JP2016133660A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging device that can remove a dew condensation part in the vicinity of a charging wire during cleaning of the charging wire, and can prevent the occurrence of leakage of charge in a high-humidity environment and within a time of first start-up of the device in the morning.SOLUTION: A projecting shape is provided on a surface on the opposite side of an end block cover 35 of a cleaning device where a charging grid 33 is not in contact with a surface. When the cleaning device moves and a grid cleaner 34 rides over and stays on the end block cover 35, the sponge-made grid cleaner 34 is deformed by the projecting shape and discharges absorbed water. An airflow inside the device is optimally controlled to improve quick-drying characteristics.SELECTED DRAWING: Figure 20

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile.

  In an electrophotographic image forming apparatus, a photosensitive drum is used as an image carrier, the surface of the photosensitive drum is charged and exposed to form an electrostatic latent image, and toner is attached to the electrostatic latent image. Image formation is performed such that the image is visualized and transferred to a sheet. In particular, in the case of an image forming apparatus that prints at high speed, a scorotron charging device (referred to as a charging charger in this specification) using corona discharge as a charging device has been put into practical use. In some cases, an image forming apparatus that prints at high speed or a color image forming apparatus uses a solid bar of zinc stearate.

  In an electrophotographic image forming apparatus, this zinc stearate is mainly mounted as a cleaning device. As a cleaning device mounted in an image forming apparatus, a device that scrapes off a zinc stearate bar with a dedicated application brush and applies it to the surface of a photosensitive drum is known.

  A charging wire cleaner (polishing pad) or a charging grid cleaner (sponge: foamed polyurethane resin) may be mounted on the charging charger as a component of the same cleaning device in the vicinity of the charging wire in the charging charger. In such a cleaning device, it is assembled to a metal (for example, SUS material) conveying screw at the center of the charging charger, and is driven by an external stepping motor. Normally, when the timing of a certain number of sheets has come, the conveying screw is rotated by a motor outside the charging charger. Therefore, the cleaning device is configured to reciprocate. The airflow from the charging duct flows at the timing when the main power supply of the image forming apparatus main body is turned on.

  The charging charger includes, for example, three charging wires. Normally, a voltage is applied by flowing a high-voltage current from the power pack. The charging wire is also equipped with a cleaning function like the charging grit and is in the same cleaning device as the charging grit. The charging wire cleaning method has a configuration in which the charging wire is sandwiched, and polishing pads are attached at two locations, and moves from a normal standby position to an intermediate point position while keeping a gap with the charging wire. Thereafter, the polishing pad bites into the wire at the intermediate point, and the foreign matter adhering to the wire surface is polished in one way to the original standby position. Then, it does not operate except when a certain number of sheets are passed and when the user manually operates. During operation, voltage application to the charging wire is performed in an off state.

  In such an apparatus, the fine powder of zinc stearate generated when scraped off by the coating brush acts as fine powder by the airflow flowing from the charging duct for sending the airflow to the charging charger. Since the flying fine powder also goes inside the charging charger, it adheres to the surface of the charging wire in the charging charger, the charging grid, the casing, and the like. In addition, this zinc stearate has a feature that it easily absorbs moisture, and moisture from the surroundings easily attaches to the location where the fine powder adheres. Although there is no particular problem in the normal environment, when the humidity is high, the humidity of the electrophotographic apparatus is increased, resulting in a more disadvantageous situation. It is the charging leak in the vicinity of the wire of the charging charger that is affected by such moisture adhesion and water absorption.

  In other words, in an electrophotographic image forming apparatus, a charging device (hereinafter referred to as a charging charger) may rarely cause charging leakage in a high humidity environment due to condensation due to humidity inside the apparatus. Mainly affected by condensation due to high humidity. However, since the cleaning device provided in the electrophotographic image forming apparatus is equipped with the solid bar of zinc stearate as described above, the zinc stearate fine powder flutters during operation (when passing paper). Adhere to. When the cleaning parts of the charging charger in the vicinity of the charging wire are exposed to dew condensation, the high voltage of the charging charger wire may be transmitted due to the water absorbed in the adhering fine powder, which may cause leakage. In order to prevent this, it is necessary to remove the water absorption of the cleaning parts of the charging device in the vicinity of the charging wire.

