JP3104303B2 - Developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for an image forming apparatus, such as a copying machine or a laser beam printer, for developing and visualizing an electrostatic latent image.

[0002]

2. Description of the Related Art Conventionally, a copying machine or a laser beam printer using a two-component developer containing a toner and a carrier as main components is provided with a means for stirring and mixing the toner and the carrier. The present invention is an improvement of Japanese Patent Application No. 2-337697, which is a prior application, wherein the developing device of the prior application constitutes the means for stirring and mixing using a plurality of spiral screws, By providing an agitating auxiliary member horizontally with respect to the axis of the screw on the outer peripheral portion of the screw shaft, the developer present around the screw is forcibly drawn into the screw by the agitating auxiliary member, and the developer is Stirring performance is improved.

[0003]

However, in the structure of the stirring assisting member disclosed in Japanese Patent Application No. 2-33797, the stirring assisting member is provided horizontally with respect to the axis of the screw. Therefore, since the stirring surface of the stirring assisting member extends perpendicularly to the radial direction of the screw,
Once the developer is caught by the agitating auxiliary member, it cannot escape from there, and an excessive mechanical load is applied to the developer. As a result,
It has been found that toner blocking occurs in the lower part of the developer container 1. SUMMARY OF THE INVENTION It is an object of the present invention to improve the stirring and mixing performance of a screw, minimize the load on the developer during stirring, and extend the life of the developer.

[0004]

Means for Solving the Problems The developing device of the present invention comprises:
The above object is achieved by providing a screw having a spiral structure for stirring and mixing the developer with a stirring auxiliary member inclined in a direction to accelerate the flow of the developer. Further, the above object is achieved by varying the distance between the partition plate disposed between the two screws and the bottom of the developer container in the screw axis direction.

[0005]

With the above construction, a developing device which does not cause toner blocking while minimizing the load on the developer at the time of stirring can be realized. Life can be extended.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a laser printer according to an embodiment of the present invention; In FIG. 1, reference numeral 1 denotes a developer accommodating container, and two screws 3 and 4 each having a stirring assisting member 2 and a spiral blade are arranged at the bottom of the container 1. The positional relationship between the screws 3 and 4 is such that the axis of the screw 4 is located at about 10 ° above the axis of the screw 3 with respect to the horizontal direction, and the developer flows smoothly from the screw 4 side to the screw 3 side. It has a configuration. Screw 3 and developing sleeve 5
The shielding plate 7 provided between the two prevents the occurrence of density unevenness due to the screw 3 itself. Without this shielding plate 7, for example, when the entire surface is printed in black, as shown in FIG. A mark 3 'of the screw 3 appears on the surface 20, and a stripe pattern is formed at a pitch p of the screw 3 on the printed matter, so that a printed matter having uneven density is formed. A shielding plate 7 is provided to prevent such printed matter from being generated. In this embodiment, the shielding plate 7 is provided at a position where the magnetic flux distribution between the magnetic poles S1 and S3 of the developing sleeve 5 becomes substantially zero. Developing sleeve 5
Has been subjected to surface treatment such as fusion of metal particles and groove processing. A permanent magnet having a plurality of magnetic poles is provided inside, and the developer 6 is attracted and transported while rotating in the direction of the arrow, and the developer attracted to the developing sleeve 5 by a regulating member 8 provided in the transport direction. 6 is restricted to a layer of a certain thickness,
It is transported to the photoconductor 9. After the surface is uniformly charged by the corona discharge of the charger 10, a latent image is formed on the photoreceptor 9 by a light source 11 such as a semiconductor laser or an LED. The developer 6 transported to the latent image portion on the photoreceptor 9 adheres only the toner to the photoreceptor 9, and the developer 6 having completed the developing process is scraped off from the developing sleeve 5 at the tip of the shielding plate 7, and again. Stir-mixing is performed in the container 1. The remaining developer regulated by the regulating member 8 is supplied to the preliminary stirring member 1 by the inclined guide plate 12.
It is carried to 3. The toner hopper 14 is provided above the developer container 1 and drives the toner supply roll 15 when the toner concentration in the developer becomes lower than a certain level.
The toner 16 is put on the preliminary stirring member 13. The replenished new toner 16 is mixed with the developer 6 sliding down on the inclined guide plate 12, and after being preliminarily stirred, the stirring is further forcibly performed by the screws 3 and 4, so that it is more effective. Mixing performance is obtained. Inclined guide plate 12
The developer 6 that slides on the upper side tends to hardly slide down due to the magnetic force received from the magnetic pole N2 in the developing sleeve 5. Therefore, the inclined guide plate 12 is made of a non-magnetic material such as aluminum or stainless steel. When the magnetic force on the inclined guide plate 12 is 50 Gauss or less, the developer on the inclined guide plate 12 can slide without being affected by the magnetic force of N2, and as a result, the replenishment can be achieved. The pre-agitation can be favorably performed by the mixed toner. Reference numeral 17 denotes a partition plate which is provided between the screws 3 and 4, and is effective in preventing insufficiently mixed toner from being conveyed to the developing sleeve 5. According to the experiment, the effect of the partition plate could be obtained if the developer 6 was partitioned to a depth of about 5 mm. Next, the screw will be described in detail. In the present invention, as shown in FIGS. 2 and 3, the stirring assisting member 2 is provided at an angle θ (preferably 30 ° to 60 °) in the direction of accelerating the flow of the developer with respect to the axis of the screw. Since the screw 3 and the screw 4 are rotating in different directions at the bottom of the developer accommodating container 1, as shown in FIGS. 4 and 5, the stirring assisting members 2 are alternately arranged at every other pitch of the screw (staggered). (Arrangement). In this way, the mechanical load exerted on the developer by the stirring assisting member 2 can be reduced, and the region in which the stirring effect of the screws 3 and 4 is exerted can be well balanced. In addition, although the stirring auxiliary member 2 was attached every other pitch of the screw, the number of pitches is not limited. As shown in FIG. 6, cutouts 171 and 1 are formed at both ends of the partition plate 17 as passages for the developer in order to prevent uneven stirring of the developer.
72 is provided so that the distance from the container bottom plate differs in the axial direction of the screw. As a result, the developer that is offset on the upstream side of the screw 4 is moved from the screw 4 side to the screw 3 side, and similarly, the developer is moved from the screw 3 side to the screw 4 side on the downstream side.

