JP5541731B2 - Image forming apparatus - Google Patents

Description

  The present invention has at least a developer accommodating portion accommodating a dry powder developer used for developing a latent image formed on an image carrier, and is detachably attached to the apparatus main body. The present invention relates to an image forming apparatus that includes a plurality of image forming units and forms an image on a recording medium.

  The image forming apparatus includes an electrophotographic apparatus for forming an image using an electrophotographic photosensitive member as an image carrier, an electrostatic recording apparatus for forming an image using an electrostatic recording dielectric, and an image using a magnetic recording magnetic body. It includes a magnetic recording device that performs the formation.

  The image forming unit that is detachably attached to the apparatus main body includes a process cartridge and a developing cartridge. The process cartridge and the developing cartridge are detachably attached to the main body of the image forming apparatus and contribute to an image forming process for forming an image on a recording medium.

  A process cartridge integrally having an image carrier and developing means is referred to as an integral type. A process cartridge that integrally includes an image carrier and process means other than the developing means is referred to as a separation type. That is, the developing means is a developing unit separate from the process cartridge, and the process cartridge that forms an image with the developing unit is referred to as a separation type.

  The developer cartridge contains a developer carrier for applying a developer to the image carrier, and a developer containing a dry powder developer used for developing the latent image formed on the image carrier by the developer carrier. And an agent storage portion, which is detachably attached to the apparatus main body. In the case of the developing cartridge, the image carrier is attached to a separation type process cartridge. Alternatively, it is attached to the apparatus main body or the cartridge support member.

  In an image forming apparatus in which a process cartridge or a developing cartridge can be attached to and detached from the apparatus main body, a developer amount detecting means for detecting the remaining amount of developer in the developer accommodating portion is provided, and the developer is consumed. In order to replace the cartridge, the cartridge must be replaced.

  As a method for detecting the amount of developer in the developer accommodating portion, a method of applying an oscillating voltage to an electrode in the vicinity of the developer and detecting an electrical response of the opposing electrode is conventionally known. In this detection method, there is a problem in that accuracy decreases due to interference of voltages other than the voltage applied for detection.

  As a solution to this problem, the present applicant has previously proposed a method as disclosed in Patent Document 1. This method corrects the amount of interference caused by a bias applied to the image forming means other than the bias applied to the developer amount detecting means to be detected. According to this method, in an image forming apparatus having a plurality of image forming means, when detecting the electrostatic capacity of the developer amount detecting means selected as a detection target, the apparatus can be increased in size and cost. Absent. In addition, it is possible to detect the developer amount with high accuracy.

JP 2007-102084 A

  The present invention is intended to further improve the detection accuracy of the above technique. The purpose of the image forming apparatus is to accurately detect the developer amount regardless of whether or not an image forming unit other than the image forming unit in which the developer to be detected is detected. Is to provide.

  In order to achieve the above object, a typical configuration of an image forming apparatus according to the present invention is a developer containing a dry powder developer used for developing a latent image formed on an image carrier. An image forming apparatus that includes at least a storage unit and includes a plurality of image forming units that are detachably mounted on a main body of the image forming apparatus, and performs image formation on a recording medium. At least one set of electrodes for applying an electric field to the developer stored therein, an oscillating voltage source connected to one electrode of the set of electrodes, and an amount of developer stored in the developer storage portion. A developer amount detecting means for detecting by an electrical signal induced in the other electrode of the set of electrodes; and a mounting state detecting means for detecting whether or not each of the plurality of image forming units is mounted. And control means In the image forming apparatus, the control unit includes a table in which correction values of developer detection results corresponding to mounting states of the plurality of image forming units are recorded, and the plurality of image formations detected by the mounting state detection unit. The developer amount information detected by the developer amount detecting means is corrected by referring to the table based on unit mounting state information.

  According to the present invention, it is possible to accurately detect the developer amount regardless of whether or not an image forming unit other than the image forming unit in which the developer to be detected is detected.

Schematic configuration diagram of the image forming apparatus of Embodiment 1 (vertical right side view) Illustration of how to replace the cartridge Enlarged view of one image forming unit portion in FIG. 1 (during image forming operation) Enlarged view of one image forming unit portion in FIG. 1 (during non-image formation) Relationship diagram between toner amount in developer container and toner amount in toner supply roller Flow chart showing toner remaining amount detection and correction operation executed by the control circuit unit Enlarged view of one image forming unit portion in the image forming apparatus of Embodiment 2 (during image forming operation) Enlarged view of one image forming unit portion in the image forming apparatus of Embodiment 2 (during non-image formation) Illustration of how to replace the cartridge

  Embodiments of the present invention will be illustrated below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. The scope is not intended to be limited to the following embodiments.

[Example 1]
(1) Overall schematic configuration and image forming operation of an example of an image forming apparatus FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus 100 according to the present invention. FIG. 3 is an enlarged view of one image forming unit portion in FIG. The apparatus 100 is a four-color full-color electrophotographic printer to which a plurality of image forming units 11 (11y, 11m, 11c, and 11k) are detachably mounted. The apparatus 100 executes color image formation on the recording medium 8 based on an electrical image signal input to a control circuit unit (control means: CPU) 200 from a host apparatus 400 such as a personal computer, an image reader, or a facsimile machine.

  The recording medium 8 is, for example, paper, a resin sheet, a label, or the like. The control circuit unit 200 exchanges various types of electrical information with the operation unit 300 and the host device 400, and at the same time, a predetermined control program or reference table in which an image forming operation of the device 100 is stored in a storage unit (memory). According to the overall control.

  Here, in the following description, the front side (front side) with respect to the apparatus 100 is a side on which a door 71 that is an opening / closing member for opening and closing the apparatus is disposed. The rear side is the opposite side. The front-rear direction is a direction from the rear side to the front side of the apparatus 100 (front direction) and the opposite direction (rear direction). Left and right are left or right when the apparatus 100 is viewed from the front side. The left-right direction is a direction from left to right (left direction) and the opposite direction (right direction). The apparatus main body 100A is an image forming apparatus portion other than the cartridge 11 and a cartridge tray 60 as a cartridge support member (moving member) described later.

