Patent Grant
9354549
The present invention relates to a developer supply container detachably mountable to a developer supplying device and also relates to the developer supplying apparatus and an image forming apparatus using the same. The developer supplying apparatus is used with an image forming apparatus such as a copying machine, a facsimile machine, a printer or a complex machine having functions of a plurality of such machines.
Conventionally, an image forming apparatus such as an electrophotographic copying machine uses a developer of fine particles. In such an image forming apparatus, the developer is supplied from a supply container (developer supply container) in response to consumption thereof resulting from image forming operation. Such a supply container is disclosed in Japanese Laid-open Patent Application 2010-256893, for example.
The apparatus disclosed in Japanese Laid-open Patent Application 2010-256893 employs a system in which the developer is discharged using a bellow pump provided in the supply container. More particularly, the bellow pump is expanded to provide a pressure lower than the ambient pressure in the supply container, so that the air is taken into the supply container to fluidize the developer. In addition, the bellow pump is contracted to provide a pressure higher than the ambient pressure in the supply container, so that the developer is pushed out by the pressure difference between the inside and the outside of the supply container, thus discharging the developer. By repeating the two steps alternately, the developer is stably discharged. In the supply container, the rotation received from the image forming apparatus is converted to a reciprocation to drive a bellow-like pump. With such a structure, the developer can be stably discharged out of the supply container.
However, with the structure of Japanese Laid-open Patent Application 2010-256893, a developer discharging efficiency immediately after the use amount of the developer supply container into the image forming apparatus may be low because of the situation before the developer supply container reaches the user.
Accordingly, it is a object of the present invention to provide a developer supply container, a developer supplying device and an image forming apparatus with which the developer can be easily discharged from the developer supply container to immediately after the use amount the developer supply container into the image forming apparatus.
According to an aspect of the present invention, there is provided a developer supply container detachably mountable to a developer supplying device, said developer supply container comprising: a developer accommodating chamber capable of accommodating a developer; a rotatable feeding portion configured to feed the developer in said developer accommodating chamber; a developer discharging chamber including a discharge opening for permitting discharge of the developer fed by said feeding portion; a driving force receiving portion configured to receive a rotational force for rotating said feeding portion; an pump portion capable of changing an inside volume of said developer accommodating chamber in a longitudinal direction of said developer supply container to apply a pressure at least to said discharge opening; a driving force converting portion configured to convert the rotational force received by said driving force receiving portion into a feeding driving force for feeding the developer by an operation of said pump portion in a longitudinal direction of said developer supply container; and wherein an expansion and contraction stroke of said pump portion provided by said driving force converting portion in a initial predetermined number of rotations in a initial stage is different from that in a subsequent stage after the initial stage.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Part (a) of
Part (a) of
Parts (a) and (b) of
Part (a) of
Embodiments of the present invention will be described in detail in conjunction with the accompanying drawings. The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings. Here, the dimensions, the sizes, the materials, the configurations, the relative positional relationships of the elements in the following embodiments and examples are not restrictive to the present invention unless otherwise stated. In the description of the embodiments, the same reference numerals as in the previous embodiment are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted for simplicity.
First, basic structures of an image forming apparatus will be described, and then, a developer supplying system, that is, a developer replenishing apparatus and a supply container used in the image forming apparatus will be described.
(Image Forming Apparatus)
The image forming apparatus 100 comprises the main assembly 100A. An original 101 is placed on an original supporting platen glass 102. A light image corresponding to image information of the original is imaged on an electrophotographic photosensitive drum 104 as an image bearing member by way of a plurality of mirrors M of an optical portion 103 and a lens Ln, so that an electrostatic image is formed. The electrostatic image is visualized with toner (one component magnetic toner) as a developer (dry powder) by a dry type developing device (one component developing device) 201a.
In this embodiment, the one component magnetic toner is used as the developer to be supplied from a supply container 1, but the present invention is not limited to the example and includes other examples which will be described hereinafter. Specifically, in the case that a one component developing device using the one component non-magnetic toner is employed, the one component non-magnetic toner is supplied as the developer. In addition, in the case that a two component developing device using a two component developer containing mixed magnetic carrier and non-magnetic toner is employed, the non-magnetic toner is supplied as the developer. In such a case, both of the non-magnetic toner and the magnetic carrier may be supplied as the developer.
Cassettes 105-108 accommodates recording materials (sheets) S. Of the sheet S stacked in the cassettes 105-108, an optimum cassette is selected on the basis of a sheet size of the original 101 or information inputted by the operator (user) from a liquid crystal operating portion of the copying machine. The recording material is not limited to a sheet of paper, but OHP sheet or another material can be used as desired. One sheet S supplied by a separation and feeding device 105A-108A is fed to registration rollers 110 along a feeding portion 109, and is fed at timing synchronized with rotation of a photosensitive drum 104 and with scanning of an optical portion 103.
Below the photosensitive drum 104, there are provided a transfer charger 111 and a separation charger 112. An image of the developer formed on the photosensitive drum 104 is transferred onto the sheet S by a transfer charger 111. Then, the sheet S carrying the developed image (toner image) transferred thereonto is separated from the photosensitive drum 104 by the separation charger 112.
Thereafter, the sheet S fed by the feeding portion 113 is subjected to heat and pressure in a fixing portion 114 so that the developed image on the sheet is fixed, and then passes through a discharging/reversing portion 115, in the case of one-sided copy mode, and subsequently the sheet S is discharged to a discharging tray 117 by discharging rollers 116.
In the case of a duplex copy mode, the sheet S enters the discharging/reversing portion 115 and a part thereof is ejected once to an outside of the main assembly 100A by the discharging roller 116. The trailing end thereof passes through a flapper 118, and a flapper 118 is controlled when it is still nipped by the discharging rollers 116, and the discharging rollers 116 are rotated reversely, so that the sheet S is refed into the main assembly 100A. Then, the sheet S is fed to the registration rollers 110 by way of re-feeding portions 119, 120, and then conveyed along the path similarly to the case of the one-sided copy mode and is discharged to the discharging tray 117.
In the main assembly 100A, around the photosensitive drum 104, there are provided image forming process equipment (process means) such as a developing device 201a as the developing means a cleaner portion 202 as a cleaning means, a primary charger 203 as charging means. The developing device 201a develops the electrostatic latent image formed on the photosensitive drum 104 by the optical portion 103 in accordance with image information of the 101, by depositing the developer (toner) onto the latent image. The primary charger 203 functions to uniformly charge the surface of the photosensitive drum 104 so that an intended electrostatic image is formed on the photosensitive drum 104. In addition, the cleanup portion 202 is to remove the developer remaining on the photosensitive drum 104.
