JPH0369982A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the driving system of a photosensitive body from vibrating and then, to prevent the occurrence of irregularities in rotating by providing a magnetizing means for magnetizing the conductive base material of the photosensitive body at a fixed cycle before passing through a developing device. CONSTITUTION:The endless belt-like photosensitive body 1 is provided with the conductive base material 3 and a photosensitive layer 4 integrated with the conductive base material 3, and it is wound to be laid between the roller 2 and the other roller while facing the photosensitive layer 4 to the outside. And the conductive base material 3 of the photosensitive body 1 is formed of a ferromagnetic material and also the conductive base material 3 of the photosensitive body 1 before passing through the developing device 5 is magnetized at the fixed cycle by the magnetizing means 11. The magnetizing means 11 is constituted of an iron core 12 positioned on the side of the conductive base material 3 of the photosensitive body 1 and an electromagnet constituted of a coil 13 wound around the iron core 12. Thus, the effects of preventing the vibration of the photosensitive body 1 can be enhanced and a failure such as the occurrence of the pitch irregularities on a visible image can be controlled.

Description

Detailed Description of the Invention [Field of Application on M Beam] The present invention relates to a photoconductor having a conductive base material and a photosensitive layer, and a non-contact device that visualizes an electrostatic latent image formed on the photoconductor. The present invention relates to an image forming apparatus comprising a developing device a having a developer carrying member that carries a magnetic developer and comes into contact with a photoreceptor through the developer, and a transfer means that transfers the visible image to a transfer material. 8 [Prior Art and Problems to be Solved by the Invention] Image forming apparatuses of J1 format configured as electronic copying machines, printers, facsimile machines, etc. have been well known (for example, see the publication No. 61-426725). ).

The developer carrier of the developing device comes into contact with the photoreceptor via the developer carried thereon, and visualizes the electrostatic latent image formed on the photoreceptor. Such a development method is generally called a contact development method.

On the other hand, the photoreceptor is rotated and moved by an active system including a motor, and the vibrations of this active system are transmitted to the photoreceptor, causing the photoreceptor to vibrate slightly during operation. The photoreceptor may also vibrate due to an external force applied to the photoreceptor.

When the photoreceptor vibrates in this way, the developing method is changed to a contact development method, and the developer is transferred to the photoreceptor 1. .

Because the developer carrier is in direct contact with the photoreceptor through the developer, the vibration of the photoreceptor directly affects the quality of the visible image, resulting in a constant pitch unevenness, which is generally referred to as pitch unevenness. Horizontal lines at intervals occur on the visible image and the image quality is significantly impaired.

In particular, an endless belt-shaped photoreceptor is more likely to vibrate than a drum-shaped photoreceptor, and image quality is more likely to deteriorate. It is possible to suppress the vibration of the belt-shaped photoconductor by increasing the tension of the belt-shaped photoconductor and increasing the contact pressure between the photoconductor and the developer carrier, but if the tension of the photoconductor is increased, the photoconductor will The photoreceptor slips against the rollers that support it, causing uneven running of the photoreceptor, which also reduces the quality of the visible image. In this way, there is a limit to increasing the tension of the belt-shaped photoreceptor.

Ideally, it would be best to prevent vibration of the photoconductor by eliminating vibrations in the photoconductor drive system and eliminating uneven rotation, but achieving this would require a significant increase in cost. I can't say it's a realistic solution.

The object of the invention is to provide an image-forming device of the type mentioned at the outset, in which the above-mentioned conventional drawbacks can be avoided by means of a simple construction.

[Means to solve the problem]

In order to achieve the above object, the present invention comprises a conductive base material of a photoreceptor made of a ferromagnetic material, and a magnetizing means for magnetizing the conductive base material of the photoreceptor at a constant cycle before passing through a developing device. We propose a configuration with .

[Effect]

By magnetizing the conductive base material of the photoconductor, the Young's modulus of the conductive base material is increased and vibration of the photoconductor is suppressed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing a part of an electronic copying machine, in which an endless belt-shaped photoreceptor 1 has a conductive base material 3 and a photosensitive layer 4 integrated therewith, as illustrated in FIG. The photosensitive layer 4 is then wound around the roller 2 shown in FIG. 1 and another roller not shown, with the photosensitive layer 4 facing outside.

During a copying operation, the photoreceptor 1 is rotationally driven in the direction of arrow A by a drive system including a motor (not shown), and at this time,
An electrostatic latent image is formed on the photosensitive layer of the photoreceptor 1 by a charger and an exposure optical system (not shown).

The electrostatic latent image is visualized by the developing device 5. The developing device shown in FIG. 1 has a developing roller 6 that rotates counterclockwise at a linear speed that is 3 to 4 times the linear speed of the photoreceptor 1, and a non-magnetic developer is placed on this roller 6. A one-component developer 7 made of, for example, non-magnetic toner is carried thereon.

The developing roller 6 is an example of a developer carrier that carries a non-magnetic developer (hereinafter simply referred to as toner), and the developing roller 6 comes into contact with the photoreceptor 1 via the toner 7. ing. Further, the layer thickness of the toner 7 on the developing roller 6 is regulated by a layer thickness regulating blade (not shown), and is frictionally charged to a predetermined polarity.

When the electrostatic latent image formed on the photoreceptor 1 contacts the toner on the developing roller 6 that is in pressure contact with the photoreceptor 1, the toner electrostatically transfers to the electrostatic latent image, and the latent image becomes visible. It is turned into an image (toner image). This is contact development.