  Various methods are known as countermeasures against dew condensation in the apparatus in the electrophotographic image forming apparatus as described above. For example, a technique for increasing the temperature inside the apparatus using a heater to prevent it and a control method therefor are known. There is also known a method of sending heat generated from a fixing device to an image forming unit that condenses (see, for example, Patent Document 1). There is also an airflow blocking method that does not allow airflow from outside air to enter the apparatus (see, for example, Patent Document 2).

  However, in the case of a charging leak that occurs in a high humidity environment, it is said that normal recovery cannot be achieved unless the charging charger is replaced. Further, it has been demanded that condensation near the charging wire that causes charging leakage occurring in the charging charger can be removed in the charging wire cleaning control.

  SUMMARY OF THE INVENTION Accordingly, the present invention provides an image forming apparatus aimed at removing condensation by using a reciprocating motion of the cleaning device and an automatic cleaning control function provided in the charging charger and by controlling airflow flowing from the charging duct to the charging charger. For the purpose.

  The charging device according to the present invention is a charging device provided in an electrophotographic image forming apparatus, the condensation removing means for removing condensation on a component to be cleaned, and the condensation removing means for increasing the condensation removal efficiency by the condensation removing means. An airflow control means for controlling the airflow around the part is provided.

  According to the present invention, the dew condensation part near the charging wire that causes the charging leak generated in the charging charger can be removed during the cleaning of the charging wire, and the first apparatus is started up in a high humidity environment and in the morning. There is an effect that it is expected to prevent the occurrence of charging leakage within the time.

1 is a diagram illustrating an apparatus configuration and an arrangement of various component units in an example of an electrophotographic image forming apparatus. FIG. 4 is a conceptual diagram of the layout around the photoconductor, showing the photoconductor, the charger, and the charging duct. FIG. 2 is a diagram illustrating a layout configuration around a photosensitive member as viewed from the back side of the electrophotographic apparatus of FIG. 1. It is detail drawing of the components block diagram of a charging duct. It is the figure which showed the flow direction of the airflow which flows in into a charging duct from a fan. FIG. 3 is a diagram showing the airflow flowing in the cross-sectional direction of the charging duct in the configuration diagram of the photoconductor and the charging duct. It is the figure which showed the inlet port of the charging duct back side. FIG. 6 is a diagram illustrating a flow path of an airflow flowing along the surface of the photoreceptor. It is a whole figure (figure seen from the upper side) of a charging charger. It is a general view (figure seen from the lower side) of a charging charger. It is the figure which removed the grid from FIG. 10 and showed arrangement | positioning of the front-and-back end block cover. It is the figure which removed and showed the end block cover from the edge part of the near side of FIG. FIG. 11 is a detailed view of the back end of FIG. 10, showing a terminal that receives a high voltage from the power pack. It is detail drawing of the end block cover which carried out the countermeasure against dew condensation, and is a figure which shows for the edge part for the near side (A) and for the edge part of the back side (B). It is a figure which shows the end block cover which carried out the dew condensation removal countermeasure. 1 is an overall view of a cleaning device. It is detail drawing 1 of the cleaning part of a cleaning apparatus. It is detail drawing 2 of the cleaning part of a cleaning apparatus. It is the figure which showed operation | movement of the cleaning apparatus. It is a figure which shows the position at the time of standby of a cleaning apparatus (set position position). It is a figure which shows the intermediate point position of a cleaning apparatus. It is a figure which shows the mode of the flow of the airflow before a charging duct.

