JPS63311285A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of cavity with a simple constitution by disposing a stirring member having magnetic circle parts of plural windings which abut on a developing sleeve at least on both ends in parallel with the developing sleeve in a developing container so that it can freely turn. CONSTITUTION:The stirring member 10 for stirring a developer has the magnetic circle parts 10a and 10b of plural windings which abut on the developing sleeve 3 at least on both ends. For example, by spirally winding the end part of one magnetic wire having a circular section plural times, the circle parts 10a and 10b are formed to be used. The stirring member 10 is disposed in parallel with the developing sleeve 3 in the toner 2 in the developing container 1 to be freely rotated. Then, the circle parts 10a and 10b of the stirring member 10 are strongly attracted by a permanent magnet 4 and made to abut on the developing sleeve 3. If the developing sleeve 3 or the permanent magnet 4 rotates, the circle parts 10 and 10b receives the rotating force and the stirring member 10 rotates as if a follower roller, so that the developer is stirred and the occurrence of the cavity can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a magnetic brush type developing device, and more specifically, a brush-like developing device is produced on the developing sleeve by the magnetic field of a permanent magnet disposed inside the developing sleeve. In a developing device that forms ears of developer and brings the ears into contact with a photoreceptor while rotating at least one of the developing sleeve or a permanent magnet to develop an electrostatic latent image formed on the photoreceptor. Regarding the Kamakura prevention structure.

(Background of the Invention) Typical types of II devices that use a dry developer include a magnetic brush type and a cascade type, but the former is often used in terms of miniaturization. In this magnetic brush type developing device, in order to form a magnetic brush on the developing sleeve, it is necessary to keep the developer in good contact with the sleeve surface at all times. It must be constructed so that no cavities are formed.For this purpose, developing devices have conventionally been equipped with a developer stirring mechanism.

Conventional stirring mechanisms include those in which a stirring member (for example, a snail) is rotatably disposed inside the developing container and the stirring member is rotationally driven from the outside, and a cantilevered vibration plate is arranged in the developing container. Some vibrate this using the rotation of a developing roller (consisting of a permanent magnet and a developing sleeve).

(Problem to be Solved by the Invention) When the former stirring mechanism is provided, one end of the stirring member must protrude outside the developing container and must be rotated via a belt or the like, and a bearing must be provided. In addition, a winding device for power transmission is required, which makes the structure complicated and increases the size. Furthermore, problems such as toner spillage from the bearings occur. Further, when the driving force is taken from an external source, the rotational speed is constant regardless of the a of the developer, so if m of the developer is large, excessive stress is applied to the developer, which may cause deterioration of the development characteristics. On the other hand, when the latter type of stirring mechanism is provided, the stirring effect is small and stagnation is likely to occur.

The present invention has been made in view of the above-mentioned problems, and its purpose is to reliably prevent the occurrence of kamakura with a simple structure, prevent developer from spilling, and avoid applying excessive stress to the developer. Current eI! The goal is to provide equipment.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, forms brush-shaped spikes of developer on the developing sleeve using the magnetic field of a permanent magnet disposed inside the developing sleeve. In a developing device that develops a static ffi latent image formed on the photoreceptor by bringing the panicle into contact with a photoreceptor while rotating at least one of the developer sleeve or a permanent magnet, The invention is characterized in that a stirring wire having magnetic ring portions at least at both ends is rotatably disposed within the developer container and alongside the developer sleeve. .

(Function) In the developing device of the present invention, the circular ring portions at both ends of the stirring wire A are attracted by the permanent magnet and are brought into contact with the developing sleeve. Therefore, when the developing sleeve or the permanent magnet rotates, this annular portion receives rotational force, causing the agitating member to rotate like a driven O-ra, agitating the developer and preventing the occurrence of stagnation.

Moreover, since the circular ring part has multiple turns, the circular ring part is strongly pulled toward the sleeve side, and sufficient stirring force can be obtained.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing the main structure of an embodiment of the present invention using a one-component magnetic toner, and FIG. 2 is a side view seen from the right side of FIG. 1. In these figures, 1
1 is a developing container containing toner 2, and a developing sleeve 3 is disposed in an exposed state from the developing container 1. The developing sleeve 3 has a cylindrical shape, is made of a non-magnetic material, and is rotationally driven in the direction of the arrow in FIG. 1 via a gear (not shown). A magnetic pole N is provided inside the developing sleeve 3.

Permanent magnets 4 having S arranged alternately in the circumferential direction are rotatably supported. The permanent magnet 4 has lN11 on the protruding part.
It is rotationally driven in the direction of the arrow in FIG. 1 through the gear 5. Reference numeral 6 denotes a spike regulating plate fixed to the developer container 1. The height of the brush-like toner spikes formed on the developing sleeve 3 is determined by the distance between the tip of the spike-standing M control plate 6 and the developing sleeve 3, and the rotation of the developing sleeve 3 and the permanent magnet 4 causes the toner to be The photoreceptor 7 rotates in the direction of the arrow in FIG.
The electrostatic am formed on the photoreceptor 7 is developed.

