surface of the latent image carrier, and the magnetic field is attracted and restrained to hold the magnetic developer on the surface of the latent image carrier and the latent image is formed. Magnetic field forming means for supplying onto the surface of the holding body, a charging member arranged at a position facing the surface of the latent image holding body with a predetermined gap, and an alternating electric field is formed between the charging member and the latent image holding body. Then, the alternating electric field vibrates the magnetic developer, which is attracted and restrained on the surface of the latent image holding member by the magnetic field of the magnetic field forming means and carried into the predetermined gap, to vibrate in the predetermined gap, and thus the latent image is formed. An electric field power source to be charged on the holding body, and the latent image holding body And having a developer collecting means for collecting the magnetic developer adhering to the non-image portion of the electrostatic latent image of the surface.

Further, in the image forming apparatus of the present invention, in order to solve the above-mentioned problems, the magnetic field forming means forms a magnetic field in a predetermined gap where the charging member and the latent image holding member face each other, thereby magnetically It is preferable that the developer is sucked and restrained on the surface of the latent image holding member to pass through the predetermined gap, and that the magnetic developer is prevented from being scattered by a vibration for charging in the predetermined gap. .

In the image forming apparatus of the present invention, in order to solve the above-mentioned problems, the magnetic field forming means forms a magnetic field in a predetermined gap where the charging member and the latent image carrier face each other and in the front and rear portions thereof. In this way, the magnetic developer is suction-restrained and held on the surface of the latent image holding body to pass through the predetermined gap, and the magnetic developer is prevented from being scattered by the vibration for charging in the predetermined gap. Is preferred.

Further, in the image forming apparatus of the present invention, in order to solve the above-mentioned problems, the magnetic field forming means applies the magnetic developer, which has passed through a predetermined gap where the charging member and the latent image carrier face each other, to the latent image. It is preferable that the image is held by suction on the surface of the image carrier and supplied to the position of the developer collecting means.

[0017]

In the image forming apparatus of the present invention, the magnetic developer is attracted and restrained by the magnetic field to supply the magnetic developer to the electrostatic latent image, and the magnetic developer is charged on the surface of the latent image carrier, Finally, the magnetic developer adhered to the non-image portion is recovered from the magnetic developer supplied to the entire surface of the electrostatic latent image, and has the following action.

The developer supplying means forms a magnetic field at a position where the magnetic developer is supplied to the surface of the latent image holding member, and this magnetic field attracts and holds the magnetic developer from the developer reservoir to hold the magnetic developer. The developer is directly supplied to the electrostatic latent image on the surface of the latent image carrier.
Since this supply supplies a large amount of developer to the entire surface of the electrostatic latent image, even if the supply amount is not particularly controlled, a sufficient amount of developer can be retained to eliminate uneven developer supply or insufficient supply. It has the effect of supplying and mounting it on the front surface of the electrostatic latent image on the body surface.

When the magnetic developer is supplied to the entire surface of the electrostatic latent image on the surface of the latent image holding member by the developer restraining force of the magnetic field, it is possible to stabilize the supply of the magnetic developer.
Even if the direction of supplying the magnetic developer is a direction against the action of gravity, sideways or slightly obliquely downward, the developer can be stably supplied.

In this way, after a sufficient amount of the developer has been placed on the latent image carrier, the developer is charged on the latent image carrier by the charging member and the electric field power source, and finally, the surface of the latent image carrier is cleaned. Since the developer adhering to the non-image portion of the electrostatic latent image is collected, the developer is placed on the surface of the latent image holder and then adhered to the non-image portion of the electrostatic latent image on the surface of the latent image holder. The developer is brought into contact with the electrostatic latent image for a long time until the developer is collected, and the electrostatic latent image is a solid image with a large area or a fine fine line image in which the developer is hard to adhere due to the wraparound of the electric field. However, due to the effect of charging the developer by mounting it, the electrostatic latent image can be faithfully developed and the developer only in the non-image portion can be collected.

