JP2012166916A - Powder carrying pump unit, powder carrying device, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder carrying pump unit that carries powder with a high degree of accuracy in conveyance.SOLUTION: The powder carrying pump unit has a mohno pump including: a rotor 601 configured of a uniaxial eccentric screw; and a cylindrical stator 602 in which the rotor 601 is inserted and a spiral groove is formed on an inner face thereof. Sides near both ends of the stator 602 are held by the powder carrying pump unit from a direction perpendicular to a rotation axis of the rotor 601.

Description

  The present invention relates to a powder conveyance device that can be applied as toner of an image forming apparatus and conveys conveyance powder to a conveyance destination.

  2. Description of the Related Art Conventionally, an image forming apparatus using a powder conveying unit that conveys toner in a powder container using a powder pump (Mono pump) is known from Japanese Patent Application Laid-Open No. 2001-175064 (Patent Document 1). .

  This type of powder conveying apparatus includes a cylindrical stator having a rotor composed of a uniaxial eccentric screw, a spiral through hole penetrating both bottom surfaces, coaxially extrapolating the rotor, and conveying powder inside. And is composed of.

  And in order to suppress rotation of a stator, it has a holding means to hold | maintain a stator in an apparatus on the bottom face of a stator.

  With the recent miniaturization of image forming apparatuses, the developing apparatuses are also required to be compact, and the capacity of the internal developer container is reduced in the developing apparatuses corresponding to the downsizing.

  Particularly in the case of two-component development, since the density ratio of the toner and the carrier greatly affects the density of the image to be formed and the image density deviation in the image, the toner that inevitably supplies the toner to the carrier. The conveyance accuracy is required at a very high level.

  However, the toner conveyance amount cannot be controlled with sufficient accuracy only by controlling the driving time of the powder pump in the powder conveyance device using the powder pump.

  This invention is made | formed in view of the above background, and it aims at providing the powder conveyance pump unit which can be conveyed with high precision in conveyance of powder.

  The inventors of the present invention conducted various investigations and studies on such a powder conveyance device equipped with a MONO pump. As a result, it has become clear that the toner conveyance amount cannot be controlled with high accuracy for the following reasons.

  That is, there is a variation in the pressure generated during the movement of the powder pump (which becomes the force for driving the powder), and this variation also causes a variation in the amount of powder transport. This variation is caused by the powder pump transporting the powder as a mixture with gas. At this time, the side surface of the spiral through hole of the stator is loaded in the direction perpendicular to the through hole axis by the rotating rotor. In the technology, it has been found that since the stator is not sufficiently held, the axis of the helical through hole of the stator is decentered with respect to the axis of the rotor, and as a result, the accuracy of the amount of powder transported decreases.

  That is, in order to solve the above-mentioned problem, the powder conveying pump unit of the present invention has a rotor composed of a uniaxial eccentric screw and the rotor inserted therein, and a spiral groove is formed on the inner surface as described in claim 1. In the powder conveyance pump unit having a Mono pump composed of a cylindrical stator, the side surfaces near both ends of the stator are held by the powder conveyance pump unit from a direction perpendicular to the rotation axis of the rotor. It is the powder conveyance pump unit characterized by the above-mentioned.

  In addition, the powder transfer pump unit according to the present invention is the powder transfer pump unit according to claim 1, wherein the stator is expanded in diameter on outer side surfaces at both axial ends of the rotor. It is a powder conveyance pump unit characterized by having the collar part comprised by the above.

  According to a third aspect of the present invention, there is provided the powder conveyance pump unit according to the first or second aspect, wherein the shaft of the rotor is held near both ends of the stator. It is characterized by being characterized.

  Moreover, the powder conveyance pump unit of this invention is the powder conveyance pump unit of any one of Claims 1 thru | or 3 as described in Claim 4, In the powder conveyance pump unit of Claim 1, The said stator is the side surface of this stator. It is fixed to the powder conveyance pump unit through a stator accommodating portion that encloses.

  According to a fifth aspect of the present invention, there is provided a powder conveying apparatus comprising the powder conveying pump unit according to any one of the first to fourth aspects.

  As described in claim 6, the process cartridge of the present invention is a process cartridge having the powder conveying device according to claim 5.

  According to a seventh aspect of the present invention, there is provided an image forming apparatus having the process cartridge according to the sixth aspect.

  In the powder conveyance pump unit of the present invention, since the side surfaces near both ends of the stator are held by the powder conveyance pump unit from the direction perpendicular to the rotation axis of the rotor, the stator has Eccentricity with respect to the router is effectively prevented, and the accuracy of the powder conveyance amount is high.

  According to the powder delivery pump unit of claim 2, since the stator has flanges that are formed on the outer side surfaces at both ends in the axial direction of the rotor, the stator rotates. It is suppressed.

  Further, according to the powder conveyance pump unit according to claim 3, since the rotor is held in the vicinity of both ends of the stator, eccentricity with respect to the spiral through hole of the rotor is effectively prevented, The accuracy of the powder conveyance amount becomes higher.

  According to the powder delivery pump unit according to claim 4, the stator is fixed to the powder delivery pump unit via a stator storage portion that encloses the side surface of the stator. In this case, eccentricity of the rotor with respect to the spiral through hole is effectively prevented, and the accuracy of the powder conveyance amount is further increased.

  Moreover, according to the powder conveying apparatus of Claim 5, since it has the said powder conveying pump unit, the precision of a powder conveying amount is high.

  Since the process cartridge of the present invention is provided with the above-described powder conveyance device, the amount of toner supply is stable. Therefore, the process cartridge is sufficiently stable even if it is reduced in size, but can be formed.

  Since the image forming apparatus of the present invention is provided with the process cartridge and the toner supply amount is stable, sufficiently stable image formation is possible even if the size is reduced.

1 is a schematic configuration diagram of a printer 100 according to an embodiment. 2 is an enlarged view showing a schematic configuration of an image forming unit 1. FIG. It is the schematic which shows the toner replenishment apparatus 200 as a powder conveying apparatus. 2 is a schematic diagram illustrating a toner supply device 200 in the image forming apparatus. FIG. It is model sectional drawing which shows the structure of the powder conveying apparatus which is one embodiment of this invention. It is a model sectional view in a field (including a collar part) perpendicular to the axis of the cylinder part of stator 602.

  FIG. 1 is a schematic configuration diagram of a printer 100 according to the present embodiment.

  The printer 100 includes four sets of image forming units 1M, 1C, 1Y, 1Bk (hereinafter referred to as symbols) for forming images of each color of magenta (M), cyan (C), yellow (Y), and black (Bk). Subscripts M, C, Y, and Bk indicate magenta, cyan, yellow, and black members, respectively).

  Each of the image forming units 1M, 1C, 1Y, and 1Bk includes a photoconductor unit having drum-shaped photoconductors 11M, 11C, 11Y, and 11Bk as latent image carriers, and a developing device.

  The image forming units 1M, 1C, 1Y, and 1Bk are arranged at a predetermined pitch in the transfer sheet moving direction so that the rotation axes of the photoconductors 11M, 11C, 11Y, and 11Bk in each photoconductor unit are parallel to each other. Is set to be arranged in

  In addition to the image forming units 1M, 1C, 1Y, and 1Bk, the printer 100 faces the optical writing unit 2, the paper feed cassettes 3 and 4, and the transfer unit that faces each of the photoconductors 11M, 11C, 11Y, and 11Bk. A transfer unit 6 having a transfer belt 90 for conveying the transfer paper P, a registration roller 5 comprising a pair of rollers for supplying the transfer paper P to the transfer belt 90, a belt fixing type fixing unit 7, a paper discharge tray 8, and a reversing unit 9 Etc.

  Further, the printer 100 includes a manual feed tray, a powder transport container, a waste toner bottle, a power supply unit, and the like which are not shown.

  The optical writing unit 2 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates the surface of each of the photoconductors 11M, 11C, 11Y, and 11Bk while scanning with laser light based on image data.

  Also, the alternate long and short dash line in FIG.

  The transfer paper P fed from the paper feed cassettes 3 and 4 is transported by transport rollers while being guided by a transport guide (not shown), and is transported to a temporary stop position where the registration rollers 5 are provided.

  The transfer paper P is supplied to the transfer belt 90 by the registration roller 5 at a predetermined timing, and is conveyed so as to pass through the transfer portions facing the photoconductors 11M, 11C, 11Y, and 11Bk.

  By such conveyance, the toner images on the photoconductors 11M, 11C, 11Y, and 11Bk formed by the image forming units 1M, 1C, 1Y, and 1Bk are sequentially superimposed and transferred onto the transfer paper, and the color is transferred onto the transfer paper. An image is formed.

  The transfer paper P on which the color image is formed is discharged onto the paper discharge tray 8 after the toner image is fixed by the fixing unit 7.

  The image forming units 1M, 1C, 1Y, and 1Bk all have the same configuration, and FIG. 2 is an enlarged view showing a schematic configuration of the image forming unit 1.

  As shown in FIG. 2, the image forming unit 1 includes the photoconductor unit 10 and the developing device 20 as described above.

  In addition to the photoconductor 11, the photoconductor unit 10 includes a swingable cleaning blade 13 that cleans the surface of the photoconductor, a non-contact type charging roller 15 that uniformly charges the surface of the photoconductor 11, and the like.

  The cleaning blade 13 is in contact with the surface movement direction of the photoconductor 11 in the counter direction.

  In addition, a lubricant is applied to the surface of the photoconductor 11 and a lubricant application / static charge brush roller 12 having a function of discharging the surface of the photoconductor is also provided.

  The lubricant application and static elimination brush roller 12 has a brush portion made of a conductive fiber, and a power source for static elimination (not shown) for applying a static elimination bias is connected to the cored bar portion.

  Each of the photosensitive units 10M, 10C, 10Y, and 10Bk is a process cartridge unit that can be replaced by releasing each stopper.

  In the photoconductor unit 10, the surface of the photoconductor 11 is uniformly charged by a charging roller 15 to which a voltage is applied.

When the surface of the photoconductor 11 is irradiated with the laser beam modulated and deflected by the optical writing unit 2 while being scanned, an electrostatic latent image is formed on the surface of the photoconductor 11.
The electrostatic latent image on the photoconductor 11 is developed by the developing device 20 and becomes a magenta toner image.

  At the transfer portion Pt through which the transfer paper P on the transfer belt 90 passes, the toner image on the photoconductor 11 is transferred to the transfer paper P.

  After the toner image is transferred, the surface of the photoconductor 11 is coated with a predetermined amount of lubricant by the lubricant application and static elimination brush roller 12 and discharged, and then cleaned by a cleaning blade 13 as photoconductor cleaning means. To prepare for the next electrostatic latent image.

  Further, the lubricant application and static elimination brush roller 12 rotates in the direction opposite to that of the photosensitive member 11, collects the transfer residual toner on the photosensitive member 11 together with the cleaning blade 13, and sends it to the waste toner conveying coil 14 side. ing.

  The transfer residual toner sent to the waste toner transport coil 14 is transported to a waste toner discharge port and collected by a waste toner bottle (not shown).

Although the non-contact charging roller 15 has been described as the charging roller 15, the invention is not limited to this, and a contact-type charging roller may be used. In this case, the charging roller 15 rotates in the direction opposite to that of the photoconductor 11 to uniformly charge the surface of the photoconductor 11.
The charging roller 15 may be provided with a charging roller cleaning member for cleaning the surface thereof. As a result, even if dirt such as toner adheres to the charging roller 15, good charging can be performed by cleaning.

  The developing device 20 uses a two-component developer (hereinafter simply referred to as “developer”) 28 including a magnetic carrier and negatively charged toner as a developer for developing an electrostatic latent image. Further, the developing device 20 is fixed to a developing sleeve 22 made of a nonmagnetic material as a developer carrying member disposed so as to be partially exposed from the opening on the photosensitive member side of the developing case 21, or fixed inside the developing sleeve 22. Magnetic roller (not shown) as magnetic field generating means arranged, stirring and conveying screws 23 and 24 as stirring and conveying members, developing doctor 25, and magnetic permeability for detecting the permeability of developer 28 as toner concentration sensor as detecting means. A sensor 26, a toner replenishing device 200 as powder conveying means, and the like are provided.

  A developing bias voltage in which an AC voltage AC (AC component) is superimposed on a negative DC voltage DC (DC component) is applied to the developing sleeve 22 by a developing bias power supply (not shown) as a developing electric field forming unit. Is biased to a predetermined voltage with respect to the metal substrate layer of the photoreceptor 11.

  In FIG. 2, the developer 28 contained in the developing case 21 is agitated and conveyed by the agitating and conveying screws 23 and 24, whereby the toner is frictionally charged.

  A part of the developer 28 in the first agitating and conveying path 30A is carried on the surface of the developing sleeve 22, the layer thickness is regulated by the developing doctor 25, and then conveyed to the developing region facing the photoconductor 11. .

  In the developing region, the toner in the developer on the developing sleeve 22 adheres to the electrostatic latent image on the photoconductor 11 by the developing electric field, and becomes a toner image.

  Thereafter, the developer that has passed through the developing region leaves the developing sleeve 22 at the developer separating pole position on the developing sleeve 22 and returns to the first stirring and conveying path 30A.

  The developer 28 conveyed to the downstream end of the first agitation conveyance path 30A moves to the upstream end of the second agitation conveyance path 30B and receives the powder conveyance in the second agitation conveyance path 30B.

  Thereafter, the developer 28 conveyed to the downstream end of the second agitation conveyance path 30B moves to the upstream end of the first agitation conveyance path 30B. A magnetic permeability sensor 26 is installed in the developing case part that forms the bottom of the second stirring and conveying path 30B.

  Since the toner concentration of the developer 28 in the developing case 21 decreases due to toner consumption accompanying image formation, based on the output value of the magnetic permeability sensor 26, a pump unit (powder conveying apparatus) having a Mono pump as a powder conveying apparatus. ) 600 (see FIG. 3), the toner is replenished.

  With such a configuration, toner density control of the developer 28 is performed, and the toner density is kept substantially constant.

  Further, as shown in FIG. 1, the four image forming units 1M, 1C, 1Y, and 1Bk are arranged in the order of M, C, Y, and Bk from the lower right in the sheet conveyance order. Note that each photoconductor unit 10 is incompatible with each color and cannot be interchanged between colors.

  Of these four photoconductors 11M, 11C, 11Y, and 11Bk, only the black photoconductor 11Bk on the most downstream side is always in contact with the transfer belt 90, and the remaining photoconductors 11M, 11M, 11C and 11Y can contact and separate from the transfer belt.

  The transfer unit 6 is also laid out in an oblique direction like the photoconductor unit 10 and transfers the image on the photoconductor 11 onto the transfer paper P while conveying the paper from the lower right.

  Further, the transfer unit 6 is configured to be pulled out by tilting the release lever. When the transfer unit 6 is to be attached or detached, such as when the transfer unit 6 is replaced, the stoppers are released and the respective photoreceptor units 10 and the transfer unit 6 can be pulled out.

  Next, an image forming operation of the printer 100 will be described.

  When a color image is formed on the transfer paper P, the four photoconductors 11M, 11C, 11Y, and 11Bk are in contact with the transfer belt 90, respectively.

  The electrostatic suction roller 91 applies a charge having the same polarity as the toner to the transfer paper P, and the transfer paper P is attracted to the transfer belt 90. As a result, the transfer failure of the toner image due to the charge-up of the transfer paper P can be eliminated.

  The transfer paper P is conveyed while being attracted to the transfer belt 90, and is transferred so that the magenta, cyan, yellow, and black color toner images formed on the photoconductors 11M, 11C, 11Y, and 11Bk overlap each other in order. The Then, the toner image transferred onto the transfer paper P is fixed by the fixing unit 7, and a full-color image is formed on the transfer paper P.

  On the other hand, when a black monochrome image is formed on the transfer paper P, for example, in FIG. 1, the color photoconductors 11Y, 11C, and 11M are separated from the transfer belt 90 to form a toner image of black toner. Only the black photoreceptor 11Bk is brought into contact with the transfer belt 90. Then, the transfer paper P is conveyed to the transfer nip of the black photoconductor 11Bk, and after the black toner image is transferred, the transfer paper P is fixed by the fixing unit 7 to form a black monochrome image on the transfer paper.

  FIG. 4 is a schematic diagram showing a toner replenishing device 200 as a powder transporting device that transports and replenishes toner from a toner cartridge 27, which is a powder container having toner as powder, to the developing device 20.

  A printer 100 that is an image forming apparatus that forms a color image includes four pump units 600 that respectively supply magenta, cyan, yellow, and black toners to four sets of image forming units 1M, 1C, 1Y, and 1Bk. I have.

  The pump unit 600 includes a mono pump serving as a powder conveying device and a flexible conveying tube 614 serving as a powder conveying path as means for conveying the replenishing toner in the toner cartridge 27 to the powder conveying port 67. .

  Further, a transport nozzle 80 is provided for fixing the toner cartridge 27 and communicating the discharge port of the toner cartridge 27 with the transport tube 65. Further, an optical sensor (not shown) is incorporated in a part of the conveying nozzle 80 to detect the near end of the toner.

  In the printer 100, the photoconductor unit 10 can be attached to and detached from the main body of the printer 100 as a process cartridge. The configuration that can be attached to and detached from the printer 100 is not limited to this, and may be a process cartridge that includes at least the photosensitive member 11, the developing device 20, and the pump unit 600.

  Further, the pump unit 600 may be detachable from the printer 100 main body, and a unit that integrally supports the pump unit 600 and the developing device 20 may be detachable from the printer 100. In the printer 100, the powder conveyance device is the pump unit 600 that conveys the toner. However, a powder conveyance device including a powder pump may be used as the developer conveyance device that conveys the developer.

  FIG. 5 is a cross-sectional view showing a configuration of a powder conveying apparatus according to an embodiment of the present invention. The stator 602 incorporated in the pump unit 600 has a cylindrical shape having a flange portion formed by expanding both ends of the outer surface, and a rotor 601 composed of a uniaxial eccentric screw is coaxially arranged inside the stator 602. Is inserted (interpolated).

  As described above, the stator 602 has a cylindrical shape having a flange portion, so that the rotation of the stator 602 can be suppressed.

  The inner surface 603A of the stator 602 is provided with spiral grooves 604 having a plurality of pitches, and the two flanges are provided on one end surface 605a and the other end surface 605b of both end surfaces 605 of the stator 602. The two held means 606 are provided.

  Examples of the material constituting the stator 602 include nitrile butadiene rubber (NBR), ethylene propylene rubber, fluorine rubber, and silicone rubber.

  The pump unit 600 having the stator 602 is fitted with a stator 602 for conveying powder, for example, toner, and the spiral groove 604 having a plurality of pitches provided on the inner surface 603A of the cavity 603 of the stator 602. And a rotor 601 composed of a single-shaft eccentric screw that is inserted (inserted) in a rotatable manner, a driving device 611 that rotationally drives the rotor 601 to convey powder, and positioning and holding means (鍔) Part) holding means 607 for holding 606, an inlet side case 612 connected to the toner conveying tube 614 and having a toner conveying port for supplying toner from a toner cartridge (not shown), and the toner conveying direction of the inlet side case 612 A pump-side case 608 that houses (encloses) the downstream stator 602 so as to wrap it; The outlet side case 609 downstream of the pump side case 608 in the toner conveying direction is accommodated so as to wrap the pump side case 608 and the inlet side case 612, the pump side case 608, and the outlet case 609 are connected. A case 615 to be made.

  The toner transport tube 614 is, for example, a flexible tube having a diameter of 4 to 10 mm and made of a rubber material excellent in toner resistance (for example, polyurethane, nitrile, ethylene propylene diene rubber (EPDM), silicone, etc.). Therefore, it is extremely effective to form a flexible tube, and the flexible tube formed from these can be easily piped in any direction up, down, left and right.

  The driving means 611 is connected to the rotor 601 and rotates to convey the powder toner (T) in the inlet case 612 in the direction of the arrow A shown in the figure. A clutch 613f that connects or disconnects the rotational power from the drive device 611 by a shaft 613e supported by three bearings of a bearing 613a and a bearing 613b accommodated in the 609 and a bearing 613c accommodated in the entry side case 612. Through this, a rotational force is applied to the rotor 601.

  Since the rotor shaft is held in the vicinity of both ends of the stator in this way, the eccentricity of the rotor itself can be effectively prevented, so that the powder can be conveyed stably.

  FIG. 6 is a cross-sectional view taken along a plane (including a flange portion) perpendicular to the axis of the cylindrical portion of the stator 602. Boss 602a is provided above and below the flange portion which is an enlarged diameter portion at the upper and lower portions of stator 602, and pump side case 608 (pump side case pieces 608a and 608b divided by a plane including the cylindrical shaft thereof). And the positioning groove 608c provided on the surface on the stator 602 side of the stator 602 to suppress rotation and eccentricity of the stator 602 itself. The configuration of FIG. 6 is provided at the flanges at both ends of the stator 602, respectively. As described above, the pump unit according to the present invention includes a pump side case having a ring-shaped cross section in the flange portion which is an enlarged diameter portion in the vicinity of both end portions of the stator from the direction in which the stator is perpendicular to the rotation axis of the rotor. 608 is effectively held by the powder conveyance pump unit itself (from all directions perpendicular to the rotation axis of the rotor), so that variation in toner conveyance amount can be suppressed, and when applied to an image forming apparatus. It is possible to provide an image forming apparatus capable of forming a high-quality image.

  In the example shown in FIG. 5, since the stator 602 is fixed to the powder conveyance pump unit via the pump-side case 608 that is a stator housing portion that encloses the side surface of the stator 602, Eccentricity with respect to the spiral through hole is effectively prevented, and the accuracy of the powder conveyance amount is further enhanced.

600 Pump unit 601 Rotor 602 Stator 608 Pump side case 609 Out side case 612 In side case 613 Bearing 614 Toner transport tube 615 Case

Japanese Patent Laid-Open No. 2001-175064

Claims (7)

In a powder conveyance pump unit having a Mohno pump composed of a rotor composed of a uniaxial eccentric screw and a cylindrical stator with the rotor inserted and a spiral groove formed on the inner surface thereof,
The powder conveyance pump unit characterized in that side surfaces in the vicinity of both end portions of the stator are held by the powder conveyance pump unit from a direction perpendicular to the rotation axis of the rotor.   The powder conveying pump unit according to claim 1, wherein the stator has flange portions each having an enlarged diameter on outer side surfaces at both axial ends of the rotor.   The powder conveying pump unit according to claim 1 or 2, wherein the shaft of the rotor is held in the vicinity of both ends of the stator.   The powder according to any one of claims 1 to 3, wherein the stator is fixed to the powder conveying pump unit via a stator housing that encloses a side surface of the stator. Conveyance pump unit.   A powder conveying apparatus comprising the powder conveying pump unit z3 according to any one of claims 1 to 4.   A process cartridge comprising the powder conveyance device according to claim 5.   An image forming apparatus having the process cartridge according to claim 6.

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