JPH01136168A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the grime of a visible image after replacement and image quality deterioration due to defective cleaning by separating a cleaning member from a latent image carrier and stopping the latent image carrier after its surface facing the cleaning member passes through a developing member. CONSTITUTION:When a copying machine stops its operation, a pressure cam 31 is rotated about 180 deg. by an operating device before a photosensitive body 7 stops its rotation. By virture of the action of a spring 30, a cleaning unit 21 tuns clockwise, centered about a pin 25a, and a cleaning brade 22 is separated from the photosensitive body 7. Since it keeps rotating, toner and paper dust banks arising when the brade 22 abutted on the photosensitive body 7 turn together with the body 7, and are recovered by the scraping force of a developing roller 14 in a developing unit 12. Thus, even if toner and paper dust banks are produced on the surface of the latent image carrier on which the cleaning member abuts do not cause the turbidness of a visible image and image quality deterioration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a developing unit for visualizing an electrostatic latent image formed on a latent image carrier that is driven once, and for transferring the visible image to a transfer material. and a cleaning unit that cleans toner remaining on the latent image carrier after being transferred to the latent image carrier, and at least a developing unit and a cleaning unit are integrally assembled and configured as a process kit that can be separated from the latent image carrier. Regarding equipment.

Image forming apparatuses of the above type configured as electronic copying machines, printers, facsimile machines, etc. are conventionally known. In this image forming apparatus, when one or both of the process kit and the latent image carrier, which are integrally assembled with at least a developing unit and a cleaning unit, reach the end of their service life, they can be replaced separately. can.

Furthermore, the color of the developer in the developing unit can be changed by replacing the previously used process kit with another process kit while the latent image carrier is attached.

An image forming apparatus is also known in which a developing unit, a cleaning unit, and a latent image carrier are integrally assembled to form a process kit, and the process kit is detachably attached to the apparatus main body so that the entire kit can be replaced. In Although,
For example, it consists of a photoreceptor. G The image carrier usually has a longer lifespan than the developing unit and cleaning unit, so if you configure these two kings to be replaced together, you will be able to replace the latent image carrier even if it has not reached the end of its lifespan. First, when a developing unit or a cleaning unit reaches the end of its life, even the latent image carrier that can still be used must be discarded, resulting in economic loss. In this regard, in the image forming apparatus of the type described at the beginning, the latent image carrier and the process kit can be replaced separately, so that the above-mentioned economic loss can be prevented from occurring. However, recent studies have revealed that this type of image forming apparatus has the following problems.

The cleaning unit has a cleaning member, such as a cleaning blade or a cleaning web, that comes into contact with the surface of the latent image carrier and removes the toner remaining on the surface. Toner, paper dust, etc. tend to accumulate on the surface. Even if such accumulation occurs, when the image forming apparatus is used normally, the accumulated toner and paper dust may leave the cleaning member and reach the developing unit or transfer material, causing it to get mixed into the unit. , it does not adhere to the transfer material, and no particular problem occurs. However, when the process kit is separated from the latent image carrier and removed from the main body of the apparatus in order to replace only the process kit while the above-mentioned accumulation is still formed.

A pool of toner or the like remains on the surface of the latent image carrier.

In this state, attach another process kit to the device body,
At the same time as assembling this onto the latent image carrier.

When the latent image carrier is driven, accumulated toner and paper dust may move to the developing unit of a new process kit and become mixed into the developing unit. At this time, if the color of the developer contained in the developing unit of the newly installed process kit is different from the color of the developer contained in the previously used developing unit, use the new developing unit separately. The toner of this color will be mixed in, and there is a risk that the color of the visible image that will be formed thereafter will become cloudy. Furthermore, even if the color of the developer in the process kit is the same before and after replacement, if there is a buildup of toner or fiber paper on the latent image carrier, it may cause background stains or poor cleaning of the visible image formed thereafter. There is also a risk that image quality may deteriorate based on the image quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an imaging device of the type mentioned at the outset, which eliminates the drawbacks of the prior art mentioned above.

