Image forming apparatus

Abstract

The image forming apparatus includes a latent image carrier, a cleaning unit, a developing device, and a control unit. The developing device includes a developer carrier and a toner collection mechanism having a filter. The control unit can execute a scattered toner recovery mode, in which, during non-image forming, the filter is vibrated, a potential difference that causes toner to move from the developer carrier to the latent image carrier is controlled, the developer carrier is rotated in a direction opposite to that during image forming, the latent image carrier is rotated in the same direction as during image forming, and scattered toner that has fallen from the filter and adhered to the developer carrier is recovered by the cleaning unit with the aid of the latent image carrier.

Description

TECHNICAL FIELD

[0001] The present application relates to an image forming apparatus. BACKGROUND

[0002] In an image forming apparatus of an electrophotographic system such as a copying machine and a printer, a device that supplies toner to an electrostatic latent image formed on the outer circumferential surface of a photoconductor or the like and develops the electrostatic latent image to form a toner image that is subsequently transferred onto a sheet is widely used. In order to continuously form a uniform image, the developer containing toner accommodated in a developing container is transported while being stirred in the developing container.

[0003] In the conventional image forming apparatus, there is a risk that toner scatters from the inside of the developing container to the outside, thereby contaminating the inside of the apparatus with the scattered toner. SUMMARY

[0004] An object of the present application is to provide an image forming apparatus that can suppress scattering of toner in the apparatus using a downsized configuration.

[0005] The image forming apparatus of the first aspect of the present application includes an image bearer, a charging section, a cleaning section, a developing device, a voltage application section, and a control section. The image bearer forms an electrostatic latent image on an outer peripheral surface. The charging section charges the outer peripheral surface of the image bearer. The cleaning section cleans the outer peripheral surface of the image bearer. The developing device has a developing container, a developer conveying member, and a developer bearer. The developing container houses a developer including toner to be supplied to the image bearer. The developer conveying member is rotatably supported in a conveying chamber of the developing container, conveys the developer while stirring, and circulates the developer. The developer bearer is rotatably supported opposite to the image bearer in the developing container, and supplies the toner in the conveying chamber to the image bearer. The voltage application section applies a developing voltage to the developer bearer. The control section controls the image bearer, the charging section, the cleaning section, the developing device, and the voltage application section. The developing device has a toner collection mechanism including an air passage, a filter, an exhaust fan, and a vibration generation section. The air passage is connected to the conveying chamber and allows air in the conveying chamber to flow. The filter is disposed above the connection between the air passage and the conveying chamber and the developer bearer, and collects the toner flowing from the conveying chamber into the air passage. The exhaust fan causes air in the conveying chamber to flow to the outside through the air passage. The vibration generation section vibrates the filter. The control section can execute a flying toner recovery mode in which, in a non-image forming time, the filter is vibrated by the vibration generation section, the charging section and the voltage application section are controlled in a manner to generate a potential difference in a direction in which the toner moves from the developer bearer to the image bearer, and the developer bearer is rotated in a direction opposite to that in an image forming time and the image bearer is rotated in the same direction as that in the image forming time, and flying toner that has fallen from the filter and adheres to the outer peripheral surface of the developer bearer is recovered by the cleaning section.

[0006] According to the first aspect of the present application, a toner collection mechanism for attracting and collecting flying toner can be formed in the developing device, and flying toner collected by the filter is recovered by the cleaning section with the aid of the developer bearer and the image bearer. Therefore, flying toner in the image forming apparatus can be suppressed with a downsized configuration. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a schematic cross-sectional front view of an image forming apparatus of an embodiment of the present application.

[0008] Figure 2 is a block diagram showing a configuration of the image forming apparatus of Figure 1 .

[0009] Figure 3 is a schematic cross-sectional front view of the image forming section 20 of the image forming apparatus 1. Figure 1

[0010] Figure 4 is a vertical cross-sectional front view of the developing device of the image forming section 20. Figure 3

[0011] Figure 5 is a horizontal cross-sectional plan view of the developing device of the image forming section 20. Figure 3

[0012] Figure 6 is a vertical cross-sectional side view of the developing device of the image forming section 20. Figure 3

[0013] Figure 7 is a partial enlarged cross-sectional front view of the image forming section 20 of the image forming apparatus 1, and is an explanatory view of the scattered toner recovery mode. Figure 3 DETAILED DESCRIPTION Hereinafter, an embodiment of the present application will be described with reference to the drawings. In addition, the present application is not limited to the following content.

