JP2000047483A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently suck a scattered toner without pulluting a machine body and to form a good image by providing a developer sucking device having a sucking wind velocity controller for changing the sucking velocity in a development state and in a nondevelopment state on a developing device. SOLUTION: This device 100 is provided with a developer feed roller 3a feeding a developer to a developing roller 1, a stirring roller 3b, a slit 5 provided below the developing roller 1 as a suction port, a sucking duct 4 provided below a developer casing 7 from the slit 5, and a sucking device having a toner filter 14, an ozone filter 13 and a sucking fan 12 provided in sequence at the end section of the sucking duct 4. The motor of the sucking fan 12 and a motor drive circuit are connected to a controller controlling the voltages impressed to various sections. When the fan voltage impressed to the sucking fan 12 is controlled, the sucking wind velocity is changed in a development state and in a nondevelopment state.

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 used for electrophotography, electrostatic recording, and the like.

[0002]

2. Description of the Related Art For example, in an electrophotographic apparatus having a developing device including a two-component developer using a developer comprising a toner and a carrier and a magnetic roll, the inside of the apparatus is contaminated by scattered toner generated from the developing device. In some cases, it caused serious quality problems. In order to solve this problem, a technique has been devised in which a suction duct is provided below the outside of the developing device casing to capture scattered toner and prevent toner contamination in the apparatus.

However, in such a suction method, scattered toner generated from the developing pole can be efficiently sucked. However, during the half-side copying operation, the toner other than the scattered toner is sucked at a constant wind speed. There is a problem in that the toner is sucked from above the magnetic roll, thereby deteriorating the toner consumption and shortening the life of the toner suction filter.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in an image forming apparatus provided with a toner suction device, efficiently removes scattered toner without sucking toner other than scattered toner. It is an object of the present invention to provide an image forming apparatus that can form a good image by suction and without fouling.

[0005]

An image forming apparatus according to the present invention is provided so as to face an image carrier, and is provided to face the image carrier. The image carrier carries a developer and supplies the developer to the image carrier. Developing device having a developer carrying member for performing development by using a developing device, a suction port provided below the developer carrying member, a discharge passage for discharging the sucked developer, and a developer via the discharge passage. Suction means for sucking, and connected to the suction means,
A developer suction device having a suction air speed control unit for changing a suction speed between a developing state and a non-developing state is provided.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention comprises a developing device and a toner suction device connected to the developing device for sucking scattered toner generated during development. A suction port provided below the developer carrier, a discharge path for discharging the sucked developer, a suction unit for suctioning the developer through the discharge path, and a suction unit connected to the suction unit. It has a suction wind speed control unit for changing the speed between the developing state and the non-developing state.

[0007] Toner scattering mainly occurs when the image carrier operates, for example, when the photosensitive drum rotates. The photoreceptor drum rotates not only in the developing state but also in a non-developing state before and after the developing state, for example, when the laser rises, and between paper feeds, ie, between papers.

In view of the above, according to the present invention, the suction means of the toner suction device controls the suction air velocity in the developing state and
A suction air speed control unit capable of changing the suction air speed in the non-development state is provided to control so as to increase the suction air velocity in the development state and decrease the suction air velocity in the non-development state. Thereby, it is possible to prevent toner other than the scattered toner from being sucked.

[0009]

The present invention will be described below in detail with reference to examples. FIG. 1 is a schematic view showing an example of a developing device with a suction device used in the present invention.

As shown in FIG. 1, the apparatus 100 includes an image carrier 10, a pair of registration rollers 9 for conveying a recording sheet to the image carrier 10, and a developing device provided to face the image carrier 10. Roller 1, a developer supply roller 3a for supplying a developer to the development roller 1, a stirring roller 3b for stirring the developer before being sent to the developer supply roller 3a, And a suction duct 4 provided from the slit 5 to a lower portion of the developer caging 7.
A suction device having a toner filter 14, an ozone filter 13, and a suction fan 12 provided in order at an end is provided. A motor and a motor driving circuit of the suction fan 12 control a voltage application to each member. This control unit controls the voltage applied to the motor. In such an apparatus, the scattered toner is generated by the following mechanism.

The mixers 3a and 3 in the developing device case shown in FIG.
b circulates the developer sufficiently stirred by the magnetic roll 1
Supplied to The magnetic roll has a plurality of magnetic poles having different polarities inside for forming a developer on a magnetic brush, transporting the developer to a developing position, and collecting the developer after development in the developing device casing 7. At the position of the magnetic pole, the magnetic brush rises and behaves between the magnetic poles. The most scattered toner is generated when the magnetic brush collides with the photoreceptor at the developing unit case and the developing point at the position of the magnetic pole where the ears rise. In particular, a large amount of toner is generated in the developing pole 2a and the downstream transport pole 2b, and the toner is accumulated at the position of the full length C below the magnetic roll of the developing device casing.

