JP2007140025A - Image forming apparatus and scattered toner collecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus where scattered toner is collected with simple constitution and restrained from being discharged to the outside, and a scattered toner collecting method. <P>SOLUTION: A scattered toner collecting film 4 is changeably connected to a power source 5 and a ground, and provided with a cleaning blade 11 to remove unnecessary toner stuck to an image carrier 2. When collecting the scattered toner, bias voltage is applied to the scattered toner collecting film 4 from the power source 5, and also re-electrification voltage is applied to the image carrier by an electrifying means, so that the scattered toner collected by the scattered toner collecting film 4 is discharged to the image carrier. The scattered toner 14 discharged to the image carrier is collected by the cleaning blade 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and a scattered toner collecting method that collects scattered toner with a simple configuration and reduces discharge to the outside.

  In general, an electrophotographic toner image forming unit includes a photosensitive member as an image bearing member having a photosensitive layer on an outer peripheral surface, a charging unit that uniformly charges the outer peripheral surface of the photosensitive member, and a uniform charging unit using the charging unit. An exposure unit that selectively exposes the outer peripheral surface charged to form an electrostatic latent image, and a toner as a developer is applied to the electrostatic latent image formed by the exposure unit to form a visible image ( Developing means for forming a toner image).

  In such an image forming apparatus, the toner may be scattered from the developing unit and contaminate the inside and outside of the image forming apparatus due to the stirring and conveyance of the toner by the developing unit. For this reason, as described in Patent Document 1 and Patent Document 2, a scattered toner collecting roller for collecting scattered toner is provided in the vicinity of the developing unit so that the toner is not scattered from the developing unit. The toner collected by the scattered toner collecting roller is scraped off by the blade.

JP-A-10-339998 Japanese Patent Laid-Open No. 10-3220

  In the prior art described in Patent Document 1 and Patent Document 2, a dedicated toner scraping blade is provided on the scattered toner collecting roller. In this type of image forming apparatus, a cleaning blade for scraping off the remaining toner is provided in order to prevent the image quality from being deteriorated by the toner remaining on the photosensitive member as the image carrier. Therefore, a blade for scraping off unnecessary toner is provided on each of the photosensitive member and the scattered toner collecting roller, and a plurality of blades are required. For this reason, there existed a problem that a structure became complicated and cost increased.

  SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide an image forming apparatus and a scattered toner collecting method that collect scattered toner with a simple configuration and reduce discharge to the outside. It is to provide.

  An image forming apparatus of the present invention that achieves the above object is an image forming apparatus in which charging units, exposure units, developing units, and transfer unit units for image formation are arranged around an image carrier, A scattering toner collecting film that is switched to be connected to a power source and a ground and a cleaning unit for unnecessary toner attached to the image carrier are provided, and when the scattering toner cleaning mode after image formation is set by the control unit, A bias voltage is applied to the toner collecting film from the power source, and a recharging voltage is applied to the image carrier by the charging means, and the scattered toner collected on the scattered toner collecting film is discharged to the image carrier. The scattered toner discharged to the image carrier is collected by the cleaning means. According to such a configuration, since the film is used as the scattered toner collecting means, the scattered toner can be collected with a simple configuration. In addition, the positive and negative polarity scattered toner adhering to the scattered toner collecting film is discharged to the image carrier by electrical control, and is provided to scrape unnecessary toner originally remaining on the image carrier. Since the scattered toner is also collected by the cleaning means, the cleaning means can be effectively used. Further, the scattered toner collecting film does not require a toner scraping blade, which simplifies the configuration and reduces the cost.

  In the image forming apparatus of the present invention, the power source connected to the scattered toner collecting film is a power source that generates a DC voltage. According to such a configuration, the configuration of the power supply can be simplified.

The image forming apparatus of the present invention is characterized in that the image carrier and the developing unit are arranged apart from each other and perform development processing in a non-contact manner. According to such a configuration,
In a non-contact developing type image forming apparatus, scattered toner can be effectively collected by a cleaning means.

  In the image forming apparatus of the present invention, the image forming apparatus is a color image forming apparatus, and the scattered toner for each color is individually collected. According to such a configuration, in a color image forming apparatus using multiple colors such as three colors or four colors, scattered toner can be collected in each color while avoiding color mixing.

The scattered toner collecting method of the present invention includes an image forming station in which image forming units including a charging unit, an exposure unit, a developing unit, and a transfer unit are arranged around an image carrier, and the transfer medium is the image medium. Forming an image by passing through a forming station;
In the scattered toner cleaning mode after image formation,
A step of applying a bias voltage to the scattered toner collecting film, a step of applying a recharge voltage to the image carrier, and discharging the scattered toner collected on the scattered toner collecting film to the image carrier; And a step of collecting the scattered toner discharged to the carrier by a cleaning means. According to such a configuration, the scattered toner can be collected with high accuracy by electrical control using an existing apparatus.

  According to the present invention, the following special effects can be obtained. (1) The positive and negative polarity scattered toner adhering to the scattered toner collecting film is discharged to the image carrier by electrical control, and is provided to scrape unnecessary toner remaining on the image carrier. Since the scattered toner is also collected by the cleaning means, the cleaning means can be effectively used. (2) Since a film is used as a means for collecting scattered toner, the scattered toner can be collected with a simple configuration. (3) The scattering toner collecting film does not require a toner scraping blade, and the configuration is simplified and the cost can be reduced. (4) Since no mechanical pressing force is applied to the scattered toner collecting film by the blade, deformation and damage of the scattered toner collecting means can be prevented. (5) Since the collected scattered toner can be reused for image formation, it is possible to effectively use toner resources. (6) Since the scattered toner is collected inside the apparatus and discharge of the scattered toner to the outside is reduced, an environment-friendly image forming apparatus and a scattered toner collecting method can be provided.

  Next, an embodiment of the present invention will be described with reference to the explanatory diagrams shown in FIGS. FIG. 2 partially illustrates the image forming apparatus 1 and is an explanatory diagram of a process of collecting the scattered toner with the scattered toner collection film. In FIG. 2, 2 is a photosensitive drum (image carrier), 4 is a scattered toner collecting film electrically connected to a power source 5 and a switch 6, and 7 is provided in the developing device 3 and is electrically connected to the power source 9. A developing roller 8 is connected to the toner supply roller 8.

  Reference numeral 13 denotes scattered toner scattered around the developing device 3 and the photosensitive drum 2, and a black circle is a negatively charged toner having a negative polarity and a white circle is a positively charged toner having a positive polarity. The switch 6 is released from the power source 5 and the scattered toner collecting film 4 is connected to the ground. At this time, both the positive and negative polarity toners of the negatively charged toner and the positively charged toner are sucked into the scattered toner collecting film 4. The example of FIG. 2 shows a non-contact type image forming apparatus in which development is performed with the photosensitive drum 2 and the developing roller 7 being separated from each other.

  FIG. 3 is an explanatory diagram of a process for discharging (discharging) the toner collected on the scattered toner collecting film 4 in FIG. 2 to the photosensitive drum 2. At this time, control is performed by switching the potential of the photosensitive drum 2 between Va (−900 V) and Vb (0 V) by charging means (not shown). Va and Vb correspond to recharging voltages applied to the photosensitive drum 2 when the cleaning mode is set by the control unit after image formation. Further, the switch 6 is connected to the power source 5, and a bias voltage of (DC−600 V), for example, is applied to the scattered toner collecting film 4. Details of voltage control of the photosensitive drum 2 and voltage control of the scattered toner collection film 4 will be described later with reference to a timing chart of FIG.

  When the potential of the photosensitive drum 2 is Va, positively charged toner indicated by white circles collected on the scattered toner collecting film 4 is discharged to the photosensitive drum 2. That is, since the photosensitive drum 2 has a negative potential, positively charged toner having a potential opposite to that of the photosensitive drum 2 is discharged to the photosensitive drum 2. When the potential of the photosensitive drum 2 is Vb, negatively charged toner indicated by a black circle is discharged to the photosensitive drum 2.

  In this example, since a film-like member is used as the scattered toner collecting means, a simple configuration can be achieved. The scattered toner collecting means may be configured to use a roller in addition to a configuration using a film-like member. After completion of the printing process, unnecessary toner remains on the photosensitive drum 2, but this unnecessary toner is collected by the cleaning means together with the scattered toner.

  FIG. 1 is an explanatory diagram of a process for collecting the scattered toner discharged to the photosensitive drum 2 with a cleaning blade. In FIG. 1, reference numeral 10 denotes charging means using, for example, a corona charger. The scattered toner collecting film 4 is opened from the power source 5 by switching a switch. A cleaning blade 11 provided in the toner recovery case 12 scrapes off unnecessary toner remaining on the photosensitive drum 2 after the printing process. Reference numeral 16 denotes recovered toner.

  In the present invention, the scattered toner discharged to the photosensitive drum 2 as shown in FIG. The collected scattered toner is accommodated in the toner collecting case 12 and can be reused during image formation. As described above, the scattered toner 14 discharged to the photosensitive drum 2 is also collected by the existing cleaning blade 11 provided to scrape off unnecessary toner originally remaining on the photosensitive drum 2. Effective use of the blade 11 can be achieved.

FIG. 4 is a timing chart showing the processing process of the present invention over time. In this image forming apparatus, the applied voltage values are shown roughly.
A period from time ta to tb indicates a change in the photoreceptor (OPC) potential due to exposure during image formation. The initial potential is −500 V, the exposure potential is 0 V, and when the exposure potential is 0 V, an image is formed on the photosensitive drum.

  A period from time tc to td is a period for applying a developing bias, and a developing bias of direct current (DC) −200 V + alternating current (AC) 2 kV is applied to the developing roller 7. At this time, a developing process is performed and scattered toner is generated. The image formation end time tb of the photosensitive drum 2 and the development end time td of the developing roller 7 are set to the same time.

  During the period from time te to tf, the bias of the scattered toner collecting film 4 is off (GND), and the scattered toner is collected by the scattered toner collecting film 4. After the elapse of time tb, a cleaning mode is set by a control device (not shown), and the process proceeds to a cleaning process after the image forming process (discharge of scattered toner to the photosensitive drum 2).

  The period from time tb to tg is a period in which the photoreceptor (OPC) potential is 0V. A DC-600 V bias voltage is applied to the scattered toner collecting film 4 at time ti within this period. The period from time ti to tj is a period in which the photosensitive drum 2 is rotated one or more times. During this period, negatively charged toner is discharged to the photosensitive drum 2. Therefore, the negatively charged toner adhering to the scattered toner collecting film 4 is dispersed and discharged on the surface of the photosensitive drum 2.

  The period from time tg to th is a period in which the photosensitive member (OPC) potential is recharged to −900V. This period is a period in which the reversely charged toner is collected on the photosensitive drum 2, and a DC-600 V bias voltage is continuously applied to the scattered toner collecting film 4. The period from time tj to tk is a period in which the photosensitive drum 2 is rotated one or more times. During this period, the reversely charged toner collected on the scattered toner collecting film 4 is discharged to the photosensitive drum 2.

  In this way, after the scattered toner having positive and negative polarities is discharged onto the photosensitive drum 2, the scattered toner is collected by the cleaning blade 11 as described with reference to FIG. In the example of FIG. 4, the cleaning mode of the scattered toner is set by the control device, and the recharging of the photosensitive drum 2 and the bias voltage application of the scattered toner collecting roller 4 are controlled in sequence. As the cleaning means for the scattered toner, a brush roller type can be used in addition to the cleaning blade.

  In the embodiment of the present invention, the positive and negative polarity scattered toner adhering to the scattered toner collecting film 4 is discharged to the photosensitive drum 2 by electrical control, and unnecessary toner originally remaining on the photosensitive drum 2 is removed. The scattered toner is also collected by the cleaning blade 11 provided for scraping. For this reason, the cleaning blade 11 can be effectively used. Further, since the scattered toner collecting film 4 does not require a toner scraping blade and only one cleaning blade 11 provided on the photosensitive drum 2 is used, the configuration can be simplified and the cost can be reduced. .

  Further, since no mechanical pressing force is applied to the scattered toner collecting film 4 by the blade, deformation and damage of the scattered toner collecting film 4 can be prevented. Since the collected scattered toner can be reused for image formation, it is possible to effectively use toner resources. As described above, in the embodiment of the present invention, the scattered toner is collected inside the apparatus, and the discharge of the scattered toner to the outside is reduced, and an environment-friendly image forming apparatus can be obtained.

  The image forming apparatus according to the present invention is intended for a configuration in which image forming units of a charging unit, an exposure unit, a developing unit, and a transfer unit are arranged around an image carrier. This image forming apparatus may be of a monochrome format or a color image forming system. In the case of a color image forming system, for example, it is configured as a tandem image forming apparatus. In this case, a scattered toner collecting film is provided in each color image forming unit, and the scattered toner is discharged from the scattered toner collecting film onto the photosensitive drum. Then, the scattered toner is scraped off from the photosensitive drum of each color with a cleaning blade. According to such a configuration, in a color image forming apparatus using multiple colors such as three colors or four colors, scattered toner can be collected in each color while avoiding color mixing. Next, a tandem image forming apparatus will be described with reference to a longitudinal sectional view of FIG.

  The tandem color printer (image forming apparatus) exposes four photoconductors as shown in the cross-sectional view of FIG. 5 with four line heads to form four color images at the same time, thereby forming one endless intermediate transfer belt ( Intermediate transfer medium). In this image forming apparatus, exposure apparatuses 101K, 101C, 101M, and 101Y having the same configuration are placed at the exposure positions of four corresponding photosensitive drums (image carriers) 41K, 41C, 41M, and 41Y. Each is arranged. The exposure apparatuses 101K, 101C, 101M, and 101Y are composed of line heads using light emitting elements such as LEDs or organic EL elements as light sources. A scanning optical system that scans with laser light may be used as the exposure apparatus.

  The image forming apparatus is provided with a driving roller 51, a driven roller 52, and a tension roller 53. The intermediate roller is tensioned by the tension roller 53 and is circulated and driven in the direction indicated by the arrow (counterclockwise). A transfer belt (intermediate transfer medium) 50 is provided. Photosensitive members 41K, 41C, 41M, and 41Y having photosensitive layers are arranged on the outer peripheral surface as four image carriers arranged at predetermined intervals with respect to the intermediate transfer belt 50.

  K, C, M, and Y added after the reference sign mean black, cyan, magenta, and yellow, respectively, and indicate that the photoconductors are black, cyan, magenta, and yellow, respectively. The same applies to other members. The photoreceptors 41K, 41C, 41M, and 41Y are rotationally driven in the direction indicated by the arrow (clockwise) in synchronization with the driving of the intermediate transfer belt 50. Around each photoconductor 41 (K, C, M, Y), charging means (corona charger) 42 (K) for uniformly charging the outer peripheral surface of the photoconductor 41 (K, C, M, Y), respectively. , C, M, Y) and the outer peripheral surface uniformly charged by the charging means 42 (K, C, M, Y) are synchronized with the rotation of the photoconductor 41 (K, C, M, Y). An exposure apparatus (line head) 101 (K, C, M, Y) that sequentially scans lines is provided.

  In addition, a developing device 44 (K, C, and Y) that forms a visible image (toner image) by adding toner as a developer to the electrostatic latent image formed by the exposure device 101 (K, C, M, and Y). M, Y) and a primary transfer roller 45 (K, Y) as transfer means for sequentially transferring the toner image developed by the developing device 44 (K, C, M, Y) to the intermediate transfer belt 50 as a primary transfer target. C, M, Y) and a cleaning device 46 (K, C, M, Y) as a cleaning means for removing the toner remaining on the surface of the photoreceptor 41 (K, C, M, Y) after being transferred. ).

  The developing device 44 (K, C, M, Y) uses, for example, a non-magnetic one-component toner as a developer, and the one-component developer is conveyed to the developing roller by a supply roller, for example, and adheres to the surface of the developing roller. The film thickness of the developed developer is regulated by a regulating blade, and the developing roller is brought into contact with or pressed against the photoreceptor 41 (K, C, M, Y), whereby the photoreceptor 41 (K, C, M, Y) The toner image is developed by attaching a developer according to the potential level.

  The black, cyan, magenta, and yellow toner images formed by the four-color single-color toner image forming station are intermediated by the primary transfer bias applied to the primary transfer roller 45 (K, C, M, Y). Primary transfer is sequentially performed on the transfer belt 50, and is sequentially superimposed on the intermediate transfer belt 50 to form a full color. The full-color toner image is secondarily transferred to the recording medium P such as paper by the secondary transfer roller 66, and is fixed on the recording medium P by passing through the fixing roller pair 61 that is a fixing unit. The sheet 62 is discharged onto a sheet discharge tray 68 formed at the upper part of the apparatus.

  In FIG. 5, 63 is a paper feed cassette in which a large number of recording media P are stacked and held, 64 is a pickup roller for feeding recording media P from the paper feed cassette 63 one by one, and 65 is a secondary transfer roller. 66, a pair of gate rollers for defining the supply timing of the recording medium P to the secondary transfer portion 66; a secondary transfer roller 66 as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 50; Is a cleaning blade as a cleaning means for removing the toner remaining on the surface of the intermediate transfer belt 50 after the secondary transfer.

  As described above, the image forming apparatus and the scattered toner collecting method of the present invention have been described based on the principle and the embodiments. However, the present invention is not limited to these embodiments and can be variously modified.

It is a schematic explanatory view showing an embodiment of the present invention. It is a schematic explanatory view showing an embodiment of the present invention. It is a schematic explanatory view showing an embodiment of the present invention. It is a timing chart which shows embodiment of this invention. 1 is a schematic cross-sectional view showing an overall configuration of one embodiment of an image forming apparatus using an electrophotographic process applied to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Photosensitive drum (image carrier), 3 ... Developing device, 4 ... Scattering toner collection film, 5 ... Power supply of scattering toner collection roller, 6. ..Power supply 5 switch, 7 ... developing roller, 8 ... toner supply roller, 9 ... developing roller power supply, 10 ... charging means (corona charger), 11 ... cleaning blade, 12 ... Toner collection case, 13 ... Scatter toner, 14 ... Discharged toner, 16 ... Collected toner

Claims (5)

An image forming apparatus in which image forming units including a charging unit, an exposure unit, a developing unit, and a transfer unit are arranged around an image carrier, and a scattered toner collecting film that is switched and connected to a power source and a ground. A cleaning unit for cleaning unnecessary toner adhering to the image carrier, and a bias voltage is applied to the scattered toner collecting film from the power source when the control unit sets a scattered toner cleaning mode after image formation. The recharging voltage is applied to the image carrier by the charging means, the scattered toner collected on the scattered toner collecting film is discharged to the image carrier, and the scattered toner discharged to the image carrier is An image forming apparatus, wherein the image is collected by a cleaning unit. The image forming apparatus according to claim 1, wherein a power source connected to the scattered toner collecting film is a power source that generates a DC voltage. The image forming apparatus according to claim 1, wherein the image bearing member and the developing unit are spaced apart from each other and perform development processing in a non-contact manner. The image forming apparatus according to claim 1, wherein the image forming apparatus is a color image forming apparatus and individually collects scattered toner for each color. An image forming station in which image forming units including a charging unit, an exposure unit, a developing unit, and a transfer unit are arranged around the image carrier is provided, and the transfer medium passes through the image forming station to form an image A process of performing
In the scattered toner cleaning mode after image formation,
A step of applying a bias voltage to the scattered toner collecting film, a step of applying a recharge voltage to the image carrier, and discharging the scattered toner collected on the scattered toner collecting film to the image carrier; A step of collecting the scattered toner discharged to the carrier with a cleaning means;
A method for collecting scattered toner, comprising:

Images