JPH02131265A - Developing device - Google Patents

Abstract

PURPOSE:To remove foreign matter, etc., which is present between a blade and a sleeve effectively by removing a pool of a developer which is present between the surface of the sleeve and the free end part of the blade by moving the sleeve or a permanent magnet in the opposite direction from a specific direction. CONSTITUTION:The sleeve 10 or permanent magnet 12 is moved in the opposite direction from the moving direction in developing operation. The movement in the opposite direction is performed before or after developing operation. At this time, the pool of the developer present between the surface of the sleeve 10 and the free end part of the blade 28 is moved in the opposite direction from the specific conveyance direction and the movement of the developer moves foreign matter, etc., present between the both in the opposite direction from the conveyance direction. Consequently, the foreign matter, etc., is removed from between the sleeve 10 and blade 28.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a developing device equipped with a magnetic brush mechanism.

[Prior art and its drawbacks]

In recent years, a magnetic brush mechanism consisting of a hollow cylindrical sleeve and a permanent magnet disposed inside the sleeve and a blade that acts on the sleeve surface have been developed, and the blade is brought into pressure contact with the sleeve surface to form a thin layer of developer on the surface. A developing device has been proposed in which the image is formed.

However, in this type of developing device, since the free end of the blade is pressed against the surface of the sleeve, a reservoir of developer is generated between the free end of the blade and the sleeve, and the developer is contained in the developing device. If foreign matter (dirt, dust, etc.) is included, this foreign matter will be interposed between the blade and the sleeve.

If such foreign matter is present, the conveyance of the developer is obstructed by the foreign matter, making it impossible to form a uniform thin layer of developer, and as a result, a good development effect cannot be achieved.

[Purpose of the invention]

The present invention has been made in view of the above facts, and an object thereof is to provide an excellent developing device that can effectively remove foreign matter existing between the blade and the sleeve.

[Summary of the invention]

In the developing device of the present invention, the sleeve or the permanent magnet is moved in the opposite direction to the direction of movement during the developing action. This movement of the sleeve or permanent magnet in the opposite direction is accomplished either before the development operation begins or after the development operation ends.

In such a developing device, since the sleeve or the permanent magnet is moved in a direction opposite to the direction of movement during the developing operation, the developer reservoir existing between the surface of the sleeve and the free end of the blade is moved in a direction opposite to the predetermined conveying direction. Due to the movement of the developer, foreign matter present between the developer is also moved in a direction opposite to the conveyance direction, and thus the foreign matter is removed from between the sleeve and the blade.

[Specific examples of the invention]

Further details will be given below with reference to the accompanying drawings.

FIG. 1 shows the main parts of an example of a developing device according to the present invention. In FIG. 1, the illustrated developing device includes a developing housing 2. As shown in FIG. An opening 4 is defined in the lower left side of the developing housing 2, and a magnetic brush mechanism 6 is disposed in this opening. This magnetic brush mechanism 6 is composed of a hollow cylindrical sleeve lO and a cylindrical permanent magnet l2 disposed within the sleeve lO. The sleeve 10 is made of a non-magnetic material such as aluminum. Permanent magnet l2 has four magnetic poles.

That is, a developing pole N, is arranged corresponding to the developing area 22, a replenishing pole N2 is arranged corresponding to the replenishing area 24 (an area opposite to the developing area 22), and the replenishing pole N2 and the developing pole N1 Transport poles S1 and S2 are arranged between them. The supply pole N2 and the development pole N1 are north poles, and the transport poles S1 and S2 are south poles.

A stirring member 14 is disposed at the bottom of the developer housing 2 . Further, a blade 2 is provided above the magnetic brush mechanism 6.
8 are arranged. The base of the blade 28 is connected to the member 30
and 32, and is attached to the upper end of the opening of the developer housing 2, and its free end extends toward the lower right in FIG. It acts on the surface of the sleeve IO in the area between the placement sites. The blade 28 can be formed from an elastic member such as phosphor bronze, and is brought into pressure contact with the surface of the sleeve 10 by its own elastic deformation. This protrusion amount 1 of the blade 28 (sleeve 1 of the blade 28
The length from the contact point P with 0 to its free end is 2 to 6.
Illffi level is sufficient. Further, a leak prevention member 26 is provided below the magnetic brush mechanism 6. The base of the leak prevention member 26 is fixed to the bottom inner surface of the developer housing 2, and its free end is in contact with the surface of the sleeve 10. This leak prevention member 26 can be formed from urethane rubber or the like.