For this reason, a method is used in which the suction duct 4 having a uniform opening width is provided over the entire length of the magnetic roll, and the scattering toner is suctioned. As shown in FIG. 1, the toner accumulated at the position C is sucked by the suction force of the rotating suction fan 12, sent to the suction duct 4 from the slit 5, and captured by the toner filter 14. The exhaust is performed through an ozone filter 13.

In this device, the suction wind speed can be changed by controlling the fan voltage applied to the fan as the suction means. For example, when the laser rises, a signal for lowering the motor drive voltage is sent from the control unit, and the suction wind speed of the control suction fan 12 is reduced. When the registration roller 9 detects the leading edge of the recording paper, development is performed on the image carrier, and a signal for increasing the motor drive voltage of the suction fan 12 is sent from the control unit. Increases to a predetermined speed. Next, when the registration roller 9 detects the trailing edge of the recording paper, a signal for lowering the motor drive voltage is sent from the control unit, the suction wind speed of the control suction fan 12 decreases, and the registration roller 9 is moved to the next position. Until the leading edge of the paper is detected, that is, between the papers, the suction wind speed is kept low.

The image developed on the image carrier 10 is then transferred to a recording sheet and fixed by a fixing device (not shown). FIG. 2 is a graph showing the state of voltage application to each member of the main motor, the charging member, the laser, the developing bias, and the registration roller in the printing operation, and the corresponding changes in the fan voltage with time. In the drawing, the leading edge and the trailing edge of the paper in the graph of the registration roller indicate the time when the leading edge of the recording paper passes through the registration roller and the time when the trailing edge of the recording paper passes, respectively. As shown, in the in-motor, the print button is pressed, the photosensitive drum starts rotating, and a portion where the drum rotates in a non-developed state due to the rise of the laser until, for example, two types of images are printed, and a copy. And a portion where the drum rotates in a non-developed state depending on the paper interval between copies.

Accordingly, in the present invention, as shown in FIG.
In the non-development state compared to the development state, the intensity of the voltage applied to the motor of the suction fan is changed to be low, and the suction speed is changed to control so as to suck the minimum necessary toner. This realizes a reduction in toner consumption and an increase in filter life.

FIG. 3 shows the amount of scattered toner generated when 8000 copies are made at a printing rate of 0%, and the amount of scattered toner generated when 8000 copies are made at a printing rate of 8%. Is shown. In the figure, each graph 301 has a printing rate of 8%,
Reference numeral 302 denotes a case where the printing rate is 0%. When a copy is made at a print rate of 8%, the amount of scattered toner is about three times as large as when a copy is made at a print rate of 0%.

FIG. 4 is a graph showing the relationship between the amount of suction toner and the fan voltage. In the drawing, a graph 401 indicates a developed state, and 402 indicates a non-developed state. From FIG. 3, the amount of scattered toner in the non-image area is about 1/3 of the amount of scattered toner in the image area. If this is applied to FIG. 14V is appropriate for the fan voltage.

Thus, in the toner suction device used in the present invention, as shown in FIG. 2, when the main motor is OFF (A), the fan OFF (0 V) print button is pressed, and from the main motor drive to the registration ON (B). ) By controlling the motor of the toner suction device so that the fan voltage is 14 V and the fan voltage is 24 V from the ON to OFF (C) of the resist, only the minimum necessary toner can be sucked.

FIG. 5 is a schematic view showing an example of an image forming apparatus according to the present invention to which the above-described developing device is applied. In the figure, reference numeral 10 denotes a photosensitive drum which is provided rotatably in the direction of the arrow and carries an image. In the peripheral portion of the photosensitive drum, a charging charger 20, an exposing unit 22, a developing device 100, a transfer / peeling charger 23, a cleaning device 24, and a static elimination charger 21 are sequentially provided in the rotation direction. Is formed.

Further, on the lower side of the developing device 100,
A pair of aligning rollers 211 for aligning the sheet is provided, and a guide body 212 for guiding the sheet is provided between the pair of aligning rollers 211 and the photosensitive drum 10.

Further, below the cleaning device 24, a transport belt 213 for transporting the paper is provided. A fixing device 26 including a heating roller and a pressure roller is provided below the conveyor belt 213.

The developing device 100 has a slit 5 as a suction port provided thereunder, a suction duct 4 provided from the slit 5 to a portion below the developer caging 7, and a suction duct 4 to a rear surface of the developing device 100. On the side, a suction device having a toner filter, an ozone filter, and a suction fan (not shown) which are sequentially provided are connected.

