JPS63106666A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent generation of image flow due to sticking paper powders, and insufficient cleaning by mixing powders having non-hygroscopic property with the toners in a developing vessel, and by making the powders in such way that the charge polarity of the toner has reverse polarity at a position of developing the toners. CONSTITUTION:An electrostatic latent image formed on the surface of an image supporting body 1 is processed to a visible image by using an one component toner. At this time, the powders having non-hygroscopic property are mixed with the toners in the developing vessel 3. The powders make in such way that the charge polarity of the toner has the reverse polarity at the position of developing the toners. In order to make the charge polarity of the powders into the reverse polarity for the toner, for example, the powder such as a hydrophobic silica having strong negative electrification or a silica which has strong positive electrification and is treated with aminosilane, and having the reverse polarity against the polarity of the toner may be used, or the powder having frictional electrification series different from that of the toner may be used, thereby injecting the charge having the reverse polarity with respect to the charge polarity of the toner to the powder by mutual frictional electrification between the toner and said powder, or the frictional electrification between the toner and the toner metering material 6. Thus, the generation of the image flow due to sticking the paper powders and insufficient cleaning are prevented, thereby always obtaining clean image.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an image forming apparatus that forms an image based on an electrophotographic recording method such as a printer, a copier, or a facsimile, and particularly relates to an image forming apparatus such as a printer, a copier, a facsimile, etc. The present invention relates to an image forming apparatus that visualizes an electrostatic latent image formed on the surface of a carrier using a one-component toner.

"Prior Art" Based on the so-called electrophotographic recording method, an electrostatic latent image formed on an image bearing member formed as a photoreceptor drum is visualized using a one-component toner, and then the toner image is exposed to light. An image forming apparatus such as a printer that forms a predetermined image by transferring it onto a recording paper inserted onto the circumferential surface of a body drum is well known. There are devices that transfer the toner image onto the recording paper by performing corona discharge of opposite polarity to the toner, and devices that transfer the toner image using the compression pressure of a transfer roller. Even in this device, since the non-image forming surface of the photoreceptor drum, which does not carry toner, is in direct contact with the recording paper, during the transfer process, paper powder, etc. peeled off from the recording paper is exposed to light. It sticks to the body drum.

For this reason, conventional devices are configured to remove the paper dust and the like along with the remaining toner using a cleaning blade located downstream of the transfer process, but unlike toner, paper dust is not particulate but fibrous. Therefore, it is difficult to completely scrape off the dirt using a mechanical scraping method using pressure contact of a blade, and jamming easily occurs between the blade and the drum.

However, due to the biting, a slight gap is created between the blade and the drum, and more paper powder enters the gap.
Particularly in image forming machines with fast conveyance speeds such as laser printers, the above-mentioned biting spreads rapidly and can cause cleaning failures, resulting in black streaks on the image surface, partial charging failures, and exposure failures. Due to this, image blurring is likely to occur.

On the other hand, since the paper dust adhering to the drum has hygroscopic properties, the surface of the photoreceptor drum absorbs moisture through the paper dust and the surface resistance decreases.As a result, the latent image charge formed on the drum surface moves, and the image Flow may occur.

Incidentally, such image deletion is caused by nitrogen oxides generated due to ozone generated due to corona discharge during the transfer process and charging process adhering to the photoreceptor drum, and due to the adhesion of nitrogen oxides. This phenomenon also occurs when the hygroscopicity of the drum surface increases. As a countermeasure against this, for example, a technique (Japanese Unexamined Patent Application Publication No. 131-131) of forming a protective layer with a developer on the surface of the photoreceptor surface or at required locations after image formation is proposed. -531379)
Also, a technique for forming a thin film using a developer, especially a carrier liquid, on the entire surface of the photoreceptor before the charging process (Japanese Patent Laid-Open No. 1986-
No. 1313758) has been proposed.

"Problems to be Solved by the Invention" However, in the former case, in order to form a protective layer using a developer, the protective layer must naturally be formed after the image formation is completed, and paper dust generated during image formation occurs. The latter is completely immune to image fading due to adhesion, and the latter cannot be applied to devices that visualize images (dry development method) using a single-component toner that does not use a developer, especially a carrier liquid. Since the thin film is in a liquid state, paper dust is more likely to adhere to it during the transfer process, and in any case, the problem arises that insufficient cleaning due to the paper dust adhesion is exacerbated.

SUMMARY OF THE INVENTION In view of the drawbacks of the prior art, it is an object of the present invention to provide an image forming apparatus that can prevent image deletion and insufficient cleaning caused by adhesion of paper dust.

