JP3070985B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus provided with a contact type charging roller for charging a photosensitive drum in contact with the surface thereof and a cleaning device for cleaning the surface of the photosensitive drum after image transfer. Related to the device.

[0002]

2. Description of the Related Art An image forming apparatus such as a copying machine or a printer using an electrophotographic system is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-136068.
As disclosed in Japanese Unexamined Patent Publication No. H10-260, there is a charging device that charges a surface of a photosensitive drum using a contact-type charging roller that has low ozone and saves energy.

[0003] Such a charging roller is preferably detachable from a main body of the apparatus together with a cleaning blade of a cleaning device for cleaning the surface of the photosensitive drum to facilitate maintenance and the like. When these are always in pressure contact with the photoconductor drum, the characteristics of the contact portion may be deteriorated depending on the photoconductor, so that the charging roller and the cleaning blade can contact and separate from the photoconductor drum. When the photosensitive members are stopped, they may be separated from the surface of the photosensitive members.

As the charging roller, for example, there is a charging roller in which a metal core is formed of metal and a roller surface is formed of a conductive rubber roller. A voltage is applied between the metal core and a photosensitive body. That is, the photoconductor is charged mainly by discharging.

[0005]

However, in the case of such a system in which the charging roller is brought into contact with the photosensitive drum to charge the photosensitive drum, the uniformity of the resistive layer on the surface of the charging roller and the uniformity of the charging roller and the photosensitive drum The charging state of the photoconductor drum tends to change due to the uniformity of the contact state with the drum, and if the charging state lacks uniformity, it may not be possible to uniformly charge the entire surface of the photoconductor drum. Was.

Further, when foreign matter such as toner adheres to the surface of the charging roller, there is a case where only a low potential can be obtained due to insufficient discharge of the portion. SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to uniformly charge the entire surface of a photosensitive drum by preventing foreign substances such as toner from adhering to the surface of a charging roller. And

[0007]

According to the present invention, in order to achieve the above object, in the above-described image forming apparatus, the cleaning member of the cleaning device is replaced with a photosensitive drum.
And the photosensitive drum.
The separated cleaning member is pressed against the photosensitive drum.
After contact, start of the rotation to drive the photosensitive drum
Thereby, a control device is provided for pressing the photosensitive drum charging roller from the separation state when the position corresponds to the cleaning member of the surface of the photosensitive drum at the time of drive start is rotationally moved until after the position corresponding to the charging roller It is a thing.

[0008]

[0009]

According to the image forming apparatus constructed as described above, the image
The cleaning member separated from the photoconductor drum is the photoconductor
When the photosensitive drum starts rotating after being pressed against the drum, the charging roller is in a state of being separated from the photosensitive drum at that time, and the position corresponding to the cleaning member on the surface of the photosensitive drum at the start of driving is charged. When the roller is rotated until it passes the position corresponding to the roller, the charging roller that has been separated from the roller contacts the photosensitive drum, so that the charging roller comes into contact with the portion of the photosensitive drum that has been cleaned by the cleaning member. No foreign matter such as toner adheres to the surface of the charging roller.

[0010] Also, at the time of the pre-stop driving the sensitive light drum, since the cleaning member is in the separated state from the photosensitive drum, when the cleaning member is pressed against the always photosensitive drum, the photosensitive drum Cleaning member
The characteristics of the parts where the parts were pressed against each other may deteriorate,
This can be prevented.

[0011]

[0012]

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic view showing the periphery of a photosensitive drum of an image forming apparatus according to an embodiment of the present invention. In this image forming apparatus, a photosensitive drum 1 is provided substantially at the center of an apparatus main body (not shown), and a charging roller 2 is provided around the photosensitive drum 1 so as to be able to contact and separate from the surface of the photosensitive drum 1.
An optical system 3 as exposure means for exposing the surface of the photoreceptor charged by the photoreceptor, a developing device 4 for making a latent image formed on the photoreceptor drum 1 by exposure by the optical system 3 visible. And a cleaning roller 8 for cleaning the surface of the photosensitive drum 1 with a fur brush 7 and a cleaning blade 8 as a cleaning member after the transfer by the transfer roller 5 is completed. The apparatus includes a device 6 and a quenching lamp 9.