The visible image formed as described above is transferred onto a transfer material 9 on a transfer belt 8 driven in the direction of arrow B by the corona discharge action of a transfer charger 10, which is an example of transfer means. The visible image transferred to the transfer material 9 is fixed by a fixing device (not shown), and the surface of the photoreceptor after the visible image is transferred is cleaned of residual toner by a cleaning device (also not shown), and static electricity is removed by a static eliminator. be affected.

The copying operation is performed as described above, but at that time, as explained earlier, it is inevitable that the photoreceptor 1 vibrates slightly due to various reasons, and in conventional copying machines, due to this vibration, Pitch unevenness occurs in the formed visible image, resulting in a deterioration in image quality.

Therefore, in the illustrated copying machine, the conductive base material 3 of the photoreceptor weight shown in FIG.
The conductive base material 3 is configured to be magnetized at regular intervals by the magnetization means 1. The magnetizing means 11 illustrated in FIG. AC power supply 14
An alternating current is caused to flow. Therefore, the conductive base material 3 passing through this electromagnet is magnetized at a constant cycle, and the photoreceptor portion that has been magnetized once passes through the developing device. Reference numerals 25 and 26 are backup rollers for holding flat the photoreceptor portion on which the conductive base material 3 is magnetized.

When the conductive base material 3 is magnetized as described above, even if an excitation force is applied to the photoreceptor l from its electrodynamic system, the photoreceptor t becomes difficult to vibrate, and its amplitude is significantly reduced. can be kept small. For this reason, the photoreceptor l passing through the developing device 5 hardly vibrates, and it is possible to prevent or suppress the occurrence of horizontal linear pitch unevenness in the visible image as in the prior art.

The reason why vibrations can be suppressed by magnetizing a ferromagnetic material is thought to be that the Young's modulus of the ferromagnetic material increases due to magnetization. In order to understand the present invention, this point will be explained in some detail.

As shown in FIG. 3, consider a perfect sphere 20 made of a ferromagnetic material, and the sphere 20 is spontaneously magnetized Is by an external magnetic field I.
It is assumed that the ball 20 is uniformly elongated by e in the direction of this magnetization Is as shown by the broken line. Here, magnetization I
Assuming that the elongation of the sphere 20 is observed along the direction CD making an angle ψ with respect to the direction of s, the elongation rate ε is expressed as ε=a cos2ψ. The average elongation ε1 at this time is as follows.

Since the elongation ε2 in the saturated state is assumed to be ε, = e,
The difference λ is λ=1. −ε, = −e Therefore, the spontaneous elongation within the magnetic domain is e=□λ. At this time, if the increase in the Young's modulus of the ball 20 is ΔE, and the Young's modulus before the increase is Eo, then (a is a constant).

From the above formula, λ1°. That is, ('L i,?) = DtO
The larger the value of strain in the direction of lO), the more significant the increase in Young's modulus becomes.

By magnetizing a ferromagnetic material as described above, its Young's modulus is increased. It is thought that the vibration can be suppressed, but apart from the reason, the vibration-proofing effect of 5-magnetization has been confirmed through experiments. In FIG. 4, the evaluation value of the image quality of the visible image is plotted on the vertical axis.
This is experimental data comparing 0 Gauss). From this, it can be seen that the magnetization has improved by about 5 dB (3 in rank).

In the embodiment shown in FIG. 1, the magnetizing means 11 is provided upstream of the developing device 5 in the moving direction of the photoreceptor 1, and is provided downstream of the developing device 5 and further from the transfer charger 10. Also, a demagnetizing means 15 is provided on the downstream side to demagnetize the conductive base material 3 of the photoreceptor 1 after passing through the developing device 5 and the transfer charger 1O, and return it to its original state. With this configuration, when the conductive base material 3 is magnetized by the magnetizing means 11 in the next step, it can be correctly magnetized at a constant period.

The degaussing means 15 illustrated in FIG.
It consists of two degaussing electromagnets 21 and 22 each having a coil 18°19 wound around them, and one of the magnets 2
1 is placed on the conductive base material 3 side of the photoreceptor l, and the other magnet 22 is placed on the photosensitive layer side, and each of them is connected to an AC power source 23.
24, currents with different phases are passed through the conductive base material 2.
is being demagnetized.

As described above, the photoreceptor 1 is magnetized or demagnetized, but since the toner 7 used in the developing device 5 is a non-magnetic material, there is no side effect in forming a visible image. ,
High quality visible images can be obtained.

Although the illustrated embodiment shows a belt-shaped photoreceptor, it is obvious that the present invention can be applied to an image forming apparatus using a drum-shaped photoreceptor without any problem.6 [Effects of the Invention] According to the present invention With the extremely simple configuration of providing a magnetizing means, it has become possible to enhance the anti-vibration effect of the photoreceptor and to suppress the problem of pitch unevenness occurring in the visible image.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention, FIG. 2 is an enlarged view schematically showing an example of a photoreceptor, and FIG.
The figure is an explanatory diagram for explaining the present invention in detail, and FIG. 4 is a diagram showing a specific example of the effects of the present invention. 1... Photoreceptor 4... Photosensitive layer 7... Developer 11... Magnetizing means 3... Conductive base material 5... Developing device 9... Transfer material

Claims (1)

[Scope of Claims] A photoreceptor having a conductive base material and a photosensitive layer, carrying a non-magnetic developer for visualizing an electrostatic latent image formed on the photoreceptor,
An image forming apparatus comprising: a developing device having a developer carrier that contacts the photoreceptor through the developer; and a transfer means for transferring the visible image to a transfer material, wherein the conductive group of the photoreceptor An image forming apparatus comprising a ferromagnetic material and a magnetizing means for magnetizing a conductive base material of a photoreceptor at a constant cycle before passing through a developing device.