Further, the magnetic field forming means uses the magnetic field to
Since the magnetic developer is always held by suction and restrained, it is excellent in earthquake resistance and transport resistance, and even if the device is transported or moved, the magnetic developer is not biased to one side. Images can be output, and operations such as idling of the developer to correct the bias of the magnetic developer are unnecessary.

Further, the magnetic field forming means uses the magnetic field to
Since the magnetic developer is sucked onto the surface of the latent image carrier and supplied, even if the fluidity of the magnetic developer changes in a high humidity environment, a defective supply of the magnetic developer does not occur, so it is always stable. A high quality image can be obtained.

A charging member and an electric field power source that forms an alternating electric field in a predetermined gap between the charging member and the latent image carrier are attracted and restrained by the magnetic field of the magnetic field forming means on the surface of the latent image carrier. The magnetic developer is vibrated in a predetermined gap between the charging member and the latent image holding member, and the magnetic developer is charged by colliding with the charging member or the latent image holding member or by colliding the magnetic developers with each other. To do. An uncharged or slightly charged developer is used as the magnetic developer. Even with uncharged magnetic developers, some of them are manufactured.
Since the magnetic developer is slightly charged due to mutual friction during transportation, the slightly charged magnetic developer becomes a starting point of vibration, and the uncharged magnetic developer vibrates and is charged accordingly. Then, by this charging, the developer is charged to a prescribed amount of charge on the surface of the latent image holding body having high insulation, and
The charge of the developer is unlikely to leak and the charging efficiency is good, and the charged developer immediately acts on the development of the electrostatic latent image on the surface of the latent image carrier, and the development efficiency of the charged charge is good. By this, even in an environment where the charge of the developer easily leaks at high temperature and high humidity, the influence of the leak is extremely small, and the effect of the specified amount of the charged charge reliably acts on the development, and the development and transfer of high resolution can be performed. Stabilization becomes possible.

When the toner is charged by vibration, the developer can be charged without disturbing the electrostatic latent image on the surface of the latent image holding member, and the developer is scattered by the vibration of the developer during charging. However, since it is in the developer reservoir, it does not leak outside.

Further, the vibration not only disperses the agglomerates of the developer, but also causes the developer to move on the surface of the latent image carrier so that the amount thereof is uniformly distributed on the surface of the latent image carrier. Since the charged developer contacts the electrostatic latent image on the surface of the latent image carrier for a long time, an excellent image faithful to the electrostatic latent image can be obtained.

The developer collecting means collects the developer supplied to the electrostatic latent image on the surface of the latent image holding member and adhering to the non-image portion.

Further, in the image forming apparatus of the present invention, the magnetic field forming means forms a magnetic field in a predetermined gap where the charging member and the latent image holding member face each other, so that the magnetic developer is applied to the latent image holding member. Since the magnetic flux passes through the predetermined gap while being held by suction on the surface, the magnetic developer does not scatter due to vibration when the magnetic developer is charged by vibrating within the predetermined gap, and A stable amount of the magnetic developer charged through the predetermined gap is secured.

Further, in the image forming apparatus of the present invention, the magnetic field forming means forms a magnetic field in the predetermined gap where the charging member and the latent image holding member face each other, and in the front and rear portions thereof.
Since the magnetic developer is suction-constrained and held on the surface of the latent image carrier in a wide range and passes through the predetermined gap, when the magnetic developer is vibrated and charged in the predetermined gap,
The magnetic developer is further prevented from being scattered by vibration, and the amount of the magnetic developer charged through the predetermined gap is more stably secured.

Further, in the image forming apparatus of the present invention, the magnetic field forming means passes through a predetermined gap between the latent image holding member and the charging member, vibrates in the predetermined gap, and the charged developer is charged again with the latent image. It is possible to supply the developer to the position of the developer collecting means that holds the developer on the surface of the holding body by suction and holds it, and collects the developer attached to the non-image portion, and stabilizes the supply of the developer.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic structure of the image forming apparatus of the present invention will be described with reference to FIG.

