JP6012243B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus, a developing device used in the electrophotographic image forming apparatus, and a process cartridge that can be attached to and detached from the electrophotographic image forming apparatus.

  Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming system. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (laser beam printer, LED printer, etc.), a facsimile apparatus and a word processor, and a complex machine (multifunction printer) thereof.

  The developing device is a device that visualizes an electrostatic latent image on an image carrier such as an electrophotographic photosensitive drum using a developer. Further, the process cartridge is a cartridge in which at least the developing means and the electrophotographic photosensitive member are integrally formed so as to be detachable from the main body of the electrophotographic image forming apparatus.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile machine, an electrostatic latent image formed on an image carrier such as an electrophotographic photosensitive member is visualized as a toner image by being developed by a developing device.

  In an image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally formed as a cartridge, and the cartridge is detachable from the main body of the image forming apparatus. The method is adopted. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved.

  In recent years, color image forming apparatuses that form color images using a plurality of color developers have become widespread. As a color image forming apparatus, photoconductors corresponding to each of image forming operations using a plurality of color developers are arranged in a line along the surface movement direction of a transfer target body onto which a toner image is transferred, so-called, An in-line image forming apparatus is known. Some in-line color image forming apparatuses have a plurality of photoconductors arranged in a line in a direction (for example, a horizontal direction) intersecting a vertical direction (gravity direction). The in-line method is a preferable image forming method in that it is easy to meet demands such as an increase in image forming speed and development to a multifunction printer.

  In addition, as an in-line image forming apparatus in which a plurality of photoconductors are arranged in a row in a direction intersecting the vertical direction, a plurality of photoconductors are used as intermediate transfer members as transfer targets or recording materials as transfer targets. There is one arranged below the recording material carrier to be conveyed (see Patent Document 1).

  When the photosensitive member is disposed below the intermediate transfer member or the recording material carrier, the intermediate transfer member or the recording material carrier is sandwiched in the image forming apparatus main body, for example, a fixing device and a developing device (or an exposure device). Can be arranged at positions separated from each other. Therefore, there is an advantage that the developing device (or the exposure device) is not easily affected by the heat of the fixing device.

  Furthermore, since the moving distance of the intermediate transfer member until the toner image is transferred to the recording material can be shortened, the first printed matter is discharged after the FPOT (First Print Out Time: print print start button is pressed). There is also an advantage of shortening the time required until.

  For example, when the photosensitive member is disposed below the intermediate transfer member or the recording material carrier as described above, it may be necessary to transport the developer against gravity in the developing device. The developing device of Patent Document 1 includes a developing chamber and a developer accommodating chamber disposed below the developing chamber. The developing chamber is provided with a developer carrier for supplying the developer to the photoreceptor and a supply member for supplying the developer to the developer carrier. Further, the developer accommodating chamber includes a developer conveying member that conveys the developer accommodated in the developer accommodating chamber through the opening provided in the developing chamber onto the supply member, and the developer remaining in the developing device. A light transmissive member for detecting the amount by the detection light is provided.

JP 2008-209897 A

  When adopting a configuration in which the remaining amount of the developer is detected by the detection light in the developer storage chamber disposed below the development chamber as in the conventional configuration described above, the toner falling from the development chamber to the developer storage chamber is detected by the detection light. This sometimes obstructs the detection of the developer remaining amount.

  Accordingly, an object of the invention according to the present application is to provide a developing device that improves the detection accuracy of the remaining amount of developer in a configuration in which the remaining amount of developer is detected by detection light in the developer storage chamber disposed below the developing chamber, To provide a process cartridge and an image forming apparatus.

In order to achieve the above object, a first invention according to the present invention is a developing device for use in an electrophotographic image forming apparatus, comprising a developer carrying member carrying a developer and a developer carrying member. A developing chamber that is disposed to form a nip portion and that supplies a developer to the developer carrying member; a developer accommodating chamber that is disposed below the developing chamber and accommodates the developer; and a developer A developer conveying member that conveys the developer accommodated in the accommodating chamber through the opening provided in the developing chamber onto the supply member, and provided in the developer accommodating chamber for detecting the remaining amount of the developer A developing member, wherein the supply member rotates in a direction in which the surface moves from the upper end to the lower end of the nip portion.

  As described above, according to the invention of the present application, in the configuration in which the developer remaining amount is detected by the detection light in the developer storage chamber disposed below the developing chamber, the surface of the supply member is a developer carrier. , The detection accuracy of the remaining amount of the developer can be improved.