  The present invention utilizes the automatic cleaning control function inside the charging charger using the first startup of the image forming apparatus in the morning so that charging leakage does not occur in a high humidity environment by utilizing the reciprocating motion of the cleaning apparatus. Remove the condensation. Further, condensation is removed by controlling the airflow flowing from the charging duct to the charging charger.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an apparatus configuration and an arrangement of various component units in an example of an electrophotographic image forming apparatus that is an object of the present invention. In this figure, reference numeral 50 denotes an apparatus main body (hereinafter referred to as “image forming apparatus main body”) of a laser copying machine as an example of an electrophotographic image forming apparatus. A drum-shaped photosensitive drum 2 as an example of an image carrier is disposed in the image forming apparatus main body 50. Around the photosensitive drum 2, a charging device 100, a developing device 3, a primary transfer roller 61, and a cleaning device 60 are arranged in order in the rotation direction of the photosensitive drum 2 (counterclockwise indicated by an arrow). The image forming unit 4 mainly includes a photosensitive drum 2, a charging device 100, an exposure device, a developing device 3, and a cleaning device 60, which will be described later. The primary transfer roller 61 is disposed below the photosensitive drum 2 with the intermediate transfer belt 62 interposed therebetween. The charging device 100 includes a charging charger 10 and a charging duct 7 that are also called a charger.

  A laser writing device 52 as an exposure device is disposed above each device. The laser writing device 52 includes well-known components such as a light source such as a laser diode, a scanning rotary polygon mirror, a polygon motor, and a scanning optical system such as a scanning lens including an fθ lens (not shown). .

  A document reading device 53 is disposed in the upper part of the image forming apparatus main body 50. The document reading device 53 includes well-known components such as a light source, a plurality of mirrors, an imaging lens, and an image sensor such as a CCD (not shown).

  An intermediate transfer device is disposed near the lower portion of the photosensitive drum 2. In the intermediate transfer device, an endless intermediate transfer belt 62 wound around three support rollers 63, 64, 65 is provided so as to be able to run and rotate in the arrow direction (clockwise) in the figure. Any one of the three support rollers 63, 64, 65 is configured as a driving roller, and the other is configured as a driven roller. The intermediate transfer belt 62 has a function of applying a reverse bias (+) voltage to transfer and convey the toner image attached to the latent image formed on the surface of the photosensitive drum 2. The repulsive roller 65 also serves as a secondary transfer roller, and presses the intermediate transfer belt 62 against the secondary transfer device 67 to form a secondary transfer nip portion. The repulsive roller 65 is applied with a secondary transfer bias by a secondary transfer device 67.

  On the left side of the secondary transfer device 67 in the figure, a belt type conveying device 68 and a fixing device 80 are arranged. The fixing device 80 includes a heating roller 81 incorporating a heater, a fixing roller 82, an endless fixing belt 83 wound around the heating roller 81 and the fixing roller 82, and the fixing roller 82 via the fixing belt 83. And a pressure roller 84 for pressing from below.

  A duplex unit 88 is provided in the lower part of the image forming apparatus main body 50. The duplex unit 88 is provided with a refeed path 87 that communicates with the feed path 75 extended to the secondary transfer device 67. The duplex unit 88 is branched from the middle of the sheet discharge path 85 extended from the exit of the fixing device 80 to form a reverse path 86. The paper feed path 75 is connected to a manual paper feed path extending in the horizontal direction from a manual feed tray (not shown).

  A contact glass 54 is installed on the upper surface of the image forming apparatus main body 50. An automatic document feeder (ADF) 51 is mounted on the apparatus main body 50 so as to be able to be opened and closed so as to cover the contact glass 54. A toner bottle 78 is provided on the right side of the automatic document feeder 51. Further, an operation panel 79 for operating the image forming apparatus is provided on the upper portion of the toner bottle 78. Two toner bottles 78 are mounted and automatically supplied to the developing device 3. When the toner in one toner bottle 78 is consumed, the other toner bottle 78 is switched.

  The image forming apparatus main body 50 is placed on a paper feed table 69. In the paper feed table 69, as paper feed units 70, paper feed cassettes 71 storing and stacking sheets S such as sheets as an example of a sheet-like recording medium are equipped in multiple stages (in this embodiment, three stages). Has been. Each paper feed cassette 71 is provided with a paper feed roller 72 correspondingly. The sheet feeding roller 72 introduces the fed sheet S into a conveyance path 73 connected to the sheet feeding path 75. A plurality of pairs of transport rollers 74 are provided in the transport path 73. A waste toner tank 89 for collecting and discarding used toner is disposed on the right side of the sheet feed table 69.

  When taking a copy using the laser copying machine having the above-described configuration, the original is set on the automatic document feeder 51 or the automatic document feeder 51 is opened and the original is directly set on the contact glass 54. Then, a start switch (not shown) is pressed and the automatic document feeder 51 is driven to feed a document conveyed on the contact glass 54 or a document previously set on the contact glass 54 by the document reading device 53 in pixel units. Read with.