"Means for Solving the Problems" In order to achieve the above technical problems, the present invention provides an image forming apparatus that visualizes an electrostatic latent image formed on the surface of an image carrier using a one-component toner. , (2) A non-water-absorbing particle group is mixed into the developer container together with the toner, and (2) The particle group is configured so that it can have a polarity opposite to that of the toner at the development position. We propose an image forming apparatus that

In this case, the particle group is configured so that it can have a polarity opposite to that of the toner at the development position, for example, hydrophobic silica with a strong negative chargeability or silica with a strong positive chargeability treated with aminosilane. Alternatively, a particle group having a polarity opposite to that of the toner may be used, or a particle group having a different triboelectrification series from the toner may be used, and the particle group may be charged by mutual frictional electrification between the two or by frictional electrification with the toner regulating member. It may be configured to inject charges having a polarity opposite to that of the toner.

In addition to the mutual frictional charging between the toner and the particle group, in an image forming apparatus configured to inject charges of different polarities into the particle group and the toner through frictional charging of a toner layer thickness regulating member, the layer thickness It is preferable that the charging series of the regulating member be located between the triboelectric charging series of the toner and particles.

The polarities of the toner and particle groups described above vary depending on the photosensitive drum used and the development method, such as reversal development or regular development, and the relationship between these is shown in the table below.

"Operation" According to this technical means, since the particle group has a polarity opposite to that of the toner at the development position, toner is present in the WJ image forming area and on the non-latent image forming surface (background area). The particle groups adhere to each other, and the surface metal of the image carrier is hidden by the toner and the particle group during the transfer process located on the downstream side, eliminating the possibility that the recording paper will come into direct contact with the image carrier.

As a result, even if an electrostatic attraction force acts on the paper powder peeled off from the recording paper due to corona discharge during the transfer, the paper powder will adhere to the image carrier side via the particle group. , the particle group of the cleaning blade located downstream of the cleaning blade and the residual toner can be easily scraped off together with the remaining toner group, thereby completely eliminating paper dust from being caught between the blade and the image carrier. This eliminates the problem of insufficient cleaning caused by the paper dust being trapped.

Incidentally, since both the particles and the toner are minute particles and not fibrous, there is no fear that they will get caught between the blade and the image carrier, and the particles will not be caught when the blade is rubbed. Since it acts as a lubricant, it is possible to prevent damage to the image bearing member caused by the sliding friction of the blade.

On the other hand, since the particles are non-water-absorbing, even if one paper powder absorbs moisture, the particles can prevent the moisture in the paper powder from leaching to the surface of the image carrier. The structure acts as a protective layer to prevent corona products generated due to corona discharge during the transfer process from adhering to the photoreceptor drum, and as a result, moisture absorption by the image bearing member during the transfer process is completely prevented. clear images without image blurring can be formed.

In addition, since the particle group has the opposite polarity to the toner, or in other words, the same polarity that repels each other to the polarity of the corona discharge during the transfer process, there is no fear that the particle group will be transferred to the recording paper side. It is possible to prevent various adverse effects caused by the adhesion of the group to the recording paper.

In addition, the presence of particle groups on the non-image forming surface may cause blurring of the image at the border with the image forming area, that is, at the edge of the image. This kind of problem can also be solved by forming it with.

Note that if the mixing ratio of the particle group is too large, the toner may not be sufficiently attached to the latent image forming area, so the mixing ratio of the particle group and toner is preferably about tOW or less.

``Example'' A preferred embodiment of the present invention will be described in detail below by way of example with reference to one drawing. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this example are not intended to limit the scope of the invention, but are merely illustrative. Just an example.

The drawing is a schematic view showing an image forming apparatus using a reversal development method according to an embodiment of the present invention. In order, an optical system 2 for writing a latent image on the drum l, a developing device 3 for visualizing the latent image, and a toner image visualized by the developing device 3 are transferred onto a recording paper 4. A transfer device 5 consisting of a corona discharger, a cleaning blade B for removing residual toner, an eraser 7 for removing static electricity from the surface of the drum 1, and a charger 8 for uniformly charging the drum 1 after static electricity removal are provided. The structure of this embodiment will be explained in order, focusing on its function. First, a latent image whose negative charge has been erased by the optical system 2 is formed on the photoreceptor drum l, which has been entirely negatively charged by the charger 8. After the latent image is formed (therefore, the background portion is negatively charged), the drum 1 rotates to visualize the latent image using the developing device 3 described below.