[0014]

[0015] is a schematic cross-sectional front view of the image forming apparatus 1 of the embodiment. Figure 1 is a block diagram showing the configuration of the image forming apparatus 1. Figure 2 is a schematic cross-sectional front view of the image forming section 20 of the image forming apparatus 1. Figure 1 Figure 3 is a schematic cross-sectional front view of the image forming section 20 of the image forming apparatus 1. As an example of the image forming apparatus 1 of the present embodiment, a serial color printer which transfers a toner image to a paper S using an intermediate transfer belt 31 is adopted. The image forming apparatus 1 can be, for example, a so-called digital multifunction peripheral which has functions of printing, scanning (image reading), facsimile transmission, and the like. Figure 1 As shown in

[0016] , Figure 1 , Figure 2 and Figure 3 , the image forming apparatus 1 is provided with a paper feeding section 3, a paper feeding section 4, an exposure section 5, an image forming section 20, a transfer section 30, a fixing section 6, a paper discharge section 7, and a control section 8 which are arranged in a main body 2.

[0017] The paper feeding section 3 is arranged at the bottom of the main body 2. The paper feeding section 3 accommodates a plurality of papers S before printing, and feeds out the papers S one by one at the time of printing. The paper feeding section 4 extends in the vertical direction along the side wall of the main body 2. The paper feeding section 4 conveys the papers S fed out from the paper feeding section 3 to the second transfer section 33 and the fixing section 6, and discharges the papers S after fixing from a paper discharge port 4a to the paper discharge section 7. The exposure section 5 is arranged above the paper feeding section 3. The exposure section 5 irradiates the image forming section 20 with laser light controlled in accordance with image data.​​​​​

[0018] The image forming unit 20 is positioned above the exposure unit 5 and below the intermediate transfer belt 31. The image forming unit 20 includes an image forming unit 20Y for yellow, an image forming unit 20C for cyan, an image forming unit 20M for magenta, and an image forming unit 20B for black. These four image forming units 20 have the same basic structure. Therefore, in the following description, unless specifically defined, the identification marks “Y,” “C,” “M,” and “B” representing each color will be omitted.

[0019] The image forming unit 20 is supported so that it can move in a predetermined direction ( Figure 1 and Figure 3 The image forming unit 20 includes a photosensitive drum (image carrier) 21 that rotates clockwise. The image forming unit 20 also includes a charged section 22, a developing unit 40, and a drum cleaning section (cleaning section) 23 arranged around the photosensitive drum 21 in its rotational direction. Furthermore, a primary transfer section 32 is arranged between the developing unit 40 and the drum cleaning section 23.

[0020] The photosensitive drum 21 is formed into a cylindrical shape extending horizontally, and has a photosensitive layer, for example, formed of an amorphous silicon photosensitive material, on its outer peripheral surface. A charging section 22 charges the surface (outer peripheral surface) of the photosensitive drum 21 to a predetermined potential. The exposure section 5 exposes the outer peripheral surface of the photosensitive drum 21, charged by the charging section 22, forming an electrostatic latent image of the original document on the outer peripheral surface of the photosensitive drum 21. The developing apparatus 40 supplies toner to the electrostatic latent image for development and forms a toner image. Four image forming sections 20 each form toner images of different colors. After the toner image is transferred once to the outer peripheral surface of the intermediate transfer belt 31, the drum cleaning section 23 cleans the outer peripheral surface of the photosensitive drum 21 by removing any residual toner or the like. Thus, the image forming section 20 forms an image (toner image) that is subsequently transferred to paper S.

[0021] The transfer unit 30 includes an intermediate transfer belt 31, primary transfer units 32Y, 32C, 32M, and 32B, a second transfer unit 33, and a belt cleaning unit 34. The intermediate transfer belt 31 is positioned above the four image forming units 20. The intermediate transfer belt 31 is supported so that it can move in a predetermined direction ( Figure 1 The intermediate transfer body is a ring-shaped transfer body formed by four image forming units 20, which rotate counterclockwise and are sequentially superimposed and transferred once. The four image forming units 20 are arranged in a so-called serial configuration, with the images arranged in a row from upstream to downstream in the rotation direction of the intermediate transfer belt 31.