In this image forming apparatus, the driving of various driving systems in the apparatus main body is controlled .
The cleaning blade 8 separated from the photosensitive drum
After pressing the 1, the photosensitive drum 1 to start the rotation driving, position Poi which corresponded to the cleaning blade 8 of the photosensitive drum 1 surface at the time of drive start, as shown in FIG. 2 when rotated moves up past the position corresponding to the charging roller 2, the charging roller 2 and a photosensitive drum to drive the solenoids Ru control device is pressed against 10 for example from 1 to the separated state as shown in FIG. I have. As will be described in detail later, the control device 10 drives the cleaning blade 8 provided to be able to contact and separate from a position indicated by a solid line and a virtual line in FIG. The charging roller 2 is also controlled to be pressed against the photosensitive drum 1 after being pressed against the photosensitive drum 1.

The charging roller 2 has a metal core portion 2a formed of metal, a roller surface side formed of a conductive rubber roller 2b, and mainly a voltage applied between the metal core portion 2a and the photosensitive drum 1. The photosensitive drum 1 is charged by discharge, and the portion of the conductive rubber roller 2b comes into contact with or separates from the surface of the photosensitive drum 1 by a mechanism using a solenoid (not shown) or a lever.

The cleaning device 6 is formed in a unit shape, and a tip portion 8a is provided in the unit casing 11 so as to be able to come into contact with and separate from the surface of the photosensitive drum 1 by a fur brush 7 and a mechanism (not shown). After the transfer, the fur brush 7 and the cleaning blade 8 scrape off the residual toner on the surface of the photosensitive drum 1 into the unit casing 11 and transfer the toner to the toner casing. The collection coil 12 collects the toner in a collection bottle (not shown) provided outside the unit.

In such an image forming apparatus, when the charging roller 2 and the cleaning blade 8 come into contact with the surface of the photosensitive drum 1 at the same time at the same time as the start of the driving of the photosensitive drum 1, inconvenience may occur. There is. That is, in the cleaning device 6, even if the residual toner and the like on the surface of the photosensitive drum 1 are scraped off by the cleaning blade 8, as shown in FIG. In some cases, the scattered toner T or the like remains on the photosensitive drum 1 in the unit casing 11, and when the scattered toner reaches the position of the charging roller 2, it is Is attached to the surface of the substrate, so that the discharge at that portion becomes insufficient.

However, in this embodiment, since each unit is operated at the timing shown in FIG. 3, the above-mentioned inconvenience does not occur. That is, when the print button is pressed by the image forming operation by the operator, first, the cleaning blade 8 is driven by a mechanism (not shown) (for example, the solenoid is turned on),
As shown in FIG. 1, the tip 8 a contacts the surface of the photosensitive drum 1.

Next, the photosensitive drum 1 is driven and an arrow A is displayed.
Start rotating in the direction. The charging roller 2 is pressed against the photosensitive drum 1 as shown in FIG. 2 after the time t1 shown in FIG. 3 has elapsed since the start of the driving of the photosensitive drum 1, and thereafter, the charging, exposure, development, and transfer processes are performed. Each operation is performed at the timing shown in FIG.

The time t1 during which the charging roller 2 is pressed against the photosensitive drum 1 is set at L between the position where the cleaning blade 8 contacts the surface of the photosensitive drum and the position where the charging roller 2 contacts as shown in FIG. When the distance (mm) and v are the linear velocity (mm / sec) of the photosensitive drum, this is the time when t1> (L / v), and this time is after the photosensitive drum 1 starts rotating. This is the time when the position Poi corresponding to the cleaning blade 8 on the surface of the photoreceptor drum 1 at the time of the start of the drive has been rotationally moved until the position Poi has passed the position corresponding to the charging roller 2 (the state in FIG. 2).

By doing so, the charging roller 2
Comes into contact with the portion of the photosensitive drum 1 that has been cleaned by the cleaning blade 8, so that foreign matter such as toner does not adhere to the surface of the charging roller 2.

Note that this series of controls are all performed by the control device 10 shown in FIG. The control device 10 includes a central processing unit (CPU) having various judgment and processing functions.
And a ROM storing various processing programs including various programs and fixed data, a RAM serving as a data memory for storing processing data, and an input / output circuit (I / O).

FIG. 4 shows that toner and the like adhere to the surface of the charging roller .
Describes the reference technology of an image forming apparatus that is difficult to perform
Figure 1 a similar schematic view showing a photosensitive drum around for,
FIG. 5 is a schematic diagram showing a state in which the cleaning blade 8 of the image forming apparatus is in contact with the surface of the photosensitive drum 1.
FIG. 6 is a timing chart showing the operation timing of each part of the image forming apparatus. Parts corresponding to those in FIG. 1 are denoted by the same reference numerals. In this image forming apparatus, when the photosensitive drum 1 is started to be driven, the photosensitive drum 1 is reversely rotated in a direction indicated by an arrow B by a predetermined amount as shown in FIG. 4 and then separated from the surface of the photosensitive drum 1. The cleaning blade 8 is pressed against the photosensitive drum 1 as shown in FIG. 5, and then the photosensitive drum 1 is rotated forward in the direction of arrow A.

