JPH0424671A - Magnet roller - Google Patents

Abstract

PURPOSE:To allow the efficient transfer of a developer without rotating a magnet roller at a high speed by fitting magnets into the plural grooves formed on a sleeve surface. CONSTITUTION:An agitating roller 46 and the magnet roller 40 are disposed in a developing tank 49. The sleeve 41 of the magnet roller 40 is formed with the plural parallel grooves 42 in the axial direction of the roller and the magnets 43 are embedded therein. The developer 9, therefore, sticks partly onto the magnets 43 and is held thereon when the magnet roller 40 rotates in the developer. The developer sticking thereto forms mounds of a projecting shape around the magnets 43. The developer is efficiently transported to a photosensitive body 30 by the projecting mounds of the developer without slipping the other developer. The need for rotating the magnet roller 40 at a high speed is eliminated in this way and the developer is efficiently supplied to the photosensitive body 30.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a magnetic roller that supplies developer to a photoreceptor in a developing device in an image forming apparatus such as an electrostatic transfer copying machine or a laser printer. (BL Conventional Technology) Generally, in the developing device of an image forming apparatus, a developer in which a toner and a magnetic carrier are mixed at a certain ratio is widely used.The toner and the magnetic carrier are frictionally charged, and the charged toner is The toner adheres to the magnetic carrier, and a magnetic roller holds and conveys the toner-adhered carrier onto its sleeve, scraping the surface of the latent image on the phosphor and causing the toner to adhere, forming a toner image. .

The magnetic rollers described above are made of aluminum, stainless steel, etc., with grooves formed on the surface of the sleeve (low-left), or a sleeve made of aluminum or stainless steel with grooves formed on the surface, in order to improve the conveyance performance of holding and transporting the developer and supplying it to the photoreceptor. A roughened material (sandblasting) is used.

(C1 Problem to be Solved by the Invention) However, with the magnetic roller as described above, the developer easily slips on the sleeve, and in order to maintain developing performance, the circumferential speed of the magnetic roller is set to 2 to 2 times the circumferential speed of the photoreceptor. 3
The high-speed rotation of such magnetic rollers, which must be rotated at twice the speed, causes the following problems.

In the above-mentioned magnet roller with a rough surface, the surface becomes smooth due to high-speed rotation, and the conveyance performance is rather reduced.

Particularly in high-speed models, the circumferential speed of the photoreceptor is fast, so the sleeve needs to be rotated even faster, but the developer slips on the sleeve surface, so the supply of developer to the photoreceptor cannot keep up. As a result, the image density was insufficient or uneven.

In addition, by rotating the magnetic roller at high speed,
Toner and carrier scatter, causing contamination of other devices such as optical devices within the image forming device, resulting in charge unevenness and
Copying stains and the like occur, reducing the quality of the image.

Furthermore, the high-speed rotation of the magnetic roller increases stress on the developer, causing problems such as deterioration of the developer and an increase in the load torque of the machine.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a magnetic roller with high transportability that can efficiently transport developer without rotating at high speed in a developing device of an image forming apparatus.

(d) Means for Solving the Problems In the present invention, in a magnet roller that holds and conveys the developer in the developing device on the surface of its sleeve and supplies it to the surface of the photoreceptor, a plurality of magnetic rollers are formed on the surface of the sleeve. The feature is that a magnet is inserted into the groove.

(81 Effect) In the magnetic roller according to the present invention, the magnets are fitted into a plurality of grooves formed on the surface of the sleeve.Thereby, when the magnetic roller rotates in the developer, the developer is deposited on the magnet. A portion of the developer adheres and is held, and the adhered developer forms a protruding mountain around the magnet, and this protruding developer mountain efficiently transports other developer to the photoreceptor without causing it to slip. can.

(f) Embodiment FIG. 3 is a schematic diagram of the main parts of a copying machine equipped with a developing device to which a magnetic roller is applied, which is an embodiment of the present invention.

A document table lO is provided on the upper surface of the main body l, and a document is placed on the document table lO. An optical device 2 including a light source, a mirror, a lens, etc. is arranged below the document table 10. The reflected light from the original travels along an optical path formed by the mirror of the optical device 2, and irradiates the photoreceptor 30 at an exposure point P. The photoreceptor 30 rotates in the direction of arrow A, and around it, downstream from the exposure point P, there are a developing device 4, a transfer charger 34, a peeling charger 35, a cleaning device 36, a static elimination lamp 37,
A charging charger 38 is provided. The developing device 4 is equipped with a magnetic roller 40 which is an embodiment of the present invention. At the lower right side of the main body 1, there is disposed a paper feed section 7, which includes a cassette for storing paper 71, a paper feed roller, a timing roller, etc., and the paper is conveyed to the transfer section in the direction of arrow B. A fixing device 5 is provided on the left side of the photoconductor 30, and a paper discharge section 6 is provided on the left side thereof.