[0022] The primary transfer units 32Y, 32C, 32M, and 32B hold the intermediate transfer belt 31 and are positioned above the respective color image forming units 20Y, 20C, 20M, and 20B. The secondary transfer unit 33 is positioned upstream of the fixing unit 6d in the paper feeding direction relative to the paper feeding unit 4, and downstream of the four image forming units 20Y, 20C, 20M, and 20B in the rotation direction relative to the intermediate transfer belt 31. The belt cleaning unit 34 is positioned downstream of the second transfer unit 33 in the rotation direction relative to the intermediate transfer belt 31.

[0023] The primary transfer unit 32 transfers the toner image formed on the outer peripheral surface of the photosensitive drum 21 to the intermediate transfer belt 31. In other words, the toner image is transferred from the primary transfer units 32Y, 32C, 32M, and 32B of each color to the outer peripheral surface of the intermediate transfer belt 31 in one pass. Moreover, as the intermediate transfer belt 31 rotates, the toner images of the four image forming units 20 are continuously overlapped and transferred onto the intermediate transfer belt 31 at predetermined times, thereby forming a color toner image with overlapping yellow, cyan, magenta, and black toner images on the outer peripheral surface of the intermediate transfer belt 31.

[0024] The toner image on the outer periphery of the intermediate transfer belt 31 is transferred to the paper S fed synchronously by the paper feed section 4 through the secondary transfer slit formed in the second transfer section 33. The belt cleaning section 34 removes and cleans the toner and other residues remaining on the outer periphery of the intermediate transfer belt 31 after the secondary transfer. In this way, the transfer section 30 transfers (records) the toner image formed on the outer periphery of the photosensitive drum 21 onto the paper S.

[0025] The fixing unit 6 is positioned above the second transfer unit 33. The fixing unit 6 fixes the toner image onto the paper S by heating and pressing it.

[0026] The paper output section 7 is positioned above the transfer section 30. The toner is conveyed to the paper S after fixing and printing, and then to the paper output section 7. The printed paper (printed material) is then removed from above at the paper output section 7.

[0027] The control unit 8 includes a CPU, an image processing unit, a storage unit, and other electronic circuits and components (not shown). The CPU controls the operation of each component of the image forming apparatus 1 based on the control program and data stored in the storage unit, performing function-related processing of the image forming apparatus 1. The paper feeding unit 3, paper delivery unit 4, exposure unit 5, image forming unit 20, transfer unit 30, and fixing unit 6 each receive instructions individually from the control unit 8 and work together to print onto the paper S. The storage unit is, for example, composed of a combination of non-volatile storage devices such as program ROM (Read Only Memory) and data ROM, and volatile storage devices such as RAM (Random Access Memory).

[0028] Furthermore, the image forming apparatus 1, such as Figure 2 As shown, it also includes a voltage application unit 12 and a current detection unit 13.

[0029] The voltage application unit 12 includes, for example, a power supply unit and a control circuit (neither shown). The voltage application unit 12 is electrically connected to the developing roller (developer carrier) 44 of the developing apparatus 40, which will be described later. The voltage application unit 12 applies a developing voltage to the developing roller 44. The control unit 8 controls the timing, voltage value, polarity, and application time of applying the developing voltage to the developing roller 44 via the voltage application unit 12.

[0030] When a developing voltage is applied to the developing roller 44, the current detection unit 13 detects the current flowing between the photosensitive drum 21 and the developing roller 44. The control unit 8 receives information about the current detected by the current detection unit 13 from the current detection unit 13.

[0031] Next, in Figure 2 and Figure 3 Based on, using Figure 4 , Figure 5 and Figure 6 Explain the structure of the developing apparatus 40. Figure 4 , Figure 5 and Figure 6 yes Figure 3 The image forming unit 20 includes a front vertical cross-sectional view, a top horizontal cross-sectional view, and a side vertical cross-sectional view of the developing apparatus 40. Furthermore, since the basic configuration of each color developing apparatus 40 is the same, descriptions and explanations of color identification marks are omitted regarding the constituent elements. Additionally, in this description, "axial direction" refers to the direction of rotation of the photosensitive drum 21, the first transport member 42, the second transport member 43, and the developing roller 44, which extend parallel to each other. Figure 3 and Figure 4 paper depth direction, Figure 5 and Figure 6 (The left and right horizontal directions).

[0032] The developing apparatus 40 supplies toner to the outer peripheral surface of the photosensitive drum 21. The developing apparatus 40 is, for example, detachable from the main body 2 of the image forming apparatus 1. The developing apparatus 40 includes a developing container 50, a first transport member (developer transport member) 42, a second transport member (developer transport member) 43, a developing roller (developer carrier) 44, and a defining member 45.

[0033] The developing container 50 is an elongated shape extending in the axial direction of the photosensitive drum 21, and the long side direction of the developing container 50 is horizontally arranged. That is, the long side direction of the developing container 50 is parallel to the axial direction of the photosensitive drum 21. The developing container 50 accommodates, for example, a two-component developer containing toner and a magnetic carrier, as a developer containing toner supplied to the photosensitive drum 21. The developer can be, for example, a magnetic one-component developer containing a magnetic toner or a non-magnetic one-component developer.

[0034] The developing container 50 has a partition portion 51, a first conveying chamber 52, a second conveying chamber 53, a first communication portion 54, and a second communication portion 55.

[0035] The partition portion 51 is provided at a lower portion of the inside of the developing container 50. The partition portion 51 is arranged at substantially the center portion in a direction (the left-right direction of the drawing, the lateral direction of the drawing) intersecting the long side direction of the developing container 50, and a direction (the up-down direction of the drawing, the vertical direction of the drawing) intersecting the long side direction of the developing container 50. The partition portion 51 is formed in a substantially plate shape extending in the long side direction of the developing container 50 and the up-down direction. The partition portion 51 divides the inside of the developing container 50 in the direction intersecting the long side direction. Figure 4 Figure 5

[0036] The first conveying chamber 52 and the second conveying chamber 53 are provided in the inside of the developing container 50. The first conveying chamber 52 and the second conveying chamber 53 are formed by dividing the inside of the developing container 50 by the partition portion 51. The first conveying chamber 52 and the second conveying chamber 53 are arranged in parallel at substantially the same height as each other.

[0037] The second conveying chamber 53 is arranged adjacent to the lower side of the arrangement region of the developing roller 44 in the developing container 50. The first conveying chamber 52 is arranged in a region farther from the developing roller 44 than the second conveying chamber 53 in the developing container 50. The first conveying chamber 52 is connected to a developer replenishing tube (not shown) and replenishes the developer by means of the developer replenishing tube. The developer is conveyed in the first conveying chamber 52 by the first conveying member 42 in a first direction fl. The developer is conveyed in the second conveying chamber 53 by the second conveying member 43 in a second direction f2 opposite the first direction fl.

[0038] The first communication portion 54 and the second communication portion 55 are arranged outside both end portions in the long side direction of the partition portion 51. The first communication portion 54 and the second communication portion 55 communicate the first conveying chamber 52 and the second conveying chamber 53 in a direction (the left-right direction of the drawing, the lateral direction of the drawing) intersecting the long side direction of the partition portion 51, and a direction (the up-down direction of the drawing, the vertical direction of the drawing) intersecting the long side direction of the partition portion 51, that is, the thickness direction of the substantially plate-shaped partition portion 51. In other words, the first communication portion 54 and the second communication portion 55 communicate with each other on both end portion sides in the long side direction of the first conveying chamber 52 and the second conveying chamber 53. Figure 4 Figure 5

[0039] ​​​​The first communication portion 54 communicates the first direction fl downstream end of the first conveying chamber 52 with the second direction f2 upstream end of the second conveying chamber 53. The first communication portion 54 conveys the developer from the first conveying chamber 52 side toward the second conveying chamber 53 side. The second communication portion 55 communicates the second direction f2 downstream end of the second conveying chamber 53 with the first direction fl upstream end of the first conveying chamber 52. The second communication portion 55 conveys the developer from the second conveying chamber 53 side toward the first conveying chamber 52 side.

[0040] The first conveying member 42 is disposed in the first conveying chamber 52. The second conveying member 43 is disposed in the second conveying chamber 53. The second conveying member 43 extends in parallel to the developing roller 44. The first conveying member 42 and the second conveying member 43 are supported by the developing container 50 so as to be rotatable about an axis extending in the horizontal direction in parallel to the axis of the developing roller 44. The first conveying member 42 and the second conveying member 43 have the same basic configuration, and are provided with helical blades on the outer periphery of the rotating shaft extending in the longitudinal direction of the developing container 50.

