JPS6265054A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of image bleeding by providing a step blowing hot air to a latent image carrier finishing a cleaning step between a step cleaning the surface of the latent image carrier and a step uniformly electrifying the surface of said carrier. CONSTITUTION:A temperature detector 18 is installed in the vicinity of the discharge port 14b of an air duct 14, detects the temperature of discharge air so as to control a heater 16, and keeps the temperature of said air constant. Accordingly the air discharged from the discharge port 14b of the air duct 14 is blown to the surface of a photosensitive drum 1 and the fur blush hair 8 of a cleaning device. As a result, water adsorbed on the surface is evaporated and dehumidified due to the rise of the surface temperature of the photosensitive drum 1, and the fur blush hair 8 is also dehumidified, thereby improving cleaning capacity. Thus the surface temperature of the latent image carrier rises, and the relative humidify in the vicinity drops, thereby preventing the occurrence of the image bleeding.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an image forming apparatus such as an electrophotographic apparatus, and more particularly to an image forming apparatus that prevents deterioration of image forming ability under high temperature and high humidity conditions. .

[Background of the invention]

Conventionally, image forming apparatuses using electrophotographic processes
As the humidity increases, the surface resistance of the image carrier tends to decrease due to changes in the characteristics of the image carrier such as the photoreceptor drum, hygroscopic deterioration of surface deposits such as developer paper dust, etc. Therefore, a state in which the electrostatic a image bleeds occurs. However, as the surface resistance decreases, the charge moves in the horizontal direction, so the area where the charge remains after the second charge and before development (
The electric charge between the dark part) and the bright part is erased by light irradiation, and the potential at the boundary between the dark part and the bright part does not change sharply in an edge-like manner, but changes gradually. As a result, the developer creates a smeared image, similar to when writing with a pen on sticky paper.

A decrease in image forming ability, called so-called image deletion, occurred.

Such image blurring is caused by the type of image carrier used, such as S@, OPC* ZnO2, CdS, *-81
It is said that the degree of sensitivity varies depending on the patient, etc., and A-8T is said to be particularly severe.

By the way, cleaning devices commonly used in the past include a method of wiping off toner using a fibrous web;
A method in which the toner is scraped off with a blade, a method in which the toner is attracted by magnetic force with a magnetic pusher, and the attracted toner is similarly attracted and collected by a toner collecting member.
There is a method in which the toner remaining on the photoconductor is brushed off with a fur brush or the like, and the toner is sucked by a proa and collected in a filter box, or a method in which a rotating rubber roller is used for cleaning. Since problems such as photoreceptor damage and toner fusion are likely to occur in high-speed copying machines and the like, devices using fur brush cleaning are often used.

However, the conventional fur brush cleaning device tube, a-
Even when used in an image forming apparatus using 8T photoreceptor, it is impossible to remove the deposits on the surface of the A-81 photoreceptor that have absorbed moisture and changed in quality due to corona charging due to the lack of rubbing ability. Although it was finally possible to remove the stain using a cleaning device such as a roller that has a very high abrasive ability, this also caused the problem of damage to the photoreceptor.

[Purpose of the invention]

The present invention has been made to solve these conventional problems, and by reducing the relative humidity on the surface of a latent image carrier such as a photoreceptor drum and its vicinity in a high humidity environment, image deletion can be prevented. The purpose is to prevent the occurrence of

[Summary of the invention]

The image forming apparatus of the present invention blows warm air toward the latent image carrier after the cleaning process between the cleaning process of cleaning the surface of the latent image carrier and the process of uniformly charging the latent image carrier. It is characterized by providing a step of spraying.

[Embodiments of the invention]

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 is a schematic view showing an embodiment of an electrophotographic apparatus to which the present invention is applied, and FIG. 2 is a sectional view showing the main parts thereof.

In the figure, reference numeral 1 denotes a photosensitive drum rotating in the direction of arrow A, around which a primary charger 19, a developing device (not shown), a transfer charger 2, a transfer paper separating means 3, a cleaning device 4, etc. are arranged. The surface of the photosensitive drum 1 is first uniformly charged by a primary charger 19, then exposed to image exposure light to form a latent image, and further, the latent image is made visible by toner in a developing device. Then, the developed toner image T1
is fed between the photoreceptor drum 1 and the transfer charger 2 by the transfer charger 2 from a paper feed section (not shown) in synchronization with the rotation of the photoreceptor drum 1 at the same speed as the peripheral rotational speed of the drum 1. The image is transferred onto a transfer paper P. Transfer paper P passing through the transfer section
are sequentially peeled from the surface of the photoreceptor drum 1 by the transfer material separating means 3 and sent to a fixing device (not shown) by the conveying means 5, where the transfer scratches T are fixed, and then discharged outside the machine. .

On the other hand, the photosensitive drum 1 that has passed through the transfer section is cleaned by a cleaning device 4 to remove residual transfer toner T adhering to its surface, and is then subjected to the next image forming process.

