JP2878042B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method applicable to a printer, a copying machine, a facsimile, and the like.

[0002]

2. Description of the Related Art Image forming methods include a cascade developing method, a touch-down developing method, and a jumping developing method.

[0003] In each of these, various improvements have been made for the purpose of improving image reproducibility and sharpness.

[0004] A developer supply member (hereinafter referred to as a "developer carrier") for carrying and supplying the developer has been arranged at a predetermined interval facing the latent image holding member. An appropriate developing bias voltage is applied between the carrier and the latent image holding member to perform development.
As shown in JP-B-63-42256, an AC jumping development method in which an AC bias is superimposed on a DC bias has been put to practical use.

In this conventional AC jumping developing method, the alternating current of the developing bias applied between the developer carrier and the latent image carrier causes the developing device in which the developer carrier and the latent image carrier are opposed to each other. An AC electric field is formed, and the developer carried on the developer carrier reciprocates between the developer carrier and the latent image holding member by the AC electric field. Attempts to precisely develop the image portion of the electrostatic latent image by sequentially attaching to the image portion.

[0006]

However, the conventional AC
In the jumping development 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 discharged from the charged developer layer by AC jumping. Since it is moved to the latent image carrier, the developer layer needs to have a uniform thickness in order to perform uniform charging. Since the thickness of the developer layer needs to be uniform in order to accurately move the developer according to the potential change, extremely uniform development is performed on the developer carrier in order to perform faithful development. It is indispensable to form an agent layer, and there is a problem that a treatment and a precision control mechanism for achieving this are required.

In a conventional AC jumping developing method using a developer carrier, as shown in FIG.
For example, for a solid image, a hole 1 in the developer layer 103 generated by moving from the developer layer 103 to the latent image holding member 102 side.
Reference numeral 06 denotes a mechanism in which when the developer is re-adhered onto the developer layer 103, the re-adhesion is a mechanism in which the developer 100 is adhered in a layer form by the blade 107, so that only the hole 106 is completely filled in the hole 106. A large amount of the developer cannot be reattached, remains as a history hole 104 even after the developer layer 103 is reattached, and the thickness of the developer layer becomes thinner at the portion of the history hole 104. There is a problem of a sleeve ghost phenomenon in which the insufficient amount of the developer in the image portion that has received the movement causes the lacking portion 105, and the lacking portion 105 appears in the current image as an afterimage of the previous image.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming method which can solve the above-mentioned problems and realizes an image forming apparatus which has a simple structure, is small, and can obtain a precise high-quality image.

[0009]

In order to solve the above-mentioned problems, the image forming method of the present invention is viewed from the side of the latent image holder near the developing unit and the latent image holder rotating in the same direction. A magnetic developer is directly supplied to the surface of the latent image holding member on the upstream side to form a developer reservoir in the proximity part, and the surface of the latent image holding member and the surface of the developing member move while moving in opposite directions. The magnetic developer in the developer reservoir is sucked and held on the surface by a magnetic flux formed in the gap between the latent image holding member and the developing member so as to extend between the two. An AC developing bias applied between the latent image holding member and the developing member by applying a magnetic developer forming an entrained flow in the opposite direction to the latent image is applied to the developing while forming an entrained flow in the opposite direction. By reciprocating between the holding member and the developing member, The circulating flow forms a stagnation portion for stagnation of the magnetic developer to be developed in the opposed gap, and the magnetic developer develops while repeatedly performing the reciprocating motion in the stagnation portion. The image portion is visualized with a magnetic developer according to the difference between the potential of the image portion of the image and the potential of the non-image portion, the magnetic developer is collected from the non-image portion, and the magnetic developer that has become excessive for development is transferred to the developing member. The developer is returned to the developer reservoir by the rotation of.

According to another aspect of the present invention, there is provided an image forming method comprising: a first magnetic field forming means included in a latent image holding member; and a second magnetic field forming means included in a developing member. Preferably, it is formed by means.

Further, in the image forming method of the present invention, in order to solve the above-mentioned problems, it is preferable that the position of the first magnetic field forming means is limited to a facing gap portion.