(Supplying Device)
Part (a) of
As shown in
As shown in parts (a) of
A developing blade 201g for regulating an amount of developer coating on the roller is provided relative to the developing roller 201f, and a leakage preventing sheet 201h is provided contacted to the developing roller 201f to prevent leakage of the developer between the developing device 201a and the developing roller 201f.
As shown in part (b) of
Furthermore, the mounting portion 10 is provided with a developer receiving port (developer reception hole) 13 (
As shown in
As shown in parts (b) and (c) of
As shown in
In this example, the driving gear 300 is rotatable unidirectionally to simplify the control for the driving motor 500. The control device 600 controls only ON (operation) and OFF (non-operation) of the driving motor 500. This simplifies the driving mechanism for the developer replenishing apparatus 201 as compared with a structure in which forward and backward driving forces are provided by periodically rotating the driving motor 500 (driving gear 300) in the forward direction and backward direction.
(Mounting/Dismounting Method of Supply Container)
The description will be made as to mounting/dismounting method of the supply container 1. First, the operator opens an exchange cover and inserts and mounts the supply container 1 to a mounting portion 10 of the developer replenishing apparatus 201. With the mounting operation, the flange portion 4 of the supply container 1 is held and fixed in the developer replenishing apparatus 201. Thereafter, the operator closes the exchange cover to complete the mounting step. Thereafter, the control device 600 controls the driving motor 500, by which the driving gear 300 rotates at proper timing.
On the other hand, when the supply container 1 becomes empty, the operator opens the exchange cover and takes the supply container 1 out of the mounting portion 10. The operator inserts and mounts a new supply container 1 prepared beforehand and closes the exchange cover, by which the exchanging operation from the removal to the remounting of the supply container 1 is completed.
(Developer Supply Control by Developer Replenishing Apparatus)
Referring to a flow chart of
The developer sensor 10d checks the accommodated developer amount in the hopper 10a (S100). When the accommodated developer amount detected by the developer sensor 10d is discriminated as being less than a predetermined amount, that is, when no developer is detected by the developer sensor 10d, the driving motor 500 is actuated to execute a developer supplying operation for a predetermined time period (S101).
When the accommodated developer amount detected with developer sensor 10d is discriminated as having reached the predetermined amount, that is, when the developer is detected by the developer sensor 10d, as a result of the developer supplying operation, the control device 600 deactuates the motor 500 to stop the developer supplying operation (S102). By the stop of the supplying operation, a series of developer supplying steps is completed. Such developer supplying steps are carried out repeatedly whenever the accommodated developer amount in the hopper 10a becomes less than a predetermined amount as a result of consumption of the developer by the image forming operations.
The stirring chamber 800x and the developer chamber 800y are communicated with each other in the opposite longitudinal end portions, and the two component developer are circulated the two chambers. The stirring chamber 800x is provided with a magnetometric sensor 800c for detecting a toner content of the developer, and on the basis of the detection result of the magnetometric sensor 800c, the control device 600 controls the operation of the driving motor 500. In such a case, the developer supplied from the supply container is non-magnetic toner or non-magnetic toner plus magnetic carrier.
In this example, as will be described hereinafter, the developer in the supply container 1 is hardly discharged through the discharge opening 4a only by the gravitation, but the developer is discharged by a volume changing operation of a pump portion 3b, and therefore, variation in the discharge amount can be suppressed. Therefore, the supply container 1 which will be described hereinafter is usable for the example of
(Supply Container)
Referring to
As shown in part (a) of
In this example, as shown in part (b) of
As shown in
(Material of Supply Container)
In this example, as will be described hereinafter, the developer is discharged through the discharge opening 4a by changing an internal volume of the supply container 1 by the pump portion 3a. Therefore, the material of the supply container 1 is preferably such that it provides an enough rigidity to avoid collision or extreme expansion against the volume change.
In addition, in this example, the supply container 1 is in fluid communication with an outside only through the discharge opening 4a, and is sealed except for the discharge opening 4a. Such a hermetical property as is enough to maintain a stabilized discharging performance in the discharging operation of the developer through the discharge opening 4a is provided by the decrease and increase of the volume of supply container 1 by the pump portion 3a.
Under the circumstances, this example employs polystyrene resin material as the materials of the developer accommodating portion 2 and the discharging portion 4c and employs polypropylene resin material as the material of the pump portion 3a. As for the material for the developer accommodating portion 2 and the discharging portion 4c, other resin materials such as ABS (acrylonitrile, butadiene, styrene copolymer resin material), polyester, polyethylene, polypropylene, for example are usable if they have enough durability against the volume change. Alternatively, they may be metal.
As for the material of the pump portion 3a, any material is usable if it is expansible and contractable enough to change the internal pressure of the supply container 1 by the volume change. The examples includes thin formed ABS (acrylonitrile, butadiene, styrene copolymer resin material), polystyrene, polyester, polyethylene materials. Alternatively, other expandable-and-contractable materials such as rubber are usable.
They may be integrally molded of the same material through an injection molding method, a blow molding method or the like if the thicknesses are properly adjusted for the pump portion 3a, developer accommodating portion 2 and the discharging portion 3h, respectively. In the following, the description will be made as to the structures of the flange portion 4, the cylindrical portion 2k, the pump portion 3a, the gear portion 2d, and a cam grooves 2X and 2Y.
(Flange Portion)
As shown in parts (a) and (b) of
The discharge portion 4c includes the discharge opening 4a which permits discharge of the developer fed by the inclined ribs 6a. More particularly, a bottom portion of the discharging portion 4c is provided with the small discharge opening 4a for permitting discharge of the developer to the outside of the supply container 1, that is, for supplying the developer into the developer replenishing apparatus 201.
Above the discharge opening 4a, there is provided a storage portion 4d capable of storing a predetermined amount of the developer before the discharge thereof to provide communication between the discharge opening 4a and the inside of the supply container 1. The size of the discharge opening 4a will be described hereinafter.
