JPS59204055A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce excessive moisture adsorption to the surface of a photosensitive body, which is a factor of a picture flow, and to raise environmental stability by installing a dehumidifying member in the vicinity of the surface of an image carrier body, and providing a drying means of the dehumidifying member. CONSTITUTION:An amorphous silicon photosensitive drum is set to a commercially available copying device serving as an image forming device. A silica gel plate 4 seving as a dehumidifying member, which has almost the same curvature as a photosensitive drum 1 and has size of 300mm. length X 30mm. width X 5mm. thickness is set so as to maintain an interval of 5mm. to the surface of the drum, in a space extending from a transfer material separating roller 2 to a cleaning device 3, an air lead-in pipe 6 having a manifold type nozzle 5 is provided in the vicinity of the back face of the plate concerned, and it is connected to a small- sized hot air device 8 serving as a drying device set to other part in the copying device through a pipe 7 made of polyethylene. A picture flow is prevented by reducing only humidity in the vicinity of the photosensitive body by the dehumidifying member 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus, particularly an image forming apparatus (hereinafter referred to as a copying apparatus) using a corona discharge device such as an electrophotographic apparatus or an electrostatic recording apparatus.

This type of copying apparatus is equipped with a corona discharge device, and during the formation of one image, the photoreceptor as an image bearing member is constantly exposed to corona discharge and deteriorates. However, since corona discharge is a partial discharge and takes place at normal pressure,
Ionization of atmospheric components.

It is believed that chemical decomposition occurs at fairly high concentrations, and that the photoreceptor deteriorates due to the chemical (or electrochemical) forces of these high concentrations of active components. What are the changes in the image due to photoreceptor deterioration?

There are many problems specific to the photoreceptor material, and although it cannot be described in detail, image deletion is one of the problems that is common to all materials and is very serious.

Image deletion is caused by charges retained on the photoreceptor surface.

A phenomenon caused by an apparent flow in the creeping direction.

Considering the electrical properties of the material, it can be considered that some kind of low-resistance portion is formed on or near the surface of the photoreceptor.

Due to its functionality, photoreceptors are usually made of materials that can be considered electrically insulating.

Normally, it is unthinkable that charges flow in the creeping direction (lateral direction). Therefore, it is likely that a photoreceptor that causes image deletion has some kind of abnormality in its manufacturing process and has formed a low-resistance component, or that a large amount of low-resistance component has been adsorbed on the surface for some reason. It is reasonable.

Of the two points mentioned above as causes of the lower surface resistance, the former is excluded as being caused by the manufacturing process,
Let's take a closer look at the latter, which has some force majeure aspects to it.

The first thing that affects low adsorption resistance components is moisture. It is believed that a normal solid surface adsorbs at least several molecular layers of water molecules at room temperature and humidity, and the surface of a photoreceptor is no exception to this.

However, considering that it is rather rare for a photoreceptor to cause image deletion at room temperature and humidity immediately after fabrication, it is thought that a few molecular layers of moisture will not cause a change in resistance until it actually causes image deletion. It is thought that this is closely related to the photoreceptor deterioration phenomenon caused by corona discharge.

Next, let's consider the relationship between the corona deterioration phenomenon and moisture adsorption in more detail.

As a chemical reaction component caused by corona discharge.

Environmental components include nitrogen molecules, oxygen molecules, carbon dioxide molecules,
water molecules, etc., and discharge decomposition products.

No.2. NO3, COO, ) 1.0, etc., and more.

Each ion etc. can be opened. Since all of these are activated in the corona electric field, they are assumed to attack the photoreceptor surface one after another and break the atomic bonds of the photoreceptor surface materials, and in some cases, they may cause new formations, including themselves. It is thought that the photoreceptor is fixed to the surface of the photoreceptor by forming a strong bond. In such a situation, the apparent chemically active surface area of the photoreceptor surface may be increased, and therefore, the water-accepting ability of the surface may be increased. In addition, since the dungulates, oxides, hydroxides, etc. generated on the 9 surface all have excellent affinity for moisture, they are the cause of accelerating the moisture adsorption effect. can also be considered. As explained above, corona deterioration acts to promote moisture adsorption, and the degree of deterioration gradually progresses over time.

It is presumed that sufficient water-receiving ability to cause image blurring will eventually be obtained.

As mentioned above, it is understood that moisture adsorption on the surface is accelerated by deterioration, but on the other hand, the inventor's study found that even photoreceptors that have deteriorated do not suffer from image deletion under appropriate environments such as low temperature and low humidity. It has been found that there are cases in which this phenomenon does not occur.The image deletion phenomenon should not be determined solely by the deterioration of the photoreceptor, but may also be caused by the structure of the copying machine or the correlation with the operating environment such as temperature, humidity, and air components. It turns out that it is of a nature that should be discussed above. In other words, countermeasures against image deletion should be taken from the perspective of the entire system, rather than focusing only on optimizing the photoreceptor itself, such as obtaining a photoreceptor that does not deteriorate.