The developing device as described above can be used in an image forming apparatus such as an electrostatic copying device or a laser beam printer, and is disposed, for example, facing the rotating drum 18, as shown in FIG. A photoreceptor is disposed on the circumferential surface of the rotating drum l8, and while it is rotated in the direction shown by arrow 20, an electrostatic latent image is formed on the surface of the photoreceptor by means known per se. Then, the area on which the electrostatic latent image is formed is moved close to the sleeve 10 of the magnetic brush mechanism 6, as shown in FIG. On the other hand, by applying the developing device in this manner, the sleeve lO of the magnetic brush mechanism 6 and the stirring member 14 are drivingly connected to the drive source 33 of the image forming apparatus (for example, driven through a gear provided on the rotating drum l8). connected)
. The drive source 33 can be constituted by an electric motor that can rotate in forward and reverse directions, and is rotated in the forward direction during a developing operation (when developing the electrostatic latent image formed on the photoreceptor). When the drive source 33 rotates forward, the driving force is applied to the rotating drum l8 and the magnetic brush mechanism 6.
The rotating tram 18 is transmitted in the direction shown by arrow 20 and the sleeve 10 is transmitted in the direction shown by arrow 8.
The stirring member l4 is rotated in the direction shown by arrow l6, and the stirring member l4 is rotated in the direction shown by arrow l6.

In this developing device, a one-component developer consisting of only magnetic toner, for example, is housed in a developing housing 2.

In connection with this, during the development operation, a development bias voltage is applied to the sleeve lO of the magnetic brush mechanism 6 by the action of the development bias source 36. The developing bias source 36 can be composed of a DC voltage source 38 that applies a DC voltage and an AC voltage source 40 that applies an AC voltage.

In the developing device having such a configuration, the developing action is performed as follows.

The agitating member 14, which rotates in the direction indicated by the arrow 16, agitates the developer present at the bottom of the developing housing 2, and then feeds the developer toward the magnetic brush mechanism 6. The developer thus fed is magnetically held on the surface of the sleeve 10 in the replenishment area 24 by the action of the replenishment pole N2 of the permanent magnet l2. The retained developer is conveyed toward the developing area 22 by the action of the sleeve 10 rotating in the direction shown by the arrow 8, and is transported to the area where the capture pole N2 is disposed and the conveyance pole S on the upstream side.
The blade 28 acts between the disposed portions of the blade 28 . Blade 28 acts on the developer retained on the surface of sleeve 10 and removes excess developer, thus removing sleeve 10
A thin layer of developer is formed on the surface. The developer held in the sleeve 10 is further moved in the direction shown by the arrow 8,
It is fed to the developing area 22 under the action of the transport pole S1. In the developing area 22, there is a corresponding developing pole N, and the developer held on the surface of the sleeve 10 is
The electrostatic latent image is supplied to the surface of the rotating drum 18 rotating in the direction shown by the arrow 20, and thus the electrostatic latent image formed on the photoreceptor of the rotating drum 18 is developed into a toner image. The developer that has passed through the developing area 22 is further transported in the direction shown by the arrow 8 by the rotation of the sleeve 10, and is acted upon by the transport pole S2 on the downstream side, passing under the magnetic brush mechanism 6 and preventing leakage from the sleeve 10. It is passed between the members 26 and returned into the developer housing 2 .

The image forming apparatus to which the developing device is applied is further configured as follows. Referring to FIG. 2 together with FIG. 1, the image forming apparatus includes a control means 50 which may be constituted by, for example, a microprocessor. The operation panel (not shown) of the image forming apparatus also includes a main switch 52 for supplying and stopping current to the main body of the apparatus.
An image forming start switch 54 such as a print switch and a main switch 52 are provided, and signals from the main switch 52 and the image forming start switch 54 are supplied to a control means 50.

The control means 50 includes timer means 56 for measuring time. As will be described later, this control means 50 generates a reverse rotation signal and a forward rotation signal in relation to a signal from the image formation start switch 54, and the reverse rotation signal and the forward rotation signal are sent to the drive source 33.

When the control means 50 sends a forward rotation sign, the drive source 33 is rotated in the normal direction, and when the control means 50 generates a reverse rotation signal, the drive source 33 is rotated in the reverse direction.