The developing device 3 is housed in a container 11 in which toner and particles, which will be described later, are mixed at a predetermined ratio. Due to mutual frictional electrification between the two and frictional electrification with the layer thickness regulating member 12, the toner is negatively charged and particles are mixed. The mixed particles, each of which is positively charged, are guided to a developing position as the developing roll 13 rotates, and at the developing position, the bias applied to the developing roll 13 causes them to fly toward the photoreceptor drum 1, and the particle groups are positively charged. Since the toner is negatively charged with the same polarity as the background, the toner adheres to the latent image forming area where the charge has been erased.

When the toner image A and particle group layer B deposited on the photoreceptor drum 1 are guided to the transfer position, the recording paper 4 inserted onto the circumferential surface of the photoreceptor drum 11 above the transfer device 5 is placed at a certain timing. Only the toner image is transferred from the back side to the recording paper 4 side by corona discharge having positive polarity, and the recording paper 4 to which the toner image A has been transferred is sent to an image fixing device (not shown) where the image is fixed.

On the other hand, the photosensitive drum 1 after the transfer is further rotated, and a cleaning blade 8 removes the remaining toner from the drum 1.
The drum 1 is cleaned by scraping off the particles adhering to it and the paper dust adhering to the particle groups.

After the drum 1 is completely neutralized by an eraser 7, it is sent to a charger 8, and this is repeated hereafter.

Next, the toner, particle groups, and layer thickness regulating member 12 in the developing device 3 will be explained in detail.The toner is a magnetic toner whose main component is polystyrene resin, and can be negatively charged in the toner container 11. The average particle size is 10 to 20 IL.

The particle group is made of an acrylic resin, such as polyacrylonitrile, which is positively charged by mutual friction with the toner, and the particle size is set around 5 layers, and the mixing ratio with the toner is 100 (toner) = 5 (Particle group) Set before and after.

Further, the layer thickness regulating member 12 is formed of a flexible member having a wall thickness of 100 gm, and the layer thickness regulating member 12 is formed of a flexible member having a wall thickness of 100 gm.
3. Stretch it with a slight inclination towards the downstream side,
The free end side thereof is configured to be able to be pressed against the developing roll 13 with a predetermined contact pressure, and is configured so that frictional electrification is also generated between the regulating member 12 and the toner and particle group.

For this purpose, the layer thickness regulating member 12 is formed of polychlorinated butadiene or the like to maintain the following relationship: triboelectric charging series of particle group>triboelectrifying series of toner regulating member>triboelectrifying series of toner. As a result, the particle group is positively charged and the toner is negatively charged by frictional charging with the layer thickness regulating member 12, thereby further satisfying the effects of the present invention.

Based on this example, we conducted an experiment in a 100% humidity environment using a laser printer (F 1010) manufactured by our company and using plain paper for PPC, which has a lot of paper dust peeling off, as the recording paper. No image blurring or image disturbance due to insufficient cleaning occurred at either time of recording 5,000 sheets or 10,000 sheets, and clear images were always obtained even at the edges of the images.

"Effects of the Invention" As described above, according to the present invention, image blur caused by adhesion of paper dust particularly during the transfer process, insufficient cleaning caused by paper dust being caught in the cleaning blade, and black spots due to insufficient cleaning. This device prevents the occurrence of streaks, charging, and poor exposure, and can always obtain clear images.The device also eliminates the need for a special particle attachment device because the particles are mixed into the conventional developer container 11. There are no restrictions in terms of miniaturization.

It has various effects such as

[Brief explanation of the drawing]

The drawing is a schematic diagram showing an image forming apparatus according to an embodiment of the present invention.

Claims (1)

[Claims] 1) In an image forming apparatus that visualizes an electrostatic latent image formed on the surface of an image carrier using a one-component toner, a group of non-water-absorbing particles is placed in a developer container together with the toner. 2) An image forming apparatus characterized in that the particle group is configured such that the particle group can have a polarity opposite to that of the toner at a development position. Image forming apparatus according to item 1 3) using a particle group different from the toner in the triboelectrification series,
4) The image forming apparatus according to claim 1, wherein the image forming apparatus according to claim 1 is configured to inject a charge having a polarity opposite to that of the toner into the particle group by mutual frictional charging between the particle group and the toner. In addition to mutual frictional charging, in an image forming apparatus configured to inject charges of different polarities into the particle group and the toner through frictional charging of a toner layer thickness regulating member, the charging series of the layer thickness regulating member is different from that of the toner. 5) The image forming apparatus according to claim 3, wherein the particle group is a particle group smaller than the average particle diameter of the toner. Any 1 from paragraph 1 to paragraph 4
6) The image forming apparatus according to any one of Claims 1 to 5, wherein the particle group is mixed and present in the developer container at a mixing ratio of 10% or less of the toner. Image forming device