Next, the cleaning device jjt4 will be explained based on FIG. 2.

In the figure, reference numeral 6 denotes a brush roller 7 that is arranged opposite to the photosensitive drum 1 along the generatrix direction and rotates in the direction of arrow B in the figure.
A fur brush having brush bristles 8 whose tips are in sliding contact with the surface of the photoreceptor drum 10 on the entire outer peripheral surface of the fur brush is used to remove transfer residual toner T adhering to the surface of the photoreceptor drum 1 by the brush bristles 8. It is meant to be swept away. Reference numeral 9 denotes a casing that covers the fur bluff 6, and is provided with an opening 10 on the surface facing the photoreceptor drum 1.
A filtergex portion 11 is integrally formed on the opposite side of 00. The filter index section 11 is provided with a planar filter 12 with a slight gap between it and its inner wall surface, and a suction port 11m formed at the top thereof is connected to a vacuum device (not shown), which will be described later. Transfer residual toner T knocked out from the bristles 8 of the fur brush 6 by flicker is sucked and collected within this filter 12 . Reference numeral 13 denotes a flat plate member whose tip end is in contact with the tip end of the bristles 8 of the fur brush 6 along the radial direction on the outer peripheral surface of the rotating shaft 13m provided along the axial direction of the fur brush 6. 13b is a flicker attached, which is provided between the filter index section 11 and the fur brush 6, and rotates in the same direction as the fur brush 6 at a speed faster than the rotational speed of the fur brush. 1
3b knocks out the transfer residual toner T adhering to the bristles 8 of the fur brush 6, and at the same time prevents the bristles 8 from curling up. 14 is a ventilation duct, and a ventilation fan 15 and a heater 1 are installed on the side of the intake port 14a.
6 is provided in the opening 1 provided in the casing 9 of the cleaning device 4, and an exhaust port 14b is provided in the casing 9 of the cleaning device 4.
0, the cleaning device 4 is also provided facing the photosensitive drum 1 on the rotationally downstream side of the photosensitive drum 1. Also, the opening edge 11 of this exhaust port 14b
A comb blade 17 made of an elastic material such as I-urethane rubber is provided, and its leading edge contacts the surface of the photoreceptor drum 1 to scrape off the transfer residual toner T that has not been removed by the cleaning device 4. It is designed to fall. 1
Reference numeral 8 denotes a temperature sensor installed near the exhaust port 14b of the ventilation duct 14, which detects the temperature of the hot exhaust air and controls the heater 16C) to keep the temperature of the hot exhaust air constant. are doing.

Therefore, the hot air discharged from the exhaust port 14b of the ventilation duct 14 is blown onto the surface of the photoreceptor drum 1 and the fur brush of the cleaning device 4, so that the surface temperature of the photoreceptor drum 1 increases and the surface The adsorbed moisture evaporates and the surface of the photoreceptor drum 10 is dehumidified, and the bristles 8 of the fur brush 6 are also dehumidified, increasing the cleaning ability.

On the other hand, if the temperature of the hot exhaust air is high, there is a risk that the toner will fuse to the photoreceptor drum 1 and the bristles 8 of the fur brush 6, and if the air volume (wind pressure) is large, the toner may be scattered. Since noise may be generated, it is desirable to reduce the amount of air (wind pressure) sucked from the suction port 111 of the cleaning device 4.
+ Inside the filter index section 11 of the coating device 4 is 30
Since the negative pressure is maintained at ~LoomHg, the wind pressure of the hot exhaust air is set below this negative pressure.

FIG. 3 is a chart showing the relationship between the degree of image blurring and the temperature of the exhaust hot air, with the volume of the hot exhaust air being expressed as a normal meter.

Area ■ is an area where toner fusion occurs, area ■ is an area where image deletion occurs, area ■ is an area where image deletion does not occur, and where toner fusion etc. do not occur, and this area ■ It becomes available for use. Also, the air volume curve A
, B, and C, curve A is small, curve B is medium, and curve C is large, and curve C is the upper limit of the air volume.

That is, increasing the temperature of the hot air makes it less likely that image deletion will occur, and increasing the air volume will make it less likely that image deletion will occur.

On the other hand, the amount of moisture adsorbed on the photoreceptor drum depends on its relative humidity. The amount of moisture adsorbed on the drum and the drum and the amount of moisture taken into the air as water vapor are equal to 5φ1, and the amount of moisture adsorbed on the drum is determined.

In experiments conducted by the present inventors, it was found that image blurring begins to occur when the relative humidity is approximately 65%.

Therefore, assuming that the external environment is 35 degrees Celsius and humidity 85 degrees Celsius, in order to increase the relative humidity to 65 degrees Celsius, the temperature should be increased by approximately 5 degrees Celsius to about 37.5 degrees Celsius. However, in this embodiment, the surface temperature of the photoreceptor drum l is maintained at a temperature of 42° C.±2° C. with a margin.

