JP2013156503A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the problem in which: a half-loosen state of a connector (harness) can be visually recognized before a developing device is set to an image forming apparatus, but thereby toner density detection means does not work.SOLUTION: A process cartridge 30 has a photoreceptor drum 3 and a developing device 9 mounted thereon. The developing device 9 uses a two-component developer comprising toner and a carrier, and includes toner density detection means for detecting density of toner in the developing device. A protective cover 43 for protecting the toner density detection means is attached to the outside of the toner density detection means. The protective cover 43 is provided with a confirmation window 44, which allows visual recognition of a connector connection part inside therefrom.

Description

  The present invention relates to a developing device that is a means for visualizing an electrostatic latent image, a process cartridge equipped with the developing device, and an image forming apparatus.

  As a means for visualizing an electrostatic latent image, a two-component developing type developing device using a two-component developer composed of a toner and a carrier is well known. In the two-component magnetic brush development, the toner is mixed with a carrier (magnetic powder) and stirred to cause tribocharging, and the developer that is a mixture of the toner and the carrier is referred to as a developer carrier (hereinafter referred to as a developing roller). ) To the developing area facing the latent image carrier, and the toner is attached to the electrostatic latent image on the latent image carrier for development.

  A developing device that has been widely used in the past is a type in which a developer stirring and conveying member such as a screw disposed adjacent to the developing roller serves both as a supply and recovery of the developer to the developing roller. . Even in a configuration including two developer agitating / conveying members, in the conventional one, two developer agitating / conveying members are arranged in the lateral direction, and the developer agitating / conveying member adjacent to the developing roller is developed. Both the supply and recovery of the agent were combined.

  In contrast, in recent years, two developer agitating and conveying members are arranged in the vertical direction and adjacent to the developing roller, and one developer agitating and conveying member is allowed to act as a supply screw for supplying the developer to the developing roller, An increasing number of other developer agitating and conveying members are configured to act as a collecting screw for collecting the developer from the developing roller, which is disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-310340 (Patent Document 1). Such a developing device is a system that circulates and conveys developer in one direction, such as a supply path parallel to the developing roller → developing roller → a collection path parallel to the developing roller → toner replenishment unit → the supply path. Hereinafter, it is referred to as a one-way circulation system.

  In the conventional developing device described above, the developer once supplied to the developing roller and the toner consumed by the image formation returns to the conveyance path again and is used for image formation. Repeat throughout the transport. As a result, the amount of toner included in the developer gradually decreases while being conveyed in the longitudinal direction of the developing roller. That is, there is a structural problem that a difference in image density (difference in density) tends to occur at both ends in the image width direction (the developing roller longitudinal direction).

  On the other hand, the above-described one-way circulation type developing device is once supplied to the developing roller, the developer that has consumed the toner by the image formation is recovered as it is, and after the toner is newly replenished, it returns to the supply path and develops again. The developer is supplied to the roller. Therefore, it can be said that the image density difference (difference in density in the longitudinal direction of the developing roller) hardly occurs as in the conventional developing device.

  By the way, a toner replenishing section (replenishing port) for replenishing toner (new toner) in the developing device is usually provided in the developing device so as to be located on the back side of the main body when the developing device is mounted on the main body of the image forming apparatus. It is done. In this case, in the one-way circulation type developing device, the toner is replenished from the back side of the main body (the replenishing portion located in the main body) and developed from the back side to the front side of the device by the lower conveying screw (developer stirring and conveying member). The developer is sent, the developer is lifted to the upper conveying screw on the near side, and the developer is conveyed from the near side to the far side by the upper conveying screw.

  In addition, it has been found that the toner density in the developing device can be detected more accurately by detecting at a location where the developer density is high. In a one-way circulation type developing device, the upper conveyance from the lower conveyance screw is known. The area where the developer is lifted onto the screw is suitable for detecting the toner density. Therefore, the toner density detection means is installed on the front side of the developing device (a place on the front side of the main body when the developing device is mounted on the main body of the image forming apparatus). The toner concentration detection means is often attached to the outside of the housing of the developing device (facing the outside), and the toner concentration detection means and the developing device main body are connected by a harness (by a connector attached to the end of the harness). Is configured to do.

  In such a configuration, when the developing device is attached / detached (attached / detached to / from the main body of the image forming apparatus), there is a possibility that the hand directly touches the toner density detecting means on the front side of the main body device. In some cases, the toner density detecting means is broken. Conventionally, in order to prevent the operator's hand from directly touching the toner density detecting means, a cover is attached to the toner density detecting means installation portion of the developing device. After the cover is attached, the connection harness is pulled. As a result, there is a problem that the connector is in a partially disconnected state from the connecting portion, and the detection means does not function.

  The present invention solves the above-mentioned problems in the conventional developing device, and can visually check the half-detached state of the connector (harness) before setting the developing device in the main body of the image forming apparatus. It is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus that can prevent the problem that the printer does not function.

  According to the present invention, there is provided a developing device that uses a two-component developer composed of toner and a carrier, and includes a toner concentration detecting unit that detects a toner concentration in the developing device. This problem can be solved by providing a confirmation window on the protective cover, which has a protective cover for protecting the toner density and allows the connector connection portion of the toner concentration detecting means to be visually observed.

  According to the developing device of the present invention, the confirmation window through which the connector connecting portion of the toner density detecting means can be visually observed is provided on the protective cover for protecting the toner density detecting means. In addition, it is possible to visually check the half-detached state of the connector (harness). As a result, the problem that the toner density detecting means does not function can be prevented.

1 is an external perspective view of a printer as an example of an image forming apparatus according to the present invention. 2 is a cross-sectional configuration diagram illustrating an example of an internal configuration of the printer. FIG. It is a schematic sectional drawing of a process cartridge. It is the perspective view which looked at the near side part of a process cartridge from the slanting lower part. FIG. 5 is a bottom view of the front side portion of the process cartridge as viewed from directly below.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an external perspective view of a printer as an example of an image forming apparatus according to the present invention. FIG. 2 is a cross-sectional configuration diagram showing an example of the internal configuration of the printer. The image forming apparatus shown in both figures is a tandem type color image forming apparatus. In FIG. 1, a double arrow Y indicates a sheet width direction orthogonal to the sheet discharge direction Xa, and a sheet discharge direction Xb indicates a direction opposite to the sheet discharge direction Xa.

  As shown in FIGS. 1 and 2, the image forming apparatus of this example is disposed almost at the center of the apparatus main body 1, and includes an image forming unit 2 including an image forming unit described later that forms an image on a sheet, and this image. A sheet feeding unit 20 that is disposed below the forming unit 2 and feeds a sheet S as an example of a sheet or a sheet-like recording medium to the image forming unit 2 and a sheet on which an image is formed by the image forming unit 2 are discharged. A sheet discharge unit 25 and a sheet stacking unit 40 that is disposed above the image forming unit 2 and stacks sheets discharged from the sheet discharge unit 25 are provided. Here, the sheet is, for example, paper such as transfer paper or recording paper (including thick paper, postcard, envelope, plain paper, thin paper, etc.), coated paper (including coated paper, art paper, etc.), OHP sheet or OHP. It means an image forming medium capable of transferring an image, including film, tracing paper and the like. The image forming unit 2 is also referred to as an image recording unit 2 that records an image on the paper S, and the sheet stacking unit 40 is also referred to as a sheet mounting unit 40 that mounts and stacks discharged sheets.

  As shown in FIG. 2, the image forming unit 2 includes a plurality of drum-shaped photoconductors 3a, 3b, 3c, and 3d configured as an image carrier or a latent image carrier, and each of the photoconductors 3a to 3d. In 3d, toner images of different colors are formed. In the illustrated example, a yellow toner image, a cyan toner image, a magenta toner image, and a black toner image are formed on the surfaces of the photoreceptors 3a to 3d, respectively. The photoconductors 3a to 3d are arranged in parallel with each other at a predetermined interval, and an intermediate transfer belt 4 configured as an intermediate transfer body is arranged facing the lower portions of the photoconductors 3a to 3d. As the image carrier / intermediate transfer member, a drum can be used. However, in the illustrated example, the drum is wound around a plurality of support rollers 5 and 6 and is driven in an arrow direction (counterclockwise in FIG. 2). An intermediate transfer belt 4 composed of a belt is used.

  Since the configuration around each of the photoconductors 3a to 3d is the same, the photoconductor 3a on which the yellow toner image arranged on the rightmost side in FIG. 2 is formed will be described as a representative. That is, there are a charging device 7 that uniformly charges the surface of the photoconductor 3a around the photoconductor 3a and an optical scanning device (LSU) 8 that irradiates the surface of the photoconductor 3a with laser light. Exposure, a developing device 9 that visualizes the electrostatic latent image formed on the surface of the photosensitive member 3a by the exposure, a transfer device 10 disposed opposite to the photosensitive member 3a via the intermediate transfer belt 4, an intermediate A cleaning device 11 that removes and collects toner remaining on the surface of the photoreceptor 3a after being transferred to the transfer belt 4 is provided. A cylindrical toner container 50 and a replenishing mechanism (not shown) are disposed above the developing device 9, and the replenishing mechanism is driven according to toner consumption in the developing device 9, and the toner replenishing path 51 from the toner container 50. Then, the toner is supplied to the developing device 9.

  When image formation is started in such an image forming apparatus, the photosensitive member 3a is rotated in the clockwise direction in FIG. 2, and at this time, the surface of the photosensitive member 3 is uniformly charged to a predetermined polarity by the charging roller 7. . Next, the charged surface is irradiated with laser light based on image information from the optical scanning device 8, thereby forming an electrostatic latent image on the photoreceptor 3 a. The electrostatic latent image formed on the surface of the photoreceptor 3 a is visualized as a yellow toner image by the developing device 9, and the yellow toner image is transferred onto the intermediate transfer belt 4 by the transfer device 10.

  At the time of full color image formation, the above-described image forming operation is performed in the same manner on all the remaining photoconductors 3b to 3d, whereby yellow toner images, cyan toner images, and magenta toner images respectively formed on the respective photoconductors 3a to 3d. Then, the black toner image is sequentially transferred onto the intermediate transfer belt 4 in a superimposed manner. In the image forming apparatus, a secondary transfer roller 12 is disposed so as to face the support roller 6 with the intermediate transfer belt 4 interposed therebetween.

  On the other hand, a paper feed unit 20 disposed below the image forming unit 2 includes a paper feed tray 21 as a sheet storage unit on which sheets S as sheets made of transfer paper, recording paper, resin film, and the like are stacked, A paper feed roller 22 that feeds the paper S stacked on the paper feed tray 21 and a friction pad 23 as a separating unit that separates the multi-feed paper into one sheet are provided.

  The sheet S fed from the sheet feeding unit 20 is sent out toward the registration roller 13 and is once abutted against the registration roller 13 whose leading end is stopped. As a result, after the oblique deviation of the leading edge of the sheet S is corrected and aligned, the registration roller 13 causes the color toner image formed on the intermediate transfer belt 4 to be printed on the secondary transfer portion provided with the secondary transfer roller 12. The rotation is resumed at a predetermined timing so as to coincide with the leading end portion of S, and the sheet S is sent out toward the secondary transfer portion including the secondary transfer roller 12.

  The sheet S on which the unfixed color toner image is transferred in the secondary transfer unit is sent to the fixing unit 14 which is a fixing device, and after the unfixed color toner image is fixed by heating and pressing by the fixing unit 14. The pair of paper discharge rollers 25a and 25b of the sheet discharge means 25 discharges and discharges the image surface downward (face down) onto the sheet stacking portion 40 provided on the upper surface of the apparatus main body 1. The fixing unit (fixing device) 14 includes a fixing roller 14a, a fixing belt 14c wound around a fixing roller 14a and a heating roller (not shown), a pressure roller 14b pressed against the fixing roller 14a via the fixing belt 14c. Consists of. The fixing unit 14 is not limited to the above-described one, and a roller type having a built-in heater and a heating method adopting IH can be appropriately employed. The transfer residual toner and the like adhering to the surface of the intermediate transfer belt 4 after the color toner image transfer is removed by the belt cleaning device 15 to prepare for the next image forming / transfer process.

  FIG. 3 is a schematic cross-sectional view of a process cartridge provided with the respective photoreceptors 3a to 3d. Since the configuration of the four process cartridges provided in the image forming apparatus of the present embodiment is the same, the configuration will be described using the process cartridge arranged on the rightmost side in FIG. 2 as an example.

  As shown in FIG. 3, the process cartridge 30 includes a photoconductor housing 31 in which the photoconductor 3 a and the like are mounted, and a developing housing 32 in which various components constituting the developing device 9 are mounted. Between both housings, a laser beam path space 33 is formed through which laser light irradiated from the optical scanning device 8 shown in FIG. In addition to the photosensitive member 3 a and the developing device 9, the process cartridge 30 includes a charging roller 7, a charging roller cleaning member 26, a cleaning blade 11, a waste toner collecting screw 27, a lubricant 28, and a lubricant application brush 29.

The developing device 9 will be described with reference to FIG.
The developing device 9 of the present embodiment includes a developing roller 34 as a developer carrying member for carrying the developer on the surface, a supply screw 36 disposed in a supply path 35 for supplying the developer to the developing roller 34, A collecting screw 38 disposed in a developer collecting 37, a doctor blade 39 as a regulating member for regulating the thickness of the developer carried on the surface of the developing roller 34, and a toner concentration sensor for detecting toner concentration 42. In the developing device of this example, a two-component developer composed of toner and carrier is used.

  The developer in the supply path 35 is conveyed by the supply screw 36, falls from the opening of the supply path 35, and is sprinkled on the developing roller 34. The developer carried on the developing roller 34 is regulated by the doctor blade 39, and after having reached a layer thickness corresponding to the doctor gap, it is conveyed to a position facing the photosensitive member 3a (photosensitive member gap). Is electrostatically transferred to the photoreceptor 3a, and the electrostatic latent image on the photoreceptor 3a is visualized as a toner image. Thereafter, the developer on the developing roller 34 is collected in the collecting path 37. The developer collected in the collection path 37 is conveyed by the collection screw 38. The collection screw 38 conveys the developer in the axial direction, and deposits the developer at the downstream end thereof. The developer that has accumulated and the toner density has risen again is lifted to the upper supply path 35 through a communication port (not shown), and is sequentially supplied to the developing roller 34 while being conveyed in the axial direction by the supply screw 36. A toner concentration sensor 42 is arranged in the vicinity of the downstream end of the collection screw 38 and the accumulation portion so as to face from the outside of the developing housing 32 (from below in this example). Then, the toner concentration of the collected developer is magnetically detected. The toner density adjustment is performed based on the toner density information detected by the toner density sensor 42. That is, there is a replenishment port (not shown) above the downstream end of the supply screw 36, and a toner replenishment mechanism (not shown) from the toner container 50 (FIG. 1) disposed above the developing device according to the consumed toner. Toner is supplied.

  As described above, in the developing device of this embodiment that adopts the one-way circulation system, the developer that has consumed the toner supplied to the developing roller is temporarily collected without being repeatedly supplied to the developing roller, and then the toner is replenished. Is done. That is, since the unused developer is supplied to the developing roller 34 or the developer supplied with toner after use is supplied, there is a difference in image density at both ends in the longitudinal direction of the developing roller 34. It can be suppressed from occurring.

  Incidentally, the supply screw 36 conveys the developer in a direction from the top to the bottom in the direction perpendicular to the drawing (from the front side to the back side in the drawing), and the recovery screw 38 is from the bottom to the top in the direction perpendicular to the drawing. The developer is conveyed in the direction from the back side to the front side of the drawing. At the downstream end of the collection screw 38 in the conveyance direction, the developer is lifted from the lower conveyance screw (collection screw 38) to the upper conveyance screw (supply screw 36). As described above, the developer recovered in the recovery path 37 is transported by the recovery screw 38 and accumulated on the downstream side in the transport direction, so that the density of the developer is high. A toner concentration sensor 42 is disposed in the vicinity of the downstream end of the collection screw 38 in the transport direction where the developer density increases. Thereby, the toner density can be detected with high accuracy.

  The process cartridge 30 is configured to be attachable to and detachable from the main body 1 of the image forming apparatus. When attaching or detaching, the front cover 17 (FIG. 1) is opened on the front side (front side) of the apparatus main body 1. It is configured. A toner replenishing portion from the toner container 50 to the developing device 9, that is, a toner replenishing port (not shown) to which the toner replenishing path 51 is connected is obtained when the developing device 9 (process cartridge 30) is attached to the apparatus main body 1. It is located on the back side of the device. The toner density sensor 42 is positioned on the front side (front side) of the apparatus when the developing device 9 (process cartridge 30) is attached to the apparatus main body 1.

  In this embodiment, the toner density sensor 42 and the developing device 9 main body are connected by a harness (not shown), and the end of the harness has a connector shape and is in contact with the toner density sensor 42. A portion where the connector shape of the harness end portion is inserted (connected) into the toner concentration sensor 42 is hereinafter referred to as a connector connecting portion.

  In the configuration in which the toner density detecting means is installed on the front side of the developing device (the front side of the main body when the developing device is mounted on the image forming apparatus main body), the main body is attached when the developing device (process cartridge) is attached or detached. There is a possibility that the hand directly touches the toner density detecting means on the front side of the apparatus.

  Therefore, in the developing device 9 of the present embodiment, a protective cover that covers the toner density sensor 42 from the outside is attached to the developing device. FIG. 4 is a perspective view of the front side portion of the process cartridge 30 as viewed obliquely from below. In FIG. 4, a toner concentration sensor 42 is provided so as to be positioned at a lower portion on the near side of the developing device 9, and a protective cover 43 that covers the toner concentration sensor 42 from the outside is attached to the developing housing 32. Yes. In this embodiment, since the front plate 24 of the process cartridge is configured to be hooked on the protective cover 43, the protective cover 43 cannot be removed unless the front plate 24 is removed.

  FIG. 5 is a bottom view of the front side portion of the process cartridge 30 shown in FIG. 4 as viewed from directly below. As shown in this figure, the protective cover 43 is provided with a confirmation window (a window composed of a plurality of openings), and the connector connection part 45 inside can be seen from the confirmation window 44. Therefore, before setting the developing device 9 (process cartridge 30) in the image forming apparatus main body 1, the state of the connector connection portion 45, that is, the connection state of the connector is directly visually checked through the confirmation window 44 of the protective cover 43. It is possible to confirm. If the harness (connector) is half-inserted or obliquely inserted, a tool (for example, a tool such as a thin flat-blade screwdriver) can be inserted from the confirmation window 44 and the connector can be correctly reinserted. Even if the harness (connector) is connected correctly, if the harness is pulled, reconfirm the connection state from the confirmation window 44, and the connector is in a half-detached state. Can be reconnected as described above.

  As described above, in this embodiment, the protective cover 43 is attached to the toner density sensor 42 installation portion of the developing device 9, thereby preventing the operator who replaces the process cartridge from directly touching the toner density sensor 42. it can.

  When the protective cover 43 is provided with a confirmation window 44 through which the connector connecting portion 45 can be visually observed, when a harness (connector) connected to the toner concentration sensor 42 is half-inserted or obliquely inserted, Alternatively, when the harness is pulled after connection and the connector is in a partially disconnected state, the connection state can be confirmed from the confirmation window 44 and the connection can be corrected using a tool from the confirmation window 44, so that the developing device (process cartridge) It is possible to prevent the problem that the toner density sensor does not function after the toner is set in the image forming apparatus main body.

  As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this. In the above-described embodiment, the present invention has been described by using a one-way circulation type developing device. However, the present invention is not limited to the one-way circulation type, and a two-component developing device having a protective cover for toner density detection means. Applicable.

  The size and shape of the protective cover of the toner concentration detection means (toner concentration sensor), the mounting position thereof, and the like can be appropriately changed according to the configuration of the developing device. In addition, the shape and size of the confirmation window provided in the protective cover, the number of openings, and the like can be set as appropriate. The configuration of each part of the developing device can be changed as appropriate, and the equipment mounted on the process cartridge is also arbitrary.

  Further, the image forming apparatus is not limited to a full-color machine, and may be a multi-color machine or a monochrome apparatus having a plurality of colors. Of course, the image forming apparatus is not limited to a printer, and may be a copier, a facsimile machine, or a multifunction machine having a plurality of functions.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus main body 2 Image forming part 3 Photosensitive drum 9 Developing device 30 Process cartridge 32 Developing housing 34 Developing roller (developer carrier)
36 Supply screw 38 Recovery screw 39 Doctor blade 42 Toner concentration sensor (toner concentration detection means)
43 Protective cover 44 Confirmation window 45 Connector connection 50 Toner container

JP 2007-310340 A

Claims (5)

In a developing device using a two-component developer composed of a toner and a carrier, the developing device including a toner concentration detecting means for detecting the toner concentration in the developing device.
A developing device having a protective cover for protecting the toner density detecting means, and provided with a confirmation window on the protective cover for visualizing a connector connecting portion of the toner density detecting means.   The developing device according to claim 1, wherein the confirmation window is provided so that a tool for repairing a connector connection state of the toner concentration detection unit can be inserted. A developer carrier that carries the two-component developer on the surface and conveys the developer to the development region, and a pair of the developer carrier that are arranged in parallel in the vertical direction adjacent to the developer carrier and that stir and convey the developer in opposite directions. Developer agitating and conveying means,
One of the pair of developer agitating and conveying means is a supply screw for supplying the developer to the developer carrying member, and the other is a recovery screw for collecting the developer,
3. The developing device according to claim 1, wherein the toner density detection unit is disposed in the vicinity of the downstream end of the recovery screw in the developer conveyance direction.   A process cartridge comprising at least a latent image carrier and the developing device according to claim 1. An image forming apparatus comprising the developing device according to claim 1 or the process cartridge according to claim 4.

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