JP3619886B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a facsimile machine, or a printing apparatus, and more specifically, collects and develops residual toner on an image carrier (photosensitive member) of the image forming apparatus. The present invention relates to an image forming apparatus including a collected toner transfer device that is reused in the apparatus.
[0002]
[Prior art]
In electrophotographic image forming apparatuses, a cleaning apparatus that removes and collects residual toner on a photoreceptor after image formation with a cleaning blade or the like has been well known in the past, but in recent years, effective use of resources has been achieved. In order to reuse the residual toner collected by the cleaning device, it is returned to the developing device by the collected toner transfer device, mixed with new toner, and again on the photoconductor. An image forming apparatus used for forming a toner image has been known.
As the above-described recovered toner transfer device, a screw pump (commonly known as MONO pump) is used as a pump capable of transferring powder with a high degree of freedom in the transfer path, and further, the recovered toner and air are removed by blowing from the air pump. For example, Japanese Patent Application No. 9-032288 discloses a technique of fluidizing and transporting in a mixed state.
[0003]
[Problems to be solved by the invention]
However, when the cleaning device removes and collects residual toner on the photoconductor after image formation, a load is applied to the collected toner by a rubber cleaning blade, a collection coil, or the like of the cleaning device. The collected toner loaded with a lot of load aggregates into a toner lump.
Further, the collected residual toner contains paper dust of transfer paper. This is because, when transferring the toner image on the photoconductor to the transfer paper, paper dust adheres on the photoconductor from the transfer paper and is removed and collected by the cleaning device together with the untransferred residual toner. .
When the above-mentioned toner lump or paper dust is transferred to the developing device by the collected toner transfer device and reused, new (regular) toner and those toner lump or paper dust are mixed in the developing device. Then, it is charged and adheres to the electrostatic latent image on the photoreceptor together with normal toner.
In the electrostatic latent image on the photoconductor, the toner lump and paper powder that became a part of the toner image together with the regular toner are removed when the transfer belt transfers the toner lump and paper powder. As a result, the toner lump portion in the solid portion becomes an abnormal image of white spots (commonly called fireflies), and the paper dust portion in the line portion becomes a beard-like abnormal image.
A proposal for removing toner lump and paper dust is also proposed in Japanese Patent Application No. 9-032288 described above, however, any of the conventional proposals requires a large additional structure.
An object of the present invention is to provide an image forming apparatus that removes the above-described toner lump and paper dust with a simple configuration in view of the above-described problems.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is an image carrier cleaning means for removing toner remaining on the image carrier after the toner image formed on the image carrier is transferred onto the transfer belt. A transfer belt cleaning unit that cleans toner remaining on the transfer belt after the image transferred to the transfer belt is transferred to transfer paper and accumulates it as a waste toner in a waste toner accumulation unit; and collects the image from the image carrier cleaning unit. In the image forming apparatus using the collected toner transfer unit for returning the toner to the developing unit and using at least a screw pump and an air pump as the collected toner transfer unit, the collected toner is transferred from the collected toner transfer unit to the developing unit. A branch path means that is divided into upper and lower parts is provided in the path, and the path to the upper side of the branch path means is the developing hand. Connected to a path to the lower side of the branch path, characterized in that connected to the waste toner storage portion of the transfer belt cleaning unit.
According to a second aspect of the present invention, the branch path means is provided at a rising portion from the collected toner transfer unit to the transfer path.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a copying machine as an example of an image forming apparatus according to the present invention.
In FIG. 1, a copying machine main body 100 reads an original image and forms an image by a known electrophotographic method based on the original image, an original reading unit 120A, an exposure unit 120B, an image forming unit 130, a paper feed. Part 140.
The original reading unit 120A includes a light source 122 for irradiating light on an original placed on the contact glass 121, an image sensor such as a CCD for reading a reflected light image from the original, and an imaging lens. 126, and mirrors 123, 124, and 125 for guiding the reflected light image from the original to the reading unit 126.
The exposure unit 120B forms an electrostatic latent image by performing light writing on the photoconductor 131 based on the image signal read by the reading unit 120A, and includes a laser light source, a rotary polygon mirror, etc. (not shown). The optical system includes a light deflector 127, a scanning imaging lens system 128 including fθ lenses, and mirror groups 129a, 129b, and 129c.
The image forming unit 130 includes a photosensitive member 131 on a drum, a charging device 132 disposed around the photosensitive member 131, a light irradiation unit from the exposure unit 120B on the photosensitive member 131, a developing device 133, a registration roller 134, and transfer / conveyance. The apparatus 600 includes a photoconductor cleaning device 200, a fixing device 135, and the like.
The paper feed unit 140 is provided with a plurality of paper feed cassettes 141, 142, and 143 that accommodate transfer papers of various sizes.
In FIG. 1, when an image forming operation is started, a document is read by the reading unit 126 of the document reading unit 120A, the photosensitive member 131 rotates in the direction of arrow A in the figure, and is charged to about −900 V by the charging device 132. The Based on the image signal read by the reading unit 126, the exposure unit 120B performs optical writing on the photoconductor 131, and an electrostatic latent image is formed on the photoconductor 131.
This electrostatic latent image is developed by a developer (two-component developer or one-component developer) of the developing device 133 to form a toner image on the photoreceptor 131.
The toner image on the photosensitive member 131 is fed from the paper feeding unit 140 and fed to the transfer position (nip portion between the photosensitive member 131 and the transfer belt 601 of the transfer / conveying device 600) via the registration roller 134. It is electrostatically transferred onto the transfer paper by the transfer / conveyance device 600.
The transfer paper onto which the toner image has been transferred is conveyed to the fixing device 135 by the transfer belt 601 of the transfer / conveyance device 600, and the toner image is fixed to the transfer paper by the fixing device 135.
The fixed transfer sheet is discharged to a discharge tray 150 outside the apparatus via a discharge roller 136. On the other hand, the photoconductor 131 after the toner image is transferred is cleaned by the photoconductor cleaning device 200, and residual toner and the like on the photoconductor 131 are removed and collected. The transfer belt after the transfer paper is conveyed is also cleaned by a cleaning device 605 in the transfer / conveyance device, and residual toner and the like on the transfer belt are removed and collected.
[0006]
FIG. 2 is a diagram showing a first embodiment of a configuration from the cleaning device to the recovered toner transfer device in the copying machine of the present invention shown in FIG.
In FIG. 2, the toner collected by the photoconductor cleaning device 200 is a toner guide unit 510 that is a part of a collected toner transfer unit 500 that engages with a collected toner discharge unit 210 provided at the lower part of the photoconductor cleaning device 200. It is transferred to. The collected toner transfer unit 500 includes at least a screw pump 520 and an air pump 532.
The toner recovered by the cleaning device 605 of the transfer belt device 600 serving as a transfer / conveyance device is transferred from a recovered toner discharge portion 610 provided on the transfer belt 600 to a transfer waste toner discharge unit that engages with the recovered toner discharge portion 610. The toner is transferred to a toner guide portion 710 which is a part of 700.
Waste toner collected from the transfer belt has a large amount of foreign matters such as paper dust and cannot be reused for image formation, and is therefore conveyed to a waste toner tank 711.
[0007]
FIG. 3 is a diagram showing a first embodiment of a configuration from the collected toner transfer device to the developing device in the copying machine of the present invention shown in FIG.
3, a portion denoted by reference numeral 110 is a rear side plate of the main body structure of the copying machine shown in FIG. 1, and includes a photoreceptor cleaning device 200, a transfer belt 600, a photoreceptor 131, a developing device 133, and the like. The collected toner transfer unit 500 and the transfer waste toner discharge unit 700 are arranged on the back side of the rear plate 110 of the copying machine main body structure. Therefore, the connection between the collected toner discharge portion 210 and the toner guide portion 510 and the connection between the collected toner discharge portion 610 and the toner guide portion 710 in FIG. 2 are performed via the rear plate 110 of the copying machine.
In order to configure the collected toner transfer unit 500, air from the air pump 532 is supplied by the air supply pipe 534, and an airflow buffer 535 is installed at the delivery end of the collected toner transfer unit 500. The collected toner transfer tube 400 extends toward the developing device 133, and is connected to a toner hopper 310 that is a part of the developing device 133 at a tube joint portion 320. The recovered toner transfer tube 400 is made of a flexible material having excellent toner resistance, such as soft vinyl chloride, nylon, silicon, or Teflon.
The waste toner collected by the transfer waste toner discharge unit 700 is discharged to a waste toner tank 711 as shown in the figure.
[0008]
FIG. 4 is a diagram showing a first embodiment of the internal configuration of the collected toner transfer device in the copying machine of the present invention shown in FIG.
In FIG. 4, a lateral conveying screw 524 is provided in the lower part in the toner guide portion 510, and the collected toner from the toner guide portion 510 is conveyed to a powder pump (screw pump) 520. Further, as the powder pump 520 of the collected toner transfer unit 500, a screw pump known as a commonly known Mono pump is used. The powder pump 520 includes a rotor 521, a stator 522, and a holder 523 for the stator 522.
The rotor 521 is coaxially connected to one end side of the lateral conveyance screw 524, and the other end portion of the lateral conveyance screw 524 is supported by a bearing 527 fixed to the support member 540 through the seal member 526, and is engaged with the clutch 528. Match.
A hopper 525 in which the lateral conveying screw 524 is disposed is supported by a support member 540 and engaged with the toner guide 510 to form a recovered toner transfer unit to the powder pump 520. The powder pump 520 is attached to the support member 540 by a holder 523 and is connected to the hopper 525 side.
When driving is transmitted from the image forming apparatus main body side via the clutch 528, the lateral conveying screw 524 and the rotor 521 rotate, and the collected toner transferred into the hopper 525 via the toner guide portion 510 is laterally transferred. It is transferred to the powder pump 520 by the conveying screw 524.
[0009]
The stateer 522 of the powder pump 520 is made of an elastic material such as a rubber material having a spiral groove formed on the inner peripheral surface, and is disposed so as to wrap around the outer periphery of the rotor 521 to form a passage of the rotor. Contact engagement. There is a gap of about 1 mm between the outer peripheral surface of the stateer 522 and the inner peripheral surface of the holder 523, and communicates with the collected toner passage (discharge unit) 530. An air supply port 531 is provided so as to blow air into the recovered toner passage 530 from the gap, and outside the air supply port 531, an air supply pipe 534 from the air pump 532 is interposed as shown in FIG. Air is supplied.
When the air pump 532 is activated, air is supplied to the collected toner through the air supply port 531 at a blowing rate of about 0.5 to 1 liter / minute. With this air, the recovered toner exiting from the recovered toner passage 530 of the powder pump 520 is promoted to fluidize and discharged together with the air flow.
When the rotor 521 of the powder pump 520 rotates, the collected toner in the collected toner transfer unit 500 advances to the collected toner passage 530 side. As shown in FIG. 4, the collected toner passage 530 is provided with an airflow buffer 535 on the outer side to be discharged (right side in FIG. 4), and a waste toner storage unit 536 is disposed below the airflow buffer 535. Is provided. The waste toner storage unit 536 is installed so as to be detachable and replaceable for maintenance. In addition, a collected toner transfer tube 400 is connected to the upper portion of the airflow buffer 535.
[0010]
The operation of the collected toner and the like transferred to the airflow buffer 535 is as follows.
The normal collected toner is transported from the toner passage 530 to the collected toner transfer tube 400 together with the air flow because its own weight is light, but the toner mixed with the toner lump or paper powder generated by the load of the cleaning device 200 or the like is Due to its heavy weight, the airflow buffer 535 descends without being put into the collected toner transfer tube 400 and accumulates in the waste toner accumulator 536.
Toner lump accumulated in the waste toner accumulation unit 536 and toner mixed with paper powder are periodically collected and discarded by a service person during maintenance of the copying apparatus.
FIG. 5 is a diagram showing a second embodiment of a configuration from the cleaning device to the collected toner transfer device in the copying machine of the present invention shown in FIG.
5 is different from the first embodiment of FIGS. 2 to 4 in that a branch path portion 635 that is bifurcated into upper and lower portions instead of the airflow buffer portion 535 in FIGS. The path that is installed first and goes upward is directed to the developing device by the collected toner transfer tube 400, but the path that goes downward is connected to the transfer waste toner discharge unit 700.
Therefore, the operation of the collected toner transferred to the branch path unit 635 is as follows.
Normal collected toner is transported from the toner path 530 to the collected toner transfer tube 400 connected to the upper path of the branch path 635 together with the air flow because its own weight is light, but is generated by the load of the cleaning device 200 and the like. Since the toner mixed with the toner lump and paper dust is heavy, it cannot go to the upper path in the branch path portion 635. As a result, the toner is not transferred into the collected toner transfer tube 400 but moved down the lower path and transferred. The waste toner enters the waste toner discharge unit 700 and is finally stored in the waste toner tank 711.
The toner lump accumulated in the waste toner tank 711 and the toner mixed with the paper powder are periodically collected and discarded by the service person during the maintenance of the copying apparatus. Therefore, as in the first embodiment, in the second embodiment as well, only good toner is reused in the developing device, and waste toner that is inappropriate for reuse is collected by periodic serviceman maintenance. Will be.
[0011]
【The invention's effect】
As described above, the image forming apparatus of the present invention is provided with the airflow buffer section or the upper and lower branch path sections in the collected toner passage. By separating the toner mixed with paper powder and the like, only the toner that is good for reuse can be sent to the developing device, and a stable image can be provided in the image forming apparatus. In addition, since the waste toner can be collected by normal periodic maintenance, an image forming apparatus that can constantly supply only a good toner for reuse to the developing device and can always provide a stable image. Can be provided.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a copying machine as an example of an image forming apparatus according to the present invention.
2 is a diagram showing a first embodiment of a configuration from a cleaning device to a collected toner transfer device in the copying machine of the present invention shown in FIG. 1; FIG.
3 is a diagram showing a first embodiment of a configuration from a collected toner transfer device to a developing device in the copying machine of the present invention shown in FIG. 1;
FIG. 4 is a diagram showing a first embodiment of an internal configuration of a collected toner transfer device in the copying machine of the present invention shown in FIG. 1;
FIG. 5 is a diagram showing a second embodiment of the configuration from the cleaning device to the collected toner transfer device in the copying machine of the present invention shown in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Copier main body, 110 ... Copier rear side plate, 120A ... Document reading part, 120B ... Exposure part, 121 ... Contact glass, 122 ... Light source, 123-125 ... Mirror, 126 ... Reading part, 127 ... Optical deflector, DESCRIPTION OF SYMBOLS 128 ... Lens system, 129a-c ... Mirror group, 130 ... Image forming part, 131 ... Photoconductor, 132 ... Charging device, 133 ... Developing device, 134 ... Registration roller, 135 ... Fixing device, 136 ... Discharge roller, 140 DESCRIPTION OF SYMBOLS ... Paper feed part, 141-143 ... Paper feed cassette, 150 ... Paper discharge tray, 200 ... Photoconductor cleaning device, 210 ... Collected toner discharge part, 310 ... Toner hopper, 320 ... Tube joint part, 400 ... Collected toner transfer tube , 500 ... Collected toner transfer unit, 510 ... Toner guide section, 520 ... Powder pump, 521 ... Rotor, 52 ... Stator, 523 ... Stator holder, 524 ... Transverse conveying screw, 525 ... Hopper, 526 ... Seal member, 527 ... Bearing, 528 ... Clutch, 530 ... Recovered toner passage, 531 ... Air supply port, 532 ... Air pump, 534 ... Air supply pipe, 535 ... Airflow buffer, 536 ... Waste toner storage, 540 ... Support member, 600 ... Transfer / conveyor, 601 ... Transfer belt, 605 ... Cleaning, 610 ... Recovered toner discharge, 635 ... Branch Path unit, 700 ... transfer waste toner discharge unit, 710 ... toner guide unit, 711 ... waste toner tank

Claims (2)

An image carrier cleaning means for removing the toner remaining on the image carrier after the toner image formed on the image carrier is transferred onto the transfer belt, and the image transferred to the transfer belt is transferred to the transfer paper A transfer belt cleaning unit that cleans toner remaining on the transfer belt later and accumulates it in a waste toner accumulation unit as waste toner, and a recovery toner transfer unit that returns the toner collected from the image carrier cleaning unit to the development unit In the image forming apparatus using at least a screw pump and an air pump as the recovered toner transfer unit, a branch path means that is divided into upper and lower parts is provided in a transfer path of the recovered toner from the recovered toner transfer unit to the developing means, and the branch path The path to the upper side of the means is connected to the developing means, and the path to the lower side of the branch path is the An image forming apparatus characterized by connecting to the waste toner storage portion of the shooting belt cleaning unit. The image forming apparatus according to claim 1, wherein the branch path unit is provided at a rising portion from the collected toner transfer unit to the transfer path.

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