  In accordance with the document reading operation, the sheet feeding roller 72 of an appropriate sheet feeding cassette 71 in the sheet feeding table 69 is rotated, and the sheet S is fed out from the corresponding sheet feeding cassette 71. Then, the toner is introduced into the conveying path 73 and conveyed by the conveying roller 74, and is put into the sheet feeding path 75 to abut against the registration roller 76 to stop. Thereafter, the registration roller 76 is rotated in synchronization with the rotation of the toner image transferred to the intermediate transfer belt 62, and the sheet is sent to the nip portion between the intermediate transfer belt 62 and the secondary transfer roller 65.

  When a start switch provided on the operation panel 79 is pressed, the photosensitive drum 2 simultaneously rotates counterclockwise in the figure, and the intermediate transfer belt 62 runs and rotates in the arrow direction in the figure. Then, along with the rotation of the photosensitive drum 2, first, the surface of the photosensitive drum 2 is uniformly charged by the charging charger 10 in the charging device 100. Next, the laser writing device 52 performs writing by irradiating the laser beam L according to the reading content read by the document reading device 53 described above, and forms an electrostatic latent image on the surface of the photosensitive drum 2. The developing device 3 attaches toner and visualizes the electrostatic latent image.

  The toner image attached to the surface of the photosensitive drum 2 is primarily transferred to the intermediate transfer belt 62 by the primary transfer roller 61. The toner image transferred to the intermediate transfer belt 62 is transferred onto the sheet fed to the nip portion between the intermediate transfer belt 62 and the secondary transfer device 67 by the secondary transfer roller 65 of the secondary transfer device 67. Are transferred at once. The surface of the photosensitive drum 2 after the image transfer is cleaned by removing residual toner with a cleaning device 60, and is neutralized with a neutralization device (not shown) to prepare for subsequent image formation. Further, the surface of the intermediate transfer belt 62 after the image transfer is cleaned by removing residual toner and paper dust with a belt cleaning device 66, and in preparation for the subsequent image formation.

  On the other hand, the image-transferred sheet is conveyed by a belt-type conveying device 68 and put into a fixing device 80, and heat and pressure are applied by a fixing roller 82 and a pressure roller 84 via a fixing belt 83 to transfer a transferred image. Fix (toner image). Thereafter, the paper is discharged through a paper discharge path 85 onto a paper discharge tray (not shown) attached to the apparatus main body 50, for example. When recording on the back side of the sheet using this copying machine, after recording on one side, it is fed into the duplex unit 88 through the reversing path 86, where it is reversed and conveyed through the refeed path 87 to feed the sheet. Lead to 75. Then, the toner is fed again into the nip portion between the intermediate transfer belt 62 and the secondary transfer roller 65. Then, the toner image separately formed on the photosensitive drum 2 and the toner image primarily transferred onto the intermediate transfer belt 62 are similarly secondarily transferred to the back surface and then discharged onto a paper discharge tray or the like.

  FIG. 2 is a conceptual diagram of the layout around the photosensitive member, showing the photosensitive member, the charging charger, and the charging duct. The charging duct 7 for flowing an airflow to the charging charger 10 will be described with reference to FIG. A charging duct 7 for holding the charging charger 10 and flowing an air flow through the charging charger 10 can take in and out the charging charger 10 to be accommodated. When the charging charger 10 is set, it is fixed at a height of, for example, 1.3 mm from the surface of the photosensitive drum 2. The charging duct 7 for fixing the charging charger 10 is connected to the charging duct 7 directly from the intake fan 5 and the exhaust fan 9 on the rear side of the main body of the electrophotographic apparatus, from the intake conveyance duct 6 and the exhaust conveyance duct 8. (See FIGS. 2 and 3). The intake air flows from the intake fan 5 to the charging duct 7 through the intake transport duct 6. The air flow exhausted from the charging duct 7 flows through the exhaust transport duct 8 and is exhausted by the exhaust fan 9.