In FIG. 2, an electrostatic latent image is held on the magnetic developer 10 in the developer reservoir 10 ′ by the attraction force of the magnetic field formed by the first magnetic field forming means 2 in the developer supplying step of this apparatus. It is directly supplied to the entire surface of the electrostatic latent image on the surface of the latent image holder 1 that is moving. The supplied magnetic developer 10 is the first
Due to the attraction force of the magnetic field formed by the magnetic field forming means 2, the latent image holder 1 moves in a state of being attracted and restrained on the entire surface of the electrostatic latent image. According to this supply method, the amount of developer required for development can be reliably supplied to the entire surface of the electrostatic latent image, and the defective development caused by the shortage of the developer supply amount in the conventional technique can be eliminated.

In the charging step, there is a charging member 5 arranged on the latent image carrier 1 with a predetermined gap, and the second electric field power source 6 generates a DC electric field between the charging member 5 and the latent image carrier 1. An AC electric field is formed, and the magnetic developer 10 is supplied to the entire surface of the electrostatic latent image on the surface of the latent image holder 1 and is attracted and held by the attraction force of the magnetic field formed by the first magnetic field forming means 2. ,
The electrostatic latent image is carried into the predetermined gap, vibrated by an AC electric field and charged, and is held by the DC electric field on the entire surface of the electrostatic latent image on the surface of the latent image holder 1. In this charging step, since the surface of the latent image carrier 1 having a high insulating property is charged, the leakage of the charged electric charge is small, and the electric charge of the charged magnetic developer 10 causes the electrostatic latent image on the surface of the latent image carrier 1. By acting on the image immediately, the development efficiency of the charged electric charge is good, and the vibration of the magnetic developer during charging makes the distribution of the magnetic developer on the electrostatic latent image uniform, and Charged magnetic developer 10
Is continuously in contact with the electrostatic latent image on the surface of the latent image holding member 1 until the developer is collected, so that even a fine line image of extremely fine line can be faithfully developed without fog or insufficient development.

In the developer collecting step, there is a developer collecting member 7 arranged on the latent image carrier 1 with a predetermined gap, and a third electric field is provided between the developer collecting member 7 and the latent image carrier 1. The power supply 8 forms a DC recovery bias and an AC recovery bias,
The second magnetic field forming unit 9 forms a magnetic field, and the attracting force of these collecting bias and magnetic field collects the developer adhering to the non-image portion of the electrostatic latent image on the surface of the latent image carrier 1. .

Next, the construction of an embodiment of the image forming apparatus of the present invention, which is a more concrete form of the basic construction of FIG. 2, will be described with reference to FIG. In FIG. 1, the same components as those in FIG. 2 are given the same numbers.

Referring to FIG. 1, in the image forming apparatus of this embodiment, the latent image holder 1 contains the first magnetic field forming means 2 composed of a fixed magnet and is formed by the electrostatic latent image forming optical system 19. It moves while holding the electrostatic latent image. The developer collecting member 7 facing the latent image carrier 1 with a facing gap of about 350 μm formed of a fixed magnet and including the second magnetic field forming means 9 facing the first magnetic field forming means 2 includes the latent image holding means 9. It rotates in the same direction as the image carrier 1. A third electric field power source 8 that forms a direct current recovery bias and an alternating current recovery bias between the developer recovery member 7 and the latent image holding member 1 is connected to the developer recovery member 7. It is composed of a combination of an AC power supply and a DC power supply. In order to directly supply the developer 10 to the surface of the latent image holding member 1 on the upstream side as viewed from the latent image holding member 1 side in the vicinity of the latent image holding member 1 and the developer collecting member 7, The developer pot 10 ′ is attached so that the developer 10 inside forms a developer reservoir 11 in the vicinity, and the developer pot 10 ′ and the developer collecting member 7 are provided with the developer pot 10 ′. Developer 10 on collecting member 7
A scraper 13 for scraping off the developer is provided, and a seal 12 for preventing the developer 10 from leaking is provided between the developer pot 10 ′ and the latent image carrier 1.