When an image is formed, an original is set on the original glass, and the original is irradiated with light from an exposure lamp (not shown). The reflected light from the document is imaged as an exposure unit 22 on the peripheral surface of the photosensitive drum 10 via the optical system 25. The surface of the photosensitive drum 10 is charged in advance by the charging charger 20, and an electrostatic latent image of the document is formed by the image formation. This electrostatic latent image is sent to the developing device 100 by the rotation of the photosensitive drum 10,
Here, when the developer is supplied, the image is visualized.

On the other hand, at this time, paper is supplied from the paper supply cassette 29, and the paper is supplied to the aligning roller pair 2
After being aligned by 11, the toner image is transferred to the photosensitive drum 10 and transferred by the peeling charger 23, then peeled from the photosensitive drum 201, and transported by the travel of the transport belt 213. This sheet is sent to the fixing device 26, where the transferred image is fixed and discharged.

Next, the printing operation of the digital PPC will be described.
Is rotated at a speed of 189 m / s by a motor (not shown), and at the same time, the surface of the photosensitive drum is charged to a predetermined voltage by the charging device 20. Subsequently, image information to be recorded on the surface of the photosensitive drum by the laser exposure device 27,
That is, an electrostatic latent image is formed for the image of the document or the image signal supplied from the host device. The electrostatic latent image thus formed is developed by the toner T supplied from the magnetic roll 28, and the toner on the photoconductor is transferred to the paper by the transfer device 23. The sheet on which the toner T has been transferred is discharged to the outside of the copying apparatus via the fixing device 26.

FIG. 6 shows a sheet passing test when a sheet passing test was performed on an image forming apparatus provided with a developer suction device having a suction wind speed controller according to the present invention and an image forming apparatus not provided with the developer suction device. FIG. 4 is a graph showing the relationship between the number of sheets and the toner scattering level. In the drawing, a graph 601 shows a case where the suction wind speed control is performed, and a graph 602 shows a case where the suction wind speed control is not performed. As shown in the figure, it was found that the life can be extended by 80 k sheets when the image formation is performed by performing the suction wind speed control as compared with the image formation without performing the suction wind speed control.

FIG. 7 shows a sheet passing test when a sheet passing test is performed on an image forming apparatus provided with a developer suction device having a suction wind speed controller according to the present invention and an image forming apparatus not provided with a developer suction device. FIG. 3 is a graph showing the relationship between the number of sheets and the toner consumption. In the drawing, a graph 701 shows a case where the suction wind speed control is performed, and a graph 702 shows a case where the suction wind speed control is not performed. As shown in the drawing, it was found that when the image formation was performed by performing the suction air velocity control, the consumption amount was reduced by about 2 mg per sheet as compared with the image formation without performing the suction air velocity control.

[0028]

According to the image forming apparatus of the present invention, by providing a developer suction device having a suction wind speed control unit,
The scattered toner can be efficiently sucked without sucking the toner other than the scattered toner, and a good image can be formed without machine body contamination.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a developing device with a suction device used in the present invention.

FIG. 2 is a graph showing a state of voltage application and a change in fan voltage over time.

FIG. 3 is a graph showing the amount of scattered toner generated by printing 8,000 sheets.

FIG. 4 is a graph showing a relationship between a suctioned toner amount and a fan voltage.

FIG. 5 is a schematic view illustrating an example of an image forming apparatus according to the present invention.

FIG. 6 is a graph showing the relationship between the number of sheets passed and the toner scattering level.

FIG. 7 is a graph showing the relationship between the number of passed sheets and the amount of consumed toner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magnetic roll 3a ... Mixer in a developing device case 3b ... Mixer in a developing device case 4 ... Suction duct 5 ... Slit 7 ... Developing device casing 9 ... Registration roller 10 ... Image carrier 12 ... Suction fan 13 ... Ozone filter 14 ... Toner Filter 22 Exposure unit 23 Transfer / peel charger 24 Cleaning device 26 Fixer 27 Exposure device 100 Developing device 200 Image forming device

Claims (2)

[Claims] An image bearing member is provided opposite to the image bearing member, carries a developer, and has a developer carrying member for supplying a developer to the image bearing member and performing development. A device, a suction port provided below the developer carrier, a discharge path for discharging the suctioned developer, a suction unit for suctioning the developer through the discharge path, and the suction unit And a developer suction device having a suction air speed control unit for changing a suction speed between a developing state and a non-developing state. 2. The image forming apparatus according to claim 1, wherein the suction wind speed control unit controls a voltage applied to a suction unit.