In the image forming method of the present invention, in order to solve the above-mentioned problems, it is preferable that the position of the first magnetic field forming means is widened from the facing gap to the upstream side.

In the image forming method of the present invention, in order to solve the above-mentioned problems, it is preferable that the first magnetic field forming means is a magnetic material.

In the image forming method of the present invention, it is preferable that the position of the second magnetic field forming means extends from the upstream side to the downstream side of the facing gap in order to solve the above problems.

[0015]

According to the image forming method of the present invention,
It has the following action.

According to the present invention, a developer is provided by directly supplying a magnetic developer to the surface of an upstream latent image carrier viewed from the side of the latent image carrier near a developing member and a latent image carrier rotating in the same direction. Since the reservoir is formed, it has the following operation.

Since the magnetic developer is directly supplied to the surface of the latent image holding member on the upstream side as viewed from the latent image holding member in the proximity portion, the supplied developer is supplied to the surface of the latent image holding member in the direction of the proximity portion. The developer is conveyed along with the movement and accumulates in the adjacent portion to form a developer reservoir. Then, since the developer is supplied from the developer reservoir to the gap between the latent image holding member and the developing member, a sufficient amount of the developer to eliminate the supply unevenness and the insufficient supply of the developer is provided. The toner can be supplied to a gap between the latent image holding member and the developing member.

According to the present invention, there is provided a magnetic head formed such that a surface of a latent image holding member and a surface of a developing member move in opposite directions, and are formed in a gap between the latent image holding member and the developing member so as to extend therebetween. Thus, the magnetic developer is held as a magnetic developer spike by suction, thereby having the following effect.

The magnetic flux attracts a magnetic developer corresponding to the magnetic flux density from a sufficient amount of magnetic developer stored in the developer reservoir, and a magnetic developer spike having a magnetic developer density corresponding to the magnetic flux density is formed. It is formed and held between the latent image holding member and the developing member.
Since the magnetic developer spike has a property of maintaining a magnetic developer density corresponding to the magnetic flux density, when a magnetic developer for development is supplied from the magnetic developer spike, the magnetic developer spike is the same as the supplied magnetic developer. When the amount of magnetic developer is magnetically replenished from the developer reservoir, the magnetic developer returns to the original magnetic developer spike, and the surface of the latent image holding member and the surface of the developing member move in opposite directions in the opposing gap. Due to the synergistic action of the above, the developer in the portion of the magnetic developer chain on the latent image holding member side corresponding to the magnetic flux density is supplied to the opposed gap as a magnetic developer for developing. Therefore, the supply amount of the magnetic developer is determined by the magnetic flux density and the moving speed of the surface of the latent image holding member, and the amount of the magnetic developer to be developed is stabilized.

The present invention has the following effects because the surface of the latent image holding member and the surface of the developing member move in opposite directions.

The synergistic effect between the magnetic flux and the magnetic developer being attracted and held by the magnetic flux causes the magnetic developer to be attracted and held by the magnetic flux at the interface between the magnetic developer, the surface of the latent image holding member, and the surface of the developing member. In the state, it moves in the opposite direction by receiving the frictional conveyance force, and particularly, in the facing gap between the latent image holding member and the developing member,
In the moving direction of the magnetic developer, an entrained flow of the magnetic developer in the opposite direction is formed.

The present invention has the following effects by applying an AC developing bias between the latent image holding member and the developing member.

Since the magnetic developer is reciprocated between the latent image holding member and the developing member, both ends of the reciprocating motion of the magnetic developer are opposed by the accompanying flow due to the synergistic action with the accompanying flow of the magnetic developer. Therefore, the magnetic developer forms a circulating flow of the magnetic developer, and the magnetic developer stays while circulating in the opposing gap between the latent image holding member and the developing member. It is formed.

The AC developing bias causes the magnetic developer staying in the staying portion to reciprocate repeatedly, so that even if an uncharged magnetic developer is supplied, the magnetic developer remains in the magnetic developer during the supply. There is a magnetic developer that is somewhat charged due to mutual friction between the agents, and this magnetic developer repeatedly starts and ends up in a reciprocating motion and reciprocates, colliding with the surface of the developing member and the latent image holding member, The magnetic developers collide with each other and become charged, and the uncharged magnetic developers are repelled by the reciprocating magnetic developer and move together, and are charged by repeating the same collision. Therefore, the magnetic developer supplied to the developer reservoir may be uncharged.