  The charging duct 7 is mainly composed of four parts (see FIG. 4). In other words, the charging duct 7 includes a side cover 14, a partition plate 15, and an exhaust partition plate 13 around the main frame 20. The airflow flowing into the charging duct 7 is as shown in FIG.

  The charging charger 10 includes three charging wires 29 therein, and a high voltage current flows through the charging wires 29. The airflow inside the charging duct 7 is as shown in FIG. FIG. 6B is a view as seen from the cross-section aa of FIG. Here, two patterns of airflow are mainly divided. The first airflow is an airflow 16 that flows to the three charging wires 29, and flows from the top to the bottom of the drawing, that is, from the top of the charging charger 10 toward the charging wire 29. The second is an air flow 17 flowing from the side cover 14 and is an air flow along the surface of the photosensitive drum 2. These two patterns of airflow merge in the vicinity of the exhaust port of the charging duct 7 and are finally exhausted. The air flow 17 is set so that the flow velocity is faster than the air flow 16. As shown in FIG. 7, the airflow 16 enters through an intake port (charging wire dedicated intake port 19) on the rear side of the charging duct 7. The airflow 17 flows from the photoconductor surface dedicated inlet 18. Further, the air flow 17 tends to have a small flow velocity on the back side of the duct due to the configuration of the charging duct 7. That is, the flow velocity at the location X indicated by the dotted line in FIG. 8 tends to be small.

  Next, the configuration of the charging charger 10 will be described with reference to FIGS. A cleaning device 32 and a conveying screw 31 for moving the cleaning device 32 are arranged at the center of the charging charger 10. End block covers 35 and 36 are provided at the standby position and the intermediate point position of the cleaning device 32. The end block covers 35 and 36 have a function of bending the charging grid 33 and tensioning it with a required tension. (See FIGS. 9 to 12). For example, molded parts are used for the end block covers 35 and 36. As the charging grid 33, for example, a mesh made of SUS material is used.

  Next, details of the cleaning device 32 will be described with reference to FIGS. The cleaning device 32 is provided with three charging wire cleaner bodies 38. The charging wire cleaner main body 38 is inserted into a shaft 40 coming out from the cleaning device 32 and rotates around the shaft 40. The charging wire cleaner body 38 is provided with two polishing pads 39 for polishing the charging wire 29. They are arranged diagonally, and when they are moved for cleaning operation (also dew condensation removal operation) and turned back at an intermediate position, they rotate around the axis 40 and come into contact with the charging wire 29. Yes. A grid cleaner 34 for cleaning the peripheral surface of the charging grid 33 is also attached to the cleaning device 32. This is attached as a separate part, but may be attached as a single part.

  As an example of the dew condensation removing means, as shown in FIGS. 20 and 21, the surface shapes of the end block covers 35 and 36 may be mentioned. In other words, the charging grid 33 of the end block covers 35 and 36 has a convex shape 37 (or a concave / convex shape) on the opposite surface that does not receive the surface. By adding this convex shape 37 (or uneven shape), the grid cleaner 34 (made of a sponge that can be compressed and absorbs water) is compressed and deformed, and the absorbed water is discharged. Normally, since the cleaning device 32 comes on the surface of the end block covers 35 and 36, the grid cleaner 34 rides on the end block covers 35 and 36 and stops. For example, the convex shape of the surface is preferably about 2 mm in height and 1.5 to 2 mm in width. Moreover, it is possible to form a groove shape by making it uneven, and this groove-shaped portion can be used for drainage to allow drainage. Since the end block covers 35 and 36 are provided at two places, the condensation removal effect can be enhanced by using these as the climbing parts. That is, the quick-drying effect can be expected by forcibly removing the water contained in the grid cleaner 34 and draining it.

  Further, the dew condensation removing means of the polishing pad 39 attached to the charging wire cleaner body 38 can remove dew condensation by borrowing the force of the air current. That is, the airflow from the charging duct 7 is used, but in order to improve the condensation removal efficiency, not only the airflow is applied while the cleaning device 32 is fixed, but the airflow is improved by applying the airflow while moving. , Has improved quick-drying. In addition, the configuration of the charging duct 7 takes advantage of the fact that the front side as an electrophotographic apparatus has a characteristic that the flow velocity of airflow is faster (see FIGS. 8 and 22). That is, for example, a predetermined time after the start of the decondensing operation, for example, about 1 minute before moving the cleaning device 32 is set to the standby state at the initial set position, and then quickly dried at a position where the flow rate is fast (flow rate up). To be able to. Further, after that, the cleaning device 32 is moved, and by making the moving speed slower than usual (for example, a speed of 1/2 or less), a large amount of airflow flowing from the charging duct 7 is applied to achieve a quick drying effect. Let me up.