The operation at the start of image formation (in other words, when the developing device performs the developing action) will be described. When forming an image (performing a developing action by the developing device), the main switch 52 is closed (ON). In this way, current is supplied to the image forming apparatus. After that, the image formation start switch 54 is closed (ON). Then, based on the signal from the image formation start switch 54, the timer means 56 starts counting time, and the control means 50 generates a reverse rotation signal, which is supplied to the drive source 33. In this way, the drive source 33 is reversed by this reversal signal, and thereby the rotating drum 18 and the magnetic brush mechanism 6
The sleeve 10 and stirring member l4 are rotated in a direction opposite to the direction of movement during the development operation. The rotating drum l8 is rotated in the direction opposite to the direction indicated by the arrow 20, the sleeve 10 is rotated in the direction opposite to the direction indicated by the arrow 8, that is, the direction indicated by the arrow in FIG. 3, and the stirring member 14 is rotated in the direction indicated by the arrow I6. It is rotated in the opposite direction to the direction shown. This reversal signal is transmitted to the timer means 56.
continues to be generated until a predetermined time has elapsed, and while the reversal signal is generated, the rotating drum 18, the sleeve IO of the magnetic brush mechanism 6, and the stirring member 14 are rotated as described above. In particular, when the developer sleeve 10 is rotated in the direction shown by the arrow in FIG. As partially shown in FIG.
With the movement of the developer reservoir, the foreign matter (dust, etc.) interposed between the blade 28 and the sleeve 10 is also moved. Interposed foreign substances can be effectively removed. The amount of movement of the sleeve 10 in the direction indicated by the arrow is sufficient to move the foreign matter existing between the blade 28 and the sleeve 10 until it is substantially removed from the action area of the blade 28, and the pressure contact force of the blade 28 is , although it differs somewhat depending on the location etc., blade 2
It may be about half of the above-mentioned protrusion fil of No. 8, or about 1 to 3 mm in a specific example. If the amount of rotation of the blade 10 in the direction shown by the arrow is small, foreign matter between the blade 28 and the sleeve 10 cannot be sufficiently removed. On the other hand, when the amount of rotation of the sleeve 10 is increased, the developer in the developer housing 2 passes between the sleeve 10 and the leak prevention member 26 and is conveyed toward the development area 22, causing developer leakage, scattering, etc. become. When the timer means 56 measures a predetermined time, the control means 50 generates a normal rotation signal instead of the reverse rotation signal based on the signal from the timer means 56, and the normal rotation signal is sent to the drive source 33. Then, the drive source 33 is rotated in the normal direction based on this normal rotation signal, the rotating drum l8 is moved in the direction shown by the arrow 20, the sleeve 1O of the magnetic brush mechanism 6 is moved in the direction shown by the arrow 8, and the stirring member 14 is moved in the direction shown by the arrow 8. They are rotated in the directions indicated by 16, and a predetermined image forming process (that is, a developing action by the developing device) is performed during this rotation.

In the developing device as described above, since the sleeve 10 is moved in the opposite direction to the moving direction during development before the start of the development action, foreign matter present between the blade 28 and the sleeve 10 is removed before the start of the development action. Thus, a uniform thin layer of developer can be formed on the surface of the sleeve IO during the development operation.

In the embodiment described above, the sleeve 10 is
is moved in the opposite direction to the direction of movement during development,
Alternatively, for example, after the development action has ended, the sleeve l
It is also possible to move O in the opposite direction to the direction of movement during development. In such a case, for example, the timer means 56 starts measuring time after the development operation ends, and the control means 50 generates a reverse rotation signal instead of the normal rotation signal, and the drive source 33 is reversed by the reverse rotation signal. When this timer means 56 measures a predetermined time, it ends the generation of the reverse rotation signal,
As a result, the drive source 33 can be controlled to be deenergized, and the same effect can also be obtained by controlling the drive source 33.

Although a specific example of the developing device according to the present invention has been described below, the present invention is not limited to this specific example, and various modifications and changes can be made without departing from the scope of the present invention. It is.

For example, in the specific example, the application is applied to a developing device in which the sleeve of the magnetic brush mechanism is moved, but the present invention is not limited to this, and the permanent magnet disposed inside the sleeve of the magnetic brush mechanism is moved. The present invention can be similarly applied to a developing device in which both the sleeve and the permanent magnet disposed within the sleeve are moved.

[Brief explanation of the drawing]

FIG. 1 is a partially simplified sectional view showing a specific example of a developing device according to the present invention applied to an image forming apparatus. FIG. 2 is a simplified diagram showing part of a control system of an image forming apparatus to which the developing device of FIG. 1 is applied. FIG. 3 is a partially simplified sectional view showing the developing device of FIG. 1 when the sleeve is moved in a direction opposite to the direction of movement during the developing operation. 2...Development housing 6...Magnetic brush mechanism 10...Sleeve l2...Permanent magnet 18...Rotating drum 22...Development area 24...Replenishment area 28...Blade 33...・Driving source 50... Control means younger brother 2 drawings 0 handwriting (self-proposal) December 19, 1985 Director General of the Patent Office Fumi Tsuyoshi Yoshida 1, Indication of the case 1985 Patent Application No. 285158 2 ．． Name of invention Developing device 3. Relationship with the case of the person making the amendment Patent Applicant Address 1-2-28 Tamatsukuri, Higashi-ku, Osaka Name (6)
15) Sanda Kogyo Co., Ltd. 4. Agent 8105 5. Date of amendment order: Showa year, month, day (shipment date) None 6. Detailed description of the invention and drawings 7. Details of the amendment (1)
+l) In the first line of page 12 of the specification, the word "current" is corrected to rpower j. (2) In the first line of page 13, replace the word “current” with “
Corrected to 'Electricity'. {3} On page 15, lines 1 and 2 of the same page, it says, “About half...
good. '' is changed to ``About half or more, preferably 1 to 3 or more in specific examples. ” Corrected. (4) On page 15, line 6 of the same page, the phrase ``increase'' is corrected to ``as it becomes larger.'' (5) On page 15, line 9 of the same page, the phrase ``Causes. In order to avoid being transported beyond the transport pole S2 in the direction opposite to the direction shown, the amount of movement is preferably less than or equal to the distance between the replenishment pole N2 and the transport pole S2. ” Corrected. (II) Proverbs 1 (11) Replace Figure 1 of the drawings with Figure 1 of the attached drawings. Figure 1

Claims (1)

[Claims] 1. A magnetic brush mechanism consisting of a hollow cylindrical sleeve that holds developer on its peripheral surface and a permanent magnet disposed within the sleeve, and a magnetic brush mechanism that acts on the sleeve surface and is held by the sleeve. The sleeve or the permanent magnet is moved in a predetermined direction to transport the developer held on the sleeve surface toward the development area, and the blade removes the excess developer. In a development device for controlling the amount of developer delivered to the development zone, the sleeve or the permanent magnet is moved in a direction opposite to the predetermined direction to create a space between the surface of the sleeve and the free end of the blade. 1. A developing device for removing a developer reservoir present in a developing device. 2. A magnetic brush mechanism consisting of a hollow cylindrical sleeve that holds developer on its peripheral surface and a permanent magnet disposed within the sleeve, and a magnetic brush mechanism that acts on the sleeve surface to remove excess developer held by the sleeve. a removing blade, the sleeve or the permanent magnet is moved in a predetermined direction to convey the developer held on the sleeve surface toward the developing area, and the developer is fed to the developing area by the action of the blade. In a developing device for controlling the amount of developer applied, the sleeve or the permanent magnet is moved in a direction opposite to the predetermined direction before the start of the developing action, so that the surface of the sleeve and the free end of the blade are A developing device characterized in that it removes a developer reservoir existing between the developing devices. 3. A magnetic brush mechanism consisting of a hollow cylindrical sleeve that holds developer on its peripheral surface and a permanent magnet disposed within the sleeve, and a magnetic brush mechanism that acts on the sleeve surface to remove excess developer held by the sleeve. a removing blade, the sleeve or the permanent magnet is moved in a predetermined direction to convey the developer held on the sleeve surface toward the developing area, and the developer is fed to the developing area by the action of the blade. In a developing device for controlling the amount of developer applied, the sleeve or the permanent magnet is moved in a direction opposite to the predetermined direction after the completion of the developing action, so that the sleeve or the permanent magnet is moved between the surface of the sleeve and the free end of the blade. A developing device characterized by removing an existing developer reservoir.