JPS63103282A - Magnetic transfer device for magnetic toner - Google Patents

Abstract

PURPOSE:To prevent the disturbance of transfer images due to oscillation, the slip of transfer sheets, or the like by constituting a device so that a powdery image (magnetic toner) on the plane transfer area of an image carrier is magnetically transferred to the transfer sheet all at a time in a condition that a belt- shaped image carrier and the transfer sheet are stopped. CONSTITUTION:The electrostatic latent image formed on a photosensitive body 5 is developed with a magnetic toner by a developing device 7 to obtain a developed image. Rotation of the photosensitive body 5 and that of a carrying belt 26 are stopped when a transfer sheet 16 is transported into the magnetic field generating element Z of a magnetic transfer device 8 and the developed powdery image on the photosensitive body 5 is set to a transfer area Y. In this state, a pinion 32 is rotated and driven in one direction with a prescribed rotation number by a motor M, and a frame 27, namely, the whole of the magnetic fixing device 8 and the carrying belt 26 is lifted to the side of the photosensitive body 5 up to a prescribed height, and the magnetic toner on the photosensitive body 5 is attracted by the magnetic force and is transferred to the transfer sheet 16 all at a time.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic transfer device for magnetic toner in an image recording device such as an electrostatographic copying machine or a facsimile machine, that is, a magnetic toner is used as a developer to carry an image. After developing an electrostatic latent image on a body (photoreceptor, etc.) with magnetic toner, the powder image (magnetic toner) adhered to the image carrier and visualized is transferred to a transfer sheet such as plain paper. It also relates to a device that transfers images from an image carrier to a transfer sheet using the magnetic force of a magnetic field generating element such as a permanent magnet or an electromagnet.

[Conventional technology]

A magnetic transfer device for magnetic toner is disclosed in Japanese Patent Application Laid-Open No. 52-20037.
This method is already known from Japanese Patent Application Laid-Open No. 58-211174. These magnetic transfer devices are equipped with a magnet roll or a linear magnetic head (electromagnet) that is parallel to the axis of the drum-shaped photoconductor, facing the transfer area of the photoconductor.
While rotating the photoconductor, the magnetic toner on the photoconductor was magnetically transferred to a transfer sheet fed between the photoconductor and a magnet roll or a magnetic head, sequentially from the leading end in the paper feeding direction. .

[Problem that the invention seeks to solve]

The above conventional example has the following problems.

That is, while rotating the photoconductor and conveying the transfer sheet, the magnetic toner on the photoconductor is sequentially transferred to the transfer sheet from the leading edge in the paper feeding direction. Vibrations caused by the rotation of the rolls, slippage of the transfer sheet, etc. may cause disturbances such as misalignment and blurring in the transferred image transferred to the transfer sheet.

In view of the above-mentioned conventional drawbacks, the present invention aims to provide a magnetic transfer device in which the transferred image is not disturbed due to vibrations, slippage of the transfer sheet, etc.

[Means for solving problems]

Technical measures taken by the present invention to solve the above problems are as follows. That is, the feature of the present invention is that the vertical and horizontal dimensions of a region where a uniform magnetic field is generated, facing a planar transfer region formed on a belt-like image carrier, are set to be equal to or larger than the vertical and horizontal dimensions of the transfer region. a magnetic transfer device including a planar magnetic field generating element, a transfer sheet is positioned between a planar transfer area of the image carrier and the planar magnetic field generating element of the magnetic transfer device, and the image carrier Another aspect of the present invention is that the magnetic toner on the image carrier is magnetically transferred to the transfer sheet while the transfer sheet is stationary.

[Effect]

According to the above configuration, when the belt-shaped image carrier and the transfer sheet are kept stationary, the powder image (magnetic toner) in the planar transfer area of the image carrier is transferred to the magnetic transfer device facing the transfer area. It is attracted by the planar magnetic field generating element, and is magnetically transferred to the transfer sheet at the same time.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows an outline of an electrostatographic copying machine equipped with a magnetic toner magnetic transfer device according to the present invention, and FIG. 2 shows the magnetic toner magnetic transfer device.

In the figure, ■ is the main body of the copying machine, and the upper portion thereof is provided with a document table 2 and a document presser 3 that covers the top thereof.

A belt-shaped photoreceptor (an example of an image carrier) 5 is provided inside the copying machine main body 1 and rotates in the direction of arrow a between a pair of rotating rolls 4, 4. A planar exposure area X is formed on the upper surface side, and a planar transfer area Y is formed on the lower surface side. Photoreceptor 5! The charging device includes a charging device 6, a developing device 7 using magnetic toner as a developer, a magnetic transfer device 8, a cleaning device 9, and a static eliminating device 1.
0 are provided in this order in the rotating direction a of the photoreceptor 5. In the space above the photoreceptor 5 of the copying machine body 1, there is an exposure device that includes a light source 11, a lens group 12, etc., and simultaneously exposes the entire surface of the document placed on the document table 2 to the exposure area X of the photoreceptor 5. 13 are provided. 14 is paper feed cassette 1
5 is a paper feeding and conveying device that conveys a transfer sheet 16 such as plain paper stored in 5 toward a magnetic transfer device 8; 17 is a fixing device;
18 is a paper discharge roll, and 19 is a paper discharge tray.

The magnetic transfer device 8 is arranged so that the vertical and horizontal dimensions of an area where a uniform magnetic field is generated (an area where the magnetic field is not distorted) are at least as long as the horizontal and vertical dimensions of the transfer area Y, which is opposite to the planar transfer area Y of the photoreceptor 5. A transfer sheet 1 is provided between the planar transfer area Y of the photoreceptor 5 and the planar magnetic field generation element Z.
The magnetic toner on the photoreceptor 5 is magnetically transferred onto the transfer sheet 16 with the photoreceptor 5 and the transfer sheet 16 stationary.

The specific structure of the magnetic transfer bag W8 is as follows.

That is, as shown in FIGS. 1 and 2, the magnetic field generating element Z is composed of a flat electromagnet 20 and a magnetic powder 21 such as iron powder that covers the entire upper surface of the electromagnet 20 to an appropriate thickness. These are housed in a case 22 with an open top. Case 2
Edge members 23 made of an elastic material such as rubber are provided at the upper ends of the side walls around the four sides of the frame 2 .

On both sides of the case 22 in the width direction, there are left and right pulleys 24°2.
Two thin belts 25.25 are provided which rotate in the direction indicated by the arrows over a distance between 25 and 25.
5, a thin and flexible conveyor belt 26 made of a non-magnetic material such as a plastic sheet is stretched over the magnetic field generating element 2, and transfers the transfer sheet 16 to the paper feed conveyor 1.
4 to the fixing device 17.

The case 22 is fixedly attached to a frame 27 that pivotally supports the pulleys 24, 24, and the frame 27 has four columns 29 erected on the bottom frame 28 of the copying machine main body l. and a cylindrical body 30 that is fitted onto this so as to be slidable in the vertical direction. An elevating drive mechanism 31 is provided between the frame 27 and the bottom frame 28. Although various configurations can be adopted as the elevating drive mechanism 31, in this embodiment,
The elevating drive mechanism 31 is configured as follows. That is, a motor M with a speed reducer is provided on the bottom frame 28'', and a rack 33 that meshes with a pinion 32 provided on its output shaft is mounted on the bottom frame 2.
A pair of X-shaped sinks 35.8 are provided on the frame 27 and the bottom frame 28 so as to be reciprocally movable, and intersect in an X-shape and are pivotally supported by a common horizontal shaft 34 at the intersecting position.
35, the lower end of one link of each X-shaped sink 35.35 is pivotally connected to the bottom frame 28 through a common horizontal shaft 36, and the lower end of the other link is pivotally connected to the rack 33 through a common horizontal shaft 37. At the upper end of each X-shaped sink 35, 35, rollers 38 supporting the rail portions 27a, 27a formed on the frame 27 are pivotally supported. Sunku 35.35 deforms and becomes frame 2
7 is configured to be driven up and down. 39...ha...
This is a compression coil spring that elastically supports the lower end of the cylindrical body 30, and serves to reduce the weight of the frame 27. 40 is a guide plate that prevents the photoreceptor 5 from being bent.

Next, the operation of the electrostatographic copying machine described above will be explained.

While the belt-shaped photoreceptor 5 that has undergone the charging process is kept stationary,
The entire surface of the document is irradiated with light from the light source 11, and so-called full surface exposure is performed.