The present invention has been made in view of the above, and an object of the present invention is to provide an image forming apparatus that reduces excessive moisture adsorption on the surface of a photoreceptor, which is a cause of image deletion, and has good environmental stability.

In order to achieve the above object, the present invention provides a dehumidifying member that is installed close to the surface of the image bearing member so as to maintain the surface of the image bearing member at a constant amount of moisture adsorption, and that this dehumidifying member has a constant dehumidifying effect. The present invention is characterized in that a means for drying the dehumidifying member is provided so as to maintain the dehumidifying member.

EMBODIMENT OF THE INVENTION Below, an example in which the effects and experimental results of the present invention are shown in the drawings will be described in detail.

The amorphous silicon photosensitive drum was set in a commercially available copying machine as an image forming device, and the copying machine was used to make a single image under normal copying conditions in an environmental test room at a temperature of 65°C and a relative humidity of 95%. I made a delivery. Next, the copying apparatus was moved outside, and 10,000 images were continuously printed under normal temperature and humidity conditions. Comparing the images obtained here at Jade, the first image is indoors and the first image is outdoors.

It was confirmed that all the 10,000th sheets had good images with almost no difference.

Next, the above-mentioned copying apparatus was again transferred to the environmental test room, and when both copies were taken out under the same high temperature and high humidity conditions as above and under the same copying conditions, partial blurring of the image occurred from the first sheet. It is understood from the above experiments that this image blurring is the so-called image deletion described above, and is caused by some change (deterioration) of the photoreceptor and the interaction with the high temperature and high humidity environment.

Next, as shown in Figure 2, the photosensitive drum has approximately the same curvature as the photosensitive drum 1 and has a length so that a distance of 511M from the drum surface can be maintained in the space from the transfer material separation roller 2 to the cleaning device M6. Size 300ys x width 60
A silica gel plate 4 as a dehumidifying member having dimensions of rope x 5 m thick is set.

A manifold type nozzle 5 is installed adjacent to the back side of the plate.
An air introduction pipe 6 having a diameter of 1.5 mm was provided, and this was connected via a polyethylene pipe 7 to a small hot air fan 8 as a drying device set at another location within the copying apparatus. The copying machine was placed in an environmental test room with the same temperature and humidity as above, and after about one hour when it could be considered that a steady state had been reached, the relative humidity near the plate was measured using a hygrometer, and it showed a value of around 70%. I confirmed that there is. Thereafter, when image output was performed under the same conditions as above, it was confirmed that the 9 image deletion disappeared and the image quality had returned to the initial level. Subsequently, 10,000 images were taken out under the same environment, but no changes were found in the 9 images thereafter. When the humidity at this time was measured again, it was found that it had increased to 82%. From the above, it has been confirmed that image deletion cannot be prevented by reducing only the humidity near the photoreceptor using the dehumidifying member 4.

After the above operations, the copying machine was temporarily stopped, and a hot air fan installed in the environmental test chamber was operated to blow hot air to dry the silica gel plate 4.

After about 1 hour of Al11, the hot air fan was stopped and the humidity around the photoreceptor was measured, and it was confirmed that the humidity had decreased by 68%. Thereafter, the copying process was started again, and the same drying process and humidity measurement as above were carried out every 10,000th copy, and images were printed at the size of the 100,000th copy in total. 1 more
After completing the 00,000th copy, I returned the copying machine to its pre-modification state and left it indoors for about an hour to print just one image. The table below shows the changes in humidity and images during the above process.

As detailed above, the present invention installs a dehumidifying member close to the surface of an image carrier to maintain the surface of the image carrier at a constant amount of moisture absorption, thereby reducing the occurrence of image deletion. be able to. It's a size.

Since a drying means for the dehumidifying member is provided so that the dehumidifying system maintains a constant dehumidifying effect, effects such as being able to maintain the performance of obtaining high-quality images without image deletion over a long period of time can be obtained. .

Additionally, a charger and a bi-light device are installed around the photosensitive drum 1.

Image forming process equipment such as a developing device is provided, but is omitted from the diagram.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a very schematic configuration diagram of the image forming apparatus of the present invention. 1 is a photosensitive drum, 4 is a silica gel plate, and 8 is a hot air heater.

Claims (1)

[Claims] A dehumidifying member is installed close to the surface of the image bearing member so that the surface of the image bearing member always maintains a constant amount of moisture adsorption, and a means for drying the dehumidifying member is installed so that the dehumidifying member maintains a constant dehumidifying effect. An image forming apparatus comprising: and.