In the developer reservoir 11, there is provided a charging member 5 facing the surface of the latent image holding member 1 near the proximity portion with a predetermined gap, and the charging member 5 has the latent member. A second electric field power source 6 for forming a DC electric field and an alternating electric field is connected between the image carrier 1 and the charging member 5, and the second electric field power source 6 is composed of a combination of an AC power source and a DC power source.

A developer supplying electrode roller 3 is provided in the developer reservoir 11 so as to face the latent image holding member 1. The developer supplying electrode roller 3 has a third electric field. The power supply 4 is connected.

On the paper 14, the developer developed on the latent image carrier 1 is transferred by the transfer charger 15 and fixed on the paper 14 by a fixing means (not shown). After the transfer, the latent image holding member 1 is cleaned by the cleaner 16 to remove the developer remaining on the latent image holding member 1, and the eraser 17 removes the potential remaining on the latent image holding member 1. The electrostatic latent image is formed by the electrostatic latent image forming optical system 19.

Next, the operation of this embodiment will be described with reference to FIGS.
It will be described based on.

In FIG. 1, first, an electrostatic latent image is formed on the surface of the latent image holder 1 by the electrostatic latent image forming optical system 19. In this case, the image portion potential and the non-image portion potential are as shown in FIG.
As shown in, the image portion potential is -100V and the non-image portion potential is -500V.

The surface of the latent image holding member 1 on the upstream side of the developer 10 in the developer pot 10 'when viewed from the latent image holding member 1 side in the vicinity of the latent image holding member 1 and the developer collecting member 7. To form a developer reservoir 11 in the vicinity. in this case,
The magnetic developer 10 is connected to the magnetic field of the first magnetic field forming means 2 contained in the latent image carrier 1 and to the developer supplying electrode roller 3 rotating facing the latent image carrier 1. One electric field is applied to the latent image carrier 1 by the electric field of the electric power source 4 to form the developer reservoir 11.

On the surface of the latent image carrier 1 in the developer reservoir 11, an alternating electric field is formed between the latent image carrier 1 and the charging member 5 by the second electric field power source 6 to vibrate the magnetic developer, The magnetic developer 10 may collide with the surfaces of the charging member 5 and the latent image carrier 1 or the magnetic developers 10 may collide with each other.
Charge to μC to −10 μC / g. The charge amount of the developer includes the AC recovery bias and the reciprocating flight force due to the charge amount.
There is a range of −0.5 μC / g to −40 μC / g as a range in which the developer can reciprocate beyond the adhesion of the developer to the latent image carrier due to the image force of the charged electric charge and the intermolecular force. In this embodiment, it is charged to −5 μC to −10 μC / g. A DC electric field may be superposed on this alternating electric field.

When the developer 10 is magnetic, it is shown in FIG. 3 by the magnetic flux formed between the latent image carrier 1 and the developer collecting member 7 by the first magnetic field forming means 2 and the second magnetic field forming means 9. In this way, the magnetic developer 10 is sucked into the facing gap between the latent image holding member 1 and the developer collecting member 7 as magnetic developer spikes 10 ″ to be restrained and held, and in this facing gap, the latent image holding member 1 is held.
Since the surface of the magnetic developer 10 and the surface of the developer recovery member 7 are moving in the opposite directions, the accompanying flow 21 of the magnetic developer 10 is formed. Since the amount of the developer in the magnetic developer chain 10 ″ is maintained at an amount determined by the magnetic flux density, the accompanying flow 21 causes the part of the magnetic developer chain 10 ″ on the latent image carrier side to be carried away. However, the same amount of developer 10 that was carried away is replenished, and there is always a certain amount of developer 10 in the magnetic developer spike 10 ″, and the developer is supplied from the magnetic developer spike 10 ″ for development. The amount of developer to be used is stabilized at a predetermined amount. Then, as shown in FIG. 3, a DC potential of −350 V
By the AC recovery bias in which the alternating rectangular potential of the peak-to-peak voltage of 1500 V is superposed on the magnetic developer 10, the magnetic developer 10 is discharged in the facing gap between the latent image carrier 1 and the developer recovery member 7 as shown in FIG. Reciprocate 22. As the waveform of this AC recovery bias, a sine wave, a triangular wave, a rectangular wave, or the like can be used, but a rectangular wave is preferable because a rectangular wave is efficient. Further, as the peak-to-peak voltage, it is possible to use a range of 500V to 2000V where a good image is obtained and no discharge occurs. Moreover, the frequency is 100 Hz to 10 kHz.
The z range can be used, but the required number of round trips is obtained 5
It is desirable that the frequency is from 00 Hz to 3 kHz where the developer 10 can sufficiently follow the reciprocating motion 22. Then, the accompanying flow 21
By the synergistic effect of the reciprocating motion 22 and the reciprocating motion 22, a circulating flow 23 of the magnetic developer 10 is formed, and a staying portion for circulating the magnetic developer 10 in the facing gap is formed. The AC recovery bias causes the magnetic developer in the staying portion that circulates and stays in the facing gap to reciprocate 22, so that the magnetic developer 10 repeatedly performs reciprocating motion 22, and the uncharged magnetic developer 10 Uncharged magnetic developer 10 even in the presence of
Reciprocally move 22 with the reciprocating motion 22 of the charged magnetic developer 10 to cause mutual friction and the developer collecting member 7.
It can be sufficiently charged by contact with.