On the other hand, in this embodiment, a-8 is used as the photoreceptor drum.
1 photoreceptor, the peripheral speed of the fur brush 6 is about 30 to 40 times faster than the peripheral speed of the photoreceptor drum 1, which is 200 to 15
00 rpm), and the error width between the bristles 8 of the fur brush 6 and the surface of the photoreceptor drum 1 is set at 2 to 15 cm.
27 bristles 8 are brought into light contact with the surface of the photosensitive drum 10.

Further, the bristles 8 of the fur brush 6 and the plate member 13b of the fur brush 13 are made of or coated with the materials described below.

(b) Brush bristles: Synthetic fibers made of polyacrylonitrile and polyvinyl chloride.

Plate member: Acetal resin.

(b) Brush bristles: Cellulose triacetate fiber.

Plate material: polytetrofluoroethylene.

From each combination K of (a) and (b), in an electrophotographic apparatus that positively charges toner, the a-8l photoreceptor Y
The transfer residual toner could be cleaned and removed from the surface of the ram with excellent results.

In the above embodiment, the means and control for generating hot air used a heater, a temperature sensor for the hot air, and a control circuit for turning on and off the heater, but P, T, and C were used instead of the heater. If used, a temperature sensor and a control circuit are not required, and the desired temperature can be easily obtained.

In addition, in the above embodiment, hot air is blown onto the photoreceptor drum from the downstream side of the 7-ar brush cleaning device and guided to the cleaning device. By blowing warm air onto the cleaning device and guiding it into the main body of the cleaning device, toner scattering and image deletion can be prevented.

Next, another embodiment of the present invention will be described based on FIG.

In this embodiment, a ventilation duct 14 is provided in the negative charger 19,
The air heated by the heater 16 is discharged into the charger 19 by the blower fan 15, and the exhaust hot air is blown onto the discharge wire 19m of the primary charger 19 and the surface of the photoreceptor drum 1.

According to such an embodiment, in addition to the effect of preventing the occurrence of image deletion as in the above-mentioned embodiment, other effects such as preventing the discharge wire 19a from becoming dirty and decomposing dioscin with hot air can be obtained. It will be done.

By the way, in each of the above examples, the temperature of the hot air was 42°C ± 2°C.
Thus, the central value of K, 42°C, is fixed. However, if the relative humidity is to be controlled to 65% or less, the temperature T. The saturated vapor pressure of water P(T,) mlHg when
Then, the vapor pressure of R,H when the relative humidity is R0H% is P(To)×106■Hg. Therefore, the temperature is converted to T by R, H ``'' P(T) = P(T6) RH inversely converted to ``''-'('5''Q(?g, iog, 1n)To is room temperature and RH is 65L here. , RoH is the outside air humidity, and if the hot air temperature T is controlled according to the room temperature so that T≧Q(To), the humidity on the photoreceptor drum can always be controlled above a certain value.Providing such a control mechanism is , Room Temperature Detector Furthermore, since the charging current is reduced, it is effective for extending the life of charging wires and photoreceptors, and preventing staining of discharge wires.

Further, in each of the above embodiments, an example is described in which the exhaust port of the ventilation duct 14 is provided near the cleaning device and in the primary charger, but the present invention is not limited to this. It may also be provided between the photosensitive drum and the charger so as to blow hot air from a ventilation duct onto the surface of the photosensitive drum.

〔Effect of the invention〕

As described above, according to the present invention, warm air is blown onto the surface of the latent image carrier, increasing its surface temperature and decreasing the relative humidity near the surface of the latent image carrier, thereby preventing the occurrence of image deletion. Effects can be obtained.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an embodiment of an electrophotographic apparatus to which the present invention is applied, Fig. 2 is a sectional view showing the main part of Fig. 1, and Fig. 3 is an image of air volume expressed in /IP parameters. A chart showing the relationship between the degree of flow and the temperature of exhaust hot air, and FIG. 4 is a schematic diagram showing another embodiment. 1: Photosensitive drum, 2: Transfer charger, 3: Transfer paper separation means, 4: IJ-ning device, 5: Conveying means,
6: Fur brush, 7: Brush roller, 8
: brush bristles, 9: casing, 10: opening,
11: Filter big 1 part, 11a: Suction port, 12: Filter, 13: Flicker, 13a double rotation shaft, 13b: Plate member, 14: Ventilation duct, 14a: Intake port, 14b: Exhaust port, 15: Ventilation fan ,
16: Heater, 17: Blade, 18: Temperature detector, 19 Secondary charger, 19a: Discharge wire. Kishi 1) Tadashi Yuki So τko 1 1 Rashi, 1 Riku 1 Shinbu Kojiro"

Claims (1)

[Claims] Between the cleaning process of cleaning the surface of the latent image carrier and the process of uniformly charging the latent image carrier, a process of blowing hot air toward the latent image carrier after the cleaning process is provided. Features of the image forming device.