Reference numeral 10 denotes an agitating member for agitating the developer, which has a plurality of magnetic circular ring portions that abut at least the developing sleeve 3 at both ends. In this embodiment, the circular ring portion 10a is formed by winding the end of one six magnetic wires with a circular cross section in a spiral shape multiple times.
, 10b is used, and this stirring member 10 is rotatably disposed in the toner 2 in the developer container 1 so as to be aligned with the developer sleeve 3. Therefore, the circular ring portion 10a of the stirring member 10, 1. Ob is strongly attracted by the permanent magnet 4 and comes into contact with the developing sleeve 3. Moreover, the circular ring part 10a,
In this embodiment, the intermediate section 100 connecting the sections 10b is a straight line, so that the annular sections 10a and 10b are arranged coaxially. Moreover, the distance between the two is determined by the circular ring portions 10a, 10b.
It is slightly narrower than the width of the developing sleeve 3 so that it comes into contact with the end of the developing sleeve 3, and when the toner 2 becomes low, the marks of the annular parts 10a and 10b remain on the developing sleeve 3 and the development is disturbed. The image width is set wider than the image width (effective image area) to prevent this. Of course BS permanent magnet 4
The ring portions 10a, 1 are located at positions where a sufficient amount of magnetic attraction force is obtained.
It is a premise that 0b exists. In addition, developing sleeve 3
The movement of the stirring member 10 is regulated in the developer container 1 so that the stirring member 10 does not move relative to the developer container 1 in the axial (width) direction. Further, the winding direction of the circular ring portion 10b is opposite to that of the circular ring portion 10a shown in FIG.

Next, the operation of the above embodiment will be explained. Development is performed by rotating the permanent magnet 4 and the photoreceptor 7 in the direction of the arrow in FIG. On the other hand, the W1 itching member 10 has a multi-roll circular ring part 10.
a and 10b are always strongly attracted by the permanent magnet 4 and in contact with the developing sleeve 3. Therefore, when the developing sleeve 3 rotates, the a! of the circular ring portions 10a, 10b and the developing sleeve 3! The agitating member 10 tends to move in that direction due to the frictional force. However, due to its own weight, the stirring member 10
It receives a force in the clockwise direction (direction of the arrow) in the figure and rotates in that direction. By this rotation of the stirring member 10, the toner 2 on the upper part of the developer container 1 is scraped off and sent to the developer sleeve 3 side. In the case of this embodiment, since there is a gap between the stirring member 10 and the developer container 1, and the intermediate portion 10c is eccentric from the common central axis of the annular portions 10a and 10b, the stirring member 10 does not only perform rotational movement. Furthermore, since the rocking motion is actively performed, the toner 2 can be sent to the developing sleeve 3 side extremely effectively. Also, as described above, the circular ring portion 10a.

If you choose the winding direction of 10b, the toner 2 will be wrapped around this circular ring part 1.
This is convenient because it is sent to the center by the rotation of Oa and 10b. Moreover, when the toner 2 has just been replenished and the inside of the developer container 1 is filled with the toner 2, the toner 2
The rotation of the agitating member 10 is slowed down due to the resistance of There is no need to put excessive stress on the person.

Although the above embodiment is of a type in which the developing sleeve 3 and the permanent magnet 4 rotate, the present invention can also be applied to a developing device of a type in which only the developing sleeve 3 rotates.

Further, although the stirring member 10 is shown as being formed by winding a wire with a circular cross section, the circular ring portion 10a is formed by press forming a plate material.
10b may be formed and fixed to the intermediate portion 1Qc. Further, the circular ring portions 10a and 10b do not need to be formed by winding a wire, and may be formed, for example, by a large-diameter screw. Furthermore, the intermediate portion 10c does not need to be a straight line.

The shape (structure) of this intermediate portion 10c and the annular portion 10a, lQ
By changing the number of turns of b, the relationship between the remaining m of toner 2 and the rotational speed of the stirring member 10 can be freely changed. For example, the circular ring portion 10a.

When the number of turns of 10b is increased, the rotational force (torque) received from the permanent magnet 4 further increases, and the rotational speed increases. Instead of increasing the number of turns, it may be possible to increase the diameter of the circular ring portions 10a, 10b or to form them into a cylindrical shape.
In reality, when this is done, the toner 2 is transferred to the annular portion iQa,
10b and the developing sleeve 3, and the annular portion 10
a and 10b are separated from the permanent magnet 4, and the rotational force is rather reduced. This will not happen if the circular ring portions 10a and 10b have a wound shape or a similar shape.