1 is a schematic cross-sectional view of an image forming apparatus in Embodiment 1. FIG. FIG. 2 is a schematic cross-sectional view of a developing device and a process cartridge according to Embodiment 1. FIG. 6 is a schematic sectional view of a conventional process cartridge. FIG. 1 is a schematic cross-sectional view 1 illustrating an operation of a toner conveying member in a process cartridge according to a first embodiment. FIG. 3 is a schematic cross-sectional view of a developing device and a process cartridge after toner is supplied to a second storage unit in Embodiment 1. FIG. 10 is a schematic cross-sectional view of a developing device and a process cartridge after toner is supplied to a second reservoir in a conventional configuration. 5 is a waveform showing the relationship between the time obtained by the light receiving unit and the amount of light in Example 1. The waveform which showed the relationship between the time and light quantity obtained in a light-receiving part in a prior art example. FIG. 6 is a schematic cross-sectional view of a developing device and a process cartridge in Embodiment 2. The relationship between the stirring rotation speed and electrostatic capacity in Example 2 and the conventional example, and the relationship between the remaining amount of toner and electrostatic capacity in Example 2.

  Hereinafter, a developing device, a process cartridge, and an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

  A first embodiment of the present invention will be described with reference to FIGS.

[Image forming apparatus]
First, the overall configuration of an electrophotographic image forming apparatus (image forming apparatus) according to the present invention will be described.

  FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 of the present embodiment. The image forming apparatus 100 of this embodiment is a full-color laser printer that employs an inline method and an intermediate transfer method. The image forming apparatus 100 can form a full-color image on a recording material (for example, recording paper, plastic sheet, cloth, etc.) according to the image information. The image information is input to the image forming apparatus main body 100A from an image reading apparatus connected to the image forming apparatus main body 100A or a host device such as a personal computer connected to the image forming apparatus main body 100A so as to be communicable.

  The image forming apparatus 100 includes, as a plurality of image forming units, first, second, and third images for forming yellow (Y), magenta (M), cyan (C), and black (K) images, respectively. And fourth image forming units SY, SM, SC, and SK. In the present embodiment, the first to fourth image forming units SY, SM, SC, and SK are arranged in a line in a direction that intersects the vertical direction.

In the present embodiment, the configurations and operations of the first to fourth image forming units SY, SM, SC, and SK are substantially the same except that the colors of images to be formed are different. Therefore, in the following, unless there is a particular distinction, the subscripts Y, M, C, and K given to the reference numerals to indicate that they are elements provided for any color are omitted, and generally explain.
In other words, in this embodiment, the image forming apparatus 100 includes four drum-type electrophotographic photosensitive members, that is, the photosensitive drums 1 arranged in parallel in a direction intersecting the vertical direction as a plurality of image carriers. . The photosensitive drum 1 is rotationally driven by a driving means (drive source) (not shown) in the direction indicated by an arrow A (clockwise). Around the photosensitive drum 1, a charging roller 2 as a charging means for uniformly charging the surface of the photosensitive drum 1, a laser is irradiated based on image information, and an electrostatic image (electrostatic) is formed on the photosensitive drum 1. A scanner unit (exposure device) 3 is disposed as exposure means for forming a (latent image). Further, around the photosensitive drum 1, a developing unit (developing device) 4 as developing means for developing an electrostatic image as a toner image, toner remaining on the surface of the photosensitive drum 1 after transfer (transfer residual toner) A cleaning member 6 is disposed as a cleaning means for removing water. Further, an intermediate transfer belt 5 as an intermediate transfer body for transferring the toner image on the photosensitive drum 1 to the recording material 12 is disposed opposite to the four photosensitive drums 1.
In this embodiment, the developing unit 4 uses a non-magnetic one-component developer toner as the developer. In this embodiment, the developing unit 4 performs reverse development by bringing a developing roller (described later) as a developer carrying member into contact with the photosensitive drum 1. In other words, in this embodiment, the developing unit 4 is a portion where the charge is attenuated due to the exposure of the toner charged to the same polarity as the charging polarity of the photosensitive drum 1 (negative polarity in this embodiment) on the photosensitive drum 1 ( The electrostatic image is developed by being attached to the image portion and the exposure portion).

  In this embodiment, the photosensitive drum 1 and the charging roller 2, the developing unit 4 and the cleaning member 6 as process means acting on the photosensitive drum 1 are integrated, that is, integrated into a cartridge, A process cartridge 7 is formed. The process cartridge 7 can be attached to and detached from the image forming apparatus 100 via mounting means such as a mounting guide and a positioning member provided in the image forming apparatus main body 100A. In this embodiment, the process cartridges 7 for the respective colors all have the same shape, and each of the process cartridges 7 for each color has yellow (Y), magenta (M), cyan (C), and blank ( K) toner of each color is accommodated.