That is, in this image forming apparatus , when the print button is pressed, first, the photosensitive drum 1 reversely rotates (direction B in FIG. 4) for a time t2 shown in FIG.
As a result, as shown in FIG. 5, the surface portion of the photosensitive drum 1 to which the foreign matter such as the scattered toner T has adhered moves upstream (downward in the figure) of the cleaning blade 8. Then, at the timing of the completion of the movement, the separated cleaning blade 8 is pressed against the surface of the photosensitive drum 1, and thereafter the photosensitive drum 1 is rotated forward in the forward direction of arrow A.

Even in this case, since the charging roller 2 comes into contact with the portion of the photosensitive drum 1 cleaned by the cleaning blade 8, foreign matter such as toner may adhere to the surface of the charging roller 2. Disappears.

The time t2 is determined in consideration of the area where the scattered toner T or the like usually adheres to the surface of the photosensitive drum 1 and the linear velocity v (mm / sec) of the photosensitive drum 1. The rotation of the photosensitive drum 1 in both the forward and reverse directions can be easily performed by using a special stepping motor having a drive control circuit, and the control is the same as that of the control device 10 of FIG. The control is performed by the control device 20 (FIG. 4) which is a microcomputer having the configuration.

FIG. 7 shows that the surface of the charging roller is coated with toner or the like.
Further reference of the image forming device that is difficult to wear
FIG. 2 is a schematic view showing the periphery of a photoconductor drum for explaining a technique , and portions corresponding to FIG. 1 are denoted by the same reference numerals. In this image forming apparatus, the cleaning member of the cleaning device 13 is used as a cleaning blade 8 serving as a first cleaning member capable of coming into contact with and separating from the surface of the photosensitive drum 1.
The cleaning blade 8 is provided on the downstream side in the rotation direction of the photoconductor drum 1 so as to close the space between the cleaning blade 8 and the photoconductor drum 1 so that the tip is always in contact with the surface of the photoconductor drum 1. And a cleaning blade 15 serving as a second cleaning member.

According to this image forming apparatus, when the cleaning blade 8 that can be separated from the photosensitive drum 1 is separated from the photosensitive drum 1 by a solid line, the scattered toner T is exposed from between the tip of the cleaning blade 8 and the photosensitive drum 1. Even if the cleaning blade 8 leaks to the downstream side in the rotation direction of the body drum 1, the cleaning blade 15 which is always in contact with the surface of the photosensitive drum 1 is provided downstream (upper side in FIG. 7) of the cleaning blade 8. The scattered toner T does not leak downstream of the photosensitive drum 1 in the rotation direction. Therefore, FIG. 1 to FIG.
As in the respective image forming apparatuses described above, the charging roller 2 always comes into contact with the portion of the photosensitive drum 1 cleaned by the cleaning blade 15, so that the charging roller 2
No foreign matter such as toner adheres to the surface of the substrate.

Next, the results of confirmation tests actually performed to confirm the effects of each of the above image forming apparatuses will be described. First, in a test performed on the image forming apparatus according to the embodiment of FIG.
The outer diameter of the drum (a-si system) is set to 180 mm / sec, and the charging roller 2 is a conductive rubber roller having a high resistance protective layer on the roller surface, and is about 1.2 KV. The charging roller 2 and the cleaning blade 8 are separated from the surface of the photosensitive drum when the apparatus is in a stopped state by applying a voltage of 550 V to the photosensitive member potential.

When the print button is pressed and started, the cleaning blade 8 first contacts the photosensitive drum 1 according to the timing chart shown in FIG. 3, and then the photosensitive drum 1 rotates at a drum linear speed of 180 mm / sec. Is started, and t1 = 0.4 sec (L =
After the passage of 50 mm, t1>"L / v = 0.27 sec", the charging roller 2 was pressed against the photosensitive drum 1, and thereafter the surface of the photosensitive drum 1 was uniformly charged.
After the formation of three images, the presence or absence of charging unevenness due to the influence of dirt on the charging roller 2 was confirmed, and no problematic one was found.

In a test conducted in correspondence with the image forming apparatus shown in FIG. 4, a photosensitive drum 1 having the same φ80 as described above was used, the drum linear velocity was set to 120 mm / sec, and the charging roller 2 similar to the above was used. A voltage of about -1.4 KV is applied to -750
After the photoconductor potential of V was obtained, the charging roller 2 and the cleaning blade 8 were separated from the surface of the photoconductor drum 1 when the apparatus was stopped, as in the above-described confirmation test.

In this test, when the print button is started by pressing the print button, the photosensitive drum 1 is first moved in the direction of arrow B in FIG. 4 for 0.2 sec, ie, about 25 mm (L / L) according to the timing chart shown in FIG. 2) The cleaning blade 8 was pressed against the photosensitive drum 1 in the reverse direction, and at the same time, the photosensitive drum 1 was rotated forward (in the direction of arrow A in FIG. 5). After the formation of three images, the presence or absence of charging unevenness due to the influence of dirt on the charging roller 2 was confirmed, and no problematic one was found.

Further, using the image forming apparatus shown in FIG. 1 with only the cleaning device shown in FIG. 7, the photosensitive drum 1 and the charging roller 2 were tested under the same conditions as the latter of the two confirmation tests described above. As a result, when the cleaning blade 8 serving as the first cleaning member is in the separated state, the scattered toner leaking from the cleaning blade 8 is removed by the constantly contacting cleaning blade 15 serving as the second cleaning member on the downstream side. Therefore, the surface of the portion of the photosensitive drum 1 where the charging roller 2 is in contact was always kept in a cleaned state, so that no unevenness of charging due to the influence of the contamination of the charging roller was observed on the three sheets of paper on which the image was formed. .

[0034]

As described above, according to the present invention, since the charging roller always comes into contact with the portion of the photosensitive drum cleaned by the cleaning member, foreign matter such as toner adheres to the surface of the charging roller. As a result, uniform charging can be performed over the entire surface of the photosensitive drum, so that charging unevenness can be prevented.

Further, the at previous stop <br/> driving the photosensitive drum, since the cleaning member is in the separated state from the photosensitive drum, the characteristics of the pressure portion by the cleaning member is pressed constantly Even if the photoreceptor has a large characteristic change , its characteristics will not change.
It is possible to sea urchin.

[0036]

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the periphery of a photosensitive drum of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a state in which the photosensitive drum rotates and a position Poi corresponding to a cleaning blade on the surface of the photosensitive drum passes a position corresponding to the charging roller and the charging roller is pressed against the photosensitive drum; is there.

FIG. 3 is a timing chart showing the operation timing of each part of the image forming apparatus.

FIG. 4 shows that toner and the like hardly adhere to the surface of the charging roller
FIG. 2 is a schematic diagram similar to FIG. 1 but showing the periphery of a photosensitive drum for explaining a reference technique of the image forming apparatus described above .

FIG. 5 is a schematic diagram showing a state in which a cleaning blade of the image forming apparatus is in contact with a surface of a photosensitive drum.

FIG. 6 is a timing chart showing the operation timing of each unit of the image forming apparatus.

FIG. 7 shows that toner and the like hardly adhere to the surface of the charging roller
A further different reference technology of the image forming apparatus will be described.
FIG. 2 is a schematic view showing the periphery of a photoconductor drum for the sake of clarity .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Charging roller 3 Optical system (exposure means) 4 Developing device 5 Transfer roller (transfer means) 6,13 Cleaning device 7 Fur brush 8,15 Cleaning blade 10,20 Control device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-76569 (JP, A) JP-A-3-136068 (JP, A) JP-A-3-48870 (JP, A) JP-A 64-64 63989 (JP, A) JP-A-63-278087 (JP, A) JP-A-63-194364 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13/02 G03G 15 / 00 303 G03G 15/02-15/02 103 G03G 15/36 G03G 21/00 370-540 G03G 21/02-21/04 G03G 21/10-21/14 G03G 21/20

Claims (1)

(57) [Claims] 1. A photoreceptor drum and a surface of the photoreceptor drum which can be separated from the photoreceptor drum.
The charging roller provided, and the charging roller
Exposure means for exposing the exposed photoreceptor surface, and
A developing device for converting the latent image formed by
Transfer means for transferring the visible image to paper, and
After the transfer, the surface of the photosensitive drum is cleaned.
Image type provided with a cleaning device for cleaning with a member
In the production equipment,The cleaning member of the cleaning device is
In addition to being provided to be able to contact and separate from the drum, The cleaning unit being separated from the photosensitive drum
After the material is pressed against the photosensitive drum, Photoconductor drum
DriveStart rotationLetAt the start of its operation
A position corresponding to the cleaning member on the surface of the drum
Rotation until the position passes the position corresponding to the charging roller.
When the charging roller is moved from the separated stateThePhotoconductor Dora
Press againstControl deviceImage characterized by the provision of
Forming equipment.