  Further, the intake fan 5 and the exhaust fan 9 generate the airflow from the charging duct 7 only in a high humidity environment and when the apparatus is turned on in the morning. The duty (current output%) of the intake fan 5 and the exhaust fan 9 is changed in terms of control. For example, the intake 20% and the exhaust 80% are changed to, for example, the intake 50% and the exhaust 100%. As a result, it is possible to aim at further quick drying effect, that is, improvement in drying efficiency, and efficient dew condensation removal.

  Various airflow control means, control methods, and control methods have been described above. However, the present invention is not limited to this, and various optimum means, methods, and methods can be employed. The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

2: Photoconductor drum 3: Developing device 4: Image forming unit 5: Intake fan 6: Intake transport duct 7: Charging duct 8: Exhaust transport duct 9: Exhaust fan 10: Charging charger 13: Partition plate 14: Side cover 15: Partition plate 16, 17: Airflow 18: Photoconductor surface dedicated inlet 19: Charged wire dedicated inlet 20: Main frame 29: Charged wire 31: Conveying screw 32: Cleaning device 33: Charged grid 34: Grid cleaner 35, 36: End block cover 37: Convex shape 38: Charged wire cleaner main body 39: Polishing pad 40: Shaft 50: Image forming apparatus main body 51: Automatic document feeder 52: Laser writing device 53: Document reading device 54: Contact glass 60: Cleaning Device 61: Primary transfer roller 62: Intermediate transfer belt 63: Support Roller 64: support roller 65: secondary transfer roller 66: belt cleaning device 67: secondary transfer device 68: transport device 69: paper feed table 70: paper feed unit 71: paper feed cassette 72: paper feed roller 73: transport path 74: Transport roller 75: Paper feed path 76: Registration roller 78: Toner bottle 79: Operation panel 80: Fixing device 81: Heating roller 82: Fixing roller 83: Fixing belt 84: Pressure roller 85: Paper discharge path 86: Inversion Path 87: Refeed path 88: Duplex unit 89: Waste toner tank 100: Charging device L: Laser light S: Sheet

JP 2009-169176 A JP 2000-181330 A

Claims (9)

In the charging device provided in the electrophotographic image forming apparatus,
Condensation removing means for removing condensation on parts to be cleaned;
An airflow control means for controlling the airflow around the component in order to increase the condensation removal efficiency by the condensation removal means;
A charging device comprising: The charging device according to claim 1,
The component is a grid, and the dew condensation removing means is a grid cleaner for cleaning the grid, and the grid cleaner has water absorption,
The grid cleaner can be compressed by providing a convex shape on the surface of the part that the grid cleaner rides on when moving for cleaning,
A charging device. The charging device according to claim 2,
An uneven shape was provided instead of the convex shape, and a groove shape for drainage could be formed in the grid cleaner.
A charging device. The charging device according to claim 1,
The component is a wire, and the dew condensation removing means is a wire cleaner;
The cleaning operation by the wire cleaner is performed when the humidity inside the machine exceeds the target value, and the dew condensation removing operation is accompanied.
A charging device. The charging device according to claim 4,
The dew condensation removing operation is performed with the voltage application control turned off.
A charging device. The charging device according to any one of claims 1 to 5,
The condensation removal operation is performed while increasing the air permeability of the airflow flowing through the machine by moving the parts.
A charging device. The charging device according to claim 6,
A predetermined time after the start of the dew condensation removing operation is set to a standby state so that the component receives a strong air current, and then the dew condensation removing unit is operated to move slower than usual.
A charging device. The charging device according to any one of claims 1 to 7,
The flow rate of the airflow can be optimally controlled to increase the drying efficiency of the parts.
A charging device. An image forming apparatus comprising the charging device according to claim 1.