The flange portion 4 is provided with a shutter 4b for opening and closing the discharge opening 4a. The shutter 4b is provided at a position such that when the supply container 1 is mounted to the mounting portion 10, it is abutted to an abutting portion 21 (see part (b) of
The flange portion 4 is constructed such that when the supply container 1 is mounted to the mounting portion 10 of the developer replenishing apparatus 201, it is stationary substantially. More particularly, a rotation regulating portion 11 shown in part (b) of
In addition, as shown in as shown in part (a) of
With the above-described structure, the developer fed by the feeding projection 2c is scooped up by the plate-like feeding member 6 in interrelation with the rotation of the cylindrical portion 2k. Thereafter, with the further rotation of the cylindrical portion 2k, the developer slides down on the surface of the feeding member 6 by the gravity, and sooner or later, the developer is transferred to the discharging portion 4c by the inclination ribs 6a. With this structure of this example, the inclination ribs 6a are provided on each of the sides of the feeding member 6 so that the developer is fed into the discharging portion 4c for each half of the full-turn of the cylindrical portion 2k.
(Discharge Opening of Flange Portion)
In this example, the size of the discharge opening 4a of the supply container 1 is so selected that in the orientation of the supply container 1 for supplying the developer into the developer replenishing apparatus 201, the developer is not discharged to a sufficient extent, only by the gravitation. The opening size of the discharge opening 4a is so small that the discharging of the developer from the supply container is insufficient only by the gravitation, and therefore, the opening is called pin hole hereinafter. In other words, the size of the opening is determined such that the discharge opening 4a is substantially clogged. This is expectedly advantageous in the following points:
(1) the developer does not easily leak through the discharge opening 4a. (2) excessive discharging of the developer at time of opening of the discharge opening 4a can be suppressed. (3) the discharging of the developer can rely dominantly on the discharging operation by the pump portion 3a. The inventors have investigated as to the size of the discharge opening 4a not enough to discharge the toner to a sufficient extent only by the gravitation. The verification experiment (measuring method) and criteria will be described.
A rectangular parallelopiped container of a predetermined volume in which a discharge opening (circular) is formed at the center portion of the bottom portion is prepared, and is filled with 200 g of developer; then, the filling port is sealed, and the discharge opening is plugged; in this state, the container is shaken enough to loosen the developer. The rectangular parallelopiped container has a volume of 1000 cm^3, 90 mm in length, 92 mm width and 120 mm in height.
Thereafter, as soon as possible the discharge opening is unsealed in the state that the discharge opening is directed downwardly, and the amount of the developer discharged through the discharge opening is measured. At this time, the rectangular parallelopiped container is sealed completely except for the discharge opening. In addition, the verification experiments were carried out under the conditions of the temperature of 24 degree C. and the relative humidity of 55%.
Using these processes, the discharge amounts are measured while changing the kind of the developer and the size of the discharge opening. In this example, when the amount of the discharged developer is not more than 2 g, the amount is negligible, and therefore, the size of the discharge opening at that time is deemed as being not enough to discharge the developer sufficiently only by the gravitation.
The developers used in the verification experiment are shown in Table 1. The kinds of the developer are one component magnetic toner, non-magnetic toner for two component developer developing device and a mixture of the non-magnetic toner and the magnetic carrier.
As for property values indicative of the property of the developer, the measurements are made as to angles of rest indicating flowabilities, and fluidity energy indicating easiness of loosing of the developer layer, which is measured by a powder flowability analyzing device (Powder Rheometer FT4 available from Freeman Technology).
Referring to
The propeller type blade 54 is made of SUS (type=C210) and has a diameter of 48 mm, and is twisted smoothly in the counterclockwise direction. More specifically, from a center of the blade of 48 mm×10 mm, a rotation shaft extends in a normal line direction relative to a rotation plane of the blade, a twist angle of the blade at the opposite outermost edge portions (the positions of 24 mm from the rotation shaft) is 70°, and a twist angle at the positions of 12 mm from the rotation shaft is 35°.
The fluidity energy is total energy provided by integrating with time a total sum of a rotational torque and a vertical load when the helical rotating blade 54 enters the powder layer and advances in the powder layer. The value thus obtained indicates easiness of loosening of the developer powder layer, and large fluidity energy means less easiness and small fluidity energy means greater easiness.
In this measurement, as shown in
The set conditions at the time of measurement are, The rotational speed of the blade 54 (tip speed=peripheral speed of the outermost edge portion of the blade) is 60 mm/s: The blade advancing speed in the vertical direction into the powder layer is such a speed that an angle θ (helix angle) formed between a track of the outermost edge portion of the blade 54 during advancement and the surface of the powder layer is 10°: The advancing speed into the powder layer in the perpendicular direction is 11 mm/s (blade advancement speed in the powder layer in the vertical direction=(rotational speed of blade)×tan (helix angle×π/180)): and The measurement is carried out under the condition of temperature of 24 degree C. and relative humidity of 55%.
The bulk density of the developer when the fluidity energy of the developer is measured is close to that when the experiments for verifying the relation between the discharge amount of the developer and the size of the discharge opening, is less changing and is stable, and more particularly is adjusted to be 0.5 g/cm^3.
The verification experiments were carried out for the developers (Table 1) with the measurements of the fluidity energy in such a manner.
From the verification results shown in
As for the bulk density of the developer, the developer has been loosened and fluidized sufficiently in the verification experiments, and therefore, the bulk density is lower than that expected in the normal use condition (left state), that is, the measurements are carried out in the condition in which the developer is more easily discharged than in the normal use condition.
The verification experiments were carries out as to the developer A with which the discharge amount is the largest in the results of
On the other hand, the lower limit value of the size of the discharge opening 4a is preferably such that the developer to be supplied from the supply container 1 (one component magnetic toner, one component non-magnetic toner, two component non-magnetic toner or two component magnetic carrier) can at least pass therethrough. More particularly, the discharge opening is preferably larger than a particle size of the developer (volume average particle size in the case of toner, number average particle size in the case of carrier) contained in the supply container 1. For example, in the case that the supply developer comprises two component non-magnetic toner and two component magnetic carrier, it is preferable that the discharge opening is larger than a larger particle size, that is, the number average particle size of the two component magnetic carrier.
Specifically, in the case that the supply developer comprises two component non-magnetic toner having a volume average particle size of 5.5 μm and a two component magnetic carrier having a number average particle size of 40 μm, the diameter of the discharge opening 4a is preferably not less than 0.05 mm (0.002 mm^2 in the opening area).
If, however, the size of the discharge opening 4a is too close to the particle size of the developer, the energy required for discharging a desired amount from the supply container 1, that is, the energy required for operating the pump portion 3a is large. It may be the case that a restriction is imparted to the manufacturing of the supply container 1. In order to mold the discharge opening 4a in a resin material part using an injection molding method, a metal mold part for forming the discharge opening 4a is used, and the durability of the metal mold part will be a problem. From the foregoing, the diameter φ of the discharge opening 4a is preferably not less than 0.5 mm.
In this example, the configuration of the discharge opening 4a is circular, but this is not inevitable. A square, a rectangular, an ellipse or a combination of lines and curves or the like are usable if the opening area is not more than 12.6 mm^2 which is the opening area corresponding to the diameter of 4 m.
However, a circular discharge opening has a minimum circumferential edge length among the configurations having the same opening area, the edge being contaminated by the deposition of the developer. However, a circular discharge opening has a minimum circumferential edge length among the configurations having the same opening area, the edge being contaminated by the deposition of the developer. In addition, with the circular discharge opening, a resistance during discharging is also small, and a discharging property is high. Therefore, the configuration of the discharge opening 4a is preferably circular which is excellent in the balance between the discharge amount and the contamination prevention.
From the foregoing, the size of the discharge opening 4a is preferably such that the developer is not discharged sufficiently only by the gravitation in the state that the discharge opening 4a is directed downwardly (supposed supplying attitude into the developer replenishing apparatus 201). More particularly, a diameter φ of the discharge opening 4a is not less than 0.05 mm (0.002 mm^2 in the opening area) and not more than 4 mm (12.6 mm^2 in the opening area). Furthermore, the diameter φ of the discharge opening 4a is preferably not less than 0.5 mm (0.2 mm^2 in the opening area and not more than 4 mm (12.6 mm^2 in the opening area). In this example, on the basis of the foregoing investigation, the discharge opening 4a is circular, and the diameter φ of the opening is 2 mm.
In this example, the number of discharge openings 4a is one, but this is not inevitable, and a plurality of discharge openings 4a, if the respective opening areas satisfy the above-described range. For example, in place of one developer receiving port 13 having a diameter φ of 3 mm, two discharge openings 4a each having a diameter φ of 0.7 mm are employed. However, in this case, the discharge amount of the developer per unit time tends to decrease, and therefore, one discharge opening 4a having a diameter φ of 2 mm is preferable.
(Cylindrical Portion)
Referring to
In order to increase a filling capacity by increasing the volume of the supply container 1, it would be considered that the height of the discharging portion 4c as the developer accommodating portion 2 is increased to increase the volume thereof. However, with such a structure, the gravitation to the developer adjacent the discharge opening 4a increases due to the increased weight of the developer. As a result, the developer adjacent the discharge opening 3a tends to be compacted with the result of obstruction to the suction/discharging through the discharge opening 4a. In this case, in order to loosen the developer compacted by the suction through the discharge opening 4a or in order to discharge the developer by the discharging, the volume change of the pump portion 3a has to be increased. As a result, the driving force for driving the pump portion 3a has to be increased, and the load to the main assembly 100A of the image forming apparatus may be increased to an extreme extent.
In this example, the cylindrical portion 2k extends in the horizontal direction from the flange portion 4 so that the amount of the developer is adjusted by the volume of the cylindrical portion 2k, and therefore, the thickness of the developer layer on the discharge opening 4a in the supply container 1 can be made small as compared with the above-described high structure. By doing so, the developer does not tend to be compacted by the gravitation, and therefore, the developer can be discharged stably without large load to the main assembly 100A of the image forming apparatus.
As shown in part (b) and part (c) of
(Pump Portion)
Referring to
The pump portion 3a of this example functions as a suction and discharging mechanism for repeating the sucking operation and the discharging operation alternately through the discharge opening 3a. In other words, the pump portion 3a functions as an air flow generating mechanism for generating repeatedly and alternately air flow into the supply container and air flow out of the supply container through the discharge opening 4a. The pump portion 3a is a part in which the inner volume of the cylindrical portion 2k can be changed in the longitudinal direction of the supply container 1 to apply a pressure at least to the discharge opening 4a.
As shown in part (b) of
The pump portion 3a of this example is capable of accommodating the developer therein. The developer accommodating space of the pump portion 3a plays an important function for the fluidization of the developer in the suction operation, as will be described hereinafter.
In this example, the pump portion 3a is a displacement type pump (bellow-like pump) of resin material in which the volume thereof changes with the reciprocation. More particularly, as shown in parts (a)-(c) of
Using the pump portion 3a of such a structure, the volume of the supply container 1 can be alternately changed repeatedly at predetermined intervals. As a result, the developer in the discharging portion 4c can be discharged efficiently through the small diameter discharge opening 4a (diameter of approx. 2 mm).
(Drive Receiving Mechanism)
The description will be made as to a drive receiving mechanism (drive receiving portion, driving force receiving portion) of the supply container 1 for receiving the rotational force for rotating the cylindrical portion 2k provided with feeding projection 2c from the developer replenishing apparatus 201. As shown in part (a) of
Therefore, the rotational force inputted to the gear portion 2d from the driving gear 300 (
In this example, the gear portion 2d is provided at one longitudinal end (developer feeding direction) of the cylindrical portion 2k, but this is not inevitable, and the gear portion 2a may be provided at the other longitudinal end side of the developer accommodating portion 2, that is, the trailing end portion. In such a case, the driving gear 300 is provided at a corresponding position.
In this example, a gear mechanism is employed as the driving connection mechanism between the drive receiving portion of the supply container 1 and the driver of the developer replenishing apparatus 201, but this is not inevitable, and a known coupling mechanism, for example is usable. More particularly, in such a case, the structure may be such that a non-circular recess is provided as a drive receiving portion, and correspondingly, a projection having a configuration corresponding to the recess as a driver for the developer replenishing apparatus 201, so that they are in driving connection with each other.
(Drive Converting Mechanism)
A drive converting mechanism (drive converting portion) for the supply container 1 will be described. In this example, a cam mechanism is taken as an example of the drive converting mechanism. The supply container 1 is provided with the cam mechanism which functions as the driving force converting mechanism for converting the rotational force for rotating the cylindrical portion 2k received by the gear portion 2d to a force in the reciprocating directions of the pump portion 3a.
N this example, one drive receiving portion (gear portion 2d) receives the driving force for rotating the cylindrical portion 2k and for reciprocating the pump portion 3a, and the rotational force received by converting the rotational driving force received by the gear portion 2d to a reciprocation force in the supply container 1 side.
Because of this structure, the structure of the drive receiving mechanism for the supply container 1 is simplified as compared with the case of providing the supply container 1 with two separate drive receiving portions. In addition, the drive is received by a single driving gear of developer replenishing apparatus 201, and therefore, the driving mechanism of the developer replenishing apparatus 201 is also simplified.
Part (a) of
The first and second cam grooves 2X and 2Y and the reciprocation member 3b as driving force converting portion converts the received rotational force into a feeding driving force to rotate the inclination rib 6a through the gear portion 2d to feed the developer by the operation of the pump portion 3a in the longitudinal direction of the supply container 1. In this example, as shown in part (c) of
A plurality of such reciprocation member engaging projections 3c are provided and are engaged with the cam grooves 2X and 2Y. More particularly, two engaging projections 3c are provided opposed to each other in the diametrical direction of the cylindrical portion 2k (approx. 180° opposing).
The number of the engaging projections 3c is satisfactory if it is not less than one. However, in consideration of the liability that a moment is produced by the drag force during the expansion and contraction of the pump portion 3a with the result of unsmooth reciprocation, the number is preferably plural as long as the proper relation is assured in relation to the configuration of the cam grooves 2X and 2Y which will be described hereinafter.
In this manner, by the rotation of the cam groove 2X or 2Y by the rotational force received from the driving gear 300, the reciprocation member engaging projection 3c reciprocates in the arrow X direction and the opposite direction along the cam groove 2X or 2Y. By this, the pump portion 3a repeats the expanded state (part (a) of
(Set Conditions of Drive Converting Mechanism)
In this example, the driving force converting mechanism effects the drive conversion such that an amount (per unit time) of developer feeding to the discharging portion 4c by the rotation of the cylindrical portion 2k is larger than a discharging amount (per unit time) to the developer replenishing apparatus 201 from the discharging portion 4c by the function of the pump portion. This is because if the developer discharging power of the pump portion 2b is higher than the developer feeding power of the feeding projection 2c to the discharging portion 3h, the amount of the developer existing in the discharging portion 3h gradually decreases. In other words, it is avoided that the time period required for supplying the developer from the supply container 1 to the developer replenishing apparatus 201 is prolonged.
In addition, in the drive converting mechanism of this example, the drive conversion is such that the pump portion 3a reciprocates a plurality of times per one full rotation of the cylindrical portion 2k. This is for the following reasons.
In the case of the structure in which the cylindrical portion 2k is rotated inner the developer replenishing apparatus 201, it is preferable that the driving motor 500 is set at an output required to rotate the cylindrical portion 2k stably at all times. However, from the standpoint of reducing the energy consumption in the image forming apparatus 100 as much as possible, it is preferable to minimize the output of the driving motor 500. The output required by the driving motor 500 is calculated from the rotational torque and the rotational frequency of the cylindrical portion 2k, and therefore, in order to reduce the output of the driving motor 500, the rotational frequency of the cylindrical portion 2k is minimized.
However, in the case of this example, if the rotational frequency of the cylindrical portion 2k is reduced, a number of operations of the pump portion 3a per unit time decreases, and therefore, the amount of the developer (per unit time) discharged from the supply container 1 decreases. In other words, there is a possibility that the developer amount discharged from the supply container 1 is insufficient to quickly meet the developer supply amount required by the main assembly of the image forming apparatus 100.
If the amount of the volume change of the pump portion 3a is increased, the developer discharging amount per unit cyclic period of the pump portion 3a can be increased, and therefore, the requirement of the main assembly of the image forming apparatus 100 can be met, but doing so gives rise to the following problem. If the amount of the volume change of the pump portion 2b is increased, a peak value of the internal pressure (positive pressure) of the supply container 1 in the discharging stroke increases, and therefore, the load required for the reciprocation of the pump portion 2b increases.
For this reason, in this example, the pump portion 3a operates a plurality of cyclic periods per one full rotation of the cylindrical portion 2k. By this, the developer discharge amount per unit time can be increased as compared with the case in which the pump portion 3a operates one cyclic period per one full rotation of the cylindrical portion 2k, without increasing the volume change amount of the pump portion 3a. Corresponding to the increase of the discharge amount of the developer, the rotational frequency of the cylindrical portion 2k can be reduced. With the structure of this example, the required output of the driving motor 500 may be low, and therefore, the energy consumption of the main assembly of the image forming apparatus 100 can be reduced.
(Position of Driving Converting Mechanism)
As shown in
By this, a problem which may arise when the driving force converting mechanism is provided in the inside space of the developer accommodating portion 2 can be avoided. More particularly, the problem is that by the developer entering portions of the driving force converting mechanism where sliding motions occur, the particles of the developer are subjected to heat and pressure to soften and therefore, they agglomerate into masses (coarse particle), or they enter into a converting mechanism with the result of torque increase. The problem can be avoided. Now, the description will be made as to the developer supplying step into the developer supplying apparatus 201 by the supply container 1.
(Developer Supplying Step)
Referring to
In this example, as will be described hereinafter, the drive conversion of the rotational force is carries out by the driving force converting mechanism so that the suction stroke by the pump operation (suction operation through discharge opening 4a), the discharging stroke (discharging operation through the discharge opening 4a) and the rest stroke by the non-operation of the pump portion (neither suction nor discharging is effected through the discharge opening 4a) are repeated alternately. The suction stroke, the discharging stroke and the rest stroke will be described.
(Suction Stroke)
First, the suction stroke (suction operation through discharge opening 4a) will be described. As shown in
At this time, the supply container 1 is substantially hermetically sealed except for the discharge opening 4a, and the discharge opening 3a is plugged substantially by the developer T. Therefore, the internal pressure of the supply container 1 decreases with the increase of the volume of the portion of the supply container 1 capable of containing the developer T. At this time, the internal pressure of the supply container 1 is lower than the ambient pressure (external air pressure). For this reason, the air outside the supply container 1 enters the supply container 1 through the discharge opening 4a by a pressure difference between the inside and the outside of the supply container 1.
At this time, the air is taken-in from the outside of the supply container 1, and therefore, the developer T in the neighborhood of the discharge opening 4a can be loosened (fluidized). More particularly, the air impregnated into the developer powder existing in the neighborhood of the discharge opening 4a, thus reducing the bulk density of the developer powder T and fluidizing. Since the air is taken into the supply container 1 through the discharge opening 4a, the internal pressure of the supply container 1 changes in the neighborhood of the ambient pressure (external air pressure) despite the increase of the volume of the supply container 1.
In this manner, by the fluidization of the developer T, the developer T does not pack or clog in the discharge opening 4a, so that the developer can be smoothly discharged through the discharge opening 4a in the discharging operation which will be described hereinafter. Therefore, the amount of the developer T (per unit time) discharged through the discharge opening 4a can be maintained substantially at a constant level for a long term.
For effecting the sucking operation, it is not inevitable that the pump portion 3a changes from the most contracted state to the most expanded state, but the sucking operation is effected if the internal pressure of the supply container 1 changes even if the pump portion changes from the most contracted state halfway to the most expanded state. That is, the suction stroke corresponds to the state in which the reciprocation member engaging projection 3c is engaged with the cam groove (second operation portion) 2h shown in
(Discharging Stroke)
The discharging stroke (discharging operation through the discharge opening 4a) will be described. As shown in part (b) of
The internal pressure of the supply container 1 is higher than the ambient pressure (the external air pressure), and therefore, the developer T is pushed out by the pressure difference between the inside and the outside of the supply container 1. That is, the developer T is discharged from the supply container 1 into the developer replenishing apparatus 201. Also air in the supply container 1 is also discharged with the developer T, and therefore, the internal pressure of the supply container 1 decreases. As described in the foregoing, according to this example, the discharging of the developer can be effected efficiently using one reciprocation type pump portion 3a, and therefore, the mechanism for the developer discharging can be simplified.
For effecting the discharging operation, it is not inevitable that the pump portion 3a changes from the most expanded state to the most contracted state, but the discharging operation is effected if the internal pressure of the supply container 1 changes even if the pump portion changes from the most expanded state halfway to the most contracted state. That is, the discharging stroke corresponds to the state in which the reciprocation member engaging projection 3c is engaged with the cam groove 2g shown in
(Rest Stroke)
The rest stroke in which the pump portion 3a does not to reciprocate will be described. In this example, as described hereinbefore, the operation of the driving motor 500 is controlled by the control device 600 on the basis of the results of the detection of the magnetometric sensor 800c and/or the developer sensor 10d. With such a structure, the amount of the developer discharged from the supply container 1 directly influences the toner content of the developer, and therefore, it is necessary to supply the amount of the developer required by the image forming apparatus from the supply container 1. At this time, in order to stabilize the amount of the developer discharged from the supply container 1, it is desirable that the amount of volume change at one time is constant.
If, for example, the cam grooves 2X and 2Y include only the portions for the discharging stroke and the suction stroke, the motor actuation may stop at halfway of the discharging stroke or suction stroke. After the stop of the driving motor 500, the cylindrical portion 2k continues rotating by the inertia, by which the pump portion 3a continues reciprocating until the cylindrical portion 2k stops, during which the discharging stroke or the suction stroke continues. The distance through which the cylindrical portion 2k rotates by the inertia is dependent on the rotational speed of the cylindrical portion 2k. Further, the rotational speed of the cylindrical portion 2k is dependent on the torque applied to the driving motor 500. From this, the torque to the motor changes depending on the amount of the developer in the supply container 1, and the speed of the cylindrical portion 2k may also change, and therefore, it is difficult to stop the pump portion 3a at the same position.
In order to stop the pump portion 3a at the same position, a region in which the pump portion 3a does not reciprocate even during the rotation of the cylindrical portion 2k is required to be provided in the cam grooves 2X and 2Y. In this embodiment, for the purpose of preventing the reciprocation of the pump portion 3a, there is provided a cam groove 2i (
The non-reciprocation of the pump portion 3a means that the developer is not discharged through the discharge opening 4a (except for the developer falling through the discharge opening 4a due to the vibration or the like during the rotation of the cylindrical portion 2k). Thus, if the discharging stroke or suction stroke through the discharge opening 4a is not effected, the cam groove 2i may be inclined relative to the rotational moving direction toward the rotation axial direction. When the cam groove 2i is inclined, the reciprocation of the pump portion 3a corresponding to the inclination is permitted.
(Change of Internal Pressure of Supply Container)
Verification experiments were carried out as to a change of the internal pressure of the supply container 1. The verification experiments will be described. The developer is filled such that the developer accommodating space in the supply container 1 is filled with the developer; and the change of the internal pressure of the supply container 1 is measured when the pump portion 3a is expanded and contracted in a range of 5 cm^3 of volume change. The internal pressure of the supply container 1 is measured using a pressure gauge (AP-C40 available from Kabushiki Kaisha KEYENCE) connected with the supply container 1.
When the internal pressure of the supply container 1 becomes negative relative to the outside ambient pressure by the increase of the volume of the supply container 1, the air is taken in through the discharge opening 4a by the pressure difference. When the internal pressure of the supply container 1 becomes positive relative to the outside ambient pressure by the decrease of the volume of the supply container 1, a pressure is imparted to the inside developer. At this time, the inside pressure eases corresponding to the discharged developer and air.
By the verification experiments, it has been confirmed that by the increase of the volume of the supply container 1, the internal pressure of the supply container 1 becomes negative relative to the outside ambient pressure, and the air is taken in by the pressure difference. In addition, it has been confirmed that by the decrease of the volume of the supply container 1, the internal pressure of the supply container 1 becomes positive relative to the outside ambient pressure, and the pressure is imparted to the inside developer so that the developer is discharged. In the verification experiments, an absolute value of the negative pressure is approx. 1.2 kPa, and an absolute value of the positive pressure is approx. 0.5 kPa.
As described in the foregoing, with the structure of the supply container 1 of this example, the internal pressure of the supply container 1 switches between the negative pressure and the positive pressure alternately by the suction operation and the discharging operation of the pump portion 3a, and the discharging of the developer is carried out properly.
As described in the foregoing, the example, a simple and easy pump portion capable of effecting the suction operation and the discharging operation of the supply container 1 is provided, by which the discharging of the developer by the air can be carries out stably while providing the developer loosening effect by the air.
In other words, with the structure of the example, even when the size of the discharge opening 4a is extremely small, a high discharging performance can be assured without imparting great stress to the developer since the developer can be passed through the discharge opening 4a in the state that the bulk density is small because of the fluidization.
In addition, in this example, the inside of the displacement type pump portion 3a is utilized as a developer accommodating space, and therefore, when the internal pressure is reduced by increasing the volume of the pump portion 3a, an additional developer accommodating space can be formed. Therefore, even when the inside of the pump portion 3a is filled with the developer, the bulk density can be decreased (the developer can be fluidized) by impregnating the air in the developer powder. Therefore, the developer can be filled in the supply container 1 with a higher density than in the conventional art.
