JPS63218987A - Cleaning device for image carrying body - Google Patents

Abstract

PURPOSE:To completely collect a toner which has been removed from the surface of an image carrying body, by specifying a correct set area (range) related to an inter-surface distance between a toner collecting roller and an image carrying body drum, and an applied voltage. CONSTITUTION:When an applied voltage, and each inter-surface distance (gap) between a conductive roller 50 and a drum 40 are denoted as V (unit kV), and (d) (unit mm), respectively, the applied voltage V exists between Vmax=4.0 d-0.2, and Vmin=1.4d-0.1, and the gap (d) exists within a range of 0.1<(d)<0.5. Also, the conductive roller 50 is positioned at the lower part of the horizontal plane containing an axis of the drum 40. In such a way, cleaning and a toner collection are executed satisfactorily, therefore, no toner filming is generated on the surface of the image carrying body drum 40, no thunderbolt is generated either, and damage and deterioration of the image carrying body are not generated.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an improvement in a cleaning device for removing residual toner on an image carrier in an electrophotographic image forming apparatus.

[Background of the invention]

As a cleaning means in electrophotography, a blade member, which has a simple structure but is said to have the highest cleaning efficiency, is often disposed on the circumferential surface of the image bearing drum for cleaning. During blade cleaning, the toner removed from the image carrier drum is removed from the blade installation position (downstream side).
There is no chance of re-adhesion, and its effectiveness is extremely high despite its simple structure. This will give good results to the next process of image formation.
Ultimately, this will lead to providing an image forming apparatus such as a copying machine that can consistently form beautiful images. Conventional toner collection means associated with this blade cleaning include a means in which an elastic member such as a Mylar blade made of a plate of polyester material is slid on the surface of the image carrier drum, and a means in which an elastic member such as a foamed plastic roll is installed. A means is provided to slide and rotate on the surface of the drum. All of these toner collecting means are often located below (upstream in the drum rotational direction) the position where the blade cleaning member is installed.

[Problems to be solved by the invention]

Such a leaning device, particularly the toner collecting means of the device, has the following drawbacks. (a) Since the cleaning blade, mylar blade, and foamed plastic all come into sliding contact with and press against the surface of the image carrier drum, they cause a toner film to form on the drum surface over a long period of time. (b) This may cause toner leakage, etc., which may cause equipment failure. (c) Foreign matter, such as carriers in some cases, may enter between the drum surface and each member that comes into sliding contact with the drum surface, causing damage and deterioration of the drum surface. According to Japanese Patent Publication No. 47-42340 (patented by Xerox Corporation), a method has been proposed for the purpose of toner recycling that eliminates the above-mentioned drawbacks. However, there are other drawbacks to this, as follows. (a) The applied voltage for collecting toner ranges from 0.5 kV to several kV, which is extremely large for the range of use, and there is a problem with the safety of the device. (b) Furthermore, the applied voltage is large and the potential of the toner is changed by 1, which is an unsuitable condition for the purpose of toner recycling. (c) The distance W1 (gap) between the toner collection roller surface and the image bearing drum surface is not specified at all, and depending on the matching with the set voltage value, dielectric breakdown (leakage), toner spillage, and carrier spillage may occur, causing the device to malfunction. It can also be a direct cause of failure. (d) According to the device diagram shown, the blade and toner collection roller are located far above the horizontal plane that includes the axis of the image bearing drum, and the distance between the blade and the toner collection roller is too far. As a result, toner always remains on the surface of the image carrier between the blade and the roller, resulting in insufficient toner collection and an increased cleaning load on the blade.

[Means to solve the problem]

(Object of the Invention) An object of the present invention is to provide an appropriate setting range (
Toner removed from the image carrier surface by the blade remains on the image carrier surface without excessively increasing the applied voltage value and without damaging or deteriorating the image carrier surface. The object of the present invention is to provide a highly safe and efficient leasing device that allows almost complete collection and recovery. (Structure of the Invention) The object is to provide a cleaning means for proactively scraping and removing toner from the surface of an image bearing drum of an electrophotographic image forming apparatus, and a rotatable device located upstream of the cleaning means at a slight distance from the drum surface. a conductive roller disposed in the residual toner and to which a potential of a polarity different from that of the residual toner is applied;
The applied voltage is V (unit: kV), and the distance (gap) between each surface of the conductive roller and the drum is d (unit: w).
m), the applied voltage V is V max = 4.
0d O,2 and Vmin=1.4d-0,1, d is in the range 0.1<d<0.5, and the conductive roller is in the horizontal plane including the sleeve of the drum. This is achieved by an image carrier cleaning device located below.