The electrostatic latent image formed on the photoreceptor 5 is developed with magnetic toner by the developing device 7 as the photoreceptor 5 rotates in the direction of arrow a, and is visualized.

When the transfer sheet 16 fed from the paper feed cassette 15 is transferred onto the magnetic field generating element Z of the magnetic transfer device 8 and the visualized powder image on the photoreceptor 5 is set in the transfer area Y, , the rotation of the photoreceptor 5 and the conveyor belt 26 is stopped.

In this state, the pinion 32 is rotationally driven in one direction by a predetermined number of rotations by the motor M, and as shown in FIG.
The entire body is lifted up to a predetermined height toward the photoreceptor 5 and becomes stationary. Thereafter, a voltage is applied to the electromagnet 20 of the planar magnetic field generating element Z, and the magnetic toner on the photoreceptor 5 is attracted by the magnetic force and is simultaneously transferred to the transfer sheet 16 over the entire surface.

In this way, magnetic transfer is performed over the entire surface at the same time with the photoreceptor 5, transfer sheet 16, and magnetic field generating element Z all stationary. , bleeding, etc.).

Further, the planar magnetic field generating element 2 may be composed only of an electromagnet having a planar shape or a similar shape, but in this embodiment, in particular, the electromagnet 20 and the magnetic field that covers the surface thereof to an appropriate thickness are used. Since the planar magnetic field generating element Z is constituted by the powder 21, even if the surface of the electromagnet 20 has some unevenness, or there is some error in the parallelism between the photoreceptor 5 and the electromagnet 20. As shown in FIG. 4, the magnetic powder 21 is transferred to the transfer sheet 1 via a thin conveyor belt 26.
6 can be pushed up and brought into close contact with the photoreceptor 5. Therefore, the transfer performance is higher than in the case where a flat plate-shaped electromagnet 20 is simply provided and magnetic transfer is performed over the entire surface at the same time, and the quality of the transferred image can be further improved.

When the transfer is completed, the electromagnet 20 is de-energized, the motor M reverses the pinion 32, and the entire magnetic transfer device 8 and conveyor belt 26 descend to their original positions.

After that, the conveyor belt 26 rotates again in the direction of the arrow.
The transfer sheet 6 after the transfer is conveyed to the fixing device 17.

In the above embodiment, the upper surface of the case 22 is open, and this opening is connected to a thin and flexible conveyor belt 26.
However, if the transfer sheet 16 is to be conveyed by being placed on two thin bells (25 and 25) provided on both sides of the magnetic field generating element Z, the conveyor belt 2
6 may be omitted and the magnetic powder 22 may be configured to directly contact the back surface of the transfer seam 6. Further, regardless of the presence or absence of the conveyor belt 26, the opening of the case 22 may be closed with a flexible thin film made of a non-magnetic material such as a plastic sheet to prevent the magnetic powder 22 from falling out.

〔Effect of the invention〕

The present invention has the above-described configuration, and when the belt-like image carrier and the transfer sheet are stationary, the powder image (magnetic l/ner) in the planar transfer area of the image carrier faces the transfer area. It is attracted by the planar magnetic field generating element of the magnetic transfer device, and is magnetically transferred to the entire surface of the transfer sheet at the same time.

Therefore, it is possible to prevent disturbances (misalignment, blurring, etc.) of the transferred image caused by vibrations, slippage of the transfer sheet, etc.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic sectional view of an electrostatic copying machine, FIG. 2 is a longitudinal sectional side view of a magnetic transfer device, and FIG.
The figure and FIG. 4 are explanatory diagrams of the operation. 5... Belt-shaped image carrier (photoreceptor), 8... Magnetic transfer device, 16... Transfer sheet, Y... Planar transfer area, Z... Planar magnetic field generating element .

Claims (1)

[Claims] A planar magnetic field generating element is provided opposite to a planar transfer area formed on a belt-like image carrier, and the vertical and horizontal dimensions of an area where a uniform magnetic field is generated are equal to or greater than the vertical and horizontal dimensions of the transfer area. a magnetic transfer device is provided, a transfer sheet is positioned between a planar transfer area of the image carrier and a planar magnetic field generating element of the magnetic transfer device, and the image carrier and the transfer sheet are kept stationary; . A magnetic toner magnetic transfer device, characterized in that the magnetic toner on the image carrier is magnetically transferred to a transfer sheet.