[0041] The first conveying member 42 conveys the developer in the first direction fl from the second communication portion 55 side toward the first communication portion 54 side while agitating the developer in the direction of the rotating axis in the first conveying chamber 52. The second conveying member 43 conveys the developer in the second direction f2 from the first communication portion 54 side toward the second communication portion 55 side while agitating the developer in the direction of the rotating axis in the second conveying chamber 53. That is, the first conveying member 42 and the second conveying member convey the developer while agitating the developer in opposite directions to each other, and circulate the developer in a prescribed circulation direction.

[0042] The developing roller 44 is disposed above the second conveying member 43 in the developing container 50 so as to oppose the photosensitive drum 21. The developing roller 44 is supported by the developing container 50 so as to be rotatable about an axis extending in parallel to the axis of the photosensitive drum 21. The developing roller 44 includes, for example, a cylindrical developing sleeve that rotates counterclockwise in Figure 3 and Figure 4 for example, and a developing roller side magnetic pole (both not shown) fixed in the developing sleeve.

[0043] A portion of the outer peripheral surface of the developing roller 44 is exposed from the developing container 50 so as to oppose and approach the photosensitive drum 21. The developing roller 44 carries toner on the outer peripheral surface, and supplies the toner to the outer peripheral surface of the photosensitive drum 21 in the opposing region of the developing roller 44 and the photosensitive drum 21. The developing roller 44 carries the toner in the second conveying chamber 53 of the developing container 50 and supplies the toner to the photosensitive drum 21. In other words, the developing roller 44 causes the toner in the second conveying chamber 53 to adhere to the latent image on the outer peripheral surface of the photosensitive drum 21, and forms a toner image.

[0044] A limiting member 45 is disposed upstream of the developing roller 44 in the rotational direction of the area opposite to the developing roller 44 and the photosensitive drum 21. The limiting member 45 is close to and opposite the developing roller 44, and a predetermined gap is provided between the front end of the limiting member 45 and the outer peripheral surface of the developing roller 44. The limiting member 45 extends throughout the entire axial direction of the developing roller 44. The limiting member 45 limits the thickness of the developer (toner) layer carried on the outer peripheral surface of the developing roller 44 through the gap between the front end of the limiting member 45 and the outer peripheral surface of the developing roller 44.

[0045] The developer in the developing container 50 circulates in a predetermined direction between the first transport chamber 52 and the second transport chamber 53 via the rotation of the first transport member 42 and the second transport member 43 through the first connecting portion 54 and the second connecting portion 55. During this time, the toner in the developing container 50 is agitated and charged, and carried onto the outer peripheral surface of the developing roller 44. After the toner carried on the outer peripheral surface of the developing roller 44 has its layer thickness limited by the limiting member 45, it is transported to the area opposite to the photosensitive drum 21 by the rotation of the developing roller 44. If a predetermined developing voltage is applied to the developing roller 44, the toner carried on the outer peripheral surface of the developing roller 44 moves towards the outer peripheral surface of the photosensitive drum 21 in the opposite area due to the potential difference between the developing roller 44 and the surface (outer peripheral surface) of the photosensitive drum 21. Thus, the electrostatic latent image on the outer peripheral surface of the photosensitive drum 21 is developed using the toner.

[0046] Next, use Figure 4 , Figure 5 and Figure 6 The specific structure of the developing apparatus 40 is explained. Additionally, Figure 4 and Figure 6 The document describes an arrow representing the direction of airflow fd within the ventilation duct 61.

[0047] The developing apparatus 40 includes a toner collection mechanism 60. The toner collection mechanism 60 includes a ventilation duct 61, a filter 62, an exhaust fan 63, and a vibration generating unit 64. The filter 62 includes a first filter 621 and a second filter 622.

[0048] Ventilation duct 61 is disposed adjacent to the second transport chamber 53. Ventilation duct 61 is positioned in a direction intersecting the long side of the developing container 50. Figure 4 The left and right horizontal directions Figure 6 In the paper depth direction, the area of ​​the developing roller 44 within the developing container 50 is opposite to the photosensitive drum 21. The ventilation duct 61 is connected to the second transport chamber 53 at its upstream end in the airflow direction. Air from the second transport chamber 53 flows into the ventilation duct 61. The ventilation duct 61 has an air intake 611 and an exhaust 612.

[0049] The suction port 611 is a connection portion of the ventilation path 61 to the second conveying chamber 53, and is disposed above the developing roller 44. That is, the suction port 611 is located at an upstream end in the air flow direction of the ventilation path 61. The suction port 611 is open over the entire range in the longitudinal direction of the second conveying chamber 53. The suction port 611 is formed, for example, in a rectangular shape extending in the longitudinal direction of the second conveying chamber 53, opposite the developing roller 44. The suction port 611 communicates the inside of the second conveying chamber 53 with the inside of the ventilation path 61. Air in the second conveying chamber 53 flows into the ventilation path 61 through the suction port 611.