[Example and action]

An embodiment of the present invention is shown in FIGS. #S1 to 5. First, the general functions of a color image forming apparatus incorporating the present invention will be explained with reference to FIG. In FIG. 3, A is a reading unit, B is a writing unit, C is an image forming section, and D is a paper feeding section. In reading unit A, 1 is a platen glass, and an original 2 is placed on this platen glass 1. original fi
2 is illuminated by fluorescent lamps 5 and 6 provided on a carriage horn 4 that moves on a slide rail 3. The movable mirror unit 8 is provided with mirrors 9 and 9', which move on the slide rail 3, and in combination with the first mirror 7 provided on the carriage 4 read the optical image of the document 2 on the platen glass 1 with the lens. Derived to unit 20. The carriage 4 and the movable unit 8 are driven by a stepping motor 10 via a wire 15.
1.12.13.14, V and 1/2v respectively
are driven in the same direction at a speed of Standard white plates 16 and 17 are provided on the back side of both ends of the platen lath 1, and are configured so that a standard white signal can be obtained before the start of original reading scanning and/or after the end of scanning. The lens reading unit 20 includes a lens 21. prism 2
2. First reading board 24, red channel (hereinafter referred to as R)
-cl+) CCD 25, second reading board 2
6. Cyan channel (hereinafter referred to as Cah) CCD 2
Consists of 7. First mirror 7, mirror 9, mirror 9
' The original optical image transmitted by
D 25, and C provided on the second reading board 26.
- The images are respectively formed on the light receiving surface of the chccD27. The fluorescent lamps 5 and 6 are commercially available warm white fluorescent lamps used to prevent certain colors from becoming strong or attenuated due to the light source when reading color documents, and 40K fluorescent lamps are used to prevent flickering.
It is turned on by a high frequency power source of Hz and is kept warm by a heater using a POSISTOR in order to maintain a constant temperature of the tube wall or to promote tsuumu-up. The image signals output from the RchccD25 and C-chccD27 are subjected to signal processing in a signal processing section. In the signal processing section, a color signal separated according to the color of the toner, which will be described later, is outputted and inputted to the writing unit)B. In the writing unit B, a laser beam generated by a semiconductor laser is rotated and scanned by a polygon mirror 32 rotated by a drive motor 30, passes through an Fθ lens 36, and the optical path is bent by a projecting mirror 37 to reach the surface of an image carrier drum 40. It is projected upward and forms a bright line. When scanning begins, the beam is detected by the index sensor and modulation of the beam by the first color signal begins. The modulated beam is charged by the charger 41 as shown in FIG.
As shown in a), the image carrier drum 40, which has been uniformly charged in advance, is scanned. During the main scanning by the laser beam and the sub-scanning by the rotation of the image carrier drum 40, a latent image corresponding to the first color is formed on the surface of the image carrier drum as shown in FIG. 5(b). The latent image is developed by a developing device 43 loaded with red toner, for example, by applying a bias as shown in PIS 5 (c), and a red toner image is formed on the surface of the image carrier drum.The obtained toner The image, while being held on the surface of the image carrier drum, passes under the cleaning device 46, which is separated and retracted from the surface of the image carrier drum, and enters the next copy cycle. Similar to the cycle, it is uniformly charged by the charger 41. Next, the second color signal output from the signal processing section is input to the writing unit) B, and the image is carried in the same manner as the first color signal. Writing is performed on the surface of the body drum to form a latent image. The latent image is developed by a developer 44 loaded with toner of a second color, for example blue. This blue toner image is formed to overlap the red toner image already formed on the surface of the image carrier drum. A developing device 45 has black toner, and forms a black toner image on the surface of the image carrier drum based on a control signal generated by a signal processing section. AC and DC biases are applied to the sleeves of these developing units 43, 44, and 45, and jumping development is performed using the two-component developer, and non-contact development is performed on the grounded image carrier drum 40. There is. The superimposed image of the toner image based on the first color signal developed in this manner, the toner image based on the fpJ2 color signal, and the toner image developed as the black toner image is formed at the transfer pole 51.
The image is transferred onto the recording paper 61, which is a transfer body, fed by the feed belt 62 and feed roller 63 of the paper feed section. The recording paper onto which the toner image has been transferred is separated from the surface of the image carrier drum by a separation pole 52, and further conveyed to a fixing device 53 to obtain a fixed color hard copy. A cleaning device 46 equipped with a cleaning means according to the present invention shown in FIG. 1 acts on the image bearing drum 40 after the transfer, and the peripheral surface is negatively charged as shown in FIG. 5 (cl). It is designed to remove unnecessary toner that remains on the machine. As a cleaning means attached to the pre-clamping and leaning device W146, a cleaning roller 49, a blade 47, and an electrically conductive roller 48 arranged at both ends from the downstream direction of the rotational direction of the image carrier drum 40 (indicated by arrow r) are used. The cleaning case 4 is opened with each cleaning member of the metal roller 50 facing the circumferential surface of the image carrier drum 40.
It is housed and arranged in 8a. The blade 47 is made of plate-shaped urethane rubber and is biased clockwise by a blade holder 47a to press against the circumferential surface of the image carrier drum 40, and the cleaning roller 49 is It is made of abrasive foamed urethane resin and rotates clockwise only for a predetermined period of time by the action of the drive device 49a when the blade 47 presses and releases the press, and presses against the circumferential surface of the image carrier drum. vl has been created. The conductive roller 50, which is disposed upstream of the blade 47 as a toner collecting roller, has insulating rollers 48 slightly larger than the outer diameter of the roller at both ends thereof. Since it is brought into contact with the non-image area, a very small amount of