  A cartridge storage portion 100B is provided in the apparatus main body 100A. In the cartridge housing portion 100B, a plurality of process cartridges 11 as a plurality of image forming units are arranged from the rear side to the front side in the apparatus main body 100A. In this embodiment, the first to fourth four cartridges 11 (11y, 11m, 11c, and 11k) are arranged in a substantially horizontal direction (lateral direction) (in-line configuration, tandem type). Each cartridge 11 is detachably mounted in the cartridge housing portion 100B of the apparatus main body 100A as will be described later.

  In this embodiment, each cartridge 11 is an integrated process cartridge. That is, an electrophotographic photosensitive drum 1 as an image carrier on which a latent image developed with a developer is formed, and charging means 2, developing means 4, and cleaning means 9 as process means acting on the drum 1. It is an integrated cartridge. Each cartridge 11 has the same configuration except that the color of the dry powder developer 12 (12y, 12m, 12c, 12k) accommodated in a developer container 13 as a developer accommodating portion is different.

  In this embodiment, the charging means 2 is a contact charging roller. The developing means 4 is a contact developing device using a one-component nonmagnetic toner as the developer 12. Hereinafter, the developer 12 is referred to as toner. The cleaning means 9 is a blade cleaning device using an elastic blade 9a as a cleaning member.

  The developing device 4 includes a developing container 13 as a developer containing portion that contains toner 12 and a developing roller 14 as a developer carrying member that develops a latent image formed on the drum 1 as a toner image. Further, a toner supply roller 15 as a developer supply member that supplies (applies) toner to the developing roller 14 and a toner regulating blade 16 that regulates the amount of toner on the developing roller 14 are provided.

  The drum 1, the charging roller 2, and the cleaning device 9 are integrally assembled in a common frame 40 to form a first unit (cleaning unit, drum unit) 11 </ b> A. The developing device 4 is swingably assembled as a second unit (developing unit) 11B with respect to the frame 40 of the unit 11A. The unit 11B is moved with respect to the unit 11A by a swinging means (not shown), and a contact position A for performing a developing operation in which the developing roller 14 is in contact with the drum 1 as shown in FIG. I can take it. Moreover, the separation position B in which the developing roller 14 is separated from the drum 1 as shown in FIG. 4 can be taken.

  In a state where the cartridge 11 is mounted on the apparatus main body 100A, the unit 11B is moved and held at the contact position A during the image forming operation of the apparatus 100, and is moved to the separation position B when the apparatus 100 is not forming an image. Held. The separation position B is a position provided to prevent toner deterioration and abrasion of the drum 1 due to friction between the developing roller 14 and the drum 1 during non-image formation of the apparatus 100, and in the developing container 13 as will be described later. It is also used for detecting the toner amount.

  The first cartridge 11 y contains yellow (y) toner 12 y in the developing container 13 and forms a y-color toner image on the surface of the drum 1. The second cartridge 11 m contains magenta (m) toner 12 m in the developing container 13 and forms an m-color toner image on the surface of the drum 1. The third cartridge 11 c contains cyan (c) toner Tc in the developing container 13 and forms a c-color toner image on the surface of the drum 1. The fourth cartridge 11 k contains black (k) toner 12 k in the developing container 13 and forms a k-color toner image on the surface of the drum 1.

  A laser scanner unit 3 serving as an exposure device is disposed above the cartridge storage unit 100B. The unit 3 outputs a laser beam L modulated in accordance with the image information of each color input from the host device 400 to the control circuit unit 200. The laser light L enters each cartridge 11 through the exposure window 40a on the upper surface side of the frame body 40. Thereby, laser scanning exposure is performed on the surface of the drum 1.

  An intermediate transfer belt unit 6 is disposed below the cartridge storage unit 100B. This unit 6 has an endless belt 6a. The belt 6 a is an intermediate transfer member (intermediate transfer belt: intermediate recording medium) that contacts the drum 1 of each cartridge 11 in order to form an image on a final recording medium (hereinafter referred to as paper) 8. The belt 6a is made of a dielectric and has flexibility. Inside the belt 6a, there are provided a driving roller 6b, a turn roller 6c, and a tension roller 6d that stretch and circulate the belt 6a.

  The drive roller 6b is disposed on the front side in the apparatus main body 100A. The turn roller 6c and the tension roller 6d are disposed on the rear side in the apparatus main body 100A. The lower surface of the drum 1 of each cartridge 11 is in contact with the upper surface of the ascending belt portion of the belt 6a to form a primary transfer nip portion N1. Four primary transfer rollers 5 are disposed inside the belt 6a. The primary transfer roller 5 faces the drum 1 of each cartridge 11 through the ascending belt portion of the belt 6a. A secondary transfer roller 7 is in contact with the turn roller 6c via a belt 6a to form a secondary transfer nip portion N2.

  A paper cassette 30 is disposed below the unit 6. A fixing device 10, a discharge roller pair 31, and a discharge port 32 are disposed on the upper rear side in the apparatus main body 100A. A paper discharge tray 33 is provided on the upper surface of the apparatus main body 100A.

  Each cartridge 11 housed in the cartridge housing portion 100B is positioned and fixed by pressing the first unit 11A against a positioning portion (not shown) on the apparatus main body 100A side by a pressing means (not shown). In addition, a drive output unit (not shown) on the apparatus main body 100A side is coupled to a drive input unit (not shown) of each cartridge 11. In addition, the corresponding electrical contacts b on the apparatus main body 100A side are electrically connected to the various electrical contacts a of each cartridge 11.

  The operation for forming a full-color image is as follows. In each of the first to fourth cartridges 11, the second unit 11B is moved to and held at the contact position A (FIG. 3) during the image forming operation as described above, and the separated position B (FIG. 4) during non-image formation. ) Is moved and held. The drum 1 is driven to rotate at a predetermined control speed in the counterclockwise direction indicated by the arrow. The belt 6a is also rotationally driven at a speed corresponding to the speed of the drum 1 in the clockwise direction of the arrow (forward direction with respect to the drum rotation). The scanner unit 3 is also driven.

  In synchronization with this drive, the charging roller 2 uniformly charges the surface of the drum 1 to a predetermined polarity and potential in each cartridge 11 at a predetermined control timing. A predetermined charging bias is applied to the charging roller 2 from the power supply unit 22. The unit 3 scans and exposes the surface of each drum 1 with a laser beam L modulated according to the image signal of each color. Thereby, an electrostatic latent image corresponding to the image signal of the corresponding color is formed on the surface of each drum 1.

  The formed electrostatic latent image is developed as a toner image by the developing roller 14 of the corresponding color developing device 4. A predetermined developing bias is applied to the developing roller 14 from the power supply unit 50 when the control circuit unit 200 switches the switch SW to the contact c side. A predetermined primary transfer bias is applied to each primary transfer roller 5 from the power supply unit 35 at a predetermined control timing.

  By the electrophotographic image forming process operation as described above, a y-color toner image corresponding to the yellow component of the full-color image is formed on the drum 1 of the first cartridge 11y. The toner image is primarily transferred onto the belt 6a by the primary transfer bias and the primary transfer pressure at the primary transfer nip portion N1. An m-color toner image corresponding to the magenta component of the full-color image is formed on the drum 1 of the second cartridge 11m. Then, in the primary transfer nip portion N1, the toner image is superimposed on the y-color toner image already transferred onto the belt 6a and is primarily transferred by the primary transfer bias and the primary transfer pressure.

  Further, a c-color toner image corresponding to the cyan component of the full-color image is formed on the drum 1 of the third cartridge 11c. Then, in the primary transfer nip portion N1, the toner image is primary-transferred by the primary transfer bias and the primary transfer pressure while being superimposed on the y color + m color toner image already transferred on the belt 6a. A k-color toner image corresponding to the black component of the full-color image is formed on the drum 1 of the fourth cartridge 11k. The toner image is primary-transferred at the primary transfer nip N1 by the primary transfer bias and the primary transfer pressure while being superimposed on the toner image of y color + m color + c color already transferred onto the belt 6a.

  Thus, a four-color full-color unfixed developer image of y color + m color + c color + k color is synthesized and formed on the belt 6a. In each cartridge 11, the transfer residual toner remaining on the surface of the drum 1 after the primary transfer of the toner image to the belt 6a is removed by the cleaning device 9, and the drum 1 is again subjected to image formation starting from charging.

  On the other hand, the feeding roller 36 is driven at a predetermined control timing. As a result, the sheet 8 loaded and stored in the sheet cassette 30 is separated and fed by the cooperation of the roller 36 and the separation roller 37, passes through the conveyance path 38 and the registration roller 39, and the secondary transfer nip portion N <b> 2. To be introduced. A predetermined secondary transfer bias is applied to the secondary transfer roller 7 from a power source (not shown) at a predetermined control timing. As a result, in the process in which the paper 8 is nipped and conveyed through the nip portion, the four color superimposed toner images on the belt 6a are sequentially transferred to the surface of the paper 8 by the secondary transfer bias and the secondary transfer pressure. The

  The paper 8 is separated from the surface of the belt 6a and introduced into the fixing device 10, and is nipped and conveyed by a fixing nip portion which is a pressure contact portion between a fixing roller (heat roller) and a pressure roller, and is heated and pressed. Thereby, the color toner images are mixed and fixed onto the paper 8. Then, the sheet 8 exits the fixing device 10 and is discharged onto the sheet discharge tray 33 by the discharge roller pair 13 and the discharge port 32 as a full-color image formed product.

  In this embodiment, the secondary transfer residual toner remaining on the surface of the belt 6a after the paper separation is electrostatically adhered to the surface of the drum 1 at the primary transfer nip portion N1 of the first cartridge 11, for example. Then, it is removed by the cleaning device 9. A dedicated belt cleaning device may be provided for the belt 6a.

(2) Developing device 4
In this embodiment, the toner 12 of the developing device 4 is a non-magnetic one-component polymerized toner and is a negatively charged toner that is negatively charged during development. When the image forming operation is performed, the developing roller 14 is moved to the contact position A so that the developing roller 14 comes into contact with the drum 1 and is driven to rotate at a predetermined speed in the forward direction of the rotation of the drum 1. One end of the blade 16 is in contact with the developing roller 14. The supply roller 15 contacts the developing roller 14 and is driven to rotate at a predetermined speed in the same direction as the developing roller 14. Accordingly, the supply roller 15 rotates in the direction in which the supply roller 15 has a speed in the opposite direction at the contact portion with the developing roller 14.

The developing roller 14 is provided with a semiconductive silicon rubber layer 14b in which a conductive agent is blended around a cored bar electrode 14a having an outer diameter φ6 (mm) which is a conductive support. Furthermore, the surface layer of the silicon rubber layer 14b is coated with urethane resin and rough particles, and the entire outer diameter of the developing roller 14 is φ12 (mm). The resistance of the developing roller 14 is about 10 ⁶ Ω when measured by the following method.

  First, the developing roller 14 was brought into contact with an aluminum drum having a diameter of 30 mm with a contact load of 9.8 N. By rotating this drum, the developing roller 14 was driven to rotate at 60 rpm. Next, the resistance of the developing roller 14 was determined by applying a DC voltage of −50 V to the cored bar electrode 14a of the developing roller 14 with the drum as the ground, and measuring the current flowing at this time. The length in the longitudinal direction of the silicon rubber layer 14b of the developing roller 14 is about 235 mm.

  The supply roller 15 is provided with a urethane foam layer 15b around a cored bar electrode 15a having an outer diameter of φ5 (mm) which is a conductive support. The entire outer diameter of the toner supply roller 15 including the foamed urethane layer 15b is φ13 (mm). The intrusion amount of the toner supply roller 15 and the developing roller 14 is 1.2 mm.

  The powder pressure of the toner 12 existing around the urethane foam layer 15b acts on the urethane foam layer 15b, and the supply roller 15 further rotates so that the toner 12 enters. The supply roller 15 including the toner 12 supplies the toner 12 to the developing roller 14 at a contact portion with the developing roller 14, and further rubs the toner 12 to give a preliminary triboelectric charge to the toner 12. The charged toner 12 supplied to the developing roller 14 adheres firmly to the developing roller 14 and enters the blade 16.

  The blade 16 is a SUS blade having a thickness of 80 μm, and is disposed in a direction against the rotation of the developing roller 14. The toner 12 on the developing roller 14 is uniformly regulated by the blade 16. Further, a desired triboelectric charge is obtained by rubbing with the blade 16. The toner 12 that has passed through the blade 16 is used for development at the contact portion with the drum 1, and the toner 12 that has not been developed is peeled off by the toner supply roller 15.

  The toner in the supply roller 15 is charged when the supply roller 15 is deformed when the contact with the developing roller 14 starts to be partly discharged, and after the end of the contact, the toner begins to contact again. As described above, although the toner 12 enters and leaves the supply roller 15, the toner amount in the supply roller 15 is generally kept in an equilibrium state unless the toner amount in the developing container 13 is changed.

(3) Cartridge Replacement Method As each cartridge 11 is used for image formation, the toner 12 accommodated in the developing container 41 of the developing device 4 is sequentially consumed. Therefore, a means (developer amount detecting means) for detecting the remaining amount of toner in each cartridge 11 is provided, and the control circuit unit 200 sets the detected remaining amount value for a preset cartridge life warning or life warning. Compare with threshold. For a cartridge whose detected remaining amount value is less than the threshold value, a life warning about the cartridge is displayed on the display unit (not shown) of the operation unit 300 or the display unit (not shown) of the host device 400. Or a life warning is displayed.

  This prompts the user to prepare a cartridge for replacement, or prompts the user to replace the cartridge to maintain the quality of the output image. In the apparatus 100 of the present embodiment, the cartridge 11 is replaced by a front access on the pull-out type moving member 60 as a cartridge support member for the purpose of improving usability. On the front side of the apparatus 100, an opening 70 is provided for allowing the cartridge 11 to pass through the apparatus body 100A so that the cartridge 11 can be inserted into the apparatus body 100A and the cartridge 11 can be taken out from the apparatus body 100A.

  And the door 71 as an opening-and-closing member which can move between the closed position which closes this opening part 70, and the open position which opens the opening part 70 is provided. In this embodiment, the door 71 is erected and rotated around a horizontal axis (hinge shaft) 71a on the lower side of the door to move the opening 70 to a closed position where the opening 70 is sufficiently closed as shown in FIG. Can be made. Further, the door 71 can be moved to the open position where the opening 70 is sufficiently opened as shown in FIG. The door 71 is opened and closed by a user's manual operation.

  Rail members 80 (FIG. 2) as a pair of left and right tray holding members are disposed on the inner side of the left frame and the inner side of the right frame of the main frame serving as the skeleton of the apparatus main body 100A. The left and right rail members are provided facing each other, and the longitudinal direction is the front-rear direction of the apparatus main body 100A. A drawer-type moving member 60 (cartridge tray: hereinafter referred to as a tray) on which the cartridge 11 is placed is a frame-type member, and is a rectangular large frame portion in which a front frame plate, a rear frame plate, a left frame plate, and a right frame plate are combined. Have The left and right frame plates are supported between the left and right rail members, respectively.

  The tray 60 is guided by the rail member and can be slid in a pulling direction indicated by an arrow X in FIG. 2 (front direction of the apparatus main body) and a pushing direction indicated by an arrow Y opposite thereto (rear direction of the apparatus main body). is there. The tray 60 is formed with four mounting portions 60a in which the first to fourth cartridges 11y, 11m, 11c, and 11k are detachably mounted in the left and right directions from the rear side to the front side in the large frame portion. Has been.

  The cartridges 11 are supported side by side on the tray 60 so that the longitudinal direction of the cartridge (in the drum axis direction) intersects the moving direction of the tray 60. The tray 60 supports the individual cartridges 11 so that they can be taken out directly above the corresponding mounting portions 60a. Further, the individual cartridges 11 are supported by moving them directly to the corresponding mounting portions 60a.

  When the door 71 in the closed position as shown in FIG. 1 is moved to the open position as shown in FIG. 2, the opening 70 is opened and the front frame plate side of the tray 60 is exposed to the opening 70. In addition, in this embodiment, the left and right rail members 80 supporting the tray 60 are moved forward along the guide member (not shown) by an interlocking mechanism (not shown) that is interlocked with the opening movement operation of the door 71. Move upward by a predetermined amount. In conjunction with the movement of the rail member 80, the coupling of the drive output unit (not shown) on the apparatus main body 100A side to the drive input unit of each cartridge 11 is released.

  Further, the pressurization of the pressurizing member (not shown) that positions and fixes the first unit 11A of each cartridge 11 is released. The second unit 11B is held at the separation position B. Then, the tray 60 supporting each cartridge 11 moves upward together with the rail member 80. Thereby, each cartridge 11 floats from a positioning part (not shown). Accordingly, the lower surface of the drum 1 of each cartridge 11 is separated from the upper surface of the belt 6a and is in a non-contact state.

  Further, the lock state (not shown) that locks the tray 60 to the apparatus main body 100A is released. In this state, the tray 60 can be pulled out from an inner position (first position: cartridge housing portion 100B) in the apparatus main body 100A to a predetermined pulling position (second position) outside the apparatus main body 100A.

  Therefore, the user puts his / her finger on the handle portion 60b provided on the front frame plate side of the tray 60 exposed in the opening 70 and slides the tray 60 horizontally in the forward direction X with respect to the rail member 80. Move. Then, as shown in FIG. 2, the tray 60 is sufficiently pulled out from the opening 70 to a predetermined pulling position outside the apparatus main body 100A. As a result, the first to fourth cartridges 11y, 11m, 11c, and 11k held on the tray 60 pass through the opening 70 and are exposed to the outside of the apparatus main body 100A. The top surface is exposed.

  When the tray 60 is sufficiently pulled out to a predetermined pulling position, further pulling movement is prevented by a stopper (not shown). Further, the tray 60 is stably maintained by the rail member 80 in a state where the tray 60 is horizontally pulled out to a predetermined pulling position. When the tray 60 is pulled out to the outermost side of the apparatus main body 100A, all the cartridges 11y, 11m, 11c, and 11k come out of the apparatus main body 100A. Therefore, when the user replaces the cartridge 11 with respect to the tray 60, the replacement work is easy to perform.

  The tray 60 supports the cartridges 11 roughly so that the individual cartridges 11 can be taken out directly to the corresponding mounting portions 60a. The tray 60 supports the individual cartridges 11 by dropping them into the corresponding mounting portions 60a. Therefore, the user lifts the used cartridge 11 to be replaced upward from the tray 60 and removes it. Then, a new cartridge is fitted into the mounting portion 60a of the tray 60 from above.

  When the user replaces the cartridge 11 with respect to the tray 60, the user pulls the tray 60 that has been pulled out in the reverse direction to the above by horizontally pushing the tray 60 in the backward direction Y with respect to the rail member 80. Slide to. When the tray 60 is sufficiently pushed into the apparatus main body 100A up to a predetermined inner position (push-in position) 100B, the stopper 60 (not shown) prevents further push-in movement. Then, the door 71 in the open position is moved to the closed position. The rail member 80 moves back in the apparatus main body 100A by a predetermined amount back and downward along the guide member by the interlocking mechanism interlocking with the closing movement operation of the door 71.

  The pressure member pressurizes the first unit 11 </ b> A of each cartridge 11 by an interlocking mechanism that interlocks with the return movement of the rail member 80. Each cartridge 11 is positioned and fixed to the main body positioning portion by the pressing force of the pressing member. Further, the drive output unit on the apparatus main body side is coupled to the drive input unit of each cartridge 11. Further, the electrical contact b on the apparatus main body side is electrically connected to the electrical contact a on the cartridge 11 side. Further, the tray 60 is locked to the apparatus main body 100A by the lock member.

  As a result, the lower surface of the drum 1 of each cartridge 11 comes into contact with the surface of the belt 6a, and each cartridge 11 returns to the state shown in FIG. 1 mounted at the latent image forming position in the apparatus main body 100A. That is, each cartridge 11 is housed in the cartridge housing portion 100B. Then, the apparatus 100 is ready for an image forming operation.

  As described above, normally, the cartridges 11y, 11m, 11c, and 11k are mounted on all the four mounting portions 60a, and a four-color full-color image forming operation is possible. However, even if one of the yellow, magenta, and cyan cartridges 11y, 11m, and 11c is not temporarily installed, monochrome printing can be performed using only the black cartridge 11k. This is intended to improve usability by enabling printing with only the black cartridge 11k even when one of the yellow, magenta, and cyan cartridges 11y, 11m, and 11c reaches the end of its life.

(4) Developer Amount Detection Unit A developer amount detection unit that detects the remaining amount of toner in the developing container 13 of each cartridge 11 in this embodiment will be described. Specifically, it has at least one set of electrodes for applying an electric field to the developer (toner) accommodated in the developing container 13. An oscillating voltage source is connected to one electrode of the set of electrodes. And it has a developer amount detecting means for detecting the amount of developer accommodated in the developing container 13 by an electrical signal induced in the other electrode of the one set of electrodes.

  In this embodiment, at least one set for applying an electric field to the developer (toner) 12 accommodated in the developing container 13 includes a developing roller 14 as a developer carrying member and a supply roller 15 as a developer supplying member. It is also used as an electrode. The supply roller 15 is used as one electrode, and an AC power source 17 that reduces the vibration voltage is connected thereto. The control circuit unit 200 is a developer amount detection unit that detects the amount of developer stored in the developer container 13 by an electrical signal induced in the developing roller 14 as the other electrode.

  FIG. 5 shows the amount of toner in the developing container 13 and the amount of toner in the supply roller 15 as the developing container 13 of the developing device 4 of this embodiment is filled with the toner 12 and the toner 12 is gradually consumed. is there. At this time, it can be seen that the amount of toner contained in the foamed urethane layer 15b correlates with the amount of toner in the developing container 13 as shown in FIG. As described above, it is considered that the powder pressure of the toner 12 acts when the toner 12 enters and leaves the supply roller 15 and the influence of the weight of the toner 12 on the powder pressure is large.

  When detecting the toner amount, the second unit 11B as the developing device 4 is moved to the separation position B (FIG. 4) and held. That is, the developing roller 14 as the other electrode is separated from the drum 1. The rotation of the developing roller 14 and the toner supply roller 15 is stopped. By separating the developing device 4 from the drum 1, the toner 12 may be transferred to the drum 1 or a striking sound may be generated between the developing roller 14 and the drum 1 even when an AC voltage is applied as described later. Absent. Further, by stopping the rotation of the supply roller 15, the toner 12 is put in and out as described above, and the toner amount can be detected with high accuracy.

  Further, the switch SW is switched to the contact d side. As a result, the circuit of the developing roller 14 is switched from the power supply unit 50 side to the ammeter 18 side. An AC voltage having a frequency of 50 kHz and Vpp = 200 V is applied to the cored bar electrode 15 a of the supply roller 15 from the AC power supply 17. Since the toner 12 has a dielectric constant and resistance different from those of air, when an AC voltage is applied to the supply roller 15, a current correlated with the amount of the toner 12 included in the foamed urethane layer 15 b and the surrounding toner 12 is applied to the developing roller 14. Induced. The ammeter 18 detects this amount of current. A detector 19 that outputs a detection result corresponding to the detected current amount is connected to the ammeter 18.

  Then, the detection result output from the detector 19 is input to the developer amount detection function unit of the control circuit unit 200. The control circuit unit 200 detects the toner amount in the developing container 13 by calculation based on the input detection result. In addition, the conditions of the application voltage of the alternating voltage with respect to the supply roller 15, frequency 50kHz, and Vpp = 200V are not limited to the said example.

  Here, in Table 1 below, the black cartridge when the cartridge 11 is mounted on all four mounting portions 60a of the cartridge 11 and when any of the yellow, magenta, and cyan cartridges is not mounted. This is shown in the 11k toner amount detection result. This detection result is a value obtained through the detector 19 and not the current itself. Here, a digital value subjected to analog / digital processing via the detector 19 is used, and the unit is called dec. This 1 dec corresponds to about 8 pF in capacitance.

  This toner amount detection result changes depending on whether or not each cartridge 11 is mounted. In particular, the influence of the adjacent cyan cartridge 11c is great. In the present embodiment, the width of the detection result that changes from the full state of toner 12 to the toner out is 22 dec, but it can be seen that 8 dec generated by the presence or absence of cyan cartridge 11c is sufficiently large.

  In the toner amount detection described above, a detection voltage is simultaneously applied to all of the mounting portions 60a of the four cartridges 11 regardless of whether or not each cartridge 11 is mounted. That is, not only the physical presence / absence of the cartridge 11 other than the detection target, but also whether or not a detection voltage is applied to the cartridge 11 other than the detection target is electrically related to the detection result as shown in the background art. There is also a possibility of having an influence.

  That is, this voltage interference is not the only factor that influences the surroundings on the detection accuracy. In the detection method of applying an oscillating voltage, in order to detect the dielectric constant and resistance around the electrode, not only the amount of developer but also the presence or absence of members around the electrode and the relative positional relationship affect the detection result. give. In a color image forming apparatus having a plurality of cartridges as in this embodiment, for the purpose of improving usability, even when a colored (yellow, magenta, cyan) cartridge has reached the end of its life, or only a black cartridge is used. There is a configuration that allows printing.

  In such a case, if the developer amount of the black cartridge is detected in a state where the colored cartridge is removed, there is a difference from the detection result when the colored cartridge is mounted. As described above, the detection result of the developer amount differs depending on whether or not an image forming unit other than the image forming unit in which the developer to be detected is detected.

  Therefore, the detection results were compared with the case where the contact of a specific mounting portion was insulated with all four cartridges 11 mounted, and not insulated. As a result, the difference between when it was insulated and when it was not insulated was only about ± 1 to 2 dec. That is, it can be seen that most of the above-mentioned 8 dec difference is not due to electrical influence, but is caused by the physical presence or absence of the cartridge 11 other than the detection target. This is because in the detection method of detecting the developer amount by applying an oscillating voltage, the electric lines of force generated from the electrodes are spread over a wide range, and the surrounding members, particularly the conductive members such as the drum 1 and the core metal of the roller. This seems to be due to the strong influence of.

  Therefore, if the mounting state of the cartridge 11 changes, the toner amount of the black cartridge cannot be accurately detected. In this embodiment, black can be printed even if any of yellow, magenta, and cyan is not mounted. Therefore, an accurate toner amount must be detected regardless of the mounted state of yellow, magenta, and cyan.

  Therefore, first, the difference from the toner amount detection results in various mounted states of the cartridges 11 is obtained from Table 1 on the basis of the toner amount detection results when all the cartridges 11 are mounted, as shown in Table 2 below. Created a table. This table shows how much the toner amount detection result changes from the state in which all the cartridges 11 are mounted in each mounting state, and is used for correcting the detection result as will be described later.

(5) Mounting State Detection Unit The mounting state detection unit is a unit that detects whether or not each of the plurality of cartridges 11 is mounted on the apparatus main body 100A. In this embodiment, in order to detect the mounting state of the cartridge 11, a DC power source 20 that applies a DC voltage between the developing roller 14 and the blade 16 is provided at a predetermined position where the cartridge 11 is mounted. When the cartridge 11 is mounted on the apparatus main body 100A, the blade 16 is connected to the DC power source 20 by the electrical contacts a and b. Further, the switch SW is switched to the contact d side. As a result, the circuit of the developing roller 14 is switched from the power supply unit 50 side to the ammeter 18 side.

  When a DC voltage is applied from the DC power source 20 to the developing roller 14 via the blade 16, a current flows between the developing roller 14 and the blade 16 if the cartridge 11 is mounted. As a result, the control circuit unit 200 can detect the current flowing through the ammeter 18 via the detector 19, thereby detecting the mounting of the cartridge 11. If the cartridge 11 is not attached, no current flows through the ammeter 18. As a result, the control circuit unit 200 detects the non-mounting of the cartridge 11. That is, the control circuit unit 200 can detect the presence or absence of each cartridge 11 by the ammeter 18.

  When the mounting state of the cartridge 11 is detected, if the developing roller 14 is driven to rotate, a larger current can be obtained, and the mounting can be easily detected. This is because the toner 12 sandwiched between the developing roller 14 and the blade 16 acts as a resistance layer, but when the developing roller 14 is driven to rotate, the toner 12 rolls and the charge moves from the blade 16 to the developing roller 14. This is probably because of this. Here, a voltage of −200 V is applied to the blade 16 with respect to the developing roller 14, and the developing roller 14 is rotationally driven to detect the mounting state of the cartridge 11.

  Of course, it is only necessary to detect the mounting state of the cartridge 11, and the method is not limited to such a method of detecting current.

  Then, the toner amount detection described above was performed to obtain a toner amount detection result. With respect to this detection result, the detection result is corrected by referring to the difference information of the detection result corresponding to the mounting state of the cartridge 11 from the table of Table 2 and subtracting this value from the detection result. The difference applied to this correction is the difference in the toner amount detection result between the current mounting state and the state where all four cartridges 11 are mounted as described above. Naturally, the corrected detection result gives the same result as when all the cartridges 11 are mounted.

  That is, the control circuit unit 200 as a control unit includes a table (Table 2) in which correction values of developer detection results corresponding to the mounting states of a plurality of cartridges are recorded. The developer amount information detected by the developer amount detecting unit is corrected with reference to the table based on the mounting state information of the plurality of cartridges detected by the mounting state detecting unit. Thereby, even when the mounting state of the cartridge 11 changes variously, the toner amount can be accurately detected.

  In this embodiment, when the toner amount is detected, an AC voltage is applied using the supply roller 15 as one electrode. However, a separate antenna electrode is provided in the developing container 13, and the AC voltage is applied to the antenna electrode to reduce the toner amount. It may be detected. Even in this case, not only the amount of toner but also the presence / absence of the members around the electrode and the relative positional relationship affect the detection result, but the amount of toner is accurately detected by applying the correction method of this embodiment. be able to.

  The toner amount detection and correction operation of this embodiment will be described with reference to the flowchart of FIG. First, the image forming apparatus is placed in a standby state (ST (step) 1). During image formation, as described above, the developing roller 14 is driven to rotate while applying a voltage of -200 V to the blade 16 (ST2), and the current flowing through the developing roller 14 is detected to detect the mounting state of the cartridge 11 (ST3). ).

  When all the cartridges 11 are mounted, ST4 is selected, and when any cartridge 11 is not mounted, ST10 is selected. The ST4 series performs full-color image formation and does not correct the toner amount detection result, and the ST10 series performs monochrome image formation and corrects the toner amount detection result.

  The preliminary rotation of the drum 1 before and after image formation is referred to as a pre-rotation operation and a post-rotation operation of the apparatus 100, respectively. The reason for detecting the cartridge mounting state in ST3 during the pre-rotation operation is that not only the correction of the toner amount detection but also the determination of whether the image forming operation should be full color or monochrome can be made.

  When the process proceeds to ST4, the four developing devices 4 (second units 11B) are moved to the contact position A with the drum 1 (ST4), and full-color image formation is performed (ST5). After the full color image formation is completed (ST6), the developing device 4 is moved to the separation position B from the drum 1 (ST7), and the developing roller 14 and the toner supply roller 15 are stopped (ST8). Then, as described above, an AC voltage having a frequency of 50 kHz and Vpp = 200 V is applied to the supply roller 15, and the toner amount detection result is obtained by the detector 19 that obtains information from the ammeter 18 connected to the developing roller 14 (ST9). This detection result is notified to the user as needed (ST17).

  When the process proceeds to ST10, only the black developing device 4 is moved to the contact position A with the drum 1 (ST10), and a monochrome image is formed (ST11). Only black is brought into contact with A in order to prevent inadvertent deterioration of the mounted yellow, magenta, or cyan toner 12 by rubbing against the drum 1, and a toner 12 called a fog in the white portion. This is because it does not cause metastasis.

  After the monochrome image formation (ST12), the developing device 4 is moved to the separation position B from the drum 1 (ST13), and the developing roller 14 and the supply roller 15 are stopped (ST14), as in ST4. Similarly to the ST4 series, an AC voltage having a frequency of 50 kHz and Vpp = 200 V is applied to the toner supply roller 15, and a toner amount detection result is obtained by the detector 19 that obtains information on the ammeter 18 connected to the developing roller 14 (ST15). ).

  In this ST10 series, since any one of the cartridges 11 of yellow, magenta, and cyan is not mounted, the correction value of the toner amount detection result in the mounted state is referred from the table, and the toner amount detection result is corrected (ST16). ). This detection result is notified to the user as needed (ST17).

  By repeating the above operation, the amount of toner can be accurately detected even when the mounting state of the cartridge 11 changes variously.

  In the present embodiment, the toner amount detection and the detection result correction are performed during the post-rotation operation. However, the present invention is not limited to this timing, and may be performed, for example, during the pre-rotation operation. Further, the interval for detecting the toner amount may be performed after printing a predetermined number of sheets, for example, even if the rotation operation is not performed every time.

  As described above, it is possible to accurately detect the developer amount regardless of whether or not an image forming unit other than the image forming unit in which the developer whose developer amount is to be detected is accommodated.

[Example 2]
7 to 9 are explanatory views of the second embodiment. In this embodiment, the first to fourth integrated process cartridges 11y, 11m, 11c, and 11k in the image forming apparatus 100 of Embodiment 1 are separated type process cartridges. Other apparatus configurations are substantially the same as those of the image forming apparatus 100 of the first embodiment. 7 corresponds to FIG. 3, FIG. 8 corresponds to FIG. 4, and FIG. 9 corresponds to FIG.

  Each of the cartridges 11y, 11m, 11c, and 11k is configured as two units of a first unit 11A and a second unit 11B that are independent of each other. In the present embodiment, the first unit 11A is a unit in which the drum 1, the charging roller 2, and the cleaning device 9 are integrated, and is detachably attached to the apparatus main body 100A (hereinafter referred to as a cleaning unit). It is. The second unit 11B is the developing device 4, and is a developing unit that is detachably attached to the apparatus main body 100A.

  The developing device 4 that is the second unit 11B includes a developing container 13 that is a developer container, a developing roller 14 that supports the toner 12 and supplies the toner 12 to the drum 1, and the toner 12 And a supply roller 15 as a developer supply member.

  The cleaning unit 11A and the developing device 4 (11B) can be independently attached to and detached from the apparatus main body 100A. This is because the life of the developing device 4 determined by the toner amount, the toner 12 and the deterioration of the developing roller 14 is different from the life of the cleaning unit 11A determined by the wear of the drum 1 and the collected toner amount. By making the developing device 4 and the cleaning unit 11A interchangeable independently, each unit can be used until the end of its life, and it is possible to prevent the wasteful use of resources and produce the merit of reducing costs.

  In the first embodiment, even if any of the yellow, magenta, and cyan cartridges is not temporarily installed, monochrome printing can be performed using only the black cartridge 11k. The purpose of this is to improve usability by enabling printing with only the black cartridge even when one of the yellow, magenta, and cyan cartridges reaches the end of its life. Similarly, in the second embodiment, even when any developing device 4 or cleaning unit 11A other than black has reached the end of its life and has been removed, monochrome printing can be performed using only black.

  In the first embodiment, the toner amount detection result of the black cartridge changes depending on whether the yellow, magenta, and cyan cartridges 11 are mounted. In the second embodiment, there is a mounting state in which the developing device 4 or the cleaning unit 11A for each of yellow, magenta, and cyan is mounted. In each mounted state, the black toner amount detection result gives a different value. Therefore, the amount of black toner cannot be accurately detected when the mounting state of each developing device 4 or the cleaning unit 11A changes.

  In the second embodiment, black can be printed without any of the yellow, magenta, and cyan developing devices 4 or the cleaning unit 11A being mounted. Therefore, an accurate toner amount must be detected regardless of the mounted state. I must.

  Therefore, first, the difference from the black toner amount detection result in each mounted state is obtained on the basis of the black toner amount detection result when all the developing devices 4 and the cleaning unit 11A are mounted, and the table of Example 1 is obtained. A table similar to 2 was created. This table shows how much the toner amount detection result changes from the state in which each developing device 4 and the cleaning unit 11A are all attached in each mounted state. For correction of the detected result as will be described later. Used.

  Next, in order to detect the mounting state of each developing device 4, a DC power source 20 for applying a DC voltage between the developing roller 14 and the toner blade 16 at a predetermined position where the developing device 4 is mounted, and at this time An ammeter 18 was prepared for detecting the current flowing through. The detection of the mounting state of the developing device 4 is the same method as the detection of the mounting state of the cartridge 11 shown in the first embodiment. A voltage of −200 V was applied to the blade 16 with respect to the developing roller 14, and the presence / absence of the developing device 4 was detected by a current flowing when the developing roller 14 was rotationally driven.

  Further, in order to detect the mounting state of the cleaning unit 11A, a DC power source 22 that applies a DC voltage to the charging roller 2 at a predetermined position where the cleaning unit 11A is mounted, and an ammeter that detects the current flowing at this time. 23 were prepared. When the cleaning unit 11A is mounted, the charging roller 2 is connected to the DC power source 22 through the contacts a and b. The DC power source 22 is common to the DC power source 22 used for charging the drum 1 during the image forming operation of the apparatus 100, and applies a voltage of −1000 V to the drum 1 to the charging roller 2.

  When the drum 1 is rotated with a voltage applied, a discharge is generated between the charging roller 2 and the drum 1 and a current flows. Since no current flows unless the cleaning unit 11A is attached, the presence or absence of the cleaning unit 11A can be detected by detecting this current.

  As described above, by detecting the current flowing through each developing device 4 or the cleaning unit 11A, it is possible to detect the mounting state. However, since it is only necessary to detect the mounting state of each developing device 4 or cleaning unit 11A, the method is not limited to such a method of detecting current.

  Then, the toner amount was detected, and the toner amount detection result was obtained. For this detection result, the difference information of the detection result corresponding to the mounting state of each developing device 4 or the cleaning unit 11A is referred to from the above table, and the detection result is corrected by subtracting this value from the detection result.

  The difference applied to this correction is the difference in the toner amount detection result between the current mounted state and all the developing devices 4 and the cleaning unit 11A as described above. Naturally, the corrected detection result gives the same result as when all the developing devices 4 and the cleaning unit 11A are mounted. Therefore, the toner amount can be accurately detected even when the mounting state of the developing device 4 and the cleaning unit 11A changes variously.

  Also in the second embodiment, a separate antenna electrode may be provided in the developing container 13, and an AC voltage may be applied to the antenna electrode to detect the toner amount. Even in this case, not only the amount of toner but also the presence / absence of the members around the electrode and the relative positional relationship affect the detection result, but the amount of toner is accurately detected by applying the correction method of this embodiment. be able to.

  The execution order of the toner amount detection and correction operation of the present embodiment is the same as the flowchart of FIG. 6 shown in the first embodiment. If the mounting state of the developing device 4 and the cleaning unit 11A is also detected during the pre-rotation operation, it is convenient because it is possible to determine whether the image forming operation is full color or monochrome. In the present embodiment, the toner amount detection and the detection result correction are performed during the post-rotation operation. However, the present invention is not limited to this timing, and may be performed, for example, during the pre-rotation operation. Further, the interval for detecting the toner amount may be performed after printing a predetermined number of sheets, for example, even if the rotation operation is not performed every time.

  As described above, it is possible to accurately detect the developer amount regardless of whether or not an image forming unit other than the image forming unit in which the developer whose developer amount is to be detected is accommodated.

[Other configurations]
1) The image forming apparatus is not limited to the electrophotographic image forming apparatus. Any image forming apparatus having an image carrier, a latent image forming unit that forms a latent image on the image carrier, and a developing unit that develops the latent image with a dry powder developer may be used. Representative examples of the image bearing member on which the latent image is formed include a dielectric in the electrostatic recording image forming method and a magnetic material in the magnetic recording image forming method in addition to the photosensitive member in the electrophotographic image forming method.

  The image forming apparatus includes a transfer type or direct type copying machine, a printer, a facsimile machine, a word processor, an output device such as a multifunction machine having a function such as those, a workstation, or the like. The transfer method is a method in which a developer image formed on an image carrier is transferred to a recording medium (recording material) or transferred to a recording medium via an intermediate transfer member to form an image on the recording medium. The direct method is a method of forming an image using the image carrier directly as a recording medium. The image forming apparatus also includes an image display device (display device) such as an electronic blackboard device that forms an image on an image display member as a recording medium and displays the image on a display unit.

  DESCRIPTION OF SYMBOLS 1 ... Image carrier, 12 ... Developer, 13 ... Developer accommodating part, 100 ... Image forming apparatus, 100A ... Apparatus body, 11y ... 11m ... 11c ... 11k ... Multiple image forming units, 8 ..Recording medium, 14.15 .. One set of electrodes (developer carrier, developer supply member), 17 .. Vibrating voltage source, 18..19.200 .. Developer amount detecting means, 20.16. 18.19.200..Installation state detection means, 200..Control means

Claims (4)

It has at least a developer containing portion for containing a dry powder developer used for developing a latent image formed on an image carrier, and is detachably attached to the apparatus main body of the image forming apparatus. An image forming apparatus that includes a plurality of image forming units and forms an image on a recording medium, and includes at least one set of electrodes that apply an electric field to the developer stored in the developer storing section, and the one set of An oscillating voltage source connected to one of the electrodes, and a developer that detects the amount of developer accommodated in the developer accommodating portion by an electrical signal induced in the other electrode of the one set of electrodes An image forming apparatus comprising: an amount detecting unit; a mounting state detecting unit that detects whether or not each of the plurality of image forming units is mounted; and a control unit.
The control unit includes a table in which correction values of developer detection results corresponding to mounting states of the plurality of image forming units are recorded, and mounting state information of the plurality of image forming units detected by the mounting state detecting unit. And correcting the developer amount information detected by the developer amount detecting means with reference to the table.   The image forming unit is an integrated process cartridge in which at least the image carrier and developing means for developing the latent image with the developer are integrated and detachably attached to the apparatus main body. The developing means includes the developer container, a developer carrier that supports the developer and supplies the developer to the image carrier, and a developer supply member that supplies the developer to the developer carrier. The image forming apparatus according to claim 1, further comprising:   The image forming unit includes a first unit that has the image carrier and is detachably attached to the apparatus main body, and a developing unit that develops the latent image formed on the image carrier with the developer. And a second unit detachably attached to the apparatus main body. The second unit carries the developer container and the developer. The image forming apparatus according to claim 1, further comprising: a developer carrier that supplies the image carrier, and a developer supply member that supplies the developer to the developer carrier.   3. The developer carrying member and the developer supplying member are also used as the one set of electrodes for applying an electric field to the developer accommodated in the developer accommodating portion. The image forming apparatus according to 3.