JP4254161B2 - Developing device and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present inventionMagneticDifferent natureToner and carrierConsist ofDeveloperTheDeveloperAs a wholeMagneticBy selectively transporting according to the physical propertiestonerAdjust the densityHave the functionElectrophotographic development equipment such as copying machines and printersPlaceAnd an image forming apparatus.
[0002]
[Prior art]
  The development system used in the electrophotographic system is a one-component development system that uses only toner that is colorant particles as a developer, and a carrier composed of magnetic particles and toner that is colorant particles as a developer. Can be roughly divided into two-component development systems using
[0003]
  The one-component development method includes a magnetic one-component development method using a magnetic toner containing magnetic particles and a non-magnetic one-component development method that does not contain magnetic toner. Since it cannot transmit, it is mainly used only as black toner. The non-magnetic one-component development method is suitable for colorization, but has a problem that toner maintenance is short, and is currently used mainly for low-speed machines.
[0004]
  The two-component development method can use a magnetic attraction force because the toner is handled through a carrier made of magnetic particles, and it is easy to handle a non-magnetic toner and is particularly excellent in maintainability. Widely used mainly in full-color machines and high-speed machines.
[0005]
  Conventionally, as an image forming apparatus using an electrophotographic two-component developing device, the one shown in FIG. 13 is generally used. FIG. 13 is a schematic configuration diagram of an image forming apparatus using a general two-component developing device. In FIG. 13, reference numeral 101 denotes a latent image carrier that is rotationally driven in the direction of arrow A. A charger 102 that uniformly charges the surface of the latent image carrier 101 and an image-like image on the surface of the latent image carrier 101 in that order. A writing device 103 that irradiates light to form an electrostatic latent image and a two-component developer composed of toner and carrier are accommodated and supplied to the surface of the latent image carrier 101 by a developer carrier 111 to electrostatically A two-component developing device 104 that develops a latent image to obtain a toner image, a transfer device 106 that transfers a toner image formed on the surface of the latent image carrier 101 to a recording material 110, and a residual image on the surface of the latent image carrier 101 A cleaning device 108 that removes the toner to be removed and a static eliminator 109 that removes the electrostatic latent image on the surface of the latent image carrier 101 are arranged.
[0006]
  FIG. 14 is a schematic cross-sectional view of a two-component developing device in the image forming apparatus shown in FIG. In FIG. 14, the developer carrier 111 has a fixed magnet 117 inside, and a sleeve 118 that is cylindrical and rotatable in the direction of arrow B on the outside. A developer 119 in which a carrier and toner are mixed and stirred is carried on the surface of the sleeve 118 by a magnetic attraction force and conveyed, and the amount is regulated by a regulating member 120 to form a layer, and the latent image carrier 101 is formed in the developing unit. The toner in the developer 119 is supplied to the latent image carrier 101 and developed to obtain a toner image. The developer 119 that has lost a part of the toner after completion of the development is transported to the lower part of the developer carrier 111 and is magnetically intermediate in the rotation direction of the sleeve 118 by the fixed magnets 121 and 122 having the same polarity (N). A portion having a weak or no suction force is provided, and the developer 119 is dropped from the surface of the developer carrier 111 by the action of gravity. The dropped developer 111 is conveyed to the screw auger 124 by the conveying member 123, conveyed in the direction of the rotation axis of the screw auger 124, and passed to the screw auger 125 by a delivery unit (not shown), where new toner is received from the toner feeding mechanism 114. In addition, while being agitated, it is fed in the opposite direction to the previous one, and is again delivered to the screw auger 124 at the opposite delivery portion and conveyed in the axial direction, and gradually brought near the developer carrier 111 by the conveying member 123. The steps of being transported and attached to the surface of the developer carrier 111 by magnetic attraction, and transporting, layer formation, and development are repeated.
[0007]
  For toner replenishment, the sensor 115 that detects a change in toner density in the developer 119 changes the toner density into an electric signal, which is sent to the CPU 116, where the toner is compared with the reference value from the electric signal. When it is determined that the density is insufficient, a drive signal is sent to the toner supply motor 113 and the toner in the toner box 112 is sent into the developing device by the toner feeding mechanism 114.
[0008]
  In the two-component development system, the toner and the carrier are adsorbed electrostatically as a result of charging the toner and the carrier to opposite polarities by frictional charging when the toner and the carrier are mixed and stirred. Uses to fit. Therefore, it is necessary to mix and stir the developer 119 supplied with toner as in the above example. In the developing unit, it is necessary to control the developer transport amount within a certain range so that the developer 119 comes into proper contact with the latent image carrier 101 and does not cause clogging. Therefore, a regulating member 120 is provided to form a developer 119 layer carried on the surface of the sleeve 118.
[0009]
  Further, since the toner is developed by an electric field formed between the latent image carrier 101, the developer carrier 111, and the developer 119 in the developing unit, the developer carrier 111 generally includes a power supply device. A development bias voltage is applied by 105. The amount of toner developed at that time (development toner amount) determines the image density, and is particularly important among the various characteristics relating to image quality. Since the amount of the developed toner is determined by neutralizing the electric field of the developing portion with the charge of the toner, it is very important to keep the charge of the toner constant. As shown in FIG. 15, in the two-component development method, since the toner concentration in the developer and the toner charge amount have an inversely proportional relationship, the toner concentration can be adjusted by adjusting the replenishment amount according to the toner consumption amount. And controlling the toner charge amount to be substantially constant.
[0010]
  In order to adjust the replenishment amount in accordance with the toner consumption amount, a method of replenishing toner by detecting the toner concentration or the development toner amount in the developer and moving the toner replenishing motor according to the detection signal (for example, In the method of the image forming apparatus shown in FIG. 13, the cost of the sensor for detecting (sensor 115 in FIG. 13), the toner replenishing motor (the toner replenishing motor 113), etc. is relatively large. is occupying. In a color machine that develops each using four color toners, the cost increase is quadrupled, which is one major factor in the cost increase.
[0011]
  Therefore, as disclosed in JP-A-61-80181, JP-A-63-225266, JP-A-8-185052, JP-A-2000-284595, etc., a sensor for detecting the toner density is disclosed. Alternatively, a method has been proposed in which toner is replenished autonomously without a separate toner replenishing motor and a constant toner density is maintained.
[0012]
  However, since these all use a phenomenon in which the volume of the developer changes depending on the toner concentration, if the carrier in the developer is spilled for some reason or taken out due to adhesion to the photoreceptor, etc., it will decrease. The entire volume of the developer is reduced and toner is taken in excessively. In general, the toner charge amount tends to deteriorate and decrease with time, but there is a drawback that the toner charge is further lowered due to excessive toner intake, and it tends to become fog or toner cloud.
[0013]
  In addition, these methods have a feature that toner intake tends to be excessive because not only the toner contacting the carrier but also the toner in the gap of the carrier is transported. As a result, the toner charge is low, and the amount of reverse polarity toner tends to increase. With magnetic toner, it is difficult to be separated from the carrier on the magnet roll, so it is difficult to become fog or toner cloud even with low charge, but non-magnetic toner cannot prevent it.
[0014]
[Problems to be solved by the invention]
  Therefore, the present inventionConsists of toner and carrierThese two types of developers can be used without using sensors or powder replenishment motors.LikeIt is possible to keep the mixing ratio of particles constant,Of developerIt is not affected by fluctuations in the amount of constituent particles (for example, it is not affected by the decrease in carriers), and some particles are not taken in excessively.ThickDegree adjustmentFeaturesAnother object of the present invention is to provide a developing device and an image forming apparatus.
[0015]
[Means for Solving the Problems]
  The above object is achieved by the present invention described below.
  That is, the present inventiondevelopingThe device is at leastA carrier comprising magnetic particles andTheToner that is attracted to the carrier by electrostatic attractionincludingDeveloperTheA developer carrying member for carrying and developing a latent image on the latent image carrying member, a developer containing portion for containing the developer and supplying the developer to the developer carrying member, the carrier and the toner. Use a replenisher with a higher toner concentration than the developer contained in the agent container.ContainA replenisher container, and between the replenisher container and the developer containerHoused in theDeveloper and said replenisherTheMagneticAdsorbed on the surfaceMutualHaving a conveying member for conveying to
  The surface of the conveying member isDeveloper containerIn the aboveDeveloperIs adsorbed and is held in a substantially vertical direction,DeveloperThe transfer / non-transfer is selected based on the relationship between the adsorbing force and the gravity acting on the mixed powder.Developer containerHoused in theDeveloperOf whichtonerLow concentrationDeveloperIs selected and moved to be held in a substantially horizontal direction,Said replenisherTo accommodate the aboveSupply agent storageTransported toAnd being separated at the replenishment container,
The surface of the conveying member adsorbs the replenisher in the replenisher container, moves without being held in a substantially vertical state, transports it to the developer container, and the adsorbed replenisher is developed. Separated by the agent containerIt is characterized by that.
[0016]
  According to the present invention having the above-described configuration, when the surface of the conveyance member that adsorbs the developer is held in a substantially vertical direction, the developer has an adsorption force due to magnetic properties and is parallel to the surface of the conveyance member. Gravity which is going to fall in the lower direction acts. At this time, if the attracting force due to the magnetic property is superior to the gravity, it is held as it is, and is held as it is in the substantially horizontal direction and conveyed. On the contrary, when the attractive force due to magnetic properties is inferior to the gravity, the developer falls and remains without being conveyed. That is, it is possible to realize a selective conveyance in which the conveyance is performed when the attractive force due to the magnetic property is larger than a certain level and the conveyance is not performed when the adsorption force is small.
[0017]
  Since the magnetic properties of the developer including the carrier and the toner having different magnetic properties as a whole are ultimately determined by the mixing ratio of these two kinds of particles, the transport according to the present invention is performed by the developer. This is selectively performed according to the mixing ratio of the two kinds of particles in the agent.
[0018]
  Thus, according to the present invention, without using a sensor or a powder replenishment motor,CareerandtonerThe mixing ratio of the particles can be kept constant,Of developerIt does not depend on fluctuations in the amount of constituent particles, and some particles are not taken in excessively.
  In the present invention, such aDeveloperFrom the containment chamberSupplementAlong with the function of conveying powder to the storage chamber,SupplementFrom the containment chamberDeveloperAlso has a function of conveying powder to the storage chamberOne.
[0019]
  Of the present inventiondevelopingapparatussoIs more than the position where the surface of the conveying member is held in a substantially vertical direction.DeveloperThe position that adsorbsMagneticSaid by natureDeveloperIt is preferable that the surface adsorbing force is increased. SaidDeveloperIf the surface adsorbing force is large at the position where it is adsorbed (hereinafter sometimes referred to as “(pickup position)”), the above-mentioned is effective.DeveloperIn the selection at a position where the surface of the conveying member is held in a substantially vertical direction (hereinafter sometimes referred to as “selection position”),DeveloperCan be reliably provided. For example, at the pickup position,DeveloperIf the surface of the material is directed downward from the vertical direction, gravity acts at or above the selected position, and before being transported to the selected position,DeveloperThere is a concern that will fall, but at the pickup position,MagneticSaid by natureDeveloperIf the surface adsorbing force is configured to be large,DeveloperIs surely transported to the selected position, and whether or not it can be transported accurately is selected here.
[0020]
  Of the present inventiondevelopingIn the apparatus, the position where the surface of the transport member is held in a substantially horizontal direction, or the downstream of the transport member in the moving direction,MagneticThe surface adsorbing force of the mixed powder due to mechanical properties is reduced, and the position from the surface of the conveying member isDeveloperIs pulled apartSupply agent storageIt is preferable to be accommodated in The transported member is selectively transported at a position where the surface of the transporting member is held in a substantially horizontal direction, or downstream in the moving direction of the transporting member.DeveloperIs pulled apart (saidDeveloperThe position at which is separated is sometimes referred to as “detachment position”. ), SaidDeveloperThe aboveSupply agent storageCan be moved and accommodated.
[0021]
  In the present inventionThe aboveDeveloperInCarrier and tonerHave different magnetic properties (ferromagnetism and weak magnetism, magnetism and non-magnetism, etc.), and this is configured so that the conveying member is attracted by magnetic force.
[0022]
  In the present invention, MagnetismDifferent temperamentCareerandtonerincludingDeveloperLastAndBy adjusting the magnetic field on the surface of the transport member, the selective transport conditions can be appropriately controlled.
[0023]
  The conveying member is preferably a rotating body whose shaft is held substantially horizontally. By using a rotating body as the conveying member,developingThe device can be produced easily and at low cost. In addition, by using a rotating body as the conveying member, the pickup position, the selection position, and the detachment position can be arranged around and the apparatus can be made compact., TimesBy continuously performing the rotation,developingA series of transport operations by the apparatus can be performed continuously without stopping.
[0024]
  In particular,As the conveying memberRotating bodyInAn optimal conveying member can be obtained by using a non-magnetic material and placing a magnet therein. In other words, the magnetic field at the pick-up position and the selected position is optimized, and the magnetic field is made small or zero at the desorption position. By selecting, a desired magnetic field can be formed.
[0025]
  Of the present inventiondevelopingIn the apparatus, when a rotating body is employed as the conveying member, any region below the rotating body or around the rotating direction thereof isDeveloperA position where the surface is picked up (pickup position), a position near the vertical portion immediately downstream in the rotation direction is a position where the surface is held in a substantially vertical direction (selection position), and the rotation direction is downstream.DeveloperAny region upstream of the position where theDeveloperCan be a position at which is separated (desorption position).
[0026]
  In addition, if a long object is used as the rotating body, the rotating body has a circumferential surface in any region in the axial direction., Transporting the developer from the developer container to the replenisher containerMachineNohIn the peripheral surface of the other region in the axial direction of the rotating body,From the replenisher container It can also be set as the range which exhibits the function of conveying the above-mentioned replenisher to the developer container. At this time,In the region below the rotating body or upstream in the rotational directionMagneticSaid by natureDeveloperThe surface adsorbing force is increased, and the surface adsorbing force is reduced downstream,It is configured to exhibit a function of transporting the replenisher from the replenisher container to the developer container.it can.The replenisher from the replenisher container to the developer containerThe transfer function is not selective transfer because adsorption-desorption is performed regardless of conditions, but the transfer function isDeveloper or replenisherCan be made to come and go.
[0027]
  Of the present inventiondevelopingapparatusInThe aboveDeveloper is, Including toner and carrier for electrophotographyMu 2Component developerInThe In a two-component developer, the carrier is a magnetic particleChildYes, the toner is non-magnetic particlesChildFor this reason, it corresponds to a mixed powder of particles having different magnetic properties, and appropriate and selective conveyance can be realized by the mixed powder concentration adjusting device of the present invention.
[0028]
  In the developing device of the present invention,tonerDensityMachineWith abilityRukoThus, the developer can be separated according to the state of the developer. For example, the developer storageClubOf the developmentTo the agentTona, a non-magnetic materialーCarry containing a magnetic substance with a low mixing ratioAWhen the ratio increases, the magnetic property of the developer as a whole changes (becomes ferromagnetic), so that only when this property change is used, the replenisher is accommodated from the developer accommodating portion.To the departmentAnd the developer can be selectively conveyed. Therefore, the developer having a lowered toner concentration can be separated from the developer having no lowered toner concentration.
[0029]
  TransportElementIt is preferable that the developer conveyed by the above is configured to come into contact with and mixed with the replenisher to become a replenisher and to return to the developer container. With this configuration, it is possible to omit a toner feeding mechanism, a toner supply motor, a sensor, and the like that are normally required for a developer, and the cost can be reduced.
[0030]
  In the developing device of the present invention, the developing device has flow means for causing the developer to flow, and the lower periphery of the position where the transport device is arranged to adsorb the developer is the flow of the developer. It is preferable that a partition member for partitioning the vertical direction of the flow path is disposed at least in part of the flow path. By arranging the partition member, the pickup position isDeveloperThe pickup amount can be made uniform, and the condition for separating the developer having a lowered toner concentration from the developer having the lowered toner concentration can be stabilized.
[0031]
  The image forming apparatus of the present invention includes at least a latent image carrier, latent image forming means for forming an electrostatic latent image on the surface of the latent image carrier, and an electrostatic image formed on the surface of the latent image carrier. An image forming apparatus comprising: a developing unit that visualizes the latent image;
  As the developing means, the developing device of the present invention is used. By using the image forming apparatus including the developing device of the present invention, a stable image forming apparatus can be obtained at low cost without fogging.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described with reference to the drawings with preferred embodiments.
<Action mechanism of the present invention>
  First, the operation mechanism of the present invention will be described. In this description, the rotating body is used as the conveying member.ForAn example will be described. FIG. 1 is a schematic explanatory diagram for explaining the operation mechanism of the present invention. In FIG. 1, reference numeral 1 denotes a conveying member that rotates in the direction of arrow A in a non-contact manner around fixed magnets 3 and 3 'disposed therein, and is configured of a non-magnetic material (for example, aluminum). A magnetic field is formed on the surface due to the influence of 3 'magnetic force. 2 is a mixed powder composed of two or more kinds of particles having different magnetic properties,For more informationCarry containing magnetic materialA andDeveloper comprising non-magnetic tonerInThe The fixed magnets 3 and 3 ′ are arranged with the fixed magnet 3 facing the N pole and the fixed magnet 3 ′ facing the inner peripheral surface of the transport member 1, and the fixed magnet 3 generates a strong magnetic field and the fixed magnet 3 ′ generates a weak magnetic field. Is generated.
[0033]
  A container (not shown) containing mainly the mixed powder 2 (mainlyDeveloper container) Is assumed that the conveying member 1 is arranged at a certain distance with the shaft held substantially horizontally. When the conveying member 1 rotates in the direction of arrow A in this state, first, it is fixed in the vicinity of the container (not shown) and around the position where the fixed magnet 3 is arranged on the inner peripheral surface (pickup position (a)). The mixed powder 2 is attracted and attracted (pick up) by the strong magnetic field generated by the magnet 3. When the relationship between the forces at the pickup position (a) is examined in detail, the magnetic attractive force Ma and the gravity Ga due to the strong magnetic field of the fixed magnet 3 act on the mixed powder 2 at the position. At the pickup position (a), the vertical component Ma ′ of the magnetic attractive force Ma is sufficiently larger than the gravity Ga, and the mixed powder 2 is conveyed while being sucked to the surface of the conveying member 1.
[0034]
  Due to the rotation of the conveying member 1 in the direction of arrow A, the adsorbed mixed powder 2 is conveyed to a position (selected position (b)) where the surface of the conveying member 1 is held in a substantially vertical direction. Here, the force to convey the mixed powder 2 above the selected position (b) is the magnetic attractive force Mb toward the surface of the conveying member 1 with respect to the mixed powder 2, and the mixed powder 2 and the conveying member. This is a conveying force Hb obtained by multiplying the friction coefficient between one surface or the mixed powders 2, and the reverse force becomes gravity Gb. If the conveying force Hb is larger than the gravity Gb, it is further conveyed, and if it is smaller, the mixed powder 2 falls in the direction of arrow B here. That is, transfer / non-transfer is selected at this selection position (b) according to the magnetic properties of the mixed powder 2 and the friction coefficient based on the powder fluidity and the surface roughness of the transfer member 1.
[0035]
  When the conveying member 1 further rotates in the direction of arrow A, a part of the gravity Gc received by the mixed powder 2 adhered and conveyed on the surface thereof is added to the force attracting the conveying member 1 (gravity component force Gc ′), In addition, since it increases with rotation, the conveying force Hc increases, and the reverse force (gravity component force Gc ″) gradually decreases. Therefore, after the selected position (b), the surface of the conveying member 1 is substantially horizontal. The mixed powder 2 is not detached from the surface of the conveying member 1 until the position (right above) is held by.
[0036]
  When the conveying member 1 rotates in the direction of arrow A and reaches the position where the surface is held in a substantially horizontal direction (directly above), the mixed powder 2 is transferred to the surface of the conveying member 1 only by gravity without depending on the magnetic attractive force. Held and transported. Therefore, after the position where the surface of the conveying member 1 is held in a substantially horizontal direction, there is no fear that the mixed powder 2 is detached and returned to a container (not shown). Pull it away as needed and place it elsewhere(Supplement storage part)It can be used by moving to.
[0037]
  Considering such a mechanism, the selection of the conveyance and non-conveyance at the selected position (b) is determined by the balance between the magnetic attraction force Mb and the conveyance force Hb generated by the friction coefficient and the gravity Gb. In order to make the selection of non-conveyance by changing the state of the magnetic properties of the mixed powder 2, the magnetic attraction, friction coefficient, gravity, etc. can be adjusted. Particle size (friction coefficient, gravity), shape (friction coefficient), fluidity (friction coefficient), specific gravity (gravity), magnetic properties (magnetic attraction force), mixing ratio (magnetic attraction force, friction coefficient), quantity ( Gravity), magnetic pole conditions of fixed magnets 3 and 3 '(magnetic attraction force), surface roughness of the conveying member (friction coefficient), etc. are adjusted according to the respective conditions to control the selection of conveyance and non-conveyance. (The values in parentheses depend on the conditions. Affect thenature). Therefore, these conditions are not particularly fixed in the present invention. However, among these, in order to create transport / non-transport by changing the toner density in the developerTheIt is an essential condition that the magnetic properties of the toner and the carrier are different.
[0038]
  In the operation mechanism of the present invention described above, an example in which a rotating member is used as a conveying member has been described. However, the shape of the conveying member is not limited to such a rotating member, and the surface is held substantially vertically and substantially horizontally. There is no problem as long as it can be shaped. In particular, it is preferable that the surface is held in a shape that can be continuously changed to substantially vertical, substantially horizontal, or other angles. Specifically, for example, in addition to a rotating body such as this example, an endless belt shape, etc. Is mentioned.
[0039]
  In addition, although the magnet has been described in the form of two fixed magnets, the magnet is not limited to a fixed magnet, and the number of magnets is not limited to two, and the necessary number and shape according to the design conditions of the apparatus. The magnetic poles and the like may be appropriately controlled.
[0040]
<Embodiment of the present invention>
  The present invention will now be described in more detail with some preferred embodiments of the invention.
  FIG. 2 illustrates the present invention.developingIt is a schematic sectional drawing which shows the test apparatus for confirming the effect of an apparatus. In FIG. 2, a container (in which mixed powder 12 is stored)Developer container) 14, screw augers 16 a and 16 b are arranged, whereby the mixed powder 12 is conveyed in the container 14. In this test apparatus, the present invention isdevelopingThis is a required configuration for the deviceReplenisher container and developer carrierIs omitted.
  Above a part of the conveyance path in the storage container 14, a conveyance member 10 including a conveyance roll 20 that is a nonmagnetic rotating body whose axis is held substantially horizontally, and a fixed magnet 18 disposed therein. Is arranged. The fixed magnet 18 having a predetermined magnetic pole pattern Mp is used, and rotates in the + direction (clockwise direction on the drawing) or the-direction (clockwise direction on the drawing) from the reference angle around the shaft 22. The magnetic field pattern on the surface of the transport roll 20 can be controlled by changing the magnetic pole pattern Mp by fine adjustment by this rotation. On the other hand, the transport roll 20 is a non-magnetic cylindrical body, is rotatable independently of the fixed magnet 18, and rotates in the direction of arrow C (counterclockwise direction in the drawing).
[0041]
  Two conveyance magnets having different magnetic pole patterns Mp were applied to the stationary magnet 18 inside the conveyance roll 20 to perform a conveyance test. Specifically, the fixed magnet of FIG. 3A, which is a magnetic pole pattern Mp with a strong pickup magnetic pole Mp, and the fixed magnet of FIG. 3B, which is a magnetic pole pattern Mp with a weak pickup magnetic pole Mp. . In the figure, Mh is a transport pole.
[0042]
  Furthermore, as the transport roll 20, an extremely smooth object having a surface roughness Rz of 1 μm or less (hereinafter simply referred to as “0 μm” for ease of explanation), and a rough surface having a surface roughness of 20 μm. And prepared. In the conveyance test, a developer obtained by mixing and stirring a ferrite carrier having a volume average particle diameter of 35 μm and a resin toner having a volume average particle diameter of 5.8 μm as the mixed powder 12 was used.
[0043]
  First, “a combination of a fixed magnet having a strong pickup magnetic pole Mp and a transport roll having a surface roughness Rz = 20 μm”, “a combination of a fixed magnet having a weak pickup magnetic pole Mp and a transport roll having a surface roughness Rz = 20 μm” and The test was conducted at three levels, “a combination of a fixed magnet having a weak pickup magnetic pole Mp and a transport roll having a surface roughness Rz = 0 μm”. At this time, at each level, the rotation angle of the fixed magnet 18 was adjusted so that a developer having a toner concentration (TC) of 3% by mass reliably formed a layer. In this state, the toner density was shaken to measure the transport amount (the amount transported upward without being dropped by gravity at the selected position (b) by the rotation of the transport roll 20 in the direction of arrow C). The results are shown in FIG.
[0044]
  Next, in each of the three levels, a “combination of a fixed magnet with a strong pickup magnetic pole Mp and a transport roll having a surface roughness Rz = 0 μm” is added to each of the four levels. In each level, the toner concentration (TC) is 15% by mass. In order to prevent the developer from being barely conveyed, the rotation angle of the fixed magnet 18 was adjusted and the test was performed in the same manner. The results are shown in FIG.
[0045]
  4A and 4B, the horizontal axis represents the toner concentration (% by mass) in the developer, which is the mixed powder 12, and the vertical axis represents the rotation in the direction of arrow C after being picked up by the transport roll 20. The mass per unit area (conveyance amount) of the mixed powder 12 conveyed from the picked-up side to the opposite side (left side of the conveyance roll 20 in FIG. 2). In the figure, the parentheses in the legend indicate the angle obtained by rotating the fixed magnet 18 around the shaft 22 from the surface roughness of the transport roll 20 and a reference angle among the conditions of each graph (+ The signs of and are as described above).
[0046]
  From the results shown in the graphs of FIGS. 4A and 4B, the toner density difference in the developer that is the mixed powder 12 is adjusted by adjusting the magnetic pole pattern, the angle, the surface roughness of the surface of the transport roll 20, and the like. It is confirmed that the mixed powder can be conveyed and not conveyed independently.
[0047]
  Next, in the same apparatus as in FIG. 2, the screw auger 16a, 16b is removed, and the test apparatus shown in FIG. 5 is provided with a partition plate 24 in the vicinity of the mixed powder 12 picked up in the storage container 14. It was used to carry out a transport test. In addition, the magnetic pole pattern of the fixed magnet 18 has a strong pickup magnetic pole Mp as shown in FIG. It should be noted that this test apparatus also uses the present invention.developingThis is a required configuration for the deviceReplenisher container and developer carrierIs omitted.
[0048]
  The partition plate 24 is changed in height from the reference height x by y (the minus sign indicates that the position is lower than x), and a certain amount of the mixed powder 12 is placed thereon, Similarly to the above, the transport amount of the mixed powder 12 transported by the transport roll 20 was measured. The result is shown in FIG.
[0049]
  As can be seen from the graph shown in FIG. 7, conveyance / non-conveyance can be completely divided by the difference in toner density when y = −14 mm. Further, depending on other conditions, the conveyance / non-conveyance can be divided to some extent. From the above, it can be seen that conveyance and non-conveyance can be controlled by the height at which the mixed powder 12 can be picked up by the conveyance roll 20.
[0050]
  FIG.Developer containerThe mixed powder picked up inSupply agent storageOf the present invention that can be picked offOther tests to confirm the effectiveness of the development equipmentIt is an example of an apparatus.In this test apparatus, the developer carrying member, which is an essential component of the developing apparatus of the present invention, is omitted.The mixed powder concentration adjusting device of the present example is a container for storing a developer 32 having a low toner concentration (Developer container) 42 and a storage container (adjacent container) for storing the developer 34 having a high toner concentration, which is disposed adjacent to theSupply agent storage) 44 and a conveying member 30 disposed between them. The conveyance member 30 includes a conveyance roll 40 that is a non-magnetic rotating body that rotates in the direction of arrow D, and a fixed magnet 38 disposed inside the conveyance roll 40. The magnetic pole pattern at the pick-up position and the selected position is the same as that of the test apparatus shown in FIGS. 2 and 5 described above, but the magnetic pole pattern at the position between the container 42 and the container 44 is both N as a magnetic pole. The part which the same polarity which is a pole adjoins is formed. By adopting such a magnetic pole pattern, the selectively conveyed developer 32 is pulled away in the region (detachment position) of the magnetic pattern and conveyed to the storage container 44. That is, according to the mixed powder concentration adjusting apparatus of the present example, pick-up and pick-off of the developer containing the carrier that is the magnetic particle can be controlled.
[0051]
  In order to surely realize the pickoff at the desorption position, it is necessary to make the absolute value of the magnetic flux density at the central part of the same pole (N-N pole) sufficiently small. Generally, it is preferable to set it to about 7 mT or less.
[0052]
  FIG. 9 is shown in FIG.testFIG. 9A is an example of a toner density control portion of a developing device in which the toner density is autonomously made constant by using a further modification of the apparatus. FIG. 9A is a plan view, and FIG. FIG. 10 is a cross-sectional view taken along the line EE in FIG. Of this exampletestThe apparatus includes a storage container (a container for storing a developer 52 having a low toner concentrationDeveloper container) 62 and a conveyance path (adjacent to it) through which the toner 54 or the developer 54 having a high toner density circulatesSupply agent storage) 64 and a conveying member 50 disposed between them. The conveyance member 50 includes a conveyance roll 60 that is a non-magnetic rotating body that rotates in the direction of arrow F, and a fixed magnet (not shown) disposed therein.
[0053]
  In the storage container 62, the developer 52 is moved to the arrow J by the screw augers 56 and 58.₁, J₂, J_Three, J_FourIt is circulating in the direction of. On the other hand, in the transport path 64, the developer 54 is moved by the arrow I by the screw auger 66.₁, I₂, I_ThreeIt is conveyed in the direction of.
[0054]
  The fixed magnets arranged inside the conveying member 50 are arranged so as to be divided into different magnetic pole patterns at the center in the axial direction, and the conveying member 50 is functionally separated into conveying parts 50A and 50B having substantially different conveying directions. ing. FIG. 10 shows a magnetic pole pattern [pattern A] in the transport unit 50A and a magnetic pole pattern [pattern B] in the transport unit 50B. This magnetic pattern is viewed from the same direction as FIG. In the transport unit 50A, as shown in [Pattern A], a fixed magnet 68A having a magnetic pole pattern similar to that in FIG. 8 is arranged in the transport roll 60, and in the transport unit 50B, as shown in [Pattern B]. A fixed magnet 68B having a magnetic pole pattern completely different from that of the transport unit 50A is disposed in the transport roll 60.
[0055]
  In the transport unit 50A, as shown in [Pattern A], the developer 52 having a low toner density is picked up at a position below the transport unit 50A and above the storage container 62, which is the pickup position (a), and in the direction of arrow G ′. In the selected position (b), transfer / non-transfer is selected. Since the toner concentration is low, that is, the carrier concentration is high, a strong magnetic developer 52 is conveyed as it is, and is conveyed in the directions of arrows G and G ″. At the separation position (c) where the magnetic field disappears adjacently, the transported developer 52 is pulled away and sent to the transport path 64.
[0056]
  On the other hand, in the transport unit 50B, as shown in [Pattern B], toner or a developer 54 having a high toner concentration is picked up at a position below the transport unit 50B and above the transport path 64. Then, the N-N same poles are adjacent to each other and separated at a position where the magnetic field disappears, and sent to the container 62. That is, the developer 54 is conveyed along the path indicated by the arrow H. Here, selective conveyance is not performed.
[0057]
  In this way, conveyance in the reverse direction is performed by the conveyance unit 50A and the conveyance unit 50B. That is, when the transport roll 60 rotates in the direction of arrow F, when the developer 52 having a lowered toner density passes below the transport roll 60, it is picked up by the transport section 50A and the toner in the transport path 64 or the toner density is high. Picked off into developer 54 flow. The developer is transported for a while by the screw auger 66, so that a sufficient amount of toner is added to the developer 54 having a high toner concentration. Then, when it reaches the lower part of the conveyance unit 50B, it is picked up and returned to the flow of the developer 52 having a lowered toner density. The returned developer 54 has a toner concentration that is excessively higher than that of the surrounding developer 52, but as the developer agitates and circulates by the screw augers 56 and 58, the developer 54 diffuses to the surroundings and becomes independent at an appropriate toner concentration. Adjusted to
[0058]
  Finally, as shown in FIG.Device configurationTheApplyAn embodiment of the developing device is shown in FIG. In addition, in FIG. 11, it shows in FIG.testMembers having the same functions as those of the apparatus are denoted by the same reference numerals, and detailed description thereof is omitted. In the developing device, the container 62 contains the developer as referred to in the present invention.Part,The conveyance path 64 is the replenisher storage according to the present inventionDepartment andBecome.
[0059]
  Including conveying member 50Device configurationThus, the developer 52 whose toner concentration is independently controlled is sent to the vicinity of the developing roll (developer carrying member) 70 by the screw augers 58 and 56 and the stirring blade 74. When the developer 52 magnetically attracted by the developing roll 70 is conveyed by the developing roll 70 rotating in the direction of arrow K, the layer thickness is controlled by the regulating member 72 while forming a so-called magnetic brush. It is sent to a position facing a photoconductor (latent image carrier) 76 that rotates in the L direction. Therefore, the electrostatic latent image formed on the surface of the photoreceptor 76 is visualized by the toner in the developer 52, and the toner is consumed. Then, the developer 52 whose toner concentration has been lowered due to consumption of the toner is sent to the vicinity of the mixed powder concentration adjusting device including the conveying member 50 by the stirring blade 74 and the screw augers 56 and 58, and the toner concentration becomes autonomous again. Adjusted to
[0060]
  The image forming apparatus of the present invention includes at least a latent image carrier, latent image forming means for forming an electrostatic latent image on the surface of the latent image carrier, and an electrostatic latent image formed on the surface of the latent image carrier. The image forming apparatus includes a developing unit that visualizes the image, and the developing unit has a configuration as shown in FIG. 11, for example. A specific configuration is similar to that shown in FIG. 13 and is characteristic of the present invention.developingThe configuration other than the apparatus is not particularly limited.
[0061]
  A running test was performed using an electrophotographic image forming apparatus including the developing device shown in FIG. The specifications of the image forming apparatus used at this time are as follows.
(Specifications of image forming apparatus)
Process speed: 108 mm / sec.
The peripheral speed of the developing roll: 215 mm / sec.
・ Gap between developing roll and photoreceptor: 0.4 mm
-Developer transport amount on the surface of the developing roll: 350 g / m²
・ Developing roll diameter: 18 mm
-Photoconductor diameter: 84mm
-Charge potential of photoconductor: -650V
-Potential of image part of photoconductor: -200V
・ Bias potential of developing roll: V_PP= 1.5kV, V_DC= -500V, Duty = 50%, f = 2kHz
・ Toner: Ground toner with a volume average particle size of 6.5 μm by classification, Black, processed external additive, negatively charged
Carrier: Volume average particle size 50 μm, ferrite core resin coated
・ Developer amount: 350g
[0062]
  In the running test, A4 paper was used, 20 half-tone or solid image prints each having a printing density of 5%, 20%, 50%, and 100% (area ratio) were printed 20 sheets each, and 20 blank sheets were flowed. Thereafter, 20 sheets of half-left solid images of the left half, right half, upper half, and lower half were printed at positions on the sheet, and finally 20 blank sheets were flowed. With this as one set, a total of 5 sets were repeated, and a total of 1000 running tests were conducted.
[0063]
  FIG. 12 shows the transition of the image density on the left and right of the paper traveling direction in the running test. As can be seen from the graph of FIG. 12, in the image forming apparatus of the present invention, the density reproducibility was very stable and no fogging was observed.
[0064]
【The invention's effect】
  As explained above, according to the present invention,Carrier and tonerKaraPresentFor image agents, without using sensors or powder replenishment motors,DeveloperParticle mixing state(GNanoEvery time)Depending on the condition, the conveyance / non-conveyance is selected independently.TheIt is possible to keep the toner concentration constant,DeveloperDo not overload some of the particles regardless of the amount of constituent particles.PresentAn image apparatus and an image forming apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram for explaining an operation mechanism of the present invention.
FIG. 2 of the present inventiondevelopingIt is a schematic sectional drawing which shows the test apparatus for confirming the effect of an apparatus.
3A and 3B are schematic diagrams showing magnetic pole patterns of two types of fixed magnets applied to the test apparatus of FIG. 2, wherein FIG. 3A is a fixed magnet having a magnetic pole pattern with a strong pickup magnetic pole, and FIG. It is a fixed magnet with a weak magnetic pole pattern.
4 is a graph showing a result of a conveyance test performed using the test apparatus of FIG.
FIG. 5 of the present inventiondevelopingIt is a schematic sectional drawing which shows the other test apparatus for confirming the effect of an apparatus.
6 is a schematic diagram showing a magnetic pole pattern of a fixed magnet applied to the test apparatus of FIG.
7 is a graph showing a result of a conveyance test performed using the test apparatus of FIG.
[Fig. 8] of the present inventionOther tests to confirm the effectiveness of the development equipmentEquipmentYet anotherIt is a schematic sectional drawing which shows an example.
FIG. 9 is shown in FIG.testMade further modifications to the devicetestAn example of the device(A) is a plan view, (b) is an EE arrow view in (a).It is sectional drawing.
FIG. 10 of FIG.testIt is a schematic diagram which shows the magnetic pole pattern in two conveyance parts in an apparatus.
FIG. 11 is a schematic cross-sectional view showing an example of the developing device of the present invention.
12 is a graph showing a result of a running test (change in image density) performed using an electrophotographic image forming apparatus including the developing device of FIG.
FIG. 13 is a schematic configuration diagram of an image forming apparatus using a general two-component developing device.
14 is a schematic cross-sectional view of a two-component developing device in the image forming apparatus shown in FIG.
FIG. 15 is a graph showing a relationship between a toner concentration and a toner charge amount in a two-component developing type developer.
[Explanation of symbols]
  1,10, 30, 50  Conveying member,
  2 Mixed powder(Developer),
  3, 3 ', 38, 68A, 68B Fixed magnet (magnet),
  10, 30, 50 conveying member,
  12 Mixed powder(Developer),
  14 Container (Developer container),
  16a, 16b, 56, 58  Screw auger,
  18 fixed magnets,
  20, 40, 60 transport roll (rotary body),
  24 partition plate,
  32, 34, 52, 54 Developer (mixed powder),
  42,62 Container (Developer container)Part)
44 container (replenishment container)
  64 Conveyance path (supplement supply accommodationPart),
  70 developing roll (developer carrier),
74 stirring blades,
  76 photoconductor (latent image carrier)

Claims (10)

A developer carrier for developing a latent image of the latent image carrier by carrying a developer including at least a carrier composed of magnetic particles and a toner adsorbed to the carrier by electrostatic attraction; and containing the developer. A developer container that supplies the developer carrier to the developer carrier, and a replenisher container that contains the carrier and the toner, and stores a replenisher having a higher toner concentration than the developer housed in the developer container. And a conveying member that adsorbs the developer and the replenisher accommodated between the replenisher accommodating portion and the developer accommodating portion to the surface due to magnetic properties and conveys them mutually .
The surface of the conveying member is held in a substantially vertical direction after the developer is adsorbed in the developer accommodating portion , and the adsorbing force of the developer on the surface of the conveying member and the gravity acting on the mixed powder by conveying / non transported in the relationship is selected, the concentration of the toner of the accommodated in the developer accommodating portion and the developer is low developer is selected, as will be further maintained in a substantially horizontal direction Go and then transported to the replenishing developer container for accommodating the supplement, with pulled apart in the replenishing developer container,
The surface of the conveying member adsorbs the replenisher in the replenisher container, moves without being held in a substantially vertical state, transports it to the developer container, and the adsorbed replenisher is developed. a developing device according to claim Rukoto pulled away by the developer container. In the transport member, the position where the surface thereof is held substantially vertically, towards the position for attracting the developer, is configured so that the surface adsorption force of the developer by the magnetic properties becomes large The developing device according to claim 1, wherein: At the position where the surface of the conveying member is held in a substantially horizontal direction, or at the downstream of the moving direction of the conveying member, the surface adsorbing force of the mixed powder due to the magnetic properties is reduced, and at that position the developing device according to claim 1 or 2, wherein the developer from the conveying member surface is accommodated in the replenishing developer container are pulled apart. The conveying member, a developing device according to any one of claims 1 to 3, wherein the shaft is a rotating body that is substantially horizontally held. The developing device according to claim 4 , wherein the transport member includes a non-magnetic rotating body whose shaft is held substantially horizontally and a magnet disposed therein. Any area below or around the rotation direction of the rotating body is a position where the developer is adsorbed, and the vicinity of the vertical portion immediately downstream of the rotation direction is a position where the surface is held in a substantially vertical direction. 5. The region according to claim 4 , wherein any one of the regions downstream of the rotation direction and upstream of the position where the developer is adsorbed is a position where the developer is separated from the surface of the conveying member. 5. The developing device according to 5 . The peripheral surface of any region in the axial direction of the rotating body is in the range to exert the function of conveying the developer from the developer accommodating portion to said supply containing portion, the other axial direction of the rotary body The surface adsorbing force of the mixed powder due to the specific physical property increases in the area below the rotating body or in the upstream area in the rotation direction, and the surface adsorbing force decreases downstream thereof . The developing device according to claim 6 , wherein a function of conveying the replenisher from the replenisher accommodating portion to the developer accommodating portion is exhibited . The conveying member, only when the mixing ratio of the toner in the developer in said developer accommodating portion is reduced, the conveying the developer from the developer accommodating section to the replenishing developer container is transported The developer according to any one of claims 1 to 7, wherein the developer is contact-mixed with the replenisher accommodated in the replenisher accommodating portion to become a replenisher and return to the developer accommodating portion again. the developing device according to any. There is a flow means for causing the developer to flow in the developer accommodating portion, and a lower periphery of a position where the conveying device is arranged to adsorb the developer serves as a flow path for the developer. The developing device according to any one of claims 1 to 8, wherein a partition member for partitioning the vertical direction of the path is disposed on at least a part of the path. At least a latent image carrier, latent image forming means for forming an electrostatic latent image on the surface of the latent image carrier, and developing means for visualizing the electrostatic latent image formed on the surface of the latent image carrier An image forming apparatus including:
Wherein as a developing unit, an image forming apparatus characterized by using the developing apparatus according to any one of claims 1-9.

Images