[0007]

As described above, according to the developing device of the present invention, since the stirring assist member is attached to the screw at a tilt in the direction of accelerating the flow of the developer,
It is possible to minimize the mechanical load exerted on the developer by the side surface of the stirring assisting member due to the rotation force of the screw, and to provide a developing device free from toner blocking.

[Brief description of the drawings]

FIG. 1 is a sectional view of a developing device according to an embodiment of the present invention.

FIG. 2 is a front view showing a configuration of a screw according to the present invention.

FIG. 3 is a top view of FIG. 2;

FIG. 4 is a top view showing a mounting position of the stirring assisting member of the present invention.

FIG. 5 is a top view showing a mounting position of the stirring assisting member of the present invention.

FIG. 6 is a diagram showing a positional relationship between a partition plate and a screw.

FIG. 7 is an explanatory diagram illustrating a printed matter when printing is performed without a shielding plate.

[Explanation of symbols]

Reference numeral 2 denotes a stirring auxiliary member, reference numerals 3 and 4 denote screws, and reference numeral 17 denotes a partition plate.

──────────────────────────────────────────────────の Continued on front page (72) Inventor Yoshitaka Fujinuma 1060 Takeda, Katsuta-shi, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (72) Inventor Akira Takizawa 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Engineering Co., Ltd. Examiner Osamu Komaki (56) References JP-A-3-42691 (JP, A) JP-A-62-136674 (JP, A) JP-A-3-4267 (JP, A) JP-A-3-80272 ( JP, A) JP-A-52-88347 (JP, A) JP-A-3-29976 (JP, A) JP-A-3-42691 (JP, A) Fully open H2-100267 (JP, U) Really open Hei 1-67651 (JP, U) JP-A 56-47540 (JP, U) JP-A 63-150962 (JP, U) JP-A 64-43364 (JP, U) Patent 2967713 (JP, B2) Table 4-504012 (JP, A) International publication 91/9350 (WO, A1) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/08-15/095

Claims (1)

(57) [Claims] 1. A developer accommodating means comprising a plurality of spiral screws in a developer accommodating container, wherein the agitated developer mainly composed of toner and carrier adheres to a developing sleeve. In the developing device for visualizing the electrostatic latent image formed on the recording medium by the developer adhered on the developing sleeve , a stirring assist member is provided on the surface of the shaft of the plurality of screws,
The agitating auxiliary member is used to flow the developer with respect to the axis of the screw.
In the direction of accelerating
Alternately placed against the opposite screws
A developing device provided at a constant pitch of the screw .