The operation of the copying machine configured as above will be explained.

First, the scanning unit (light source and mirror) of optical device 2
scans the original on the original platen 10, and the reflected light of the original irradiates the photoreceptor 30 with exposure electricity P.

As a result, an electrostatic latent image is formed on the surface of the photoreceptor. The formed latent image is transferred by a transfer charger 34 onto a sheet 71 fed from the sheet feed section 7 at the same timing in the developing device 4.

After the development and transfer, the photoreceptor 30 has residual toner removed by a cleaning device 36, and the charge is removed by a charge removal lamp 37. On the other hand, the sheet 71 on which the image has been transferred is peeled off from the photoreceptor 30 by the peeling charger 35 and conveyed, subjected to heat treatment by the fixing device 5 to fix the image, and then discharged to the sheet discharge section 6. Ru.

FIG. 1 is a configuration diagram of a developing device to which the same magnetic roller is applied.

A developing device R4 provided downstream of the exposure point P of the photoreceptor 30 includes a developer tank 49 and a toner hopper 48.

A stirring roller 46 and a magnet roller 40 are disposed in the developer [49]. A doctor blade 45 is provided on the top of the magneto troller. Toner hopper 48
A toner supply roller 47 is provided at the supply port from the developer tank 49 to the developer tank 49.
is installed. Sleeve 4 of magnet roller 40
1, a plurality of parallel 'a42' are formed in the roller axial direction, and a magnet is embedded therein.

In the developer tank 49, the stirring roller 46 rotates to stir the developer 9 made of toner and carrier to charge the toner.
Attach to carrier. Magnet roller 40 is indicated by arrow C
The developer 9 is rotated in the direction of the agitation roller, and the developer 9 is deposited on the stirring roller side, and the toner is conveyed to the photoreceptor side and the adhered toner is supplied to the photoreceptor 30.

FIG. 2 is a diagram showing how the magnetic roller conveys the developer. Components that are the same as those in FIG. 1 are given the same numbers and their explanations will be omitted.

The magnet 43 fitted into the groove 42 on the sleeve 41 attracts the developer 9, and the attached developer 9 forms a protruding mountain 90 on the sleeve and is held by the magnet 43. The mountain 90 of the developer 9 transports other developer due to its own protruding shape, and prevents the developer from slipping on the sleeve (it can be efficiently supplied to the photoreceptor).

The maximum value of developer conveyance performance using the magnetic roller configured as described above (roller diameter 50n in this embodiment) is compared with conventional low left and sandblasting as follows.

As is clear from the above table, it was found that the developer conveying performance of the magnetic roller was the best in this example.

In addition, it is most efficient to form the grooves on the sleeve at equal intervals in the axial direction of the roller as in this example, but the number and spacing of magnets may vary depending on the diameter of the roller, the type of developer, the developing method, etc. It can be set arbitrarily.

(g) Effects of the invention As described above, according to the invention, a magnet is fitted into a groove formed on the sleeve surface of a magnetic roller commonly used in a developing device in an image forming apparatus such as a copying machine or a laser printer. . For this reason, the developer adheres to the sleeve in a chevron shape centered around the magnet, and the chevron transports other developer, and the developer is transported without slipping on the sleeve and supplied to the photoreceptor. be able to.

Therefore, the developability is improved and stabilized, and proper images can be continuously obtained even in high-speed machines. In addition, by improving the conveyance of the magnetic roller, there is no need to rotate the magnetic roller at high speed, preventing developer from scattering due to high-speed rotation, preventing contamination inside the image forming apparatus, and preventing stains on copies. be able to. Furthermore, by not rotating at high speed, stress on the developer is reduced and the life of the developer can be extended.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a developing device using a magnetic roller according to an embodiment of the present invention. FIG. 2 is a diagram showing how the magnetic roller conveys the developer. FIG. 3 is a schematic diagram of an image forming apparatus including a developing device to which the same magnetic roller is applied. 4-developing device, 40-magnet roller, 41-sleeve, 42-groove, 43-magnet, 9-developer.

Claims (1)

[Claims] (1) In the magnetic roller that holds and transports the developer in the developing device on the surface of the sleeve and supplies it to the surface of the photoreceptor, magnets are fitted into a plurality of grooves formed on the surface of the sleeve. Features a magnetic roller.