Further, the reciprocating motion 22 of the magnetic developer 10 is performed.
By repeating the above, the magnetic developer 10 is dispersed in particles one by one and actively moves, and even if the magnetic developer 1 is not charged and adheres to the non-image portion of the electrostatic latent image, the electric recovery force does not work.
Even if there is 0, flip it to eliminate fog.

Further, the magnetic developer 1 by the AC recovery bias is used.
As shown in FIG. 3, the reciprocating motion 0 of 0 is a negative peak of the alternating rectangular potential of the peak-to-peak voltage of 1500 V in the image portion, and the outward path of the magnetic developer 10 to the image portion is −1100 V. It flies with a potential difference of 1000 V, and at 400 V, which is the peak on the positive side of the alternating rectangular potential, the return path from the image portion of the magnetic developer 10 flies with a potential difference of 500 V, so only one difference between these potential differences occurs in one round trip.
The magnetic developer 10 moves to the image portion and the image formation proceeds, and the peak-to-peak voltage 1500 V is generated in the non-image portion.
At −1100 V, which is the negative peak of the alternating rectangular potential, the outward path of the magnetic developer 10 to the non-image portion flies with a potential difference of 600 V, and the positive peak of the alternating rectangular potential is 400.
At V, the return path from the non-image portion of the magnetic developer 10 is 900
Since the magnetic developer 10 flies with a potential difference of V, the magnetic developer 10 is recovered from the non-image portion by the difference between these potential differences in one reciprocation. However, due to the synergistic action with the above-described repelling action, even a delicate image is accurate without fog. It can be developed.

When the gap between the electrostatic latent image on the surface of the latent image holding member 1 and the developer collecting member 7 becomes large due to the rotation of the latent image holding member 1, the electric field strength is gradually attenuated. As a result, the movement of the magnetic developer 10 is attenuated, and the development is completed.

The surface of the developer collecting member 7 is the latent image holding member 1.
And a magnetic flux extending between the latent image carrier 1 and the developer collecting member 7 facing each other in a direction opposite to the surface of the latent image holding member 1 and the developer collecting member 7. The magnetic developer 10 floating between the latent image carrier 1 and the developer collecting member 7 is easily collected by the developer collecting member 7 and returns to the developer reservoir 11 by the rotation of the developer collecting member 7, The loss of the magnetic developer 10 is small, and the magnetic developer 10 can be prevented from scattering outside.

Further, as shown in FIG. 3, the developer collecting means 7
And the accompanying flow 21 generated by the rotation of the developer collecting means 7 is collected.
The part of the developer 10 that has returned to the magnetic developer chain 10 ″ is the magnetic developer chain 10 ″ part.
It becomes a part of 0 ″ and again the wake 21 of the latent image carrier 1
And is supplied to the circulation flow 23.