Further, due to repetition of the reciprocating motion of the magnetic developer, the magnetic developer disperses the particles one by one and moves vigorously. Fogging is also eliminated by flipping off the magnetic developer that does not work well.

Also, due to the long-term stay and reciprocation, and the difference between the potential of the image portion of the electrostatic latent image and the potential of the non-image portion,
In the image portion, the magnetic developer remains due to the difference in the amount of flight of the magnetic developer between the forward path and the return path each time a round trip occurs, and visualization proceeds.From the non-image part, the magnetic development between the forward path and the return path occurs each time the round trip occurs The magnetic developer is recovered by the difference in the amount of the flying agent. However, a synergistic effect with the above-described flipping action enables accurate development of a delicate image without fogging.

After the development is completed, according to the present invention, the surface of the developing member moves in the opposite direction to the surface of the latent image holding member, and there is a magnetic flux between the latent image holding member and the developing member in the opposing gap. Therefore, it has the following operation.

The excess magnetic developer for development and the magnetic developer floating between the latent image holding member and the developing member having a large gap are collected by the developing member and are stored in the developer reservoir by the rotation of the developing member. Since it returns, the magnetic developer can be prevented from scattering outside.

The magnetic developer collected by the developing member and returned to the developer reservoir with the rotation of the developing member is attracted and held by the magnetic flux to become the magnetic developer spike.
Provided for development.

According to the present invention, the first magnetic field forming means included in the latent image holding member and the second magnetic field forming means included in the developing member form a magnetic flux.

Further, according to the present invention, when the vicinity of the latent image holding member and the developing member faces upward, the magnetic developer is supplied to the surface of the latent image holding member by the action of gravity, and the magnetic developer is removed. Since the suction force of the first magnetic field forming means for supplying is not required,
The position of the first magnetic field forming means may be limited to the facing gap between the latent image holding member and the developing member. May be limited to the gap between the latent image holding member and the developing member.

Further, according to the present invention, since the position of the first magnetic field forming means is widened from the developing gap to the upstream side, the first magnetic field forming means attracts and holds the magnetic developer on the latent image holding member side. By setting the direction of the proximity portion between the latent image holding member and the developing member regardless of the direction of action of gravity, a developer reservoir can be formed in this proximity portion.

Further, according to the present invention, even when the first magnetic field forming means is made of a magnetic material, the same operation as in the case of a magnet can be obtained.

Further, according to the present invention, the position of the second magnetic field forming means is widened from the upstream side to the downstream side of the developing gap.
A magnetic field can be formed in the vicinity, a magnetic field can be formed in the gap between the latent image holding member and the developing member, and the action of the second magnetic field forming means for recovering excess magnetic developer for development can be established.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus using an image forming method according to the present invention will be described with reference to FIG.

In FIG. 1, in the image forming apparatus of the present embodiment, the latent image holder 1 includes first magnetic field forming means 2 composed of a fixed magnet and is formed by an electrostatic latent image forming optical system 19. The moving electrostatic latent image is held on the surface. A developing member 3 facing the latent image holding member 1 with a facing gap of about 350 μm includes a second magnetic field forming means 4 which is constituted by a fixed magnet and faces the first magnetic field forming means 2 and includes the latent image. It rotates in the same direction as the holder 1. This developing member 3
Is connected to a first electric field power supply 5 for forming an AC developing bias between the developing member 3 and the latent image holding member 1. The first electric field power supply 5 is composed of a combination of an AC power supply and a DC power supply. In order to directly supply the magnetic developer 8 to the surface of the latent image holding member 1 on the upstream side when viewed from the latent image holding member 1 side in the vicinity of the latent image holding member 1 and the developing member 3, The developer pot 8 ′ is mounted so that the magnetic developer 8 inside forms a developer reservoir 9 in the vicinity of the developer pot 8 ′. A scraper 10 for scraping off the developer is provided, and a seal 11 for preventing the magnetic developer 8 from leaking out is provided between the developer pot 8 'and the latent image holder 1.

