JPH0741014Y2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an image forming apparatus of the type that develops an electrostatic latent image using a one-component non-magnetic toner.

[Problems to be solved by conventional techniques and devices]

A roller-shaped toner-carrying rotary member carrying one-component non-magnetic toner is contact-rotated with an endless belt-shaped photoconductor that is stretched between a plurality of rollers, and the toner is belt-shaped at this portion. An image forming apparatus, such as an electrophotographic copying machine or an electrostatic recording device, is known in which an electrostatic latent image formed on a belt-shaped photosensitive member is developed by electrostatically transferring it to the photosensitive member. (JP-A-61-43767 and JP-A-62)
-118366 gazette etc.).

In such an image forming apparatus, the toner-carrying rotary member is rotated at a linear velocity higher than that of the belt-shaped photosensitive member with respect to the free belt portion that is stretched between the rollers. The development is carried out by bringing the toner-bearing rotary member into contact with the surface of a rigid drum-shaped photoconductor. Since the contact pressure with respect to is low, if the drive source such as the belt-shaped photoconductor driving motor has uneven rotation or the drive transmission system including this type of motor vibrates, the pressure fluctuation easily occurs at the contact portion.

When such a pressure fluctuation occurs, for example, when a solid image is formed, a dark density portion and a light density portion are striped at a predetermined pitch (the striped direction is a direction orthogonal to the running direction of the belt-shaped photoconductor). Go out to. If the image is not a solid image, horizontal lines may appear at a predetermined pitch with an interval between them. Hereinafter, such a thing as "to cause pitch unevenness on the image"
Say

Therefore, it is possible to increase the contact pressure of the toner-carrying rotary member with respect to the belt-shaped photoconductor to increase the tension of the belt-shaped photoconductor, but in this case, a slip or the like occurs in the drive transmission system. Running unevenness will occur. From this point, there is a limit to increase the contact pressure.

Incidentally, in the technology disclosed in Japanese Patent Laid-Open No. 52-123621,
There is also proposed a method in which a toner carrier belt is brought close to a photosensitive drum, and a vibrating means is used to vibrate the belt portion, but this technique causes the toner to fly by the vibration. This is intended to improve the developing efficiency of the low-potential portion (low-density portion of the original) of the body, and is essentially different from that of the example of the present invention described below.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having an extremely simple structure and preventing occurrence of pitch unevenness on an image.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides an image forming apparatus according to the present invention, in which a belt-shaped photosensitive member that forms an electrostatic latent image on the surface and a belt-shaped photosensitive member that carries one-component non-magnetic toner on the peripheral surface. A toner-carrying rotary member that rotates in contact with the body and electrostatically transfers the carried toner to a belt-shaped photoconductor in the developing unit that rotates in contact with the body, and a toner-carrying rotary member that develops the electrostatic latent image, and a belt-like member in the developing unit. And a means for vibrating the photoconductor in a direction substantially orthogonal to the traveling direction.

〔Example〕

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

In FIG. 1, reference numeral 1 denotes a part of a belt-shaped photoconductor, which is composed of an endless belt, is stretched over a plurality of rollers (not shown), and is driven in a direction indicated by an arrow by a drive motor (not shown). It is supposed to be done. As shown in FIG. 2, the belt 1 has a photosensitive layer 1b formed on a conductive substrate 1a.

The belt-shaped photoconductor 1 is driven and driven in the direction of the arrow as described above, but the roller-shaped toner-carrying rotary member 2 is carried on the photoconductor layer 1b in the same direction as this moving direction. The belt-shaped photosensitive member 1 is contact-rotated at a linear velocity 3 to 4 times the linear velocity of the belt-shaped photosensitive member 1 through the one-component non-magnetic toner. An electrostatic latent image is formed on the belt-shaped photosensitive member 1 by charging and exposure as is well known, and one-component non-constituent is formed on the toner carrying rotating member 2 as described above. The magnetic toner T is carried, and in the developing unit 3 which is the contact rotation unit, the toner is electrostatically transferred to the belt-shaped photoconductor 1 by the developing electric field, and the toner is formed on the belt-shaped photoconductor. The latent image is developed and visualized. This visible image is transferred to a transfer paper (not shown),
The transferred visible image is fixed by a fixing device (not shown). The developing section 3 is a developing area in which the toner carrying rotating member 2 contacts the belt-shaped photosensitive member 1. The contact length is set to, for example, about 2 to 3 mm, which is called a developing nip width.