3 to 8 show specific examples of the shape of the stirring member 10, respectively. First, the configuration shown in FIG. 3 has a plurality (4) of straight intermediate portions 10c in order to increase the stirring effect, and the configurations shown in FIGS. 4 and 5 have intermediate portions 10c bent into a rectangular wave shape and a sine wave shape, respectively. It is something that The structure shown in FIG. 6 has one long stirring blade 10d provided in the intermediate portion 10c, and the structure shown in FIG. 7 has a large number of short stirring blades 10d. Furthermore, the configuration shown in FIG. 8 is a circular ring portion 10a.

The diameter of the winding 10b is made smaller as it goes inward. By the way, in order for the intermediate portion 10c not to have an adverse effect on the image, it is necessary that the intermediate portion 10c be separated from the developing sleeve 3 by at least the standing height. On the other hand, at least a portion of the annular portions 10a and 10b must be in contact with the developing three 13, and preferably outside the effective image area. Therefore,
If the winding diameter is made smaller toward the inside as shown in FIG. 8 above, the annular portions 10a and 10b (a portion) located further away from the developing sleeve 3 than the height of the spike will be within the effective image area. This is convenient because rotational force can be generated without adversely affecting the image even when the image is in use. Various shapes of the stirring member 10 can be considered.

Further, although the above embodiment uses a one-component magnetic toner, the present invention can also be applied to a developing device using a two-component developer.

As described above, the rotational speed of the stirring member 10 decreases when there is a large amount of developer, and increases when the amount of developer decreases. Therefore, the remaining amount of developer can be detected based on the signal corresponding to this rotational speed. In this case, the rotation speed of the stirring member 10 can be detected by various methods, but among them, magnetic detection is the easiest method. In this method, a magnet is fixed to the intermediate portion 10c, a reed switch is disposed near the rotation locus of the magnet, and the reed switch is turned on/off.
The reed switch is connected as shown in FIG. 9 to detect the rotational speed of the stirring member 10 from the OFF state. In the figure, 12 is a reed switch, one contact is grounded, and the other contact is connected to a positive voltage source E via a resistor R. In addition, D
is a diode connected in parallel to the resistor R, and C is a capacitor connected between the connection point A between the reed switch 12 and the resistor R and the ground, and chattering is prevented by this circuit. 14 is a retriggerable mono-multi vibrator (hereinafter simply referred to as mono-multi); 1. It is designed to be triggered by a signal from the connection point.

Therefore, the interval between the output pulses of the monomulti 14 is M corresponding to (inversely proportional to) the rotational speed of the stirring member 10.

FIG. 10 shows an example of the relationship between the remaining amount of developer and the output pulse interval of the monomulti 14.

As is clear from this figure, as the remaining amount of developer decreases, the output pulse interval of the monomulti 14 also decreases. Using this characteristic, the microprocessor 15 detects that the amount of remaining ffi X o that requires developer replenishment has been reached, since the output pulse interval of the monomulti 14 has become Yo.
Output an alarm.

In addition, if the shape of the stirring member, especially the middle part, receives large stirring resistance from the developer during stirring (for example, if it has stirring blades, the area of the stirring blade is increased), the first
The slope of the characteristic curve shown in Figure 0 becomes larger. Therefore,
By increasing or decreasing the stirring resistance, the accuracy of detecting the remaining amount of developer and the degree of stress applied to the developer can be adjusted.

(Effects of the Invention) As described above, according to the present invention, the reliable rotation of the agitation member allows the developer to be sent to the developing sleeve side in a good manner, so that it is possible to realize a developing device in which no stagnation occurs. Also, if the developer container is filled with developer and the developer has just been replenished, the rotation of the agitating member is slow due to the resistance of the developer, and the developer may spill. When the toner is consumed and the toner tends to form, the rotation becomes faster and sufficient agitation is performed, making it possible to realize a developing device in which the agitation member does not rotate unnecessarily and apply excessive stress to the developer.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the main structure of an embodiment of the present invention, FIG. 2 is a side view seen from the right side of FIG. 1, and FIGS. 3 to 8 each show a specific example of the stirring member. FIG. 9 is a block diagram of detecting the remaining m of the active drug, and FIG. 10 is a diagram showing the output of the monomulti in FIG. 9.゛1...Developing container 2...Toner 3...Developing sleeve 4...Permanent magnet 6...Standing regulation plate
7... Photoreceptor 10... Stirring member 10a, 1
0b...Circular portion 10c...Intermediate portion Patent applicant: Roku Konishi Photo Industry Co., Ltd. Agent
Person Patent attorney Fuji Ijima 1 person

Claims (1)

[Claims] A brush-like spike of developer is formed on the developing sleeve by the magnetic field of a permanent magnet disposed inside the developing sleeve, and the spike is brought into contact with the photoreceptor while rotating the developing sleeve to form it on the photoreceptor. In the developing device for developing an electrostatic latent image, a stirring member having at least both ends thereof a plurality of magnetic ring portions that come into contact with the developing sleeve is rotatable in the developing container and in line with the developing sleeve. A developing device characterized in that it is disposed in.