In order to achieve the above object, the present invention is provided with a separating means for separating the cleaning member of the cleaning unit from the latent image carrier when the operation of the image forming apparatus is stopped, and facing the cleaning member at the time of separation. A configuration is proposed in which the operation of the latent image carrier is stopped after the surface portion of the latent image carrier passes a developing member of a developing unit.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an example of an electronic copying machine, and in order to understand the present invention, the overall structure thereof will first be explained.

As shown in FIG. 2, the main body of this copying machine is divided into a lower structure 1 and a main structure 2, and the main structure 2 is pivotally connected to the lower structure 1 via a pin 3. ing. Normally, the main structure 2 is positioned overlapping the lower structure 1, as shown in FIG.

The contact glass 4 is placed on the upper part of the main structure 2 in a horizontal direction (
It is supported so as to be able to reciprocate in the left-right direction in FIG. Further, the shafts 8, 8a of the drum-shaped photoreceptor 7 are attached to the respective supporting members 6, 6a fixedly installed on the back side and the front side of the lower structure 1.
are rotatably supported, and the photoreceptor 7 is rotationally driven by a drive device (not shown). The drum-shaped photoreceptor 7 is an example of a latent image carrier, and in addition to such a photoreceptor, a belt-shaped photoreceptor can also be used.
Depending on the type of image forming apparatus, a dielectric drum, a dielectric belt, or the like may be used.

The copying operation is performed in the state shown in FIG. 1. During the operation, the contact glass 4 moves horizontally, and at this time, the document is illuminated by a light source (not shown) provided on the upper structure 2, and the reflected light is emitted from the document. The light passes through a converging light transmitting body 9 also attached to the upper structure 2, reaches the photoreceptor 7 which is rotationally driven in a clockwise direction, and forms an original image on the surface thereof. Since the surface of the photoreceptor is previously charged to a predetermined polarity by the charger 11, an electrostatic latent image corresponding to the original image is formed on the photoreceptor by the exposure, and when this latent image passes through the developing unit 12, Visualized by toner.

The developing unit 12 shown as an example in the figure includes a developing case 13 that stores toner, a developing roller 14 that is rotatably supported by the case, and a supply roller 15 that supplies toner to the roller 14.

The developing roller 14 is rotated, for example, in a counterclockwise direction, and the toner supplied to the roller 14 is conveyed by the rotation of the roller 14, and after the layer thickness is regulated by a regulating blade 16, it is transferred to a developing area facing the photoreceptor 7. The electrostatic latent image is visualized as described above. The developing roller 14 is an example of a developing member. In the illustrated example, the developing roller 14 is in pressure contact with the photoreceptor 7, but this roller can also be positioned close to the photoreceptor 7 without contacting it. A developing member made of a belt may be used instead of the developing roller 14. In addition to using a one-component developer as in this example as the developer stored in the developing case 14, a two-component developer containing toner and carrier may be used.

On the other hand, a transfer material made of transfer paper is fed to the photoreceptor 4 from the paper feed cassette 17 attached to the lower structure 1, and the lower structure 1
A visible image on the photoreceptor is transferred to transfer paper by a transfer charger 18 supported by the transfer charger 18 .

After the transfer process, the transfer paper passes through a fixing device 19, where the visible image is fixed, and is discharged to a paper discharge tray 20.

Toner remaining on the surface of the photoreceptor after the visible image has been transferred is scraped off by the cleaning blade 22 of the cleaning unit 21, and on the other hand, the surface of the photoreceptor is subjected to a static eliminating action by a static eliminator (not shown).

The toner scraped off by the blade 22 is stored in a cleaning case 23. The cleaning blade 22 is an example of a cleaning member that comes into pressure contact with the surface of the photoreceptor 7 to remove residual toner.

Instead of the blade 22, for example, a cleaning member made of a web in contact with the photoreceptor may be used.

The above-mentioned developing unit 12 and cleaning unit 21
constitutes an integrally assembled process unit 24, and in the illustrated example, both units 12, 21 are rotatably connected to each other by connecting bins 25, 25a provided on the back side and the front side. The two are thus integrated. The process kit 24 can be separated from the photoreceptor 7 as described below. Also process kit 24
is a combination of at least a developing unit and a cleaning unit, and may also include other image forming process means. In the illustrated example, the charger 11 is also assembled integrally with the process kit 24.