(Regulating Portion)
Referring to
As shown in part (a) of
The regulating portion 7 has such a configuration as to cover the storage portion 4d provided in the flange portion 4 depending on the rotational phase, and it periodically repeats covering and uncovering the upper portion of the storage portion 4d in interrelation with the rotation. The operation will be described in detail. The developer fed from the cylindrical portion 2k is stored in the storage portion 4d and in the neighborhood of the upper part thereof, and thereafter, the developer in the upper portion of the storage portion 4d is pushes aside by the regulating portion 7. When the discharging stroke is carried out in this state, only the developer in the storage portion 4d discharged. At this time, as long as the regulating portion 7 covers the upper portion of the storage portion 4d, the flow of the developer into the storage portion 4d from the portion therearound is limited, and therefore, the developer other than that within the storage portion 4d is not discharged.
Therefore, by covering the upper portion of the storage portion 4d by the regulating portion 7, the flow of the developer into the storage portion 4d is prevented, and the developer powder surface in the storage portion 4d is maintained constant. In the discharging stroke, when the developer in the storage portion 4d is discharged, the spaces inside and outside of the supply container 1 are communicated with each other, and then only the air is discharged, so that the continuous discharging of the developer due to the pressure difference between the inside and the outside of the supply container 1 can be prevented.
As will be understood from the foregoing, with this structure of this example having the regulating portion 7, a constant amount of the developer stored in the storage portion 4d can be discharged at all times in the discharging stroke, and therefore, the developer can be discharged with stabilized supply accuracy.
After the developer is discharged, no developer exists inside the storage portion 4d apart from the developer deposited on the walls. From this state, the developer is fed into the storage portion 4d again by the further rotation of the feeding member 6, and the same steps are repeated. Accordingly, the developer can be discharged with the stabilized supply accuracy from the initial stage to a later stage of the discharging operation.
(Cam Grooves)
Referring to
In
As shown in
The reciprocation member 3b reciprocates in the longitudinal direction of the supply container 1 by a part thereof moving in engagement with the first cam groove 2X or the second cam groove 2Y. After the part of the reciprocation member 3b moves in engagement with the first cam groove 2X, it moves in engagement with the second cam groove 2Y only.
The first cam groove 2X and the second cam groove 2Y are connected with each other at the position of a stepped portion 2p. Here, the stepped portion 2p is provided at the connecting position between the first cam groove 2X and the second cam groove 2Y, and the surface of the second cam groove 2Y is lower than the surface of the first cam groove 2X toward the rotation axis of the cylindrical portion 2k.
The operation of the engaging projection 3c and the cam grooves 2X, 2Y will be described. When the supply container 1 is used for the first time, the engaging projection 3c is at a position downstream of the first cam groove 2X with respect to the rotational direction of the cylindrical portion 2k, as shown in
When the cam grooves 2X, 2Y start to rotate with this state, the engaging projection 3c move along the first cam groove 2X. The engaging projection 3c moves along the cam groove 2n, the cam groove 2i, the cam groove 2m, and the stepped portion 2p then to the second cam groove 2Y. The function of the stepped portion 2p will be described in detail hereinafter. The operation of the pump portion 3a at this time is an above-described suction stroke because the engaging projection 3c moves along the cam groove 2n in the direction of expanding the pump portion 3a (B direction). In addition, when the engaging projection 3c moves along the cam groove 2m, the pump portion 3a move in the compressed in the direction indicated by the arrow C, that is, the discharging stroke is carried out. The amplitude of the reciprocation of the pump portion 3a at this time is K1 as depicted in
Then, the engaging projection 3c having moved to the second cam groove 2Y moves thereafter along the cam groove 2i, the cam groove 2h, the cam groove 2g in the order named, and subsequently, the engaging projection 3c moves always along the second cam groove 2Y. When the engaging projection 3c moves along the cam groove 2h, the pump portion 3a moves in the expanding direction, that is, the suction stroke is carried out. When the engaging projection 3c moves along the cam groove 2g, the pump portion 3a moves in the compressed in the direction, that is, the discharging stroke is carried out. The amplitude of the reciprocation of the pump portion 3a at this time is K2 as depicted in
The stepped portion 2p will be described. The stepped portion 2p is a step provided at a connecting portion between the first cam groove 2X and the second cam groove 2Y, and the second cam groove 2Y is lower than the first cam groove 2X (the diameter of the second cam groove Y as measured from the center of the container). The reciprocation member 3b is supported by the flange portion 4 as described hereinbefore, and the engaging projection 3c is urged toward the cam grooves 2X and 2Y.
The operation will be described in detail. The engaging projection 3c moving from the first cam groove 2X to the second cam groove 2Y passes the stepped portion 2p and enters the second cam groove 2Y which is at a lower level than the bottom surface of the first cam groove 2X. Then, the engaging projection 3c moves in the first cam groove 2X to the stepped portion 2p. At this time, the engaging projection 3c is urged toward the second cam groove Y, and therefore, the engaging projection 3c does not ride on the step back into the first cam groove 2X. With such a structure, after the engaging projection 3c enter the second cam groove 2Y from the first cam groove 2X, the engaging projection 3c does not return into the first cam groove 2X.
Without the stepped portion 2p, there is a possibility that the engaging projection 3c enters back again into the first cam groove 2X at the connecting portion between the first cam groove 2X and the second cam groove 2Y. If this occurs, the pump portion 3a makes an expanding-and-contracting operation adjacent the stepped portion 2p with the result of an intentional developer discharge. The provision of the stepped portion 2p at the connecting portion between the first cam groove 2X and the second cam groove 2Y is effective to prevent the occurrence of such unintentional discharged.
The stepped portion 2p is an example of the structures effect in the prevention, and a flap 2q may replace the stepped portion 2p. The flap 2q is capable of rotating about a rotational axis 2q1. When the engaging projection 3c moves from the first cam groove 2X into the second cam groove 2Y, the engaging projection 3c pushes the flap 2q away, as shown in part (a) of
After the engaging projection 3c moves into the second cam groove 2Y, the engaging projection 3c rotates the flap 2q in the direction indicated by an arrow B as shown in part (b) of
As described above, after the engaging projection 3c move along the first cam groove 2X, the engaging projection 3c enters the second cam groove 2Y and thereafter moves along the second cam groove 2Y at all times. When the engaging projection 3c move along the first cam groove 2X, the amplitude of the pump portion 3a is K1, and thereafter, the amplitude is K2 (along the second cam groove 2Y). As described in the foregoing, K1>K2 is satisfied.