Further, in the image forming apparatus of the present invention, as shown in FIG. 5, the position of the first magnetic field forming means 2 contained in the latent image holding member 1 is magnetically arranged on the latent image holding member 1. Developer 10
The magnetic developer 10 is attracted and restrained on the latent image carrier 1 to limit the magnetic developer to the predetermined gap portion even in a portion of the predetermined gap portion facing the charging member 5 and the charging member 5. The supply amount of can be stabilized.

Further, in the image forming apparatus of the present invention, as shown in FIG. 6, the position of the first magnetic field forming means 2 contained in the latent image carrier 1 is set to a predetermined gap facing the charging member 5. Even if it is limited to a portion, the magnetic developer 10 is suction-constrained and held at the predetermined gap portion, the magnetic developer 10 is charged without being scattered, and the amount of the magnetic developer supplied to the predetermined gap portion is increased. Can be stabilized.

Further, in the image forming apparatus of the present invention, as shown in FIG. 7, the position of the first magnetic field forming means 2 contained in the latent image carrier 1 is set to a predetermined gap facing the charging member 5. In the portion and its front and rear portions, the magnetic developer 10 is suction-constrained and held in a wide range on the latent image holding member 1 to charge the magnetic developer 10 without scattering, and to the predetermined gap portion. The supply amount of the magnetic developer can be further stabilized.

Further, in the image forming apparatus of the present invention, as shown in FIG. 1, the position of the first magnetic field forming means 2 contained in the latent image holder 1 is held by the magnetic developer 10 to hold the latent image. From the position where the latent image carrier 1 and the developer collecting member 7 are supplied to the body 1.
When the range up to the position facing the latent image holding member 1 is reached, the developer 10 that has passed through a predetermined gap between the latent image holding member 1 and the charging member 5 and is vibrated in the predetermined gap to be charged again The developer 1 which is suction-constrained and held on and is attached to the non-image portion
The developer can be supplied to the position of the developer collecting means 7 that collects 0, and the supply of the developer 10 is stabilized.

The image forming apparatus of the present invention is not limited to the above embodiment, but various modes are possible. For example, in the example,
The charging is carried out by the second electric field forming means 7 by vibrating the developer 10 by forming an alternating electric field between the latent image carrier 1 and the charging member 5. The developer may be rubbed between the image carrier 1 and the charging member 5 to be charged.
Although charging may be performed using a corona discharger, it is difficult to charge only the developer without disturbing the electrostatic latent image, which is not so preferable.

In the embodiment, the AC recovery bias of the third electric field power source 8 is used to recover the developer 10 attached to the non-image portion of the electrostatic latent image on the surface of the latent image carrier 1. However, in addition to this, the DC recovery bias of the third electric field power source 8 or the magnetic field of the second magnetic field forming means 4 can be used.

When this recovery is performed by forming a direct current recovery bias between the latent image carrier 1 and the developer recovery member 7, the developer 10 supplied to the surface of the latent image carrier 1 is a latent image. The force received between the holder 1 and the developer collecting member 7 is the intermolecular force,
The image force and the electric field force, that is, the latent image potential, the recovery bias potential, and the Coulomb force between the charged charges of the developer. Among them, the intermolecular force and the image force are different from those of the image portion of the latent image. Since it is almost constant regardless of the image area, the electric field force that changes due to the DC recovery bias is such that the developer is collected in the non-image area, and the developer remains on the latent image in the image area. By applying a DC recovery bias having a magnitude, the developer in the non-image portion is recovered.

When the developer 10 is a magnetic developer and the magnetic field formed between the latent image carrier 1 and the developer recovery member 7 is used for recovering the magnetic developer, the latent image carrier 1 is used. The force that the developer 10 supplied to the surface of the sheet receives between the latent image carrier 1 and the developer collecting member 7 is the intermolecular force, the image force, the electric field force,
That is, the Coulomb force between the latent image potential and the charge of the developer,
The magnetic force, that is, the magnetic attraction force between the second magnetic field forming means 9 and the magnetic developer, among which the intermolecular force and the image force are
Since it is almost constant regardless of the image part and non-image part of the latent image,
The electric field force and the magnetic force form a magnetic field having a size such that the developer is collected in the non-image portion and a size such that the developer remains on the latent image in the image portion. The developer in the non-image portion is collected.

In any case of recovery, the latent image carrier 1
And the direction of rotation of the developer collecting member 7 may be the same or opposite.

Further, in the embodiment, no mechanical means is used as the developer supplying means, but at the time of supplying the developer, the developer reservoir is once formed and the developer is supplied from the developer reservoir. Form mechanical developer supply means may be used, and as the mechanical means, a developer carrier may be used.

[0059]

According to the image forming apparatus of the present invention, after the developer is supplied to the entire surface of the electrostatic latent image on the surface of the latent image carrier by the attraction of the magnetic field, the developer is charged on the surface of the latent image carrier. The characteristic feature is that the developer attached to the non-image portion is recovered from the developer supplied to the entire surface of the electrostatic latent image, and the following effects are obtained.

The magnetic field forming means attracts and holds the developer by the magnetic field, and directly supplies the developer to the entire surface of the electrostatic latent image on the surface of the latent image carrier. Therefore, since the conventional developer carrier is not used, the process and the precision control mechanism for forming an extremely uniform developer layer on the developer carrier are not required, the image forming apparatus is downsized, and the cost is reduced. In addition, since the developer necessary for development can be sufficiently supplied, the sleeve ghost phenomenon can be eliminated.

Further, even if the direction of supplying the developer is against the action of gravity, sideways, or slightly obliquely downward,
The developer can be stably supplied.

Further, since it is excellent in earthquake resistance and transportation resistance and the magnetic developer is not biased to one side even when the apparatus is moved or transported,
Images can be output immediately even after they are transported or moved, and operations such as idling of the developer to correct the bias of the developer are unnecessary.

Further, even if the fluidity of the magnetic developer changes in a high humidity environment or the like, a defective supply of the magnetic developer does not occur.
A stable, high-quality image is always obtained.

Since the charging member and the electric field power source vibrately charge the magnetic developer which is attracted and restrained on the surface of the latent image holding member by the magnetic field forming means, the developer is charged on the surface of the latent image holding member having a high insulating property. Charged to a specified amount of charge, the charge of the developer is less likely to leak, and the charging efficiency is good, and the charged developer immediately forms an electrostatic latent image on the surface of the latent image carrier. Even if the charge of the developer easily leaks at high temperature and high humidity due to the fact that it acts on the development and the development efficiency of the charged charge is good, the influence of the leak is extremely small and the effect of the specified amount of charge can be secured. It also contributes to the development and enables high-resolution development and stabilization of transfer.

Further, when charged by vibration, the electrostatic latent image on the surface of the latent image holding member can be charged without disturbing, and even if the developer is scattered by the vibration of charging, it is still in the developer reservoir. It does not leak outside.

Further, the vibration not only disperses the agglomerates of the developer, but also causes the developer to move on the surface of the latent image holding member so that the amount thereof is uniformly distributed on the surface of the latent image holding member. Since the charged developer is in contact with the electrostatic latent image for a long time, an excellent image can be obtained.

Further, in the image forming apparatus of the present invention, when the magnetic field forming means forms a magnetic field also in a predetermined gap where the charging member and the latent image carrier face each other, the magnetic developer is charged in the predetermined gap. It is possible to suppress the magnetic field from vibrating and scattering to stabilize the amount of the magnetic developer carried into the predetermined gap, and to secure the stable amount of the charged magnetic developer.

Further, in the image forming apparatus of the present invention, when the magnetic field forming means forms a magnetic field also in the predetermined gap where the charging member and the latent image carrier face each other and in the front and rear portions thereof, the magnetic developer causes the predetermined gap. The magnetic field further suppresses vibration and scattering due to charging, the amount of magnetic developer carried into the predetermined gap is further stabilized, and the amount of charged magnetic developer can be secured more stably.