The process kit 24 is detachably supported by the upper structure 2, and in the illustrated example, the pins 25, 25a are attached to the upper structure 2.
It is removably supported by a side plate 26 on the back side and a side plate (not shown) on the front side of the machine frame.

In addition, the side plate 26 on the back side and the side plate on the front side of the upper structure 2 have
Lock levers 27, 27a are each pivotally supported, and a connecting rod 28 is pivotally attached to these levers 27, 27a, respectively.
, 28a extend to the right in the figure, and their tips are pivotally connected to operating levers 29, which are connected to the upper structure 2.
It is rotatably supported on side plates 26 at the front and rear sides.

As described above, the upper structure 2 normally assumes the attitude shown in FIG. Axis 8, 8
It is engaged with a. Further, at this time, the cleaning unit 21 and the developing unit 12 are biased in a direction in which they open from each other, that is, in a direction away from the photoreceptor 7, by a tension spring 30 that is locked at each end thereof. However, the developing unit 12 is held at the position shown in FIG. 1 by a stopper or positioning member (not shown), and at this time, the cleaning unit 21 is held by a pressure cam 31 rotatably supported on the side plate of the soil structure 2. The cleaning blade 22 is pressed against the surface of the photoreceptor. In this way, each unit 12.21 can perform its respective function as described above.

When the developing unit 12 runs out of toner or the cleaning unit 21 is full of collected toner, it is necessary to replace the process kit 24 with a new one.

Furthermore, when the photoreceptor 7 reaches the end of its life, it must be replaced with a new one. Also, when a visible image is to be formed using toner of a different color from the toner of the developing unit that was previously used, it is necessary to replace the process kit 24 with a kit that includes the developing unit 1- of toner of a different color. .

When performing the above-described replacement work, the operating lever 29 is pulled to the right in FIG. 1 to separate the lock levers 27, 27a from the shafts 8, 8a of the photoreceptor 7.

Next, by lifting the earth structure 2 upward, the structure 2
rotates as shown in FIG. At this time, since the photoreceptor 7 remains in the lower ditch body 1, the process kit 24 supported by the soil structure 2 is separated from the photoreceptor 7. By lifting the earth structure 2 and separating the kit 24 and the photoreceptor 7 in this way, the kit 24 or the photoreceptor 7 can be removed from the earth structure 2 or the bottom groove body 1, and these can be replaced separately. Can be done. Therefore, there is no economic loss that would occur if the process kit was configured to include the photoreceptor 7.

After installing a new process kit or photoreceptor, the soil structure 2 is lowered, and the kit and photoreceptor can be reassembled as shown in FIG.

By the way, when the copying machine is set in the state shown in FIG. 1 and the copying operation is being performed as described above, the cleaning blade 22
It is unavoidable that some amount of toner or paper powder accumulates at the tip of the photoreceptor 7 that contacts the photoreceptor 7.

Even if such an accumulation occurs, no problem will occur during normal use of the copying machine. However, as explained earlier, if the soil structure 2 is lifted as described above and the cleaning blade 22 is separated from the photoreceptor 7 while this puddle is still formed, the soil structure 2 remains supported by the Shimozo body 1. A puddle is left on the photoreceptor 7. Next, in this state, only the process kit 24 is replaced, and the soil structure 2 is replaced with the first one.
When returning to the state shown in the figure and assembling a new kit to the photoreceptor 7 and driving the photoreceptor 7 to rotate and restarting the copying operation, the pool on the photoreceptor also rotates together with the photoreceptor 7, and this is transferred to the transfer paper. There is a risk that it will stick and cause background stains.

To be more specific, when the copying operation is resumed with the toner accumulated, the charger 11 is turned on, and the photoreceptor 7 is exposed, the accumulated toner is removed by the charger 11.
The toner is charged to a polarity opposite to that of the toner in the developing unit 12 (temporarily assumed to be negative).

This moves to the developing roller 14, but at this time, since a bias voltage of the same negative polarity as the above-mentioned negative polarity is normally applied to the developing roller 14, all of the toner on the photoreceptor 7 is transferred to the developing roller 14. Some of the toner passes through the roller 14 and adheres to the transfer paper. Furthermore, if the toner contained in the developing unit of the kit before replacement is different in color from the toner of the new kit, the toner in the pool may mix into the developing unit containing toner of a different color. If such a situation occurs, the colors of the primary visible image formed will become cloudy due to the color mixing of the toners.