The expansion and contraction stroke of the reciprocation member 3b in the initial rotation period (the amplitude of the first pumping strokes) provided by the inclination rib 6a receiving the rotational force through the gear portion 2d is different from the expansion and contraction stroke in the subsequent rotation period (the amplitude of the second and subsequent pumping strokes). In the initial rotation period, the cylindrical portion 2k having the inclination rib 6a rotates at predetermined turns in the initial stage.
Particularly, the first cam groove 2X, the second cam groove 2Y and the reciprocation member 3b are constituted such that the expansion and contraction stroke in the initial rotation period of the pump portion 3a is larger than that in the subsequent rotation periods. More specifically, the amplitude in the initial one pumping operation is relatively larger, and the amplitude of the second and subsequent operations is relatively smaller.
The reasons for such an arrangement will be described. After the manufacturing of the supply container 1, it is subjected to various kinds of vibration during the transportation to a user. During the transportation, the bulk density of the developer powder in the supply container 1 may be caked (not easily loosened). Particularly if the developer in the storage portion 4d (
By making the amplitude of the pump portion 3a large so that the pressure imparted to the developer is made high for assured functions of the suction stroke and the discharging stroke. Particularly in the suction stroke, the suction of the air is effective to loosen the developer in the storage portion 4d, and therefore, the loosening effect by increasing the amplitude in the suction stroke is strong. The amplitude of the pump portion 3a to assure the discharging of the developer may be properly determined by one skilled in the art depending on the kind of the developer and the transportation level.
In this manner, the larger amplitude of the pump portion 3a is effective to assure the discharged of the developer in the initial stage, and once the developer is loosened, the pressure required to discharged the developer is not very high. For this reason, if the pressure is selected to meet the pressure required in the initial stage, the pressure is higher than the required pressure for the developer discharged in the subsequent operation. As a result, the developer is discharged normally with the pressure of higher than necessary, and therefore, the load to the driving system of the image forming apparatus is too large with the waste of energy.
In this embodiment, the amplitude is changed only in the first one bump in the stroke, but the amplitude is made larger in a plurality of pumping strokes in the initial stage by increasing the number of cam grooves 2n and cam grooves 2m of the first cam groove 2X, as shown in
In this example, the two engaging projections 3c are employed, and therefore, the first cam groove 2X is provided for one half rotation, but only one engaging projection 3c may be provided, and first cam groove 2X is provided for one full rotation. With such a structure, the first cam groove 2X is provided for one or a plurality of rotations using a helical structure, a plurality of suction and discharge strokes of the pump portion 3a can be carried out. Then, the pump portion 3a can be operated a plurality of times with the amplitude which is different from that provided by the second cam groove 2Y. The specific structures to be employed can be properly determined by one skilled in the art in view of the property of the developer and the level of the transportation.
As described in the foregoing, using the above-described structures, the amplitude of the operation of the pump portion 3a is made larger only in the initial stage or stages, and thereafter, the amplitude can be made smaller after the developer begins to discharge, by which the initial discharging property and the reduction of the drive load in the subsequent stage can be assured. Accordingly, with the above-described the structures, the developer can be stably discharged with less drive energy from the initial stage to the subsequent stage.
Referring to
As shown in
More particularly, in this embodiment, the driving force converting portion includes a first cam groove 2X which is formed on and which extends in the rotational moving direction of the supply container 1 while snaking in the longitudinal direction of the supply container 1. The driving force converting portion includes a second cam groove 2Y which is formed on and which extends in the rotational moving direction of the supply container 1 while snaking in the longitudinal direction of the supply container 1. A part of the reciprocation member 3b moves along the first cam groove 2X with second cam groove 2Y, by which the reciprocation member 3b reciprocates in the longitudinal direction of the supply container 1. After the part of the reciprocation member 3b moves in engagement with the first cam groove 2X, the part moves in engagement with the second cam groove 2Y only. The driving force converting portion effects the conversion such that the expansion and contraction stroke in the initial rotation period of the pump portion 3a is smaller than the expansion and contraction stroke after the initial rotation period.
As shown in
Thereafter, with the rotation of the cam grooves 2X, 2Y, the engaging projection 3c moves along the first cam groove 2X. The engaging projection 3c moves along the cam groove 2n, the cam groove 2i, the cam groove 2m, and the stepped portion 2p in the order named and then to the second cam groove 2Y. The function of the stepped portion 2p and the operation of the pump portion 3a are similar to those of Embodiment 1. The amplitude of the reciprocation of the pump portion 3a at this time is K1 as depicted in
As described above, after the engaging projection 3c move along the first cam groove 2X, the engaging projection 3c enters the second cam groove 2Y and thereafter moves along the second cam groove 2Y at all times. When the engaging projection 3c move along the first cam groove 2X, the amplitude of the pump portion 3a is K1, and thereafter, the amplitude is K2 (along the second cam groove 2Y). Since K2>K1, the amplitude of the first pump operation is relatively small, and the amplitude thereafter is relatively large.
In Embodiment 1, the amplitude of the pump portion 3a in the initial discharging the stage is relatively larger, and it is made relatively smaller subsequently, but in this embodiment, the situation is the opposite, that is, the amplitude in the initial stage is relatively small, and it is relatively larger in the subsequent stage.
The reason for this arrangement will be described. Here, it is assumed that the caking of the developer during the transportation so less that the developer can be discharged with the amplitude K2 (
In view of this, the amplitude of the pump portion 3a in a plurality of initial strokes is made relatively smaller, by which the expansion and contraction force decreases, the suppressing the increase of the drive load. After the engaging projection 3c enters the second cam groove 2Y thereafter, the pump portion 3a is operated with an amplitude K2 optimum for the discharge of the developer. If the pump portion 3a is operated with the amplitude K1 from the initial stage to the subsequent stage, the drive load is relatively smaller, but the amplitude is not enough stably discharge the developer, and therefore, the developer is not discharged stably.
The initial amplitude of the pump portion 3a may be provided determined by one skilled in the art depending on the balance of the time duration to the start of the discharged and the drive load. The time duration to the start of the discharging and the drive load are in a trade-off relationship, and when the amplitude is 0, the drive load is the minimum, and with the increase of the amplitude, the drive load increases.
As described in the foregoing, according to the embodiment of the present invention, the amