JP2016142878A - Cartridge, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cartridge with high cleaning performance.SOLUTION: There is provided a cartridge comprising a cleaning member that is in contact with an image carrier to remove a developer on the image carrier, a storage chamber that stores a developer removed from the image carrier by the cleaning member, and a conveyance member that is provided immediately above the image carrier in the gravity direction to convey the removed developer from the storage chamber, where a time to start driving the conveyance member is after a time to start driving the image carrier.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a cartridge, a process cartridge, and an image forming apparatus using these.

  Here, the cartridge has at least a conveying member that conveys the developer. The process cartridge has at least an image carrier such as a photosensitive drum. Further, the process means acting on the image carrier is integrally formed into a cartridge and is detachably attached to the image forming apparatus main body.

  For example, a photosensitive drum as an image carrier and at least one of a developing unit, a charging unit, and a cleaning unit as a process unit are integrally formed into a cartridge. Examples of the image forming apparatus include an apparatus that forms an image on a recording material using an electrophotographic image forming system.

  Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (such as an LED printer and a laser beam printer), a facsimile machine, and a word processor.

  In an electrophotographic image forming apparatus (hereinafter also referred to as “image forming apparatus”), a drum-type electrophotographic photosensitive member (hereinafter also referred to as a photosensitive drum) is generally charged uniformly. Next, an electrostatic latent image (electrostatic image) is formed on the photosensitive drum by selectively exposing the charged photosensitive drum. The electrostatic latent image formed on the photosensitive drum is developed as a toner image with toner as a developer. The toner image formed on the photosensitive drum is transferred to a recording material such as recording paper or a plastic sheet, and the toner image is further transferred to the recording material by applying heat or pressure to the toner image transferred onto the recording material. The image is recorded by fixing it to the surface.

  Such an image forming apparatus generally requires toner replenishment and maintenance of various process means. In order to facilitate this toner replenishment and maintenance, the photosensitive drum, charging means, developing means, cleaning means, etc. are put together into a cartridge to form a cartridge, and a process cartridge that can be attached to and detached from the image forming apparatus main body is put into practical use. Has been.

  According to this process cartridge system, since the user can perform maintenance of the apparatus himself, the operability can be remarkably improved, and an image forming apparatus excellent in usability can be provided. For this reason, this process cartridge system is widely used in image forming apparatuses.

  In the process cartridge described above, it may be necessary to transport the toner collected from the surface of the photosensitive drum by the cleaning unit to a position away from the photosensitive drum. As a means for conveying the toner, a conveying member such as a configuration using a screw as described in Patent Document 1 is known.

Japanese Patent Laid-Open No. 10-312142

  However, when the toner collected by the cleaning means is transported by the transport member disposed above the photosensitive drum, the pressure of the toner accumulated in the cleaning frame is applied to the contact portion between the cleaning member and the photosensitive drum. Under such circumstances, further, when the cleaning capability at the start of driving of the photosensitive drum is low, there is a possibility that toner or an external additive of the toner may slip through the cleaning member.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a cartridge or the like having a high cleaning performance by reducing the pressure caused by the developer applied to a contact portion where the cleaning member and the image carrier are in contact with each other when driving of the image carrier is started.

  Accordingly, the present invention provides a cleaning member that contacts the image carrier and removes the developer on the image carrier, a storage chamber that contains the developer removed from the image carrier by the cleaning member, and the image A conveying member that is provided immediately above the carrier in the direction of gravity and conveys the removed developer from the storage chamber, and the driving of the conveying member is started when the driving of the image carrier is started. It also provides a slower cartridge.

  The present invention also provides a process cartridge and an image forming apparatus.

  As described above, according to the present invention, the pressure due to the developer applied to the contact portion where the cleaning member and the image carrier are in contact with each other can be reduced, and the cleaning performance can be improved.

1 is a cross-sectional view of an image forming apparatus main body and a process cartridge of an electrophotographic image forming apparatus according to Embodiment 1. FIG. 2 is a cross-sectional view of a process cartridge according to Embodiment 1. FIG. 3 is a cross-sectional view of the inside of a cleaning container of a process cartridge according to Embodiment 1. FIG. It is the figure which showed the change of the distortion | strain of the cleaning blade before and behind the drum drive which concerns on Example 1. FIG. It is an image figure of sensor pasting at the time of distortion measurement of a cleaning blade. FIG. 3 is a diagram illustrating a shape of a conveyance member according to the first embodiment.

[Example 1]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Note that the direction of the axis of rotation of the photosensitive drum as the image carrier is the longitudinal direction.

  The overall configuration and the image forming process will be described with reference to FIG. FIG. 1 is a cross-sectional view of an image forming apparatus main body (hereinafter referred to as apparatus main body A) and a process cartridge (hereinafter referred to as cartridge B) of an electrophotographic image forming apparatus according to an embodiment of the present invention. .

  Here, the apparatus main body A is a portion obtained by removing the cartridge B from the electrophotographic image forming apparatus.

<Image formation process>
Next, an outline of the image forming process will be described. As shown in FIG. 1, based on the print start signal, the photosensitive drum 1 (hereinafter referred to as drum 1) is rotationally driven in the direction of arrow R with a predetermined peripheral speed (process speed). A charging roller 2, which is a charging means to which a bias voltage is applied, contacts the outer peripheral surface of the drum 1 and is driven by the drum 1 to uniformly and uniformly charge the outer peripheral surface of the drum 1. The exposure device 3 outputs a laser beam L corresponding to the image information. The laser beam L scans and exposes the outer peripheral surface of the drum 1. Thereby, an electrostatic latent image (electrostatic image) corresponding to the image information is formed on the outer peripheral surface of the drum 1.

  On the other hand, as shown in FIG. 1, in the developing unit 4 as a developing device, the developer in the toner chamber 5 (hereinafter referred to as toner T) is agitated by the rotation of the first conveying member 6 and the second conveying member 7. It is conveyed and sent out to the toner supply chamber 8. The toner T is carried on the surface of the developing roller 10 which is a developing sleeve by the magnetic force of the magnet roller 9 (fixed magnet). The layer thickness of the toner T on the peripheral surface of the developing roller 10 is regulated while being frictionally charged by the developing blade 11.

  The toner T is developed on the drum 1 in accordance with the electrostatic latent image, and is visualized as a toner image. Further, as shown in FIG. 1, in synchronization with the output timing of the laser beam L, the sheet material P, which is a recording material sent out from the sheet tray 12, is conveyed to a transfer position between the drum 1 and the transfer roller 13. . At this transfer position, the toner images are sequentially transferred from the drum 1 to the sheet material P.

  The sheet material P to which the toner image has been transferred is separated from the drum 1 and conveyed to the fixing device 14. Then, when the sheet material P passes through the fixing device 14, a pressure / heat fixing process is performed, and the toner image is fixed to the sheet material P. The sheet material P that has undergone the toner image fixing process is discharged to the discharge tray 15.

  On the other hand, as shown in FIG. 1, the drum 1 after the transfer is used again in the image forming process after the residual toner on the outer peripheral surface (on the image carrier) is removed by the cleaning member 16. The toner removed from the drum 1 is stored in the storage chamber 19b. The toner stored in the storage chamber 19b is stored in the waste toner chamber 19a of the cleaning unit 18 by the screw 17 that is a conveying member. In this embodiment, the storage chamber 19 including the waste toner chamber 19a is used. For example, the storage chamber 19b and the waste toner chamber 19a may be separated by a partition wall. In such a case, the toner is moved to the end of the conveying member 17 in the axial direction by the conveying member, and is moved from the storage chamber 19b toward the waste toner chamber 19a at the end. When the end of the waste toner chamber 19a is reached, it may be moved to the center of the waste toner chamber with a screw or the like.

  In this embodiment, the charging roller 2, the developing roller 10, the transfer roller 7, and the cleaning member 77 are process means that act on the drum 1.

<Configuration of the entire cartridge>
Next, the overall configuration of the cartridge B will be described with reference to FIG. The cartridge B has a cleaning unit 18 and a developing unit 4. In this embodiment, the cartridge in which the cleaning unit 18 and the developing unit 4 are combined is used as a cartridge, but the present invention is not limited to this. For example, the cleaning unit may be a cleaning cartridge alone.

  As shown in FIG. 2, the developing unit 4 includes a developing blade 11, a developing roller 10, a first conveying member 6, and a second conveying member 7. Further, the developing roller 10, the first conveying member 6, and the second conveying member 7 can transmit driving from a developing driving source (not shown) of the image forming apparatus main body via a gear (not shown). It is mounted for rotation. The developing roller 10 is held on the frame body at a predetermined interval from the drum 1 by a gap holding member 22 (not shown) attached to both ends of the developing roller 10.

  On the other hand, the cleaning unit 18 includes a drum 1, a charging roller 2, a cleaning member 16, a screw 17 that is a conveying member, and a drum contact sheet 20. In the cleaning unit 18, the charging roller 2, the cleaning member 16, and the drum contact sheet 20 are arranged in contact with the outer peripheral surface of the drum 1. Further, in the relationship of the contact position with the drum 1, the cleaning member is at a position of 10 ° on the downstream side in the rotation direction of the drum 1 with respect to the uppermost end in the gravity direction of the drum 1. In other words, the contact portion where the cleaning member and the drum are in contact with each other is located on the downstream side in the drum rotation direction with respect to the closest position on the drum surface closest to the screw. On the other hand, the drum contact sheet 20 is in contact with the drum contact sheet 20 at a position of 10 ° upstream.

  In the configuration of FIG. 3 of the present embodiment, the drum rotates clockwise and the screw rotates counterclockwise, but the present invention is not limited to this. For example, the screw may rotate clockwise as well as the drum.

  The cleaning member 16 includes a rubber blade 16a that is a blade-like elastic member formed of rubber as an elastic material, and a support member 16b that supports the rubber blade 16a. The cleaning member 16 is in contact with the drum 1 in a counter direction with respect to the rotation direction of the drum 1. That is, the rubber blade 16 a is in contact with the drum 1 such that the tip end portion thereof faces the upstream side in the rotation direction of the drum 1. The angle formed between the outer peripheral surface of the drum 1 and the rubber blade 16b at the contact position is 21 °, and the rubber blade 16a is disposed so as to enter the outer peripheral surface of the drum 1 with a width of 1.0 mm. The drum 1 is a drum drive source (not shown) of the main body of the image forming apparatus, and the screw 17 is rotatably mounted via a drive gear from a conveyance drive source.

  In this embodiment, there are two drive sources, a drive source for the drum 1 and a drive source for the screw, but the drum 1 and the screw 17 can be changed by changing the drive transmission timing by switching the clutch or the like with one drive source. The drive timing may be changed. In the present embodiment, the drive of the screw 16 and the developing roller 10 is transmitted from the same drive source in order to reduce the size of the main body, but the screw 16 and the developing roller 10 may be transmitted from different drive sources. good. Here, the drive source refers to the number of drive units on the apparatus main body side for transmitting drive to the cartridge, and the cartridge has a driven unit that receives drive from the drive unit. Driving from a plurality of driving sources means that the cartridge is driven from a plurality of locations and has a plurality of driven parts.

<Details of cleaning unit>
Next, details of a portion to be cleaned will be described with reference to FIG. FIG. 3 is a view showing a cross section of a configuration related to cleaning of the cartridge B as viewed from the longitudinal direction (drum axial direction).

  As shown in FIG. 3, the drum 1 and the screw 17 are arranged so that the axis of rotation is parallel to the axis of rotation of the screw 17. The screw 17 includes a rotating shaft 17a and a spiral blade 17b provided outside the rotating shaft 17a (see FIG. 6). Further, the screw 17 is disposed immediately above the drum 1 when viewed from the direction of gravity. Directly above means that the entire cross section of the screw is disposed within the range of the diameter of the drum in the horizontal direction (region V). Further, the screw 17 is preferably arranged so that the axis of the screw 17 enters the region H determined by the contact position between the drum contact sheet 20 and the drum 1 of the cleaning member 16. More preferably, the entire cross section of the screw is disposed in the region H.

  The toner remaining on the surface of the drum 1 after the transfer passes through the drum contact sheet 20 and is scraped off from the drum 1 by the cleaning member 16. The toner scraped off by the cleaning member 16 is accumulated on the drum contact sheet 20, the drum 1, and the cleaning member 16. When the upper surface of the accumulated toner reaches a height at which it contacts the screw 17, the accumulated toner is conveyed in the longitudinal direction by the spiral blade 17b as the screw 17 rotates.

  When the screw 17 is driven, the screw 17 applies a pressure F to the toner below the screw 17 downward in the direction of gravity. The screw 17 is driven to apply pressure to the toner accumulated above the contact position between the drum 1 and the cleaning member 16, so that the drum 1 rotates upstream from the contact portion between the drum 1 and the cleaning member 16. In this region, the powder pressure by the toner increases. On the other hand, the toner or the external additive externally added to the toner easily slips through the cleaning member 16 immediately after the start of driving of the drum 1 where the state of the cleaning member 16 is not stable until it rotates once. For this reason, if the screw 17 is driven immediately after the drum 1 is driven, the cleaning performance may be deteriorated. For this reason, the driving start time of the screw as the conveying member is set later than the driving start time of the drum. Thereby, when the cleaning performance of the cleaning member is unstable, the powder pressure by the toner or the like is not increased, thereby reducing the passage of powder. In this embodiment, the drum is rotated once by the start of drum driving to stabilize the cleaning state of the cleaning member. However, the present invention is not limited to this, and the drum may be rotated one or more times.

  Next, the effect of the present embodiment will be described by comparing the comparative example and the first embodiment. In the cleaning unit of this embodiment, a signal at the start of driving the drum drive source and the conveyance drive source is sent from the CPU as the control means. By shifting the transmission of this signal, the drive start time of the screw 17 is delayed by 0.2 s from the start time of the drum 1 drive start. On the other hand, in the comparative example, a signal is transmitted from the CPU which is the control means so that the driving timing of the drum 1 and the screw 17 is the same. Here, the time when the control means transmits the drive start signal is the drive start time.

  In the comparative example, since the screw 17 and the drum 1 start driving simultaneously, the driving of the screw 17 is started in a state where the behavior of the cleaning member 16 is not stable. When the toner on the drum 1 after passing through the transfer roller at the time of image formation is scraped off from the drum 1 by the cleaning member 16, a blocking layer made of an external additive or toner is formed. The blocking layer is formed from the contact position between the drum 1 and the cleaning member 16 to the upstream side in the rotation direction of the drum 1. Although the cleaning performance is improved by forming the blocking layer, the blocking layer is easily broken by an external force at the timing when the shape of the cleaning member 16 is deformed as the driving of the drum 1 is started or stopped. When driving is started at the same time, the powder pressure of the toner in the vicinity of the blocking layer is increased by the screw 17 in a state where the blocking layer tends to collapse, so that a part of the blocking layer collapses and the external additive or toner forming the blocking layer is removed. The cleaning member 16 passes through. When the slipped external additive or toner adheres to the charging roller 2, charging failure occurs, and the surface potential of the drum 1 at the location where the charging failure occurs changes, resulting in streak density unevenness.

  On the other hand, in the configuration of the first embodiment, the drive start timing of the screw 17 is delayed with respect to the drive start timing of the drum 1. Therefore, when the deformation of the cleaning member 16 is unstable, an increase in the toner pressure to the contact position by the screw 17 can be prevented, and the cleaning performance can be improved. This is considered to be because a blocking layer is formed in the contact position between the cleaning member and the drum and in the vicinity of the upstream by driving the drum 1. FIG. 4 shows data representing the deformation of the cleaning member 16 before and after the driving of the drum 1 is started. As shown in FIG. 5, the deformation is measured by using a strain gauge 21 (KFG-6120-C1-11L3M3R manufactured by KYOWA) with an adhesive at a position facing the screw 17 of the rubber blade that is a part of the cleaning member. Paste. The amount of deformation of the rubber blade 16a is measured by the amount of change in the output value of the strain gauge 21. The horizontal axis of FIG. 4 is time, and the vertical axis is the output value of the strain gauge 21, and the driving of the drum 1 is started at 0 second. 4 that the rubber blade 16a is greatly deformed immediately after the drum 1 is driven, and the behavior of the rubber blade 16a is stabilized 0.2 s after the drum 1 is driven.

  Table 1 compares the level of horizontal streaks on the image due to contamination of the charging member of the comparative example and that of Example 1.

O: No horizontal or vertical streak occurs on the image.
N: A horizontal stripe or a vertical stripe is generated on the image.

  Examination conditions are as follows: in an environment where the ambient temperature and humidity are 15 ° C. and 10% humidity, after passing 5000 half-tone images with a printing rate of 30% and leaving them for 24 hours, the half-tone images are then fed again. The streak level is described. From Table 1, the horizontal streak was generated in the comparative example, whereas the configuration of Example 1 improved the horizontal streak due to poor cleaning.

  From the above, it is possible to provide a process cartridge with high cleaning performance by starting the driving of the screw 17 after the driving of the drum 1 is started.

  It should be noted that the functions, materials, shapes, and relative arrangements of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Any device that transports toner may be used, and the present invention is not limited to a process cartridge.

[Example 2]
In the configuration of the first embodiment, the cleaning failure is improved by delaying the driving start time of the screw 17 with respect to the driving start time of the drum 1, while the driving time of the screw 17 is reduced, thereby reducing the waste toner transportability. May decrease. On the other hand, if the drive time of the screw 17 is increased in order to improve the waste toner transportability, the drive time of the drum 1 is increased and the life of the drum 1 is reduced.

  Therefore, in the present embodiment, the point at which the driving start time of the screw can be changed according to the difference in temperature and humidity will be described by comparing the first and second embodiments.

  In the configuration of the first embodiment, the start of driving of the screw 17 with respect to the start of driving of the drum 1 is uniformly delayed by 0.2 seconds at the temperature and humidity in the atmosphere. In contrast, the configuration of the second embodiment does not change the driving time of the drum 1 at the time of image formation. The driving start time of the screw 17 relative to the driving start time of the drum 1 is 0.01 s in a high temperature and high humidity environment, and the low temperature and low humidity. 0.2s slower in the environment.

  In a high-temperature and high-humidity environment, the chargeability of the toner on the developing roller 10 decreases, so the charge amount of the toner on the drum 1 decreases, and the transfer efficiency of the toner to the transfer roller decreases. As the transfer efficiency decreases, the amount of toner collected by the cleaning unit increases. On the other hand, if the driving start time is slow, the conveying capacity of the screw 17 cannot catch up, so that the collected toner near the contact position between the cleaning member 16 and the drum 1 becomes a compacted state, which may increase the powder pressure. In such a state, a part of the blocking layer breaks down, and the toner or the external additive passes through the contact position between the clean member and the drum, so that the longitudinal part of the cleaning roller can be contaminated with the toner or the external additive. There is sex. As a result, the contaminated portion may be poorly charged and appear as vertical stripes on the image. On the other hand, the rubber hardness of the cleaning member 16 decreases under a high temperature and high humidity environment, so that the blade is easily deformed in accordance with minute irregularities on the surface of the drum 1, and the blocking layer at the start of driving of the drum 1 is unstable. Even in such a state, the cleaning performance is higher than in a low temperature and low humidity environment. For this reason, the slipping of the toner or the external additive at the start of driving of the drum 1 is improved.

  As described above, by increasing the drive time of the screw 17 in a high-temperature and high-humidity environment as compared with the low-temperature and low-humidity environment as in the second embodiment, the transportability of waste toner is improved while ensuring the cleaning performance. Therefore, an increase in toner powder pressure near the contact position between the cleaning member 16 and the drum 1 in a high-temperature and high-humidity environment can be reduced, and the occurrence of vertical stripes can be reduced.

  Table 2 shows horizontal streaks and vertical streak levels on the image due to the contamination of the charging member in the first and second embodiments.

O: No horizontal or vertical streak occurs on the image.
N: A horizontal stripe or a vertical stripe is generated on the image.

  The study conditions were as follows: First, 5000 half-tone images with a printing rate of 30% were passed in a low-temperature and low-humidity environment where the temperature and humidity in the atmosphere were 15 ° C and 10% and 30 ° C and 80%. . Then, after leaving it for a long time, the level of the horizontal stripe when the halftone image is passed again is examined. In the configuration of the first embodiment, vertical and horizontal streaks are not generated on the image in the low temperature and low humidity environment, whereas vertical streaks are generated in the high temperature and high humidity environment. On the other hand, in the configuration of the second embodiment, neither vertical stripes nor horizontal stripes are generated in both environments.

  From the above, by utilizing the fact that the relationship between the cleaning property and the transfer efficiency varies with temperature, and changing the difference in the driving start of the screw 17 with respect to the driving start of the drum 1, more efficient use is possible. Specifically, the drive time of the screw 17 is lengthened by setting the drive of the screw 17 in the high temperature and high humidity environment from the start of the drum drive earlier than the start of the drive of the screw 17 in the low temperature and low humidity environment. In addition, the toner conveying ability is improved. In this way, by changing the timing difference according to the temperature and humidity of the atmosphere, it is possible to obtain a good image without streaking without increasing the driving time of the drum 1.

  In this embodiment, data is stored in the storage means so that the time difference between the start of drum driving and the start of screw driving can be changed within a range of 0.01 seconds to 0.2 seconds. The CPU serving as the control means is configured to transmit a signal at the start of driving based on a signal relating to temperature / humidity information from the temperature detecting means or the like. In this embodiment, the drive start time is shifted in consideration of both temperature and humidity. However, the drive start time may be shifted based on only one of temperature and humidity. For example, it is possible to perform change control in which the time difference of the start time is less than 25, and the time difference of the start time is reduced when the temperature difference becomes 25 ° C. or more. In addition, it is also possible to perform change control in which the difference in start time when the humidity is less than 70% becomes smaller than 70% when the humidity becomes 70% or more. The temperature of 25 ° C. and the humidity of 70% are used for convenience of explanation, and may be controlled by providing a predetermined threshold value.

  Furthermore, the time difference at the start of driving, the control method, and the like are changed depending on the arrangement of the conveying members.

  Further, in the present embodiment, an apparatus has been described in which the start of drum driving is the same and the start of screw driving is changed. However, the present invention is not limited to this, and depending on the device design, the time difference between the drum drive start time and the screw drive start time may be changed by changing the drum drive start time.

DESCRIPTION OF SYMBOLS 1 Drum 16 Cleaning member 16a Rubber blade 16b Support member 17 Screw 18 Cleaning unit 19b Storage chamber 20 Drum contact sheet A Image forming apparatus main body (apparatus main body)
B Process cartridge (cartridge)

Claims (10)

A cleaning member that contacts the image carrier and removes the developer on the image carrier;
A storage chamber for storing the developer removed from the image carrier by the cleaning member;
A conveyance member that is provided immediately above the image carrier in the direction of gravity and conveys the removed developer from the storage chamber;
2. The cartridge according to claim 1, wherein the driving start of the conveying member is later than the driving start of the image carrier.   The contact portion where the image carrier and the cleaning member are in contact with each other is located on the downstream side in the rotation direction of the image carrier with respect to the closest position of the image carrier that is closest to the transport member. Cartridge.   The cartridge according to claim 1, wherein the driving start time of the transport member is changed according to temperature.   4. The cartridge according to claim 1, wherein the driving start time of the transport member is changed according to humidity. 5.   5. The cartridge according to claim 1, wherein the driving of the conveying member is started after the image carrier has rotated one or more rounds after the driving of the image carrier is started. 6. .   6. The time difference between the start of driving of the image carrier and the start of driving of the conveying member is within a range of 0.01 seconds to 0.2 seconds. 6. The cartridge described.   The cartridge according to claim 1, wherein an axial direction of the image carrier and an axial direction of the transport member are parallel to each other.   The cartridge according to claim 1, wherein the conveying member is a screw. An image carrier;
A cartridge according to any one of claims 1 to 8,
A process cartridge comprising:   An image forming apparatus comprising at least one of the cartridge according to claim 1 or the process cartridge according to claim 9 and forming an image on a recording material.

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