The feature of this invention example is the developing section (developing nip width)
The point is that the belt-shaped photosensitive member portion in 3 is vibrated at a high frequency in a direction orthogonal to the traveling direction.

Next, the configuration of this vibrating means will be described.

First, the first vibrating means uses a photoconductor vibrating device 4 as shown in FIG. On the other hand, the conductive substrate 1a (FIG. 2) of the belt-shaped photosensitive member 1 is made of a magnetic material such as nickel, and the N pole and the S pole are alternately magnetized. On the other hand, the photoconductor vibrating device 4 is similarly magnetized.

The photoconductor vibrating device 4 is driven to reciprocate in a direction parallel to the traveling direction of the belt-shaped photoconductor 1. Due to this reciprocation, the magnetic field between the two is changed, and the belt-shaped photoconductor in the developing section 3 is changed. The part vibrates in the direction orthogonal to the traveling direction.

By the way, it has already been described that pressure fluctuates when the belt-shaped photosensitive member comes into contact with the toner carrying rotating member 2 due to vibration of the drive transmission system and the like, and uneven pitch on the image occurs. It is usually in the range of 100Hz or less.

As described above, by vibrating the belt-shaped photoconductor portion of the developing portion and setting the vibration frequency higher than the above frequency, it is possible to cancel the pressure fluctuation caused by the vibration of the drive transmission system. For example, when vibrating at a relatively high frequency of 300 Hz or higher, the degree of pitch unevenness is almost unknown in appearance, and a high quality image with substantially no pitch unevenness can be obtained. Further, due to the vibration, the toner on the toner carrying rotating member 2 is smoothed and smoothed,
It is possible to obtain an image in which uneven density is less likely to occur.

Assuming that the linear velocity of the belt-shaped photoconductor 1 is 60 mm / sec, the magnetization pitch of the belt-shaped photoconductor 1 and the photoconductor vibrating device 4 is set as narrow as possible (about 1 mm),
When the photoconductor vibrating device 4 is vibrated in the direction of the arrow at a frequency of about 300 Hz, the pitch unevenness becomes 0.1 mm or less, and a solid image having a uniform density can be obtained.

The photoconductor vibrating device 4 is provided at a portion opposite to the toner carrying rotating member 2 with the belt-shaped photoconductor 1 interposed therebetween, but in this case, it may be arranged so as to be separated from the belt-shaped photoconductor 1. Alternatively, it may be arranged so as to contact the belt-shaped photoreceptor 1. In addition, the reciprocating stroke of the photoconductor vibrating device 4 is set to a length larger than the developing nip width.

FIG. 3 shows an alternating magnetic field generator 5 using a coil as a vibrating means.

In FIG. 4, the toner carrying rotating member 2 itself is magnetized in the same manner, and when it is rotated, the belt-shaped photosensitive member portion in the developing portion is vibrated. Also in the examples of FIGS. 3 and 4, the arrow-belt-shaped photoreceptor 1 is magnetized as described above.

In FIG. 5, the backup roller 6 is reciprocally oscillated in the direction of the arrow so that the belt-shaped photosensitive member portion in the developing portion is oscillated while being struck. It is also possible to use such mechanical means as the vibrating means.

[Effect of device]

It occurs due to uneven rotation of the drive source and vibration of the drive transmission system. Since the pressure fluctuation of the belt-shaped photoconductor portion in the developing section is suppressed, it is possible to suppress the occurrence of pitch unevenness on the image due to this pressure fluctuation, and this can be realized with an extremely simple configuration. Is.

[Brief description of drawings]

FIG. 1 is a schematic view of a developing component of an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view of a belt-shaped photoconductor, and FIGS. 3 to 5 show another embodiment for each developing. It is a schematic diagram of a component. DESCRIPTION OF SYMBOLS 1 ... Belt-shaped photoconductor, 2 ... Toner carrying rotary member 4 ... Photoconductor vibrating device 5 ... Alternate magnetic field generator, 6 ... Backup roller

Claims (1)

[Scope of utility model registration request] 1. A belt-shaped photoreceptor on which an electrostatic latent image is formed on a surface thereof, and a one-component non-magnetic toner carried on a peripheral surface thereof to rotate in contact with the belt-shaped photoreceptor, and a developing unit which rotates in contact therewith. A toner carrying rotating member for electrostatically transferring the carried toner to a belt-shaped photoconductor to develop the electrostatic latent image, and a means for vibrating the belt-shaped photoconductor in the developing section in a direction substantially orthogonal to the running direction. An image forming apparatus comprising: