JP6638206B2 - Image forming apparatus and image forming system - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming system.

  2. Description of the Related Art Generally, an image forming apparatus (a printer, a copying machine, a facsimile, etc.) using an electrophotographic process technology irradiates (exposes) a charged photosensitive body with a laser beam based on image data to form an electrostatic latent image. Form. Then, toner is supplied from the developing device to the photoconductor on which the electrostatic latent image is formed, thereby visualizing the electrostatic latent image to form a toner image. Further, after the toner image is directly or indirectly transferred to a sheet, the image is formed on the sheet by fixing the sheet by heating and pressing.

  The image forming apparatus is provided with a charging device for uniformly charging the surface of the photoconductor to negative polarity. In this charging device, a discharge product generated in the band electrode accommodating portion may adhere to the surface of the photoreceptor, causing an image defect such as an image flow (an image with an unclear image contour). As a measure for preventing an image defect caused by a discharge product adhering to the surface of a photoreceptor, many methods have been devised for discharging a discharge product generated in a band electrode accommodating portion by gas. Among them, an image having a mechanism in which gas is sucked in by suction means provided in a part of the band electrode accommodating portion, and discharge products are discharged out of the apparatus (outside the image forming apparatus) by exhaust means provided in another part. There is a forming device.

  FIG. 1 is a diagram illustrating a photosensitive drum 413 and a band electrode housing 320 of such an image forming apparatus. In the figure, the band electrode housing section 320 is arranged along the axial direction of the photosensitive drum 413. The band electrode housing section 320 houses the band electrode 321 and the grid 322, and has an opening on the photosensitive drum 413 side. The band electrode accommodating section 320 is provided with an intake section 330 having an intake duct 330A and an intake fan 330B for taking in air into the band electrode accommodating section 320 at one end, and from the band electrode accommodating section 320 at the other end. An exhaust unit 340 having an exhaust duct 340A for exhausting air to the outside of the apparatus (outside the image forming apparatus) and an exhaust fan 340B is provided. The band electrode accommodating section 320 sucks air in the suction section 330 and discharges discharge products in the exhaust section 340. The arrows in the figure indicate the flow of airflow, and the air sucked in by the suction unit 330 flows toward the exhaust unit 340 along the image forming area 413A of the photoconductor drum 413, and the non-production of the photoconductor drum 413. It flows in the direction of the image area 413B. The air flowing along the image forming area 413A toward the exhaust unit 340 is exhausted by the exhaust unit 340 together with the air around the non-image forming area 413C of the photosensitive drum 413. The air collected by the exhaust fan 340B of the exhaust unit 340 is discharged to the outside through an ozone filter (not shown).

  The image forming apparatus described in Patent Document 1 has the same configuration as the above-described image forming apparatus. That is, air is fed in the longitudinal direction of the band electrode accommodating portion by the intake fan, and the sent air is discharged by the exhaust fan. In particular, in the image forming apparatus described in Patent Literature 1, the intake air velocity is set to be higher than the exhaust air velocity.

  Note that there is a technique described in Patent Document 2, for example, in which a flow of air is generated not by a fan but by a difference in air pressure. That is, the relationship between the pressure A in the shield of the corona discharger, the pressure B in the space inside the duct disposed around the corona discharge, and the pressure C in the space outside the duct is such that A> B> C when the image carrier rotates. Set.

JP 2008-076777 A JP 2003-241484 A

  However, in the image generating apparatus shown in FIG. 1, when the ratio of the intake air flow rate into the band electrode accommodating section 320 and the exhaust air flow rate from the band electrode accommodating section 320 is such that the intake air volume <the exhaust air flow rate, the inside of the band electrode accommodating section 320 Dirt such as toner and dust is sucked, and an image defect occurs. Conversely, similarly to the image forming apparatus described in Patent Document 1, when the exhaust air volume is smaller than the intake air volume, suction of dirt such as toner and dust can be prevented, but since the exhaust capability is reduced, discharge generation is reduced. The object cannot be efficiently exhausted, and the discharge product leaks out of the gap between the charging accommodating section 320 and the photoconductor drum 413 to deteriorate the seal member (not shown) in the apparatus (image forming apparatus). Problems such as odor will occur. FIG. 2 is a sectional view taken along line BB of FIG. As shown in the drawing, when the intake air volume is larger than the exhaust air volume, discharge products that cannot be exhausted from the gap GP between the charging housing 320 and the photosensitive drum 413 leak out of the charging housing 320. .

  In the technique described in Patent Literature 2, dirt is not sucked into the band electrode accommodating portion due to the relationship of A> B, but discharge products leak from the duct to the outside of the duct due to the relationship of B> C.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus and an image forming system capable of discharging a discharge product to the outside of a device without leaking to the outside of a band electrode accommodating portion in a charging device.

The image forming apparatus according to the present invention includes:
A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position different from the gas outlet of the band electrode housing portion and at a position deviating from the first region in the axial direction of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The gas inlet is provided at a central portion in the longitudinal direction of the band electrode housing portion extending along the axial direction of the photoconductor,
The gas outlets are provided at both ends in the longitudinal direction of the band electrode housing.
Further, the image forming apparatus according to the present invention,
A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position different from the gas outlet of the band electrode housing portion and at a position deviating from the first region in the axial direction of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The gas outlet is provided in a gap between both ends of the band electrode accommodating portion in the rotation direction of the photoconductor and the photoconductor.
Further, the image forming apparatus according to the present invention,
A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position different from the gas outlet of the band electrode housing portion and at a position deviating from the first region in the axial direction of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
A seal member that closes a gap between both end portions of the band electrode housing portion in the rotation direction of the photoconductor and the image forming area of the photoconductor,
Having.
Further, the image forming apparatus according to the present invention,
A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position deviating from the first region in the axial direction of the photoconductor in the band electrode housing portion and including a region outside an end of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The gas outlet and the preliminary opening are provided at positions corresponding to each other in a direction orthogonal to the axis of the photoconductor, and at different positions on a plane orthogonal to the axis of the photoconductor.

The image forming system according to the present invention includes:
An image forming system including a plurality of units including an image forming apparatus,
A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position different from the gas outlet of the band electrode housing portion and at a position deviating from the first region in the axial direction of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The gas inlet is provided at a central portion in the longitudinal direction of the band electrode housing portion extending along the axial direction of the photoconductor,
The gas outlets are provided at both ends in the longitudinal direction of the band electrode housing.
Further, the image forming system according to the present invention,
An image forming system including a plurality of units including an image forming apparatus,
A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position deviating from the first region in the axial direction of the photoconductor in the band electrode housing portion and including a region outside an end of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The gas outlet and the preliminary opening are provided at positions corresponding to each other in a direction orthogonal to the axis of the photoconductor, and at different positions on a plane orthogonal to the axis of the photoconductor.

  ADVANTAGE OF THE INVENTION According to this invention, in a charging device, a discharge product can be discharged | emitted out of a machine, without leaking outside a belt electrode accommodating part.

FIG. 10 is a diagram illustrating a photoconductor and a band electrode accommodating portion of a conventional image forming apparatus. FIG. 2 is a sectional view taken along line BB of the image forming apparatus of FIG. 1. FIG. 1 is a diagram schematically illustrating an entire configuration of an image forming apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a main part of a control system of the image forming apparatus according to the embodiment. FIG. 5 is a diagram illustrating an arrangement relationship between a band electrode accommodating portion and a photosensitive drum according to the embodiment. FIG. 4 is a diagram illustrating a positional relationship between a first region and a second region in the embodiment. It is XX sectional drawing of FIG. FIG. 6 is a cross-sectional view taken along line YY and ZZ of FIG. 5. FIG. 3 is a diagram showing a flow of gas in the embodiment. It is a figure which shows the flow of gas in embodiment seen from another angle. FIG. 9 is a diagram illustrating a modification of the configuration of the charging device of the embodiment. 5 is a graph showing the results of an experiment for confirming the effectiveness of the present invention in terms of the ozone concentration of a gas. It is a graph which shows the result of the experiment which confirms the effectiveness of the present invention from a viewpoint of wind speed. 9 is a graph showing the results of an experiment for confirming the effectiveness of the present invention from the viewpoint of image unevenness rank.

Hereinafter, the present embodiment will be described in detail with reference to the drawings.
FIG. 3 is a diagram schematically illustrating an overall configuration of the image forming apparatus 1 according to the embodiment of the present invention. FIG. 4 is a block diagram showing a main part of a control system of image forming apparatus 1 according to the present embodiment. The image forming apparatus 1 shown in FIGS. 3 and 4 is an intermediate transfer type color image forming apparatus using an electrophotographic process technology. That is, the image forming apparatus 1 transfers the Y (yellow), M (magenta), C (cyan), and K (black) color toner images formed on the photosensitive drum 413 to an intermediate transfer belt (first transfer member). The image is formed by transferring (primary transfer) to the sheet 421, superimposing toner images of four colors on the intermediate transfer belt 421, and then transferring (secondarily transferring) the sheet S.

  In the image forming apparatus 1, the photosensitive drums 413 corresponding to the four colors of YMCK are arranged in series in the running direction of the intermediate transfer belt 421, and the respective color toner images are sequentially transferred to the intermediate transfer belt 421 in one procedure. The tandem system is adopted.

  As shown in FIG. 4, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a sheet conveying unit 50, a fixing unit 60, a storage unit 70, a communication unit 80, The control unit includes an intake fan driving unit 90, an exhaust fan driving unit 91, and a control unit 100.

  The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads out a program corresponding to the processing content from the ROM 102 and develops the program on the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the developed program. At this time, various data stored in the storage unit 70 are referred to. The storage unit 70 is composed of, for example, a nonvolatile semiconductor memory (a so-called flash memory) or a hard disk drive.

  The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) and a WAN (Wide Area Network) via the communication unit 80. Do. The control unit 100 acquires data (input image data) of an image to be printed on the paper S, and forms an image on the paper S based on the acquired input image data. The control unit 100 acquires input image data by receiving, for example, image data transmitted from an external device.

  The communication unit 80 is configured by a communication control card such as a LAN card. As shown in FIG. 3, the image reading unit 10 includes an automatic document feeder 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like. The automatic document feeder 11 transports the document D placed on the document tray by a transport mechanism and sends it out to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of a large number of documents D placed on a document tray at once.

  The document image scanning device 12 optically scans a document conveyed from the automatic document feeder 11 onto the contact glass or a document placed on the contact glass, and reflects reflected light from the document into a CCD (Charge Coupled Device). 3.) Form an image on the light receiving surface of the sensor 12a and read the original image. The image reading unit 10 generates input image data based on a result of reading by the document image scanning device 12. The input image data is subjected to predetermined image processing in the image processing unit 30.

  The operation display unit 20 is configured by, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image status display, operation status of each function, and the like according to a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by a user, and outputs an operation signal to the control unit 100.

  The image processing unit 30 includes a circuit that performs digital image processing on input image data according to initial settings or user settings. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, compression process, and the like, on the input image data, in addition to gradation correction. The image forming unit 40 is controlled based on the input image data on which these processes have been performed.

  The image forming unit 40 includes an image forming unit 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image using each color toner of the Y component, the M component, the C component, and the K component based on the input image data. Etc. are provided. The image forming units 41Y, 41M, 41C, and 41K for the Y, M, C, and K components have the same configuration. For the sake of convenience in illustration and description, common constituent elements are denoted by the same reference numerals, and when they are distinguished from each other, Y, M, C, or K is added to the reference numerals. In FIG. 3, only the components of the image forming unit 41Y for the Y component are denoted by reference numerals, and the reference numerals of the other components of the image forming units 41M, 41C, and 41K are omitted.

  The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413, a charging device 414, a drum cleaning device 415, and the like. The photoconductor drum 413 has, for example, an undercoat layer (UCL: Under Coat Layer) and a charge generation layer (CGL: Charge) on the peripheral surface of an aluminum conductive cylinder (aluminum tube) having a drum diameter of 80 [mm]. It is a negatively charged organic photoconductor (OPC: Organic Photo-conductor) in which a Generation Layer (CTL) and a charge transport layer (CTL) are sequentially stacked. The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, a phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and generates a pair of positive and negative charges by exposure with the exposure device 411. The charge transport layer is formed by dispersing a hole transport material (an electron donating nitrogen-containing compound) in a resin binder (for example, a polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. I do.

  The control unit 100 controls a drive current supplied to a drive motor (not shown) for rotating the photosensitive drum 413, so that the photosensitive drum 413 rotates at a constant peripheral speed.

  The charging device 414 uniformly charges the surface of the photoconductive drum 413 having photoconductivity to a negative polarity. Although the details will be described later, the charging device 414 has a structure capable of discharging the discharge product to the outside of the apparatus (outside the apparatus: outside the image forming apparatus 1) without leaking out of the band electrode. The exposure device 411 includes, for example, a semiconductor laser, and irradiates the photosensitive drum 413 with laser light corresponding to an image of each color component. Positive charges are generated in the charge generation layer of the photoconductor drum 413 and transported to the surface of the charge transport layer, thereby neutralizing surface charges (negative charges) of the photoconductor drum 413. An electrostatic latent image of each color component is formed on the surface of the photosensitive drum 413 due to a potential difference from the surroundings.

  The developing device 412 is, for example, a two-component developing type developing device, and visualizes an electrostatic latent image by adhering toner of each color component (oil-less toner containing wax in toner particles) on the surface of the photosensitive drum 413. To form a toner image. The drum cleaning device 415 has a drum cleaning blade or the like that slides on the surface of the photoconductor drum 413, and removes transfer residual toner remaining on the surface of the photoconductor drum 413 after the primary transfer.

  The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like. The intermediate transfer belt 421 is formed of an endless belt, and is stretched around a plurality of support rollers 423 in a loop shape. At least one of the plurality of support rollers 423 is configured by a driving roller, and the other is configured by a driven roller. For example, it is preferable that the roller 423A disposed downstream of the primary transfer roller 422 for the K component in the belt traveling direction is a driving roller. This makes it easier to keep the running speed of the belt at the primary transfer unit constant. As the driving roller 423A rotates, the intermediate transfer belt 421 runs at a constant speed in the direction of arrow A.

  The primary transfer roller 422 is disposed on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photosensitive drum 413 of each color component. The primary transfer roller 422 is pressed against the photosensitive drum 413 with the intermediate transfer belt 421 interposed therebetween, thereby forming a primary transfer nip for transferring a toner image from the photosensitive drum 413 to the intermediate transfer belt 421.

  The secondary transfer roller 424 is disposed on the outer peripheral surface side of the intermediate transfer belt 421 so as to face a roller 423B (hereinafter referred to as “backup roller 423B”) disposed downstream of the drive roller 423A in the belt traveling direction. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 interposed therebetween, thereby forming a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the sheet S.

  When the intermediate transfer belt 421 passes through the primary transfer nip, the toner images on the photosensitive drums 413 are sequentially superimposed on the intermediate transfer belt 421 and primary-transferred. Specifically, by applying a primary transfer bias to the primary transfer roller 422 and applying a charge having a polarity opposite to that of the toner to the back side of the intermediate transfer belt 421 (the side in contact with the primary transfer roller 422), the toner image is formed. The image is electrostatically transferred to the intermediate transfer belt 421.

  Thereafter, when the sheet S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the sheet S. More specifically, a secondary transfer bias is applied to the secondary transfer roller 424 to apply a charge having a polarity opposite to that of the toner to the back side of the sheet S (the side in contact with the secondary transfer roller 424), thereby forming a toner image. Is electrostatically transferred to the sheet S. The sheet S to which the toner image has been transferred is conveyed toward the fixing unit 60.

  The belt cleaning unit 426 has a belt cleaning blade or the like that slides on the surface of the intermediate transfer belt 421, and removes transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer. Note that, instead of the secondary transfer roller 424, a configuration in which a secondary transfer belt is stretched in a loop shape over a plurality of support rollers including the secondary transfer roller (a so-called belt-type secondary transfer unit) is employed. Is also good.

  The fixing unit 60 includes an upper fixing unit 60 </ b> A having a fixing surface side member disposed on a surface (fixing surface) of the sheet S on which the toner image is formed, and a rear surface (opposite to the fixing surface) of the sheet S. A lower fixing unit 60B having a back side supporting member to be disposed, a heating source 60C, and the like are provided. A fixing nip for nipping and transporting the sheet S is formed by pressing the back surface side support member against the fixing surface side member. The fixing unit 60 fixes the toner image on the sheet S by heating and pressing the sheet S, on which the toner image is secondarily transferred and conveyed, by the fixing nip. The fixing unit 60 is disposed as a unit in the fixing device F. Note that the fixing unit 60 and the control unit 100 function as a fixing device.

  The upper fixing section 60A includes an endless fixing belt 61, a heating roller 62, an upper pressing roller 63, and a stretching member 64, which are members on the fixing surface side (belt heating method). The fixing belt 61 is stretched by a predetermined belt tension (for example, 400 [N]) around a heating roller 62, an upper pressure roller 63, and a stretching member 64 (tension roller). The fixing belt 61 forms a fixing nip together with the lower pressure roller 65.

  The fixing belt 61 contacts the sheet S on which the toner image is formed, and heat-fixes the toner image to the sheet S at a fixing temperature (for example, 160 to 200 ° C.). Here, the fixing temperature is a temperature capable of supplying an amount of heat necessary to melt the toner on the sheet S, and differs depending on the type of the sheet S on which an image is formed. The heating roller 62 heats the fixing belt 61. The heating roller 62 has a built-in heating source 60C (halogen heater) for heating the fixing belt 61. The temperature of the heating source 60C is controlled by the control unit 100. The heating roller 62 is heated by the heating source 60C, and as a result, the fixing belt 61 is heated.

  The upper pressure roller 63 is pressed through a fixing belt 61 to a lower pressure roller 65 driven and rotated by a main drive source (not shown) in the fixing unit 60. The lower fixing unit 60B includes, for example, a lower pressure roller 65 that is a back-side support member (roller pressure method). The control unit 100 controls the main drive source (drive motor) to rotate the lower pressure roller 65 in a counterclockwise direction. The drive control of the drive motor (for example, rotation on / off, peripheral speed, and the like) is performed by the control unit 100. The lower pressure roller 65 has a built-in heating source (not shown) such as a halogen heater. When the heating source generates heat, the lower pressure roller 65 is heated. The control unit 100 controls the power supplied to the heating source to control the lower pressure roller 65 to a predetermined temperature (for example, 80 to 120 [° C.]).

  The lower pressure roller 65 is pressed against the upper pressure roller 63 via the fixing belt 61 with a predetermined fixing load (for example, 2650 [N]). In this way, a fixing nip for nipping and transporting the sheet S is formed between the fixing belt 61 and the lower pressure roller 65. When the lower pressure roller 65 is driven to rotate, the fixing belt 61 is driven to rotate clockwise. Accordingly, the upper pressure roller 63 is driven to rotate clockwise. Further, the tension member 64 is driven to rotate clockwise.

  The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a transport path unit 53, and the like. In the three paper feed tray units 51a to 51c constituting the paper feed unit 51, paper S (standard paper, special paper) identified based on the basis weight, size, or the like is stored for each preset type. . The transport path unit 53 has a plurality of transport roller pairs such as a pair of registration rollers 53a.

  The sheets S stored in the sheet feed tray units 51 a to 51 c are sent out one by one from the uppermost portion, and are conveyed to the image forming unit 40 by the conveying path unit 53. At this time, the inclination of the fed sheet S is corrected by the registration roller unit provided with the registration roller pair 53a, and the transport timing is adjusted. Then, in the image forming unit 40, the toner image on the intermediate transfer belt 421 is collectively and secondarily transferred onto one surface of the sheet S, and the fixing unit 60 performs a fixing process. The sheet S on which an image has been formed is discharged outside the apparatus by a sheet discharging section 52 provided with a sheet discharging roller 52a.

  Next, the charging device 414 will be described. FIGS. 5 to 8 are diagrams for explaining the configuration of the charging device 414 used in the image forming apparatus 1 of the present embodiment. FIG. 5 shows the positional relationship between the band electrode accommodating portion 350 and the photosensitive drum 413, and FIG. 6 shows the positional relationship between the first region where the gas inlet is provided and the second region where the gas outlet is provided. 5 is a sectional view taken along line XX of FIG. 5, and FIG. 8 is a sectional view taken along line YY and ZZ of FIG. In FIG. 5, a band electrode housing section 350 of the charging device 414 houses the band electrode 355 and the grid 356 and has an opening on the photosensitive drum 413 side. The band electrode accommodating section 350 is arranged to extend along the axial direction of the photoconductor drum 413.

  A suction part 351 having a suction duct 351A and a suction fan 351B for sucking air into the band electrode housing part 350 is provided at the center of the band electrode housing part 350. Further, an exhaust portion 352 having an exhaust duct 352A and an exhaust fan 352B for exhausting air from the electrode housing portion 350 to the outside of the apparatus is provided at one end of the electrode housing portion 350. Further, an exhaust portion 353 having an exhaust duct 353 </ b> A and an exhaust fan 353 </ b> B for exhausting air from the band electrode accommodating portion 350 to the outside of the device is provided at the other end of the electrode electrode accommodating portion 350. Further, an ozone filter (not shown) is provided in the exhaust units 352 and 353.

  The intake fan 351B of the intake unit 351 is driven by the intake fan drive unit 90 (see FIG. 4), and the exhaust fans 351B and 352B of the exhaust units 352 and 353 are driven by the exhaust fan drive unit 91 (see FIG. 4). Is done. The rotational speed of the intake fan 315B of the intake unit 351 and the rotational speed of the exhaust fans 352B and 353B of the exhaust units 352 and 353 are controlled by the control unit 100 to the intake unit fan drive unit 90 and the exhaust unit fan drive unit 91, respectively. Thus, the exhaust air volume is adjusted to be larger than the intake air volume.

  The suction section 351 is arranged such that a gas inlet 350A for introducing a gas into the band electrode accommodating section 350 introduces a gas into a predetermined first region 360. The exhaust unit 352 is disposed such that the positions of the gas outlets 350B1 and 350B2, which are the outlets of the gas extracted from the band electrode housing unit 350 by the exhaust units 352 and 353, are in the predetermined second region 361.

  FIG. 6 shows a positional relationship between the first region 360 where the gas inlet 350A is arranged and the second region 361 where the gas outlets 350B1 and 350B2 are arranged. This figure is a view in which the band electrode accommodating section 350 and the photosensitive drum 413 are overlapped with the band electrode accommodating section 350 positioned at the front, but for the sake of simplicity, the intake section 351 and the exhaust section 352 are used here. , 353 are omitted. The first region 360 is a region where the opening of the band electrode accommodating portion 350 and the image forming region 413A of the photosensitive drum 413 face each other. From the description of FIG. 6, this definition can be rephrased as a region that overlaps with the image forming region 413A of the photoconductor drum 413 in the region corresponding to the band electrode accommodating portion 350. The gas inlet 350A is disposed in a part of the first region 360. On the other hand, the second area 361 is an area adjacent to the first area 360, and is an area surrounding the first area 360, for example, as shown in FIG. In the present embodiment, the gas outlets 350B1 and 350B2 are arranged in a part of the second region 361 located at a position outside the image forming region 413A in the axial direction of the photosensitive drum 413.

  In the band electrode accommodating section 350, preliminary openings 350C and 350D are arranged at positions different from the gas outlets 350B1 and 350B2 and at positions deviated from the first region 360 in the axial direction of the photosensitive drum 413. More specifically, in a region corresponding to the image forming region 413A, a gap formed between both ends of the band electrode accommodating portion 350 in the rotation direction H of the photoconductor drum 413 and the photoconductor drum 413 is a band electrode. Although it is closed by the seal member 357 fixed to the housing portion 350 (see FIGS. 5 and 7), in the regions corresponding to the non-image forming regions 413B and 413C, no seal member is provided and the band electrode housing is provided. A gap GP formed between the portion 350 and the photosensitive drum 413 is left open. Thus, preliminary openings 350C and 350D are formed (see FIGS. 5 and 8). By closing the gap between the image forming areas 413A with the seal member 357, unnecessary gas inflow and outflow in the image forming area 413A can be prevented. It is desirable that the end of the seal member 357 be disposed close to the photosensitive drum 413 so that a negligible minute gap remains, but the end of the seal member 357 is exposed so that the gap is completely closed. It may be arranged in contact with the body drum 413. Therefore, in preparation for the latter case, it is preferable that the seal member 357 be formed of a flexible or flexible material (for example, polyethylene terephthalate or urethane) that does not damage the photosensitive drum 413.

  Next, the flow of gas in the charging device 414 will be described with reference to FIGS. When gas is introduced into the electrode housing 350 through the gas inlet 350A by the airflow W1 generated in the suction part 351, the gas does not leak from the electrode housing 350 in the area corresponding to the image forming area 413A. It moves toward the both ends in the axial direction from the central portion in the axial direction (airflows W2 and W3), and reaches a region corresponding to the non-image forming region 413B. From here, this gas passes through the gas outlets 350B1 and 350B2 and is exhausted to the outside at the exhaust units 352 and 353. Here, the total exhaust air volume of the exhaust units 352 and 352 is equal to the intake air amount of the intake unit 351. Since the air flow is larger than the intake air flow, not only does the gas flow into the area corresponding to the non-imaging area 413B due to the airflows W2 and W3, but also external gas flows from the preliminary openings 350C and 350D (airflow W4 (airflow W4)). W4a, W4b, W4c) and airflow W5 (airflows W5a, W5b, W5c)), and these gases are combined to form airflows W6, W7 and flow out of the gas outlets 350B2, 350B3. That is, the gas taken in by the suction unit 351 is uniformly distributed throughout the entire region corresponding to the image forming region 413A, and is reliably discharged from the exhaust units 352 and 353 without leaking along the way, and is discharged from the preliminary openings 350C and 350D. The gas taken in is reliably discharged from the exhaust units 352 and 353 without passing through the region corresponding to the image forming region 413A.

  As described above, according to the present embodiment, the gas inlet that introduces gas from the intake duct 351A to the first area 360 where the opening of the band electrode accommodating section 350 and the image forming area 413A of the photoconductor drum 413 face each other; Gas outlets 350B1 and 350B2 for extracting gas discharged from the exhaust ducts 352A and 353A from the second region 361 adjacent to the first region 360 are provided in the band electrode accommodating portion 350, and preliminary openings 350C and 350D are formed in the band electrodes. The storage unit 350 is provided at a position different from the gas outlets 350B1 and 350B2 and at a position deviated from the first area 360 in the axial direction of the photosensitive drum 413. Then, the total air volume of the exhaust units 352 and 353 is adjusted by the intake unit 351. Is controlled to be larger than the air volume. With this configuration, since the above-described airflow is formed in the band electrode accommodating section 350, dirt such as toner and dust in the image forming apparatus 1 is accumulated in the charging device 414, specifically, in the band electrode accommodating section 350. Needless to say, the discharge products are not taken in, and the discharge products in the band electrode accommodating section 350 can be surely discharged out of the apparatus without leaking out of the discharge electrodes.

  The above-described embodiment is merely an example of an embodiment for carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner. That is, the scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. The present invention is applicable to an image forming system including a plurality of units including an image forming apparatus. The plurality of units include, for example, external devices such as a post-processing device and a control device connected to a network.

  For example, by providing the gas outlets 550B1 and 550B2 through which the gas can be discharged to the outside through the exhaust ducts 502A and 503A at the positions where the seal members 357 are provided in the above embodiment, the seal members 357 can be omitted (FIG. 11). reference).

Finally, results of an experiment for confirming the effectiveness of the above embodiment will be described with reference to FIGS.
With respect to the conventional configuration shown in FIG. 1 and the configuration of the present embodiment, the ozone concentration and the wind speed around the band electrodes 321 and 355 in the longitudinal direction of the band electrode housing portions 320 and 350 were measured. FIG. 12 is a graph showing the ozone concentration around the band electrode. FIG. 13 is a graph showing the wind speed around the band electrode. 12 and 13, graphs indicated by solid lines are measurement results obtained by the configuration of the present embodiment, and graphs indicated by chain double-dashed lines are measurement results obtained by the conventional configuration. In the figure, the longitudinal position “0” is the center, and the range where the longitudinal position is a positive value is the intake duct side in the conventional configuration, and the longitudinal position is a negative value. The range in the conventional configuration is on the exhaust duct side.

  The measurement results of the wind speed show a positive value for the airflow exiting from the electrode housings 320 and 350 and a negative value for the airflow entering the electrode housings 320 and 350. In the conventional configuration, the ozone concentration and the wind speed at the end on the intake side are high, and ozone leaks from the inside of the band electrode housing 320. In the conventional configuration, the wind speed on the exhaust side shows a negative value up to the inside of the image forming area, and it can be seen that the gas is sucked into the band electrode housing 320. On the other hand, in the configuration of the present embodiment, the ozone concentration is low as a whole, and it can be seen from the measurement result of the wind velocity that an airflow that draws in only the non-image forming area is generated.

  Next, a real-photo durability test was performed on the conventional configuration and the configuration of the present embodiment, and halftone images after 1000 kp durability were compared. FIG. 14 is a graph showing a halftone image uneven rank. In FIG. 14, the graph shown by the solid line is the measurement result by the configuration of the present embodiment, and the graph shown by the two-dot chain line is the measurement result by the conventional configuration. In the conventional configuration, unevenness due to contamination of the band electrode accommodating portion 320 occurred at the end on the exhaust side (there is a portion having an image unevenness rank of 3 or less). On the other hand, in the configuration of the present embodiment, no streaks occurred in the halftone image (there was no portion with an image unevenness rank of 3 or less).