The structure is such that counterclockwise rotation and a predetermined applied voltage can be applied at a position where a constant gap determined by the outer diameter of the insulating roller 48 and the outer diameter of the conductive σ-250 is maintained. . Therefore, regarding the cleaning process by each of the cleaning members described above, before the leading edge of the toner image that has been transferred reaches the blade 47, the blade 47 is brought into pressure contact with the image carrier drum 40 by the action of the blade holder 47a. The remaining toner begins to peel off and fall off. The conductive roller 5 is maintained at a constant gap from the image carrier drum 40 by the insulating flow 50.
0 is a scraper 50a that is extremely uniformly charged to a polarity that attracts toner by an applied voltage based on the experimental results shown in FIG. The toner can be scraped off and sent to the toner transport path 46b. Further, when the cleaning action by the pressure contact of the blade 47 is started and when the pressure contact is released after the cleaning action, the rotational pressure contact of the cleaning roller 49 acts to create a space between the circumferential surface of the image carrier drum 40 and the blade 47. A small amount of toner left behind on the image carrier drum 40 is removed.
The peripheral surface of the lens is thoroughly cleaned in preparation for the next exposure. As described above, in the present invention, a conductive metal roller is provided around the image carrier drum 40 as a toner collection roller on the upstream side of the cleaning means that actively scrapes and removes toner from the surface of the image carrier drum 40. They are placed with a slight but constant gap from the surface, allowing the removed toner to be collected. What dimensions did the gear 7b d have and how did the value of the voltage V applied to the conductive roller be determined?
This will be explained based on the applicant's experimental results shown in FIG. 2, and the effect of the stroke will be clarified. Here, in the arrangement of each member shown in FIG. 1, the angle G and the separation F representing the positions of the cleaning blade 47 and the conductive roller 50 were set to about 50° and about 0.0 mm, respectively. The image bearing member is an OPC photosensitive drum with an outer diameter of 1501Il+a, the conductive roller is a stainless steel roller with an outer diameter of 8m+s to 12mm, the toner is a particle size of 15μm, and the carrier is a particle size of about 40μm, for example 7mm. The magnetic carrier, which is a nearly spherical particle made of resin-coated light particles, and the cleaning blade are made of urethane rubber, and the line speed of both the drum and the roller is 70I.
The experiment was conducted at the same speed of III/sec. Then, by two-component jumping development, toner adhesion f
i O,86-1,02IIg/257r at 0m2
The screen area of mX 3630111 was developed solidly, and this was cleaned with a cleaning blade without being transferred.
The recovery performance of the removed toner scraped off was confirmed by the amount recovered. Therefore, this experiment was a forced collection test with a very large amount of cleaning toner. In this state, by changing the gap d and the applied voltage V, the limit of the toner collection method is determined by the line I in FIG.
It is expressed by the empirical formula of V m1n = 1.4d-0,1. That is, it can be seen that the area below the line (2) is a region where the toner collecting ability is reduced, and the larger the gap d and the smaller the applied voltage, the lower the toner collecting ability. However, if the gap d is made too small or the applied voltage is too high, the drum will be damaged between the rollers Pl (
It was found that lightning strikes can occur. Under ideal environmental conditions, Paschen's law states that voltage leaks will not occur in the arrangement of this example, but in reality, moisture, paper dust, dirt, foreign matter, etc. can occur between the drum and rollers. I found out that this caused a leak. The insulation limit line becomes line H in diagram PA2, and V
max=1. ○It is expressed by the empirical formula of d-0,2. Furthermore, if the ear d is made too large, it becomes difficult to prevent the carrier from spilling out, which may be accidentally mixed in. This limit line is line ■, d=o, 5
It is expressed as In this way, the range of the relationship between the applied voltage V and the gap d may be defined as the range surrounded by lines 2, 3, and 3 shown in FIG. 2. However, if d becomes less than 0.1, it becomes difficult to adjust the precision, so it is preferable to avoid this. Therefore, in this embodiment, during assembly work, maintenance, and inspection,
111i! ! Good results were obtained by setting the gap d to 0.25 mm, the applied voltage V voltage, and 5 kV as good conditions without requiring severe conditions and without unnecessarily increasing the voltage applied to the conductive roller. However, without being limited thereto, all the applications within the range of use shown in FIG. 2 above were satisfactory. Further, in order to prevent the scraped toner from adhering to the image bearing drum again, the cleaning blade was set below the horizontal plane including the drum axis. The voltage applied to the conductive roller has a polarity different from that of the drum charging voltage and the residual toner, as shown in FIG. 5(e). The sequence of color image formation in the color image forming apparatus of the present invention equipped with such a cleaning means will be explained with reference to the time chart of FIG. 40, in the first rotation, the image exposure starts using the first color signal, and after undergoing development I processing delayed by the time interval X, the second rotation starts, and the image exposure starts using the second color signal. After undergoing development process (2) delayed by time y, image exposure is started by a black signal in the third rotation, and development process (2) is performed with a delay of time 2 to form a color toner image. Here, the time X% ys Z is the time required for the image carrier drum 40 to reach a certain position (the leading edge of the image in the figure) from the image exposure position to the position where each development process is performed, and m is the time within that time. Transfer pole 5 from image exposure position
The time required to reach 1 or less time, n
is the time required to reach the cleaning device 46 from the image exposure position or a time shorter than that. Also, l is the time required for the entire image surface of the document to pass through a fixed point such as an image exposure or development processing position, and the actions of image exposure, development processing, transfer, cleaning, etc. are as shown by the broken line. It is designed to be operated with a little margin of time before and after. That is, in the embodiment described above, the blade 47
The cleaning roller 49 is operated for approximately 1 second each from the time when the blade 47 starts operating and from the time when the entire image surface has been cleaned. Conductive roller 50 according to the present invention
The timing of voltage application to the blade 47 may be the same as the operation of the blade 47, or the voltage may be constantly applied.