  The intermediate transfer belt 5 formed of an endless belt as an intermediate transfer member abuts on all the photosensitive drums 1 and circulates (rotates) in the direction of arrow B (counterclockwise) in the figure. The intermediate transfer belt 5 is wound around a driving roller 51, a secondary transfer counter roller 52, and a driven roller 53 as a plurality of support members.

  On the inner peripheral surface side of the intermediate transfer belt 5, four primary transfer rollers 8 as primary transfer means are arranged in parallel so as to face the respective photosensitive drums 1. The primary transfer roller 8 presses the intermediate transfer belt 5 toward the photosensitive drum 1 to form a primary transfer portion N1 where the intermediate transfer belt 5 and the photosensitive drum 1 abut. A bias having a polarity opposite to the normal charging polarity of the toner is applied to the primary transfer roller 8 from a primary transfer bias power source (high voltage power source) as a primary transfer bias applying unit (not shown). As a result, the toner image on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5.

  A secondary transfer roller 9 as a secondary transfer unit is disposed at a position facing the secondary transfer counter roller 52 on the outer peripheral surface side of the intermediate transfer belt 5. The secondary transfer roller 9 is pressed against the secondary transfer counter roller 52 via the intermediate transfer belt 5 to form a secondary transfer portion N2 where the intermediate transfer belt 5 and the secondary transfer roller 9 come into contact. A bias having a polarity opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 9 from a secondary transfer bias power source (high voltage power source) as a secondary transfer bias applying unit (not shown). As a result, the toner image on the intermediate transfer belt 5 is transferred (secondary transfer) to the recording material 12.

  More specifically, at the time of image formation, first, the surface of the photosensitive drum 1 is uniformly charged by the charging roller 2. Next, the surface of the charged photosensitive drum 1 is scanned and exposed by laser light corresponding to the image information emitted from the scanner unit 3, and an electrostatic image according to the image information is formed on the photosensitive drum 1. Next, the electrostatic image formed on the photosensitive drum 1 is developed as a toner image by the developing unit 4. The toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the intermediate transfer belt 5 by the action of the primary transfer roller 8.

  For example, when forming a full-color image, the above-described process is sequentially performed in the first to fourth image forming units SY, SM, SC, and SK, and the toner images of the respective colors are next superimposed on the intermediate transfer belt 5. The primary transfer.

  Thereafter, the recording material 12 is conveyed to the secondary transfer portion N2 in synchronization with the movement of the intermediate transfer belt 5. The four color toner images on the intermediate transfer belt 5 are secondarily transferred onto the recording material 12 collectively by the action of the secondary transfer roller 9 that is in contact with the intermediate transfer belt 5 via the recording material 12.

  The recording material 12 onto which the toner image has been transferred is conveyed to a fixing device 10 as a fixing unit. The toner image is fixed on the recording material 12 by applying heat and pressure to the recording material 12 in the fixing device 10.

  Further, the primary transfer residual toner remaining on the photosensitive drum 1 after the primary transfer process is removed and collected by the cleaning member 6. The secondary transfer residual toner remaining on the intermediate transfer belt 5 after the secondary transfer process is cleaned by the intermediate transfer belt cleaning device 11.

  Note that the image forming apparatus 100 can form a single-color or multi-color image using only one desired image forming unit or using only some (not all) image forming units. It is like that.

[Process cartridge]
Next, the overall configuration of the process cartridge 7 mounted on the image forming apparatus 100 of the present embodiment will be described.

  FIG. 2 is a schematic cross-sectional view (main cross-sectional view) of the process cartridge 7 of this embodiment viewed along the longitudinal direction (rotational axis direction) of the photosensitive drum 1. The posture of the process cartridge 7 in FIG. 2 is a posture in a state where the process cartridge 7 is mounted on the image forming apparatus main body. When the positional relationship and direction of each member of the process cartridge are described below, the positional relationship and direction in this posture are described below. Etc. In the present embodiment, the configuration and operation of the process cartridge 7 for each color are substantially the same except for the type (color) of the developer stored therein.

  The process cartridge 7 is configured by integrating a photosensitive unit 13 including the photosensitive drum 1 and the developing unit 4 including a developing roller 17 and the like.

  The photoconductor unit 13 has a cleaning frame 14 as a frame that supports various elements in the photoconductor unit 13. The photosensitive drum 1 is rotatably attached to the cleaning frame 14 via a bearing (not shown).

