JPH0423242Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a developing device applied to an image forming apparatus applying electrophotographic technology.

[Prior art and its problems]

In a developing device applied to an image forming apparatus that applies electrophotographic technology, toner is attached to the outer periphery of a rotating sleeve containing a magnet roll and regulated in order to obtain a stable visible image with toner on a photoreceptor. A method is known in which the thickness of the toner on the outer circumferential surface of the sleeve is regulated by a plate to form a regulated layer of a constant thickness, and the toner is conveyed to the photoreceptor. Conventionally, developing methods for electrostatic latent images can be roughly divided into two types: two-component developers in which toner particles and carrier particles are mixed, and one-component developers in which only toner particles are used without using carrier particles. There is a method using a developer. In the former method, the toner particles are attached to the electrostatic latent image using electrostatic force generated by the frictional electrification of the toner particles and the carrier particles, and the image is developed by mixing the toner particles and the carrier particles. It is necessary to keep the ratio constant, which requires complex devices such as toner concentration detection means and advanced control technology.

On the other hand, the latter method using a one-component developer is
Currently, the one-component development method uses a one-component developer made of magnetic toner, which has the advantages of not having to control the toner concentration mentioned above, simplifying the device, and making it easy to form a developer layer. are widely adopted. However, in this case, the certain regulation layer of the toner called the so-called doctor gap is usually
Since it is very narrow at about 0.3 to 0.5 mm, toner clogging is likely to occur, and it is not easy to maintain this regulation layer constant.

Conventionally, as shown in FIG. 4, the regulating plate 1 is arranged such that both ends thereof are in contact with the abutment member 2 while the tip thereof maintains a predetermined gap from the outer circumferential surface of the sleeve 3.
The parts were fastened with mounting screws 4, 4 and fixed in place. In this case, since the two mounting screws 4, 4 were both right-handed, when the mounting screws 4, 4 were tightened, the left side of the regulating plate 1 was raised and tilted. fixed, and the gap with the surface of the sleeve 3 is not constant and inaccurate along the longitudinal direction, making it difficult to obtain a stable visible image during the development process, especially in the one-component development method where the regulating layer is very narrow. This was a major problem as the impact was noticeable in some cases.

[Purpose of invention]

SUMMARY OF THE INVENTION In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a developing device in which a regulating plate is accurately attached and a stable visible image is formed.

[Key points of the idea]

In order to achieve the above object, the present invention includes a layer thickness regulating member, a non-magnetic sleeve containing a magnet, and a fixing member that adjusts and fixes the layer thickness regulating member at a predetermined gap with respect to the non-magnetic sleeve. The developing device is characterized in that the fixing means includes a plurality of fixing screws, and at least one of the screws rotates in the opposite direction to the other screws.

[Example of idea]

Embodiments of the present invention will be described with reference to the drawings, taking an image forming apparatus using a photoreceptor drum as an example.

FIG. 3 is a partially enlarged vertical sectional view showing the main parts of a developing device according to an embodiment of the present invention.

The developing device includes a magnet roll 6 provided near the outer peripheral surface of the photoreceptor drum 5, a developing sleeve 7,
It includes a developing casing 8, a regulating plate 9, and the like.

The photosensitive drum 5 is rotatably supported, driven in the direction indicated by arrow X, and rotated at a predetermined speed. After the circumferential surface of the photosensitive drum 5 is uniformly charged with a charger (not shown), an electrostatic latent image formed by exposing the circumferential surface to light is transferred to a developing area D.
will be transported to.

The magnet roll 6 is rotatably supported,
Approximately 1300R.PM clockwise as shown by arrow Y
The magnet is driven and rotated at a relatively high speed, and a total of eight magnetic poles are evenly magnetized along the circumferential surface, with adjacent magnetic poles having different polarities S and N.

The developing sleeve 7 encloses the magnet roll 6 and is rotatable, and a part of the circumferential surface is close to the outer circumferential surface of the photoreceptor drum 5 in the developing area D.
It is arranged facing the opening 8a formed at the bottom of the developer casing 8, and is driven and rotated at a low speed of about 30 R.PM in the same direction as the magnet roll 6, and functions as a developer conveyor. It is something that we fulfill. The developing sleeve 7 of this example is made by applying an alumite treatment to the surface of a cylindrical body made of aluminum, a non-magnetic material, to uniformly deposit an oxide film with a thickness of about 10 μm, and then sandblasting the surface. Fine irregularities with a depth of about 20 μm are formed.

The developing casing 8 accommodates the magnetic toner 10 in its lower part along a moving path substantially opposite to the developing area D on the peripheral surface of the developing sleeve 7, and supplies the magnetic toner 10 in an appropriate amount onto the peripheral surface of the developing sleeve 7. A toner hopper 8b is formed.

The regulating plate 9 is made of a non-magnetic material, and its tapered lower end faces the opening 8a of the developing casing 8 and is fixed to the developing casing 8c with a predetermined gap from the surface of the developing sleeve 7. .

FIG. 1 is a partially enlarged perspective view showing the main parts of the developing device.

The regulating plate 9 has a rectangular shape and has two through holes 9a, 9a formed at symmetrical positions on the left and right sides. There are two female screws 1 at corresponding positions on the developing casing 8c.
1a and 11b are provided, and among these, one female thread 11a is a right-hand thread, and the other female thread 11b is a left-hand thread. Correspondingly, one mounting screw 12a for mounting the regulation plate 9 is a right-handed screw,
The other mounting screw 12b is a left-hand thread, and the mounting screws 12a, 12b are inserted into the through holes 9a, 9a,
Attach the regulation plate 9 to the screws 12a, 12b and the female screw 1.
Attach by screwing 1a and 11b together.

FIG. 2 is a front view showing how to attach the regulating plate 9.

The thickness of the regulating layer 10a (see Fig. 3) of the magnetic toner 10, which is called a so-called doctor gap, is usually about 0.3 to 0.5 mm, and this tool is used as a jig for adjusting a predetermined thickness according to the thickness of the regulating layer 10a. The abutting members 13, 13 are arranged near both ends of the developing sleeve 7 corresponding to the position of the regulating plate 9, and after positioning by abutting the regulating plate 9 against the abutting members 13, 13, a right-handed thread is formed. Mounting screw 12
a and the left-hand threaded mounting screw 12b to mount and fix the regulating plate 9. Thus, in FIG. 2, the left mounting screw 12b
Since the is a left-handed thread, the regulating plate 9 can be sufficiently pressed against the abutment member 13 without tilting left or right.
The gap with the developing sleeve 7 is maintained uniform along the longitudinal direction. Further, as the development is repeated, the tightening force of the left and right mounting screws 12a and 12b is set in the opposite direction of rotation, so that the regulation plate 9 is less likely to loosen.

Next, the operation of the developing device having the above configuration will be explained. In Figure 3, the magnet roll 6
The magnetic toner 1 that comes into contact with the circumferential surface of the developing sleeve 7 or exists near the circumferential surface as the developing sleeve 7 rotates.
0 moves in the direction indicated by the dotted arrow, which is opposite to the direction of rotation, under the action of the fluctuating magnetic field of the magnet roll 6, and when it reaches the position where the regulation plate 9 is installed, it is moved by the regulation plate 9. Movement is regulated and the regulation layer 10a is thinned to have an appropriate thickness. That is, the moving magnetic toner 10 is forced to pass through a certain minute gap S formed between the lower end of the regulating plate 9 and the surface of the developing sleeve 7, thereby achieving a desired desired state suitable for development. The layer thickness is reduced to . This thin layer of magnetic toner 10 is conveyed to the development area D as the magnet roll 6 rotates, and is used to develop the electrostatic latent image formed on the surface of the photoreceptor drum 5. Since the regulating plate 9 is held with a constant gap between it and the developing sleeve 7, a regulating layer 10a having a uniform thickness is formed in both the circumferential direction and the longitudinal direction of the developing sleeve 7. Stable image formation is performed.

In the above embodiment, the mounting screw 12a on the right side of the front is a right-hand thread, and the mounting screw 12b on the left side of the front is a right-hand thread.
Although the left-hand thread is shown, the left and right mounting screws may be interchanged, as long as the directions of rotation of the left and right mounting screws are opposite to each other during tightening. Furthermore, the number of mounting screws is not limited to two, but it is also possible to provide three or more, in which case at least one of the mounting screws only needs to rotate in the opposite direction to the other mounting screws, and is further limited to one-component development. Of course, it is also applicable to a two-component development method.

[Effect of idea]

According to the present invention, the fixing means for adjusting and fixing the layer thickness regulating member at a predetermined gap with respect to the rotating non-magnetic sleeve containing a magnet includes a plurality of fixing screws, and at least one of the screws includes a plurality of fixing screws. Since one screw rotates in the opposite direction to the other screws, when the screws are rotated and tightened, the layer thickness regulating member is accurately attached to the non-magnetic sleeve with a predetermined gap without one end lifting up. A developing device that forms stable visible images can be provided.

[Brief explanation of the drawing]

FIG. 1 is an enlarged partially cutaway perspective view showing the main parts of a developing device according to an embodiment of the present invention, FIG. 2 is a front view showing how to attach a regulating plate, and FIG. FIG. 4 is a partially enlarged vertical cross-sectional view showing the main parts, and is a front view showing a conventional method of attaching a regulating plate. 5... Photosensitive drum, 6... Magnet roll, 7... Development sleeve, 8... Development casing, 8a... Opening, 8b... Toner hopper, 9
...Regulation plate, 9a...Through hole, 10...Magnetic toner, 11a, 11b...Female screw, 12a, 12a
...Mounting screw, 13...Abutment member.

Claims (1)

[Scope of utility model registration request] In a developing device comprising a layer thickness regulating member, a non-magnetic sleeve containing a magnet, and a fixing means for adjusting and fixing the layer thickness regulating member with respect to the non-magnetic sleeve with a predetermined gap, the fixing means A developing device comprising a plurality of fixing screws, at least one of which rotates in the opposite direction to the other screws.