Therefore, in the copying machine according to the present invention, when stopping the operation of the copying machine, before the photoreceptor 7 stops rotating, the pressure cam 31 is activated by an actuating device (not shown) as indicated by the solid line in FIG. Approximately 180″ from the position shown by the chain line
It is configured to be rotated. When the pressure cam 31 rotates in this manner, the cleaning unit 21 rotates slightly clockwise about the pin 25 due to the action of the spring 3o, and the cleaning blade 22 separates from the photoreceptor 7. At this time, since the photoconductor 7 continues to rotate, the toner and paper dust accumulated when the blade 22 was in contact with the photoconductor 7 also rotates with the photoconductor 7, and the developing roller 14 of the developing unit 12 However, at this time, the developing roller 14 also continues to rotate, so that the above-mentioned accumulation is collected by the scraping force of the developing roller 14. That is, the toner and paper powder accumulated on the surface of the photoreceptor are cleaned by the developing roller 14. Furthermore, when a pool of toner or paper dust passes under the charger 11, the charger 11 is inactive. Therefore, the toner in the pool is not charged by the charger 11 to the opposite polarity to the toner in the developing unit 12, and therefore, when the toner on the photoreceptor 7 reaches the developing roller rough, it is biased to the opposite polarity. It is also electrostatically collected by the developing roller 14 to which a voltage is applied. In this way, the toner and paper powder accumulated on the photoreceptor 7 are collected in the developing unit, but after such cleaning is completed, the photoreceptor 7 and the developing roller 1
4 will stop rotating, and the entire copying machine will stop operating. In this state, if the earth structure 2 is lifted and the process kit 24 is replaced as described above, the toner and paper powder will no longer accumulate, so the above-mentioned problem will not occur. It goes without saying that before restarting the developing operation, the pressure cam 31 is rotated to the position shown by the solid line in FIG. 1 to bring the cleaning blade 22 into pressure contact with the photoreceptor 7.

In this example, the above-mentioned pressure cam 31 constitutes a separating means for separating the cleaning blade 22 of the cleaning unit from the photoreceptor 7 when stopping the operation of the copying machine,
After the surface portion of the photoreceptor that was facing the cleaning blade 22 at the time of separation, that is, the accumulation of toner and paper dust, passes through the developing roller 14 of the developing unit, the operation of the photoreceptor 7 is stopped.

By the way, as described above, the mode in which the photoreceptor 7 is stopped after the cleaning blade 22 is separated from the photoreceptor 7 is referred to as the stop mode. You can do this every time the copying machine stops, regardless of whether or not you lift it.However, if you execute this mode every time the copying operation stops, the toner and paper powder buildup will be removed from the developing unit. Since the toner is collected in the case 13, paper dust and collected toner gradually become mixed into the toner contained in the case 13. Furthermore, in general, the amount of charge between the toner originally stored in the developing case 13 and the toner used to visualize the latent image is different, and the polarity of the charge is different. Since the toner may be reversed, a difference occurs in the amount of charge and the polarity between the toner collected in the developing case 13 and the toner originally stored there.

Variations may occur in the charging state of the toner inside the case 13. Therefore, if a large amount of toner and paper powder are collected in the developing case 13, the resulting visible image is likely to deteriorate in quality, such as background stains.

Therefore, it is desirable to configure the above-mentioned stop mode to be executed only when the operation of the copying machine is stopped in a state where the lifespan of the process kit 24 has been detected. That is, the toner runs out in the developing case 13 of the developing unit 12,
Furthermore, when the cleaning case of the cleaning unit 21 is full of collected toner, it is usually configured to detect this, inform the operator of the lifespan of the process kit, and prompt the operator to replace it. In conjunction with the life detection means of such a process kit, only when stopping the operation of the copying machine while the life is detected,
The above-mentioned stop mode is executed. In this way, while the above-mentioned effects can be obtained when replacing the process kit, it is also possible to prevent the problem of toner and paper powder being collected in the developing case 13 at times other than when the process kit is replaced. When replacing the previously used process kit with a new one and discarding the old one, no inconvenience will occur even if paper dust or the like is collected in the developing unit.

Also, when replacing the process kit to change the toner color, the copying machine is equipped with a color change instruction means such as a color change button, so that the operator can immediately press the button before replacing the process unit. Operate the change button to execute the above-mentioned stop mode. That is, when stopping the operation of the copying machine after the button is operated, the cleaning blade 22 is separated from the photoreceptor 7, and the photoreceptor is stopped after the toner and paper dust accumulated in the developing unit 12 is collected. be.

FIG. 3 shows an example of a configuration in which only the cleaning blade of the cleaning unit, rather than the entire cleaning unit, approaches and separates from the photoreceptor. For reference, the overall structure will be described. In this embodiment as well, the cleaning unit 21, the developing unit 12', and the charger 11 constitute a process kit 24, which is detachably attached to the holder 40. Retained. In this example, the cleaning unit 21 and the developing unit 12 may be integrally and immovably connected. Alternatively, as in the previous embodiment, both may be pivotably connected to each other. The holder 40 has a pivot pin 41
When the upper and lower structures are set overlapping each other as shown in Fig. 1,
The process kit 24 is assembled to the photoreceptor 7 and performs a copying operation in the same manner as in the previous embodiment. The holder 40 is positioned and held in the position shown in FIG. 3 by positioning means (not shown).

The holder 40 can also be pivoted to the main structure.

Cleaning blade 22 of cleaning unit 21
In this case as well, the blade 22 comes into pressure contact with the photoconductor 7 and serves to scrape off the residual toner.
The blade 22 is fixed to the support plate 50 and is slidably mounted on the support plate 50 below the blade 22. The support plate 42 supports the compression spring 4
3, the blade 22 is pressed to the right in the figure, thereby bringing the blade 22 into pressure contact with the photoreceptor 7.

When performing the same stop mode as in the previous embodiment, the pressurizing cam 31, which had been at the position shown by the solid line, is rotated by an actuating means (not shown) to the position U shown by the chain line, so that the cam 31 is supported. Press the plate 42 to the left in the figure. As a result, the support plate 42 moves to the left in the figure together with the blade 22, and the blade 22 separates from the photoreceptor 7. After that, as in the previous embodiment, after the toner and paper dust pools are collected in the developing unit 12, the photoreceptor 7 and the developing roller 14 stop rotating. Thereafter, the main structure is opened, the holder 40 is rotated counterclockwise, the kit 24 and the photoreceptor 7 are separated, and the kid can be replaced.

As described above, in the embodiment shown in FIG. 3, only the cleaning blade, not the entire cleaning unit, is moved toward and away from the photoreceptor 7 by the pressure cam 31.

In each of the illustrated embodiments, the pressure cam 31 constitutes the spacing means, but it is clear that the spacing means can also be constituted by other suitable devices. It goes without saying that the present invention can also be applied to various image forming apparatuses other than copying machines.

According to the present invention, even if toner or paper dust accumulates on the surface portion of the latent image carrier with which the cleaning member comes into contact, it is possible to prevent this from causing clouding of the visible image and deterioration of the image quality.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a copying machine to which the present invention is applied;
FIG. 2 is a cross-sectional view showing the main structure in an open state, taken at the front side of FIG. 1, and FIG. 3 is a cross-sectional view showing another embodiment. 12...Developing unit 21...Cleaning unit 24...Process kit

Claims (1)

[Scope of Claims] A developing unit for visualizing an electrostatic latent image formed on a rotationally driven latent image carrier, and a developing unit for visualizing an electrostatic latent image formed on a rotationally driven latent image carrier; In an image forming apparatus configured as a process kit that can be separated from a latent image carrier by integrally assembling at least a developing unit and a cleaning unit, the image forming apparatus is equipped with a cleaning unit for cleaning residual toner, and the operation of the image forming apparatus is controlled. When stopping, a separating means is provided to separate the cleaning member of the cleaning unit from the latent image carrier, and after the surface portion of the latent image carrier that was facing the cleaning member at the time of separation passes the developing member of the developing unit, the latent image carrier is separated from the latent image carrier. An image forming apparatus characterized in that the operation of an image carrier is stopped.