  The photosensitive drum 1 is rotationally driven in the direction of the arrow A (clockwise) in accordance with the image forming operation by transmitting the driving force of a driving motor (not shown) as a driving means (driving source) to the photosensitive unit 13. Is done. In this embodiment, the photosensitive drum 1 which is the center of the image forming process is an organic photosensitive drum in which an outer surface of an aluminum cylinder is coated with a functional undercoat layer, a carrier generation layer, and a carrier transfer layer in this order. 1 is used.

  Further, the cleaning unit 6 and the charging roller 2 are disposed in the photosensitive unit 13 so as to come into contact with the peripheral surface of the photosensitive drum 1. The transfer residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls and is stored in the cleaning frame 14.

  The charging roller 2 as charging means is driven to rotate by bringing the roller portion of conductive rubber into pressure contact with the photosensitive drum 1.

  Here, as a charging process, a predetermined DC voltage is applied to the core of the charging roller 2 with respect to the photosensitive drum 1, whereby a uniform dark portion potential (Vd) is applied to the surface of the photosensitive drum 1. Is formed. The spot pattern of the laser beam emitted in accordance with the image data by the laser beam from the scanner unit 3 described above exposes the photosensitive drum 1, and the exposed portion is charged on the surface by the carrier from the carrier generation layer. Disappears and the potential drops. As a result, an electrostatic latent image is formed on the photosensitive drum 1 with a predetermined light portion potential (Vl) at an exposed portion and a predetermined dark portion potential (Vd) at an unexposed portion.

  On the other hand, the developing unit 4 has a developing roller 17 as a developer carrying member for carrying a developer (toner) 80 and a supply roller 20 as a developer supplying member that supplies toner to the developing roller 17. doing. Further, the developing unit 4 is provided below the supply roller 20 in the gravity direction, and includes a developer storage chamber that stores the toner 80, that is, a toner storage chamber 19. A developing chamber 18 provided with a developing roller 17 and a supply roller 20 is also provided. The developing chamber 18 has an opening 18 d for feeding toner from the toner storage chamber 19.

  Further, in the toner storage chamber 19, the toner transport member 22 rotatably supported in the toner storage chamber 19 is used to stir the stored toner and transport the toner above the supply roller 20 (on the supply member). Is provided.

  The toner storage chamber 19 is connected to the bottom wall surface W1 and the bottom wall surface W1 along the rotational direction G of the toner conveying member 22 in a state where it is mounted on the cartridge, that is, in the posture shown in FIG. It has the 1st wall surface W2 inclined inward of the storage chamber 19. As shown in FIG.

  Further, the toner storage chamber 19 has a second wall surface W3 connected to the first wall surface W2 and reaching the opening 18c, and a third wall surface W4 extending from the second wall surface W3 to the bottom wall surface W1.

  In the toner storage chamber 19, the toner conveying member 22 moves in contact with the bottom wall surface W1 and the first wall surface W2, as will be described in detail later. Therefore, the toner T in the toner storage chamber 19 is conveyed by being lifted from the bottom wall surface W1 to the first wall surface W2, and is guided along the third wall surface W3 to above the supply roller 20.

  The toner sent above the supply roller 20 is stored in a second storage area in a region above the nip N between the developing roller 17 and the supply roller 20 (a portion where the toner is sandwiched between the developing roller 17 and the toner supply roller 20). It is stored in the part 18b.

The toner T that has not been introduced above the supply roller either falls into the toner storage chamber 19 or is guided along the third wall surface W4 into the toner storage chamber 19.
In this embodiment, the developing unit has a longitudinal width of 230 mm.

  Further, the supply roller 20 and the developing roller 17 are in contact with each other with the nip portion N so that the surfaces of the supply roller 20 and the developing roller 17 move in the same direction (in this embodiment, the direction of movement from the upper end to the lower end of the nip portion). Rotate.

  The developing blade 21 is in contact with the developing roller 17 at a counter, and regulates the coating amount of toner supplied by the supply roller 20 and applies charge. The developing blade 21 is made of a thin plate-like member, forms contact pressure by utilizing the spring elasticity of the thin plate, and the surface thereof is in contact with the toner and the developing roller 17. The toner is triboelectrically charged by rubbing between the developing blade 21 and the developing roller 17 to be charged, and at the same time the layer thickness is regulated. In this embodiment, a predetermined voltage is applied to the developing blade 21 from a blade bias power source (not shown) to stabilize the toner coat.

  The developing roller 17 and the photosensitive drum 1 rotate so that the surfaces of the developing roller 17 and the photosensitive drum 1 move in the same direction (in this embodiment, the direction from the bottom to the top) in the facing portion (contact portion).