  According to the results of the experiment, in the conventional configuration, a part of the air leaks out of the band electrode housing 320 without flowing in the direction of the exhaust duct 340A in the vicinity of the intake duct 340A in the band electrode housing 320, and the band electrode housing near the exhaust duct 340A. It is considered that toner and dust were sucked together with the gas in the image forming area within the frame of the section 320, and the band electrodes 321 and the grid 322 were contaminated to cause uneven streaks. On the other hand, in the configuration of the present embodiment, no problem was found, and good results were obtained.

DESCRIPTION OF REFERENCE NUMERALS 1 image forming apparatus 40 image forming unit 41 image forming unit 90 intake unit fan driving unit 91 exhaust unit fan driving unit 100 control unit 101 CPU
102 ROM
103 RAM
350 band electrode accommodating section 350A gas inlet 350B1, 350B2, 550B1, 550B2 gas outlet 350C, 350D preliminary opening 351 intake section 351A intake duct 351B suction fan 352, 353 exhaust section 352A, 353A, 502A, 503A exhaust duct 352B, 353B exhaust Fan 355 Band electrode 356 Grid 357 Sealing member 360 First region 361 Second region 411 Exposure device 412 Developing device 413 Photoconductor drum 413A Image forming region 413B, 413C Non-image forming region 414 Charging device GP Gap

Claims (9)

A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position different from the gas outlet of the band electrode housing portion and at a position deviating from the first region in the axial direction of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The gas inlet is provided at a central portion in the longitudinal direction of the band electrode housing portion extending along the axial direction of the photoconductor,
The image forming apparatus is provided with the gas outlets at both ends in the longitudinal direction of the band electrode accommodating portion. A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position different from the gas outlet of the band electrode housing portion and at a position deviating from the first region in the axial direction of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The image forming apparatus, wherein the gas outlet is provided in a gap between both ends of the band electrode accommodating portion in the rotation direction of the photoconductor and the photoconductor. A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position different from the gas outlet of the band electrode housing portion and at a position deviating from the first region in the axial direction of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
A seal member that closes a gap between both end portions of the band electrode housing portion in the rotation direction of the photoconductor and the image forming area of the photoconductor,
An image forming apparatus having: A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position deviating from the first region in the axial direction of the photoconductor in the band electrode housing portion and including a region outside an end of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The image forming apparatus, wherein the gas outlet and the preliminary opening are provided at positions corresponding to each other in a direction perpendicular to the axis of the photoconductor and at positions different from each other on a plane orthogonal to the axis of the photoconductor.   The gas inlet is provided at a central portion in the longitudinal direction of the band electrode housing portion extending along the axial direction of the photoconductor,
  The gas outlet is provided at both ends in the longitudinal direction of the band electrode housing portion,
  The image forming apparatus according to claim 4.   Another gas outlet provided in a gap between both ends of the band electrode housing portion and the photoconductor in the rotation direction of the photoconductor,
  The image forming apparatus according to claim 1.   A seal member that closes a gap between both end portions of the band electrode accommodating portion in the rotation direction of the photoconductor and the image forming area of the photoconductor,
  The image forming apparatus according to claim 1. An image forming system including a plurality of units including an image forming apparatus,
A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position different from the gas outlet of the band electrode housing portion and at a position deviating from the first region in the axial direction of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The gas inlet is provided at a central portion in the longitudinal direction of the band electrode housing portion extending along the axial direction of the photoconductor,
The image forming system, wherein the gas outlets are provided at both ends in a longitudinal direction of the band electrode housing. An image forming system including a plurality of units including an image forming apparatus,
A band electrode accommodating portion that accommodates the band electrode and has an opening on the photoconductor side,
An intake unit having an intake duct for sucking gas in the band electrode housing unit,
An exhaust unit having an exhaust duct for exhausting gas from the band electrode housing to the outside of the machine,
A gas inlet that is provided in the band electrode accommodating portion and that introduces gas from the intake duct to a first region where the opening of the band electrode accommodating portion and the image forming region of the photoconductor oppose each other;
A gas outlet provided in the band electrode accommodating portion, for taking out gas discharged from the exhaust duct from a second region adjacent to the first region;
A preliminary opening provided at a position deviating from the first region in the axial direction of the photoconductor in the band electrode housing portion and including a region outside an end of the photoconductor;
A control unit that controls the intake unit and the exhaust unit such that the air volume of the exhaust unit is larger than the air volume of the intake unit;
Has,
The image forming system, wherein the gas outlet and the preliminary opening are provided at positions corresponding to each other in a direction perpendicular to the axis of the photoconductor and at different positions on a plane orthogonal to the axis of the photoconductor.

Images