JPH0636063U - Development unit of electrophotographic printer - Google Patents

Abstract

(57) [Abstract] [Purpose] An electronic device that can easily attach a doctor blade and keep the developer layer on the magnet roll at a predetermined thickness by keeping the magnet roll and the doctor blade at a predetermined distance. A developing unit for a photographic printer is provided. A magnet roll 4 is rotated at a constant speed with a small gap between the photosensitive member 1 and a developer layer formed by magnetic attraction on the surface in the rotating process to adhere to the photosensitive member 1.
And both sides of the doctor blade 5 in a developing unit of an electrophotographic printer having a doctor blade 5 provided in proximity to the magnet roll 4 in order to regulate the developer layer to a predetermined thickness. On the edge
A roller 10 protruding in the direction of the magnet roll 4 from the doctor blade tip edge 5a by an amount corresponding to the thickness of the developer layer,
11 is rotatably attached, and the rollers 10 and 11 are brought into contact with the outer peripheral surface of the magnet roll 4 by biasing members 14 and 15.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a developing unit of an electrophotographic printer, and more particularly to a mechanism for maintaining a gap between a magnet roll (developing sleeve) and a doctor blade.

[0002]

[Prior art]

 FIG. 1 is a configuration diagram of a main part of a developing unit according to a conventional example. In the figure, 1 is a drum-shaped photoconductor (a belt-shaped photoconductor may be used), 2 is a developing unit having a toner hopper 3, a magnet roll 4, a doctor blade 5, etc. A stirrer paddle, etc. are provided, but they are omitted because they are not directly related to the present invention), and 6 is a transfer and peeling device. Of the electrophotographic process unit around the photoconductor, the charger, the cleaning unit, the discharge lamp, etc. are omitted for the same reason.

The magnet roll 4 faces the photoconductor 1 with a minute gap and rotates in the direction of the arrow at a constant peripheral speed. During the rotation process, the magnetically attracted developer (two-component developer consisting of toner and carrier, or one-component developer consisting of magnetic toner) is attached to the surface of the magnet roller 4 onto the photoconductor 1 and the static It is attracted to the latent image and visualizes it.

The doctor blade 5 has a length in the longitudinal direction substantially equal to that of the magnet roll 4, and is disposed above the magnet roll 4 and close to the magnet roll 4 with a predetermined gap. Therefore, the developer on the magnet roll 4 is regulated to a predetermined thickness by the doctor blade 5. The doctor blade 5 is fixed to a mounting piece 9 fixed to the developing unit casing 8 with a screw 7.

[0005]

[Problems to be solved by the device]

 As described above, since the conventional doctor blade 5 is fixed to the attachment piece 9, the flatness of the doctor blade 5 and the concentricity variation (eccentricity) of the magnet roll 4 remain the same between the magnet roll 4 and the doctor blade 5. However, there is a problem in that the developer on the magnet roll 4 cannot always be stably secured to a predetermined thickness.

Further, there is a problem that the mounting accuracy when the doctor blade 5 is mounted on the mounting piece 8 with the screw 7 becomes a problem, and that the mounting time is long.

The present invention has been made in view of such a background, solves the above-mentioned drawbacks of the conventional apparatus, facilitates the installation of the doctor blade, and always keeps the magnet roll and the doctor blade at a predetermined distance. Thus, it is an object of the present invention to provide a developing unit for an electrophotographic printer, which can maintain the developer layer on the magnet roll at a predetermined thickness.

[0008]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, in the present invention, a magnet roll that rotates at a constant speed with a minute gap between it and a photoconductor and attaches a developer layer formed by magnetic attraction on the surface to the photoconductor during the rotation process. In a developing unit of an electrophotographic printer having a doctor blade provided in proximity to the magnet roll in order to regulate the developer layer to a predetermined thickness, both sides of the doctor blade are provided. A roller having an amount corresponding to the developer thickness protruding from the leading edge of the doctor blade in the magnet roll direction is rotatably attached, and the roller is brought into contact with the outer peripheral surface of the magnet roll by an urging spring. It is a thing.