  In the present embodiment, the developing roller 17 is disposed in contact with the photosensitive drum 1, but the developing roller 17 is disposed close to the photosensitive drum 1 at a predetermined interval. May be.

In this embodiment, a toner charged negatively by frictional charging with respect to a predetermined DC bias applied to the developing roller 17 has a bright portion potential portion in a developing portion where the toner contacts the photosensitive drum 1 from the potential difference. The electrostatic latent image is visualized by transferring only to.
The supply roller 20 is disposed with a predetermined contact portion (nip portion) N formed on the peripheral surface of the developing roller 17 at the opposing portion, and rotates in the direction of the arrow E (clockwise) in the drawing. The supply roller 20 is an elastic sponge roller in which a foam layer is formed on the outer periphery of a conductive metal core. The supply roller 20 and the developing roller 17 are in contact with each other with a predetermined intrusion amount, that is, the recess amount ΔE in which the supply roller 20 is recessed by the developing roller 17. In the contact portion N, the surfaces rotate so as to move in the same direction. With this operation, the supply roller 20 supplies the developing roller 17 and the toner remaining on the developing roller 17 is removed from the developing roller 17. ing. The toner T introduced above the supply roller 20 is charged by passing through a contact portion (nip portion) N between the supply roller 20 and the development roller 17, and the toner not supplied to the development roller 17 is supplied to the development chamber. 18 is guided to a first reservoir 18c (a region below the developing roller 17 and the supply roller 20 in the developing chamber 18) that stores toner. In this embodiment, the supply roller is driven to rotate at 200 rpm, and the developing roller is driven to rotate at 100 rpm. The supply roller 20 rotates in the direction indicated by the arrow E, and the toner conveying member 22 rotates in the same direction so as to rotate in the direction indicated by the arrow G.

  In this embodiment, both the developing roller 17 and the supply roller 20 have an outer diameter of 15 mm, and the amount of penetration of the supply roller 20 into the development roller 17, that is, the supply roller 20 is recessed by the development roller 17. The dent amount ΔE was set to 1.0 mm. Further, the supply roller 20 and the developing roller 17 are arranged so that the center height is the same.

Hereinafter, the details of the supply roller 20 used in the present embodiment will be described.
The supply roller 20 in the present embodiment includes a conductive support and a foam layer supported by the conductive support. Specifically, a foamed urethane layer as a foamed layer composed of a cored bar electrode 20a having an outer diameter of φ5 (mm), which is a conductive support, and an open cell body (open cells) in which bubbles are connected to the periphery thereof. 20b is provided and rotates in the direction E in the figure. The longitudinal width of the supply roller used in this example is 220 mm.

A large amount of toner can enter the supply roller 20 by making the urethane of the surface layer into an open cell body. Further, the resistance of the supply roller 20 in this embodiment is 1 × 10 ⁹ (Ω).

  Here, a method for measuring the resistance of the supply roller 20 will be described. The supply roller 20 is brought into contact with an aluminum sleeve having a diameter of 30 mm so that an intrusion amount described later becomes 1.5 mm. By rotating the aluminum sleeve, the supply roller 20 is driven to rotate with respect to the aluminum sleeve at 30 rpm.

  Next, a DC voltage of −50 V is applied to the developing roller 17. At that time, a resistance of 10 kΩ is provided on the ground side, the current is calculated by measuring the voltage at both ends, and the resistance of the supply roller 20 is calculated. In this embodiment, the surface cell diameter of the supply roller 20 is 50 μm to 1000 μm and the porosity is 0.6.

  Here, the cell diameter means the average diameter of the foamed cells having an arbitrary cross section. First, the area of the foamed cell that is the maximum is measured from the enlarged image of the arbitrary cross section, and the maximum cell diameter is converted from this area by converting the equivalent circle diameter. Get. And after deleting the foam cell which is 1/2 or less of this maximum cell diameter as noise, it points out the average value of each cell diameter converted similarly from the remaining individual cell area. The porosity means the ratio of foam cells in an arbitrary cross section. First, the area of each foam cell is measured from an enlarged image of the arbitrary cross section, and the total area of the foam cells is obtained. And the ratio for which the total area of this foaming cell occupied in arbitrary cross sections was calculated | required, and the value was made into the porosity.

[Toner level detection configuration]
Next, the light transmission type developer remaining amount detection (hereinafter referred to as “toner remaining amount detection”) of this embodiment will be described with reference to FIG.

As shown in FIG. 2, the toner agitating member 22 provided in the toner storage chamber 19 for storing the toner rotates in the G direction to convey the toner above the supply roller 20.

  As shown in FIG. 2, the toner conveying member 22 includes a shaft member 22a of a resin molded product, and an agitation sheet 22b that is a flexible sheet-like member that is attached to the shaft member 22a and has one end attached to the shaft member 22a. Composed. As flexible sheet-like member 22b, it can produce suitably using flexible resin sheets, such as a polyester film and a polyphenylene sulfide film, for example. The thickness of the sheet-like member 22b is preferably 50 to 250 μm.

  The length of the stirring sheet 22b in the short direction is longer from the toner transport member rotation center O to the toner storage chamber wall surfaces W1, W2, and W4 so that the toner can be stirred and transported to the toner at the bottom of the toner storage chamber 19. doing. Further, the length W0 in the longitudinal direction of the stirring sheet 22b is the length between both side wall surfaces of the toner storage chamber 19 positioned on both sides of the conveying member 22 in the rotation axis direction.

  The driving force is transmitted to the conveying member 22 by a driving gear (not shown) inserted through the side surface of the toner storage chamber 19 into a fitting hole 22c provided at the end of the shaft member 22a.

  On the other hand, the toner storage chamber 19 is provided with a toner remaining amount detecting means for detecting a light transmissive toner remaining amount. In this embodiment, a pair of light transmitting members 40 as developer detecting members for detecting a light transmitting toner remaining amount are formed on the wall surface forming the toner storage chamber 19, particularly on the side wall on the downstream side of the toner supply. The developing roller 17 is disposed so as to face the longitudinal direction of the developing roller 17.

  Each of the light transmitting members 40 includes a transmission window that is an emission portion and a transmission window that is an incidence portion.

  The light transmission member 40 includes a light guide (not shown) that guides the detection light L emitted from an LED (not shown), which is a light emitting unit provided in the electrophotographic image forming apparatus main body 100A, to the inside of the toner storage chamber 19, and a detection. A transmission window capable of transmitting the light L is integrated. The detection light L that has passed through the toner storage chamber 19 passes through a light guide (not shown) and is guided to a phototransistor that is a light receiving portion provided in the electrophotographic image forming apparatus main body 100A.

[Toner level detection method]
The details of the toner remaining amount detection method will be described with reference to FIGS. 4A to 4E and FIG.

  FIG. 4A shows a state in which a predetermined amount of toner T has accumulated in the toner storage chamber 19 and the toner transport member 22 is above the toner surfaces H1 and H2. FIG. 7 shows a waveform obtained by a phototransistor (not shown). A control unit (not shown) provided in the image forming apparatus main body that receives an electrical signal obtained according to the amount of light from a phototransistor (not shown) receives a light amount equal to or greater than a predetermined light amount (threshold). Is measured as transmission time. Then, the toner remaining amount is estimated from the transmission time.

  The waveform obtained by the phototransistor (not shown) in the state of FIG. 4A corresponds to the portion (A) in FIG. That is, since the toner does not reach the light transmission member 40, the detection light L is transmitted through the toner storage chamber 19.

  In this state, the toner conveying member 22 rotates, and the stirring sheet 22b presses the toner surface H2 on the right side of the toner conveying member in FIG. 4A, whereby the toner surface H1 on the left side of the toner conveying member. Rises.

  The toner surface H1 rises along the inclined wall surface W2 of the toner accommodating chamber 19, and in FIG. 4B, the toner surface H1 reaches the light transmitting member 40.

  Immediately after this, the toner is interposed between the pair of light transmitting members 40 provided on the toner accommodating chamber wall surface W2, whereby the detection light L emitted from the LED (not shown) is blocked, and as shown in FIG. The phototransistor (not shown) does not receive the detection light L (state (B)).

  Thereafter, the toner agent surface H1 rises along the toner storage chamber wall surface W2 by the rotation of the toner conveying member 22.

  As shown in FIG. 4C, the toner on the toner stirring sheet 22b falls from the toner stirring sheet 22b and accumulates again on the toner storage chamber 19 when the slope of the toner becomes steep.

  At this time, the toner is still present in the pair of light transmitting members 40 provided on the toner accommodating chamber wall surface W2, and the detection light L is blocked as shown in FIG. 7 (state (C)).

  4D shows a state immediately after the stirring sheet 22b passes through the light transmitting member 40 due to the rotation of the toner conveying member 22. FIG.

  The toner T on the stirring sheet 22b pushed up along the toner storage chamber wall surface W2 by the rotation of the toner conveying member 22 still remains on the sheet 22b. However, since the stirring sheet 22b has passed, the pair of light transmitting members 40 provided on the toner storage chamber wall surface W2 loses the toner T, and the detection light L is again transmitted as shown in FIG. State).

  Here, as described above, the length of the stirring sheet 22b in the short direction is longer than the distance R from the center O of the conveying member 22 to the toner accommodating chamber wall surface W2. Therefore, the toner T carried on the stirring sheet 22b is prevented from spilling from the gap between the stirring sheet 22b and the toner storage chamber wall surface W2 as much as possible.

  Thereafter, as the toner conveying member 22 rotates, the toner stirring sheet 22b continues to convey the toner along the toner storage chamber wall surface W2. The toner conveying member 22 reaches a position where the tip of the toner stirring sheet 22b is released from contact with the wall surface W2.

  Here, by being released, the toner stirring sheet 22b that has been bent and rotated so far extends straight, and at the same time, the toner T placed on the toner stirring sheet 22b jumps up above the supply roller 20. (See FIG. 4 (e)).

  As will be described in detail later, in this embodiment, the toner sent to the upper side of the supply roller 20 by the toner conveying member 22 moves in the direction of arrow H, and the supply roller 20 moves in the same direction (direction of arrow E). Since the toner rotates, the toner can be stably stored in the second storage portion 18b.

  Therefore, at this time, the toner supplied to the upper side of the supply roller 20 falls between the pair of light transmitting members 40 as shown in FIG. 7 and prevents the light transmitting member 40 from transmitting the detection light L. It can be suppressed (state (E)). In the present embodiment, the developing chamber is configured so that the lower end of the opening 18d is positioned above the lower end of the supply roller 20, thereby increasing the amount of toner stored in the first storage unit 18c. The toner drop from 18d is suppressed.

  In the case of the conventional configuration shown in FIG. 3, most of the toner adhering to the supply roller 20 is immediately sent to the second reservoir 18b when the first reservoir 18c is not filled with toner. It moves to the 1st storage part 18c and is stored. For this reason, since there is almost no toner returned to the toner storage chamber 19 among the toners sent above the supply roller 20, the detection light L is not blocked (state shown in FIG. 8A). After that, when the toner is filled in the first reservoir 18c, the supply roller 20 is moved in the direction of the opening 18d (the direction of the arrow E in the figure), so that the toner sent above the supply roller 20 is As the supply roller 20 rotates, the toner is returned to the toner storage chamber 19 without being stored in the second storage portion 18b (see FIG. 6). As a result, the detection light L emitted from the LED (not shown) may be blocked, and the accuracy of the toner remaining amount detection may be lowered (the states of FIGS. 8B and 8C). In particular, when the light transmitting member 40 is provided at a position opposite to the supply roller 20 with respect to the vertical plane passing through the lower end of the opening 18d in the toner storage chamber, this problem becomes significant. This is because the toner sent to the upper side of the supply roller 20 receives the centrifugal force accompanying the rotation of the supply roller 20 and falls toward the light transmitting member 40. As a result, the toner easily reaches between the pair of light transmitting members 40 provided on the toner storage chamber wall surface W2.

  In this embodiment, as shown in FIG. 4E, the toner conveying member 22 rotates in the direction of the arrow G, so that the toner is sent in the direction of the arrow H through the opening 18d. Then, the supply roller 20 rotates in the direction of the arrow E in the figure, thereby assisting the conveyance of the toner sent in the direction of the arrow H to the second storage unit 18b. That is, the supply roller 20 rotates in the direction in which the surface of the supply roller 20 moves from the upper end to the lower end of the nip portion, so that even if the toner is filled in the first storage portion 18c, the supply roller 20 and the developing roller 17 The toner can be stored in the second storage portion 18b on the nip portion (see FIG. 5). Accordingly, it is difficult for the toner to overflow from the opening 18d. As a result, it is difficult for the toner to fall on the light transmission member as compared with the conventional configuration, and it is possible to suppress a decrease in the remaining toner detection accuracy.

  When the printing rate is low, not only the first reservoir 18c but also the second reservoir 18b may be filled with toner. At this time, the toner overflows from the second reservoir 18b and the first reservoir 18c and returns to the toner storage chamber 19. However, since the surface of the supply roller rotates in a direction in which the surface moves from the upper end to the lower end of the nip portion, the toner falls from the opening 18d in the gravitational direction without scattering from the supply roller toward the light transmission member. . Accordingly, it is difficult for the toner to fall on the light transmitting member as compared with the conventional configuration, and it is possible to suppress a decrease in the remaining toner detection accuracy.

  In this embodiment, the rotation direction of the developing roller 17 is rotated in the direction of the arrow D (counterclockwise) in the figure, but it may be rotated in the opposite direction.

  Next, a second embodiment of the present invention will be described. In addition, description is abbreviate | omitted about the part which description overlaps with Example 1. FIG.