[0050] The exhaust port 612 is disposed, for example, at the back of the developing container 50. The exhaust port 612 is located at a downstream end in the air flow direction of the ventilation path 61. Air in the second conveying chamber 53 is exhausted from the inside of the ventilation path 61 through the exhaust port 612. In addition, the ventilation path 61 can be connected to other exhaust paths provided with a fan in the main body 2 at the exhaust port 612.

[0051] The exhaust fan 63 is connected to the exhaust port 612. If the exhaust fan 63 is driven, air in the second conveying chamber 53 is forcibly exhausted to the outside through the ventilation path 61. In other words, the exhaust fan 63 causes air in the second conveying chamber 53 to flow to the outside with the aid of the ventilation path 61.

[0052] The first filter 621 is disposed at the position of the connection portion of the ventilation path 61 to the second conveying chamber 53, that is, the suction port 611. The first filter 621 is the same shape as the suction port 611, for example, formed in a rectangular shape extending in the longitudinal direction of the second conveying chamber 53. The first filter 621 covers the suction port 611. That is, the first filter 621 is opposite the developing roller 44. The first filter 621 is composed of, for example, a non-woven fabric, and collects toner contained in air flowing from the second conveying chamber 53 into the ventilation path 61.

[0053] The second filter 622 is disposed on the downstream side in the air flow direction in the ventilation path 61 than the first filter 621. The second filter 622 is the same shape as the cross-sectional shape of the ventilation path 61 in the direction intersecting the air flow direction, for example, formed in a rectangular shape extending in the longitudinal direction of the second conveying chamber 53. The second filter 622 covers the air flow cross section in the ventilation path 61. The second filter 622 is composed of, for example, a non-woven fabric, and collects toner contained in air flowing in the ventilation path 61 through the first filter 621.

[0054] (Table 1)

[0055] Pressure loss [mmAq] First filter 0.42 Second filter 4.50

[0056] Table 1 shows an example of the performance of the first filter 621 and the second filter 622. The pressure loss when measuring the upstream side static pressure and the downstream side static pressure at an air flow of 10 cm / s is 0.42 mmAq for the first filter 621 and 4.50 mmAq for the second filter 622. Also, for example, the 0.3 μm collection efficiency, the 8 μm collection efficiency are higher for the second filter 622 than for the first filter 621.

[0057] According to the configuration of the filter 62 described above, the first filter 621 can be configured so as not to collect a large amount of toner in the second conveying chamber 53 and so as not to be easily clogged. Also, the second filter 622 can prevent toner from leaking outside the developing container 50.

[0058] The vibration generating portion 64 is disposed, for example, in contact with the back surface of the developing container 50. The vibration generating portion 64 includes, for example, a vibration motor, a control board, and other electronic circuits and electronic parts (none of which is shown). A weight that is offset from the rotational axis of the output shaft of the vibration motor is attached to the output shaft of the vibration motor.

[0059] The vibration generating portion 64 is connected to the first filter 621. When the vibration motor is driven, the vibration generating portion 64 vibrates the first filter 621. By vibrating the first filter 621 using the vibration generating portion 64, toner that has been collected by the first filter 621 and adheres to the first filter 621 can be caused to fall. Thus, the performance of the first filter 621 can be restored, and the scattering of toner in the image forming apparatus 1 can be continuously suppressed.

[0060] Also, the control portion 8 of the image forming apparatus 1 can execute a scattered toner recovery mode for recovering toner collected by the first filter 621 by the drum cleaning portion 23. Figure 7 is Figure 3 is a partially enlarged cross-sectional front view of the periphery of the image forming portion 20, and is a diagram for explaining the scattered toner recovery mode.

[0061] In addition, Figure 7 In the drawing, the direction of rotation R11 of the photosensitive drum 21 at the time of image formation, the direction of rotation R21 of the developing roller 44 at the time of image formation, and the direction of rotation R22 of the developing roller 44 at the time of the scattered toner recovery mode are shown by arrows. The direction of rotation R21 of the developing roller 44 and the direction of rotation R22 are in opposite directions to each other. Also, in order to facilitate explanation, Figure 7 In the drawing, the direction of rotation R11 of the photosensitive drum 21 at the time of image formation, the direction of rotation R21 of the developing roller 44 at the time of image formation, and the direction of rotation R22 of the developing roller 44 at the time of the scattered toner recovery mode are shown by arrows. The direction of rotation R21 of the developing roller 44 and the direction of rotation R22 are in opposite directions to each other. Also, in order to facilitate explanation, Figure 7 In the drawing, the direction of rotation R11 of the photosensitive drum 21 at the time of image formation, the direction of rotation R21 of the developing roller 44 at the time of image formation, and the direction of rotation R22 of the developing roller 44 at the time of the scattered toner recovery mode are shown by arrows. The direction of rotation R21 of the developing roller 44 and the direction of rotation R22 are in opposite directions to each other. Also, in order to facilitate explanation,

[0062] In the toner spill recovery mode, when not forming an image, the control unit 8 vibrates the first filter 621 via the vibration generating unit 64. Furthermore, the control unit 8 controls the charged unit 22 and the voltage applying unit 12 to generate a potential difference that moves the toner from the developing roller 44 towards the photosensitive drum 21, and directs the developing roller 44 in the opposite direction to that during image formation. Figure 7 Rotate the photosensitive drum 21 in the same direction as when the image was formed (R22 direction) and make the photosensitive drum 21 rotate in the same direction as when the image was formed (R22 direction) Figure 7 The toner is rotated in the R11 direction. In this way, in the toner spillage recovery mode, the toner spilled from the first filter 621 and adhering to the outer peripheral surface of the developing roller 44 is recovered by the drum cleaning section 23 via the photosensitive drum 21. Furthermore, in the toner spillage recovery mode, no transfer bias is applied in the primary transfer section 32, and the toner adhering to the outer peripheral surface of the photosensitive drum 21 does not move from the photosensitive drum 21 towards the intermediate transfer belt 31.

[0063] (Example)

[0064] Next, the evaluation of toner scattering within the image forming apparatus 1 will be described. In this evaluation, an image equivalent to a 20% print rate was printed on paper S, and 600,000 sheets were printed. Toner scattering within the image forming apparatus was confirmed. The evaluation conditions are shown in Table 2. As shown in Table 2, comparative example 1 and comparative example 2 image forming apparatuses were prepared for the image forming apparatus 1 of the embodiments of the present invention capable of performing a scattered toner recovery mode.

[0065] (Table 2)

[0066]

[0067] The image forming apparatus 1 of the embodiment includes a filter 62. Furthermore, in the image forming apparatus 1 of the embodiment, the vibration generating unit 64 is activated after every 4000 prints, and the developing voltage when the developing roller 44 reverses is 150V, and the surface potential of the photosensitive drum 21 is 20V. The image forming apparatus of Comparative Example 1 does not include a toner collection mechanism containing a filter. Furthermore, in the image forming apparatus of Comparative Example 1, the developing roller does not reverse, and the toner does not move from the developing roller to the photosensitive drum. The image forming apparatus of Comparative Example 2 has a filter identical to that of Embodiment 1. Furthermore, in the image forming apparatus of Comparative Example 2, the vibration generating unit is activated after every 4000 prints, and the developing voltage when the developing roller reverses is 150V, and the surface potential of the photosensitive drum is 250V. The evaluation results are shown in Table 3.

[0068] (Table 3)

[0069] Confirm toner scattering Example Good Comparative Example 1 Not good Comparative Example 2 Not good

[0070] With regard to Table 3, for the toner scattering confirmation, the state of the toner scattering in the image forming apparatus was visually confirmed. The criterion for the "toner scattering confirmation" was "good" in the case where no toner scattering was confirmed and the inside of the apparatus remained clean, and "bad" in the case where toner scattering was confirmed and the inside of the apparatus was contaminated with the scattered toner.

[0071] As is apparent from Table 3, the image forming apparatuses according to Comparative Examples 1 and 2 generated toner scattering in the apparatus. In this regard, the image forming apparatus 1 according to the embodiment of the present application did not generate toner scattering in the apparatus.

[0072] Thus, according to the configuration of the embodiment, the toner collecting mechanism 60 for attracting and collecting the scattered toner is formed in the developing device 40, and the scattered toner collected by the filter 62 can be recovered by the drum cleaning portion 23 with the aid of the developing roller 44 and the photosensitive drum 21. Therefore, with the configuration that achieves downsizing, the toner scattering in the image forming apparatus 1 can be suppressed.

[0073] Further, the control portion 8 executes the scattered toner recovery mode at every prescribed number of printed sheets. For example, in the image forming apparatus 1 of the above-described embodiment, the control portion 8 executes the scattered toner recovery mode at every 4000 printed sheets. According to the configuration, the scattered toner collected by the filter 62 can be periodically recovered by the drum cleaning portion 23 with the aid of the developing roller 44 and the photosensitive drum 21. Therefore, the suppression effect of the toner scattering in the image forming apparatus 1 can be improved.

[0074] Furthermore, the developer for the formation of the toner image is a two-component developer including a magnetic carrier and toner. It has been known that, in the case of the two-component developer, toner scattering is easily generated from the developing container 50. Therefore, by executing the above-described scattered toner recovery mode in the image forming apparatus 1 using the two-component developer, the toner scattering in the image forming apparatus 1 can be further effectively suppressed.

[0075] Furthermore, the photosensitive drum 21 has a photosensitive layer formed of an amorphous silicon photosensitive body on the outer peripheral surface. It has been known that the photosensitive layer formed of the amorphous silicon photosensitive body has a high dielectric constant and a low toner charge amount. If the toner charge amount is low, toner scattering is easily generated from the developing container 50. Therefore, by executing the above-described scattered toner recovery mode in the image forming apparatus 1 using the photosensitive drum 21 having the amorphous silicon photosensitive body, the toner scattering in the image forming apparatus 1 can be further effectively suppressed.

[0076] The above describes the embodiment of the present application, but the scope of the present application is not limited thereto, and various modifications can be added within the scope of the idea of the present application.

[0077] For example, according to the above-described embodiment, the image forming apparatus 1 is a so-called tandem type image forming apparatus for color printing that sequentially superimposes multicolor images, but is not limited to this type. The image forming apparatus can be a non-tandem type image forming apparatus for color printing or an image forming apparatus for black-and-white printing.

Claims

1. An image forming apparatus characterized by comprising: including: an image carrier on which an electrostatic latent image is formed on an outer peripheral surface; a charging section that charges the outer peripheral surface of the image carrier; a cleaning section that cleans the outer peripheral surface of the image carrier; a developing device that has a developing container that accommodates a developer including toner to be supplied to the image carrier, a developer conveying member that is rotatably supported in a conveying chamber of the developing container, conveys and circulates the developer while stirring, and a developer carrier that is rotatably supported in the developing container opposite to the image carrier, supplies the toner in the conveying chamber to the image carrier; a voltage application section that applies a developing voltage to the developer carrier; and a control section that controls the image carrier, the charging section, the cleaning section, the developing device, and the voltage application section, the developing device is provided with a toner collection mechanism including: an air passage that is connected to the conveying chamber and through which air in the conveying chamber flows; a filter that is disposed above the developer carrier at a connection portion of the air passage and the conveying chamber and collects the toner flowing from the conveying chamber into the air passage; an exhaust fan that causes air in the conveying chamber to flow out to the outside via the air passage; and a vibration generation section that vibrates the filter, the control section can execute a flying toner recovery mode in which, at a time other than an image forming time, the filter is vibrated by the vibration generation section, the charging section and the voltage application section are controlled in a manner that generates a potential difference in a direction in which the toner moves from the developer carrier to the image carrier, the developer carrier is caused to rotate in a direction opposite to that at the image forming time, and the image carrier is caused to rotate in the same direction as at the image forming time, and flying toner that has fallen from the filter and adheres to the outer peripheral surface of the developer carrier is recovered by the cleaning section via the image carrier. The control section executes the flying toner recovery mode every predetermined number of printed sheets.

2. The image forming apparatus according to claim 1, characterized by, The developer is a two-component developer including a magnetic carrier and the toner.

3. The image forming apparatus according to claim 1, characterized by, The image carrier has a photosensitive layer formed of an amorphous silicon photosensitive body on an outer peripheral surface.

4. The image forming apparatus according to claim 1, characterized by, 5. The image forming apparatus according to any one of claims 1 to 4, wherein the filter includes: a first filter that covers a suction port that is opened throughout a whole domain in a longitudinal direction of the conveying chamber and communicates the conveying chamber and the air passage; and a second filter that is disposed on a downstream side in a direction of air flow in the air passage from the first filter and covers a cross section of the air flow in the air passage. ​

Images