In the developer reservoir 9, there is provided a charging member 6 which faces the surface of the latent image holder 1 near the proximity portion with a predetermined gap therebetween. Second forming an alternating electric field between the image carrier 1 and the charging member 6
An electric field power supply 7 is connected, and the second electric field power supply 7 is configured by a combination of an AC power supply and a DC power supply. An electrode roller 12 for supplying developer is provided in the developer reservoir 9 so as to face the latent image holding member 1. A third electric field power supply 13 is connected to the electrode roller 12 for supplying developer. Have been.

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

Next, the operation of the image forming method according to an embodiment of the present invention will be described with reference to FIGS.

2, the electrostatic latent image is formed on the surface of the latent image holding member 1 by the electrostatic latent image forming optical system 19 in the electrostatic latent image forming step of step # 1. Then, the process proceeds to step # 2. In this case, as shown in FIG. 4, the image portion potential and the non-image portion potential are -100 V for the image portion potential and -500 V for the non-image portion potential.
In the supply step of Step # 2, as shown in FIG.
The magnetic developer 8 in the developer pot 8 ′ is directly supplied to the surface of the latent image holding member 1 on the upstream side as viewed from the latent image holding member 1 near the latent image holding member 1 and the developing member 3. . The directly supplied magnetic developer 8 is formed by the third electric field power supply 13 between the developer supply electrode roller 12 and the latent image holding member 1, and its own weight due to gravity, the attraction force of the first magnetic field forming means 2, and the like. The DC electric field attracts the latent image holding member 1 to the latent image holding member 1.
The developer reservoir 9 is formed in the proximity part by the rotation of.
In this case, the developer supply electrode roller 12 and the latent image holding member 1
The direct current electric field acts on the charged electric charge when the supplied magnetic developer is charged, and between the magnetic developer generated during the supply when the supplied magnetic developer is uncharged. Acts on naturally charged electric charges due to mutual friction and the like. On the surface of the latent image holder 1 in the developer reservoir 9, an alternating electric field is formed between the latent image holder 1 and the charging member 6 by the second electric field power source 7 to charge the magnetic developer to a predetermined charge amount. It can be done, but is not required.

The magnetic flux formed between the latent image holding member 1 and the charging member 6 by the first magnetic field forming means and the second magnetic field forming means,
3, the magnetic developer 8 is sucked and retained as a magnetic developer spike 8 ″ in the opposing gap between the latent image holding member 1 and the charging member 6. In the opposing gap, the latent image is held. Since the surface of the body 1 and the surface of the charging member 6 are moving in opposite directions, an accompanying flow 21 of the magnetic developer in the opposite direction is formed, and the process proceeds to step # 3. Since the amount of the developer in the 8 ″ portion is maintained at an amount determined by the magnetic flux density, even if the portion of the magnetic developer spike 8 ″ on the latent image holding member 1 side is carried away, The same amount of the developer 8 is replenished from the developer reservoir 9, and a certain amount of the developer 8 always exists in the magnetic developer spike 8 "portion. The amount of developer supplied from is stabilized at a constant amount.

In the developing step of step # 3, as shown in FIG. 4, the first electric field power supply 5 generates a peak-to-peak voltage of -350 V DC between the latent image holding member 1 and the developing member 3. As shown in FIG. 3, the magnetic developer is caused to reciprocate 22 in the opposed gap between the latent image holding member 1 and the developing member 3 by the AC developing bias on which the alternating rectangular potential of 1500 V is superimposed. The waveform of this AC developing bias is 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. The peak-to-peak voltage can be in the range of 500 V to 2000 V where a good image is obtained and no discharge occurs. The frequency can be in the range of 100 Hz to 10 kHz, but is desirably from 500 Hz at which the required number of reciprocations can be obtained to 3 kHz at which the reciprocating motion 22 of the developer can sufficiently follow. By the synergistic action of the accompanying flow 21 and the reciprocating motion 22, a circulating flow 23 of the magnetic developer is formed, and a stagnant portion for circulating and stagnating the magnetic developer in the opposed gap is formed. The AC developing bias causes the magnetic developer in the staying portion circulating and staying in the opposed gap to reciprocate 22,
The magnetic developer in the stagnant portion repeatedly performs the reciprocating motion 22, so that even when an uncharged magnetic developer is supplied, the magnetic developer slightly charged due to mutual friction in the supply of the magnetic developer is supplied. Starting from the reciprocating motion 22, charging proceeds due to mutual friction and contact with the developing member 3, and the uncharged magnetic developer also repeats the reciprocating motion 2 along with the reciprocating motion 22.
2, the charging member 6 and the second electric field power source 7 are not necessarily required.