  A second embodiment will be described with reference to FIGS. In the first embodiment, the content of the toner remaining amount detection method using the light transmitting member 40 in the toner storage chamber 19 is described. However, in the present embodiment, the toner remaining amount detection method in the second storage unit 18b is described. Propose.

  In this embodiment, the second reservoir 18b is provided with an antenna as an electrode member for the remaining toner amount detecting device. Other configurations are the same as those of the first embodiment. As shown in FIG. 9, in this embodiment, an electrostatic capacitance measuring antenna 50 is provided in the second reservoir 18b where the toner is stored. As the toner remaining amount detection bias applied to the antenna 50, an AC bias having a frequency of 50 kHz and Vpp = 200V is used. The detector (not shown) was provided in a circuit on the cored bar side of the supply roller 20.

  In the present embodiment, the toner supply method to the second reservoir 18b is performed by the toner conveying member 22 as in the first embodiment. However, in this case, a method other than stirring may be used.

  In the case of the conventional configuration, the toner adhering to the supply roller 20 is sent to the first reservoir 18c while adhering to the surface of the supply roller 20 because the supply roller 20 rotates in the direction of the arrow E (counterclockwise) in the figure. End up. As a result, the toner cannot be stably stored in the second storage portion 18b. As can be seen from FIG. 10A, the electrostatic capacity is instantaneously increased by one rotation of the toner conveying member 22, but then the toner in the second reservoir 18b is sent to the first reservoir 18c. As a result, the capacitance is rapidly reduced. In other words, the amount of toner in the second reservoir 18b changes greatly with the rotation period of the toner conveying member 22, so that the variation in the measurement of the remaining amount of toner becomes large.

  In this embodiment, the toner adhering to the supply roller 20 is located between the supply roller 20 and the developing roller 17 as the supply roller 20, which is a feature of the present invention, rotates in the direction of the arrow E (clockwise) in the figure. The two storage portions 18b can be stored stably. As a result, as can be seen from FIG. 10A, the change in the toner amount in the second reservoir 18b is small during one agitation rotation. Further, a change in the electrostatic capacity in the second storage unit 18b with respect to the remaining amount of toner in the developing device is as shown in 10 (b). As can be seen from 10 (b), the measurement can be performed with high accuracy particularly in the region where the toner amount has decreased.

  In this embodiment, the rotation direction of the developing roller 17 is rotated in the direction of the arrow D (counterclockwise) in the figure, but it may be rotated in the opposite direction.

1 Photosensitive drum (electrophotographic photosensitive member)
4 Development unit (developing device)
7 Process Cartridge 17 Developing Roller 18 Developing Chamber 18d Opening 19 Toner Storage Chamber 20 Supply Roller 22 Toner Conveying Member 40 Light Transmitting Member 100 Image Forming Apparatus

Claims (9)

A developing device used in an electrophotographic image forming apparatus,
A supply member configured to form a nip portion between a developer carrying body that carries a developer and develops an electrostatic latent image and the developer carrying body, and that supplies the developer to the developer carrying body A developing chamber comprising:
A storage chamber disposed below the development chamber and storing the developer;
A rotatable conveying member that conveys the developer contained in the accommodating chamber through the opening provided in the developing chamber onto the supply member;
A transmission member provided in the storage chamber and capable of transmitting detection light for detecting the remaining amount of developer;
The opening is located above the vertical direction in a region between the wall surface of the storage chamber provided with the transmission member and the rotation center of the transport member,
The developing device according to claim 1, wherein the supply member rotates in a direction in which a surface moves from an upper end to a lower end of the nip portion. The developing device according to claim 1, wherein the transmissive member is provided at a position opposite to the supply member with respect to a vertical plane passing through a lower end of the opening in the storage chamber.   The developing device according to claim 2, wherein a lower end of the opening is positioned above a lower end of the supply member.   The developing device according to claim 1, wherein an electrode member for detecting a remaining amount of the developer is provided above the nip portion.   The developing device according to claim 1, wherein the supply member includes a foam layer on a surface thereof.   The developing device according to claim 1, wherein the developer carrying member rotates in a direction in which a surface moves from an upper end to a lower end of the nip portion.   An image carrier that carries the electrostatic latent image and the developing device according to claim 1, wherein the image carrier is configured to be detachable from the image forming apparatus main body. To process cartridge.   An image forming apparatus comprising: an image carrier that carries the electrostatic latent image; and the developing device according to claim 1, and forms an image on a recording material.   An image forming apparatus comprising the process cartridge according to claim 7 and forming an image on a recording material.

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