Further, in the image forming apparatus of the present invention, the magnetic field forming means is in a range from a position where the magnetic developer is supplied to the latent image holding member to a position where the latent image holding member and the developer collecting member face each other. When a magnetic field is formed, the developer that has passed through a predetermined gap between the latent image holding member and the charging member and is vibrated in the predetermined gap and charged is again suction-held and held on the surface of the latent image holding member, and the non-image portion The developer can be supplied to the position of the developer collecting means for collecting the developer adhering to, and the supply of the developer is stabilized.

[Brief description of drawings]

FIG. 1 is a sectional view of an image forming apparatus using a method according to an embodiment of the present invention.

FIG. 2 is a basic configuration diagram of an image forming method of the present invention.

FIG. 3 is a partially enlarged view showing the operation of FIG.

FIG. 4 is an operation diagram showing an example of the operation of FIG.

5 is a configuration diagram of another embodiment of the magnetic field forming means of FIG. 1. FIG.

6 is a configuration diagram of another embodiment of the magnetic field forming means of FIG. 1. FIG.

FIG. 7 is a block diagram of another embodiment of the magnetic field forming means of FIG.

FIG. 8 is a principle diagram of sleeve ghost generation.

[Explanation of symbols]

 1 Latent Image Holder 2 First Magnetic Field Forming Means (Magnetic Field Forming Means) 3 Developer Supply Electrode Roller 4 First Electric Field Power Supply 5 Charging Member 6 Second Electric Field Power Supply (Electric Field Power Supply) 7 Developer Collecting Member (Developer Collecting Means) ) 8 third electric field power source (developer collecting means) 9 second magnetic field forming means (developer collecting means) 10 developer 10 'developer pot 10 "magnetic developer spike 11 developer reservoir 21 adjoint flow 22 reciprocating motion 23 circulation Flow

Claims (4)

[Claims] 1. A latent image carrier that holds and moves an electrostatic latent image on the surface, and a portion that is contained in the latent image carrier and at least a magnetic developer is directly supplied to the surface of the latent image carrier. A magnetic field is formed on the surface of the latent image carrier by the magnetic field, and the magnetic developer is attracted and restrained on the surface of the latent image carrier to supply the magnetic developer to the surface of the latent image carrier, and a predetermined gap is formed on the surface of the latent image carrier. And an alternating electric field is formed between the charging member and the latent image holding member, which are arranged at positions opposed to each other, and the alternating electric field is generated on the surface of the latent image holding member by the magnetic field of the magnetic field forming means. An electric field power source for vibrating in the predetermined gap and charging the magnetic developer, which is held by suction and held in the predetermined gap, into the predetermined gap, and the electrostatic charge on the surface of the latent image holder. Development to recover the magnetic developer adhering to the non-image part of the latent image An image forming apparatus comprising: an agent collecting unit. 2. The magnetic field forming means forms a magnetic field in a predetermined gap in which the charging member and the latent image holding member face each other, thereby attracting and holding the magnetic developer on the surface of the latent image holding member. The image forming apparatus according to claim 1, wherein the magnetic developer is allowed to pass through a predetermined gap, and is prevented from being scattered by a vibration due to charging in the predetermined gap. 3. The magnetic field forming means forms a magnetic field in a predetermined gap where the charging member and the latent image holding body face each other and in the front and rear portions thereof, thereby attracting and restraining the magnetic developer on the surface of the latent image holding body. The image forming apparatus according to claim 1, wherein the magnetic developer is held and passed through the predetermined gap to prevent the magnetic developer from scattering due to a vibration for charging in the predetermined gap. 4. The magnetic field forming means attracts and holds the magnetic developer, which has passed through a predetermined gap where the charging member and the latent image holding body face each other, on the surface of the latent image holding body to hold the magnetic developer at the position of the developer collecting means. The image forming apparatus according to claim 1, wherein the image forming apparatus supplies the image to the image forming apparatus.