【Effect of the invention】

Since the electrophotographic image forming apparatus incorporating the cleaning device of the present invention performs good cleaning and toner recovery, toner filming does not occur on the surface of the image bearing drum, and lightning strikes do not occur. It was found that damage and deterioration of the image bearing body was eliminated, and the life of the image bearing member was extended compared to the conventional one. In addition, the results of a long-run continuous test of 20,000 images confirmed that toner was being recovered smoothly and stably, the contamination inside the device was far less than before, and the accident rate was reduced. This has led to a significant reduction in the burden of internal cleaning and inspection services.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the cleaning device of the present invention. FIG. 2 is a V-d diagram illustrating the toner collecting power decreasing region and leak generation region of the conductive roller used as the toner collecting roller. FIG. 3 is a schematic diagram of a color image forming apparatus. Figure 4 is a time chart. fjS5 diagram is a potential pattern diagram of each process. 40... Image carrier drum 41... Transfer pole 43.4
4, 45... Developing device 46... Cleaning device 46a... Housing 46b... Toner transport path 47... Cleaning blade 48... Insulating roller 50... Conductive roller 5
0a...Scraper applicant: Konishiroku Photo Industry Co., Ltd., 10-RaiP! ! #t(m n )0
Tsuge

Claims (1)

[Claims] A cleaning means for actively scraping and removing toner from the surface of an image bearing drum of an electrophotographic image forming apparatus, and a cleaning means rotatably disposed slightly apart from the drum surface on the upstream side of the cleaning means and different from the residual toner. A conductive roller to which a polar potential is applied is provided, where the applied voltage is V (unit: kV), and the distance (gap) between each surface of the conductive roller and the drum is d (unit: mm). , the applied voltage V is Vmax=4.0d-0.2 and V
min=1.4d-0.1, d is 0.1<d
<0.5, and the conductive roller is located below a horizontal plane including the axis of the drum.