The charge amount of the developer is within a range in which the reciprocating flying force due to the AC developing bias exceeds the adhesive force of the developer to the latent image holding member due to the mirror image force of the charged charge and the intermolecular force. -0.5 μC to −3 μC / g to −4
Although there is a range of 0 μC / g, in this embodiment, −5 μC to −
Performed at 10 μC / g.

Further, due to the repetition of the reciprocating motion of the magnetic developer, the magnetic developer disperses the particles one by one and actively moves, and even if it is uncharged, it adheres to the non-image portion of the electrostatic latent image. Even if there is a magnetic developer 10 that does not have an electrical recovery force, the magnetic developer 10 is flipped off to eliminate fog.

Further, as shown in FIG. 4, the reciprocating motion 22 of the magnetic developer caused by the AC developing bias has a negative peak at -1100 V of an alternating rectangular potential of 1500 V peak-to-peak voltage in the image portion. The forward path to the image portion of the magnetic developer flies with a potential difference of 1000 V, and at 400 V, which is the positive peak of the alternating rectangular potential, the return path from the image portion of the magnetic developer flies with a potential difference of 500 V. By the difference between these potential differences, the magnetic developer moves to the image portion and the visualization proceeds, and in the non-image portion, the magnetic developer at -1100V which is the negative peak of the alternating rectangular potential of 1500V peak-to-peak voltage is applied. The forward path to the non-image portion of the developer flies with a potential difference of 600 V, and the 400 V which is the positive peak of the alternating rectangular potential returns from the non-image portion of the magnetic developer. Flies at a potential difference of 900 V, so the magnetic developer is recovered from the non-image portion by one round trip difference by the difference between these potential differences. Can be developed.

When the gap between the electrostatic latent image on the surface of the latent image holding member 1 and the developing member 3 becomes large due to the rotation of the latent image holding member 1, the electric field intensity is gradually attenuated. The movement of the developer is attenuated, the development is completed, and step #
Proceed to 4.

In the recovery step of step # 4, the surface of the developing member 3 moves in the opposite direction to the surface of the latent image holding member 1,
Since there is a magnetic flux between the latent image holding member 1 and the developing member 3 in the opposed gap between the latent image holding member 1 and the developing member 3, excess magnetic developer for the development and the floating between the latent image holding member 1 and the developing member 3 with the gap increased. The magnetic developer is easily collected by the developing member 3 and returns to the developer reservoir 9 by the rotation of the developing member 3, so that the magnetic developer can be prevented from scattering outside.

Then, as shown in FIG. 3, a part of the magnetic developer collected by the developing member 3 and returned to the magnetic developer spike 8 ″ as an entrained flow 21 due to the rotation of the developing agent 3, The magnetic developer spike 8 ″ becomes a part of the magnetic developer spike 8 ″, and the accompanying flow 2 due to the rotation of the latent image holding member 1 again occurs.
It is supplied to the circulation stream 23 and is subjected to development.

The image forming method of the present invention is not limited to the above-described embodiment, but can be implemented in various modes. For example, as shown in FIG. 5, the position of the first magnetic field forming means 2 which is included in the latent image holding member 1 and faces the second magnetic field forming means 4 which is included in the developing member 3 is set in the facing gap portion. Latent image carrier 1
When the proximity of the developer and the developing member 3 is upward, the gravity acting on the magnetic developer acts, so that the developer is directly supplied to the surface of the latent image holding member 1 and the developer is supplied to the proximity. A reservoir 9 can be formed. The same applies to a case in which a supply unit using another mechanical force is used.

Further, as shown in FIG. 6, the position of the first magnetic field forming means 2 is widened from the developing gap to the upstream side thereof, so that the first magnetic field forming means 2 stores the magnetic developer in the developer reservoir 9. Since the latent image holder 1 is held by suction on the latent image holder 1, the magnetic developer 8 is applied to the latent image holder 1 against the gravity in some cases regardless of the direction of the proximity of the latent image holder 1 and the developing member 3. The developer reservoir 9 can be formed in the vicinity by directly supplying the developer to the surface of the developer container 9.

Further, the first magnetic field forming means 2 can form a magnetic flux required for the present invention even if it is made of a magnetic material.

Also, as shown in FIGS. 1, 5 and 6, the second
The position of the magnetic field forming means 4 extends from the upstream side to the downstream side of the opposing gap, but the upstream side spread forms the developer reservoir 9 due to the interaction with the movement of the surface of the developing member and the downstream side. The extent of the spread is related to the recovery of the magnetic developer, so it is designed according to the conditions.

In the embodiment, no mechanical means is used for supplying the developer. However, when the developer is supplied, a developer reservoir is formed once and the developer is supplied from the developer reservoir. May be used, or a developer carrying member may be used.

[0054]

According to the image forming method of the present invention, a sufficient amount of a magnetic developer is directly supplied from a developer reservoir to an opposing gap for development.
Since the developer carrier of the prior art is not used, the effect of eliminating the sleeve ghost phenomenon, which is a problem of the conventional example, and an extremely uniform layer of the developer on the surface of the developer carrier, which is a problem of the conventional example, are provided. There is an effect that the forming process and the precision control mechanism are not required, and the size can be reduced.

A magnetic flux is formed in a gap between the latent image holding member and the developing member where development is performed, and the magnetic developer is attracted and held as a magnetic developer spike having a developer density corresponding to the magnetic flux density. Therefore, not only the supply amount of the magnetic developer is stabilized, but also the suction and holding is maintained, the surface of the latent image holding member and the surface of the developing member move in opposite directions. A synergistic effect of applying a bias and causing the magnetic developer to reciprocate between the latent image holding member and the developing member forms a circulating flow of the magnetic developer in the opposed gap, thereby circulating and retaining the magnetic developer. Therefore, the magnetic developer stays in the opposed gap to form a staying portion, and reciprocates repeatedly in the staying portion. Triggered reciprocating motion of charged magnetic developer It can develop while charging sufficiently, and it can develop a precise image without fog by reciprocatingly flicking off the magnetic developer, which is uncharged and adheres to the non-image area and does not act on the electric recovery power. Play.

Further, since the surface of the developing member moves in the opposite direction to the surface of the latent image holding member, and there is a magnetic flux extending between the latent image holding member and the developing member in the opposing gap, there is an excess amount of development. The magnetic developer and the magnetic developer floating between the latent image holding member and the developing member having a larger gap are collected by the developing member and returned to the developer reservoir by the rotation of the developing member. It is possible to prevent the magnetic developer from returning to the outside and to reuse the magnetic developer returned to the developer reservoir.

[Brief description of the 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 flowchart showing the operation of FIG.

FIG. 3 is a partially enlarged view showing the operation of FIG. 1;

FIG. 4 is an operation diagram of FIG. 1;

FIG. 5 is a sectional view showing an example of a first magnetic field forming means of FIG. 1;

FIG. 6 is a sectional view showing another example of the first magnetic field forming means of FIG. 1;

FIG. 7 is a diagram illustrating the generation principle of a sleeve ghost.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 latent image holder 2 first magnetic field forming means 3 developing member 4 second magnetic field forming means 5 first electric field power supply 8 magnetic developer 8 ′ developer pot 8 ″ magnetic developer spigot 9 developer reservoir 12 developer supply electrode Roller 13 third electric field power supply 21 accompanying flow 22 reciprocating motion 23 circulating flow

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroto Inoue 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-48-68237 (JP, A) JP-A-52-66438 (JP, A) JP-A-53-100247 (JP, A) JP-A-54-5730 (JP, A) JP-A-55-105267 (JP, A) JP-A-58-105273 (JP, A) JP-A-60-2970 (JP, A) JP-A-60-83058 (JP, A) JP-A-60-101570 (JP, A) JP-A-60-181754 (JP, A) JP-A-61-270777 (JP, A) JP-A-62-63970 (JP, A) JP-A-62-67577 (JP, A) JP-A-62-94359 (JP, A) JP-A-62-211681 (JP, A) JP-A-62-220968 (JP, A) JP-A-63-11975 (JP, A) JP-A-1-239568 (JP, A) JP-A-2-22682 (JP, A) JP-A-4-242771 (JP, A) JP-A-5-72890 (JP, A) JP-A-6-43759 (JP, A) JP-A-6-161266 (JP, A) JP-A-6-161267 (JP, A) JP-A-6-161255 ( JP, A) JP-A-6-161256 (JP, A) JP-A-6-161257 (JP, A) JP-A-6-161268 (JP, A) JP-A-6-161269 (JP, A) JP JP-A-6-161270 (JP, A) JP-A-6-161271 (JP, A) JP-A-6-161272 (JP, A) JP-A-6-161258 (JP, A) JP-A-6-161259 (JP) JP-A-6-161273 (JP, A) JP-A-6-161274 (JP, A) JP-A-5-100574 (JP, A) JP-A-5-241449 (JP, A) 5-341602 (JP, A) JP-A-6-95489 (JP, A) JP-A-6-110320 (JP, A) JP-A-6 110321 (JP, A) JP-A-6-110322 (JP, A) JP-A-6-123998 (JP, A) JP-A-6-175502 (JP, A) JP-A-6-175507 (JP, A) JP-A-6-208304 (JP, A) JP-A-6-230679 (JP, A) JP-A-6-282171 (JP, A) JP-A-5-181356 (JP, A) JP-A-6-266226 (JP, A) Japanese Utility Model Showa 58-157342 (JP, U) Japanese Utility Model Showa 59-25556 (JP, U) Japanese Patent Publication No. 52-44204 (JP, B1) (58) Field surveyed (Int. Cl. ⁶⁾ , DB name) G03G 15/08-15/095

Claims (6)

(57) [Claims] 1. A magnetic developer is directly supplied to an upstream surface of a latent image holding member viewed from the latent image holding member side in a vicinity of the latent image holding member and the developing member rotating in the same direction to supply the magnetic developer to the adjacent portion. A developer reservoir was formed, and the surface of the latent image holding member and the surface of the developing member were formed so as to extend in the opposing gap between the latent image holding member and the developing member while moving in opposite directions. By holding the magnetic developer with suction on the surface with magnetic flux,
The magnetic developer in the developer reservoir is subjected to development while forming an entrained flow in the opposite direction in the opposing gap, and the magnetic developer forming the entrained flow in the opposite direction is separated from the latent image holding member and the latent image holder. An AC developing bias applied between the developing members causes a circulating flow by reciprocating between the latent image holding member and the developing member, and the circulating flow stagnates a magnetic developer for developing in the opposed gap. Is formed, and the magnetic developer is developed while repeatedly performing the reciprocating motion in the stagnation portion, so that the image portion is formed with the magnetic developer by the difference between the potential of the image portion of the electrostatic latent image and the potential of the non-image portion. An image forming method, wherein a magnetic developer is recovered from a non-image portion after being visualized, and a magnetic developer which has become excessive for development is returned to the developer reservoir by rotation of the developing member. 2. The image forming method according to claim 1, wherein the magnetic flux is formed by first magnetic field forming means included in the latent image holding member and second magnetic field forming means included in the developing member. 3. The image forming method according to claim 1, wherein the position of the first magnetic field forming means is limited to a facing gap portion. 4. The image forming method according to claim 1, wherein the position of the first magnetic field forming means extends upstream from the facing gap. 5. The image forming method according to claim 1, wherein the first magnetic field forming means is a magnetic material. 6. The method according to claim 1, wherein the position of the second magnetic field forming means extends from the upstream side to the downstream side of the facing gap.
2. The image forming method according to 1.,