[0009]

[Action]

 The roller is projected from the tip of the doctor blade by an amount corresponding to the thickness of the developer. The amount of protrusion can be set by the doctor blade alone. Then, by pressing this roller against the magnet roll by the biasing spring, even if the magnet roll has an eccentricity, the roller is made to follow the eccentricity and a predetermined amount of protrusion is always secured.

[0010]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. The same members as those of the conventional example shown in FIG. 1 are designated by the same reference numerals, and the duplicated description will be omitted.

FIG. 2 is a main part configuration diagram of the developing unit according to the embodiment, and FIG. 3 is a front view of the magnet roll and the doctor blade. In this embodiment, rollers 10 and 11 projecting from the front edge (lower edge) 5a of the doctor blade 5 in the direction of the magnet roll 4 by a predetermined distance are provided at both ends of the doctor blade 5 by ball bearings so as to rotate on their own. ing. The step (projection amount) between the tip edge 5a of the doctor blade 5 and the rollers 10 and 11 can be accurately measured with a dial meter or the like. It can be set according to the required thickness of the image developer layer above.

Then, biasing members 14, 15 such as compression coil springs are locked between the spring locking members 12, 13 fixed to the casing 8 of the developing unit 2 and the upper surfaces of both end portions of the doctor blade 5. The biasing springs 14 and 15 press the rollers 10 and 11 against the outer peripheral surfaces of both ends of the magnet roll 4. In the present invention, the mounting piece 9 and the screw 7 are used as a guide member for moving the doctor blade 5 at a predetermined position relative to the magnet roll 4 in a far distance.

Therefore, between the tip edge 5 a of the doctor blade 5 and the outer peripheral surface of the magnet roll 4, a predetermined protrusion amount set in the individual stage of the doctor blade 5, that is, the developer on the doctor blade 5 is set. A predetermined space is formed to regulate the thickness of the metal to a predetermined thickness.

The magnet roll 4 may be eccentric in a range of, for example, about 0.03 mm to 0.05 mm in the manufacturing process, but the rollers 10 and 11 are always urged by the biasing members 14 and 15. Since the rollers 10 and 11 and hence the doctor blade 5 move up and down in accordance with the eccentricity, the distance between the magnet roll 4 and the doctor blade 5 is always the first set predetermined value. To be kept. As a result, the doctor blade 5 can always secure the developer thickness on the magnet roll 4 at a predetermined value.

[0015]

[Effect of device]

 As described above, according to the present invention, the roller protruding from the front edge of the doctor blade by the thickness of the desired developer layer is pressed against the outer peripheral surface of the magnet roll by the biasing member. Regardless of the amount of eccentricity of the roll, the distance between the magnet roll and the doctor blade can always be kept accurately at a predetermined value, and as a result, the developer on the magnet roll can be kept at a predetermined thickness. Therefore, it is possible to obtain a highly reliable development operation and a high-quality image accompanying it.

Further, since the doctor blade is attached by the biasing member so as to make elastic contact with the magnet roll via the roller, an installation error does not occur, and the installation work time can be further shortened.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a developing unit according to a conventional example.

FIG. 2 is a configuration diagram of a main part of a developing unit according to an embodiment of the present invention.

FIG. 3 is a front view of a magnet roll and a doctor blade of the developing unit according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Development unit 4 Magnet roll 5 Doctor blade 5a Tip edge 9,10 Roller 13,14 Energizing member

Claims (1)

[Scope of utility model registration request] 1. A magnet roll which is rotated at a constant peripheral surface speed with respect to the photoconductor with a minute gap between the photoconductor and a developer layer formed by magnetic attraction on the surface of the photoconductor during the rotation process. And, in order to regulate the developer layer to a predetermined thickness, in a developing unit of an electrophotographic printer having a doctor blade provided in proximity to the magnet roll, on both side edges of the doctor blade, A roller having a developer amount equivalent to the thickness of the developer protruding from the leading edge of the doctor blade in the direction of the magnet roll is rotatably attached, and the roller is brought into contact with the outer peripheral surface of the magnet roll by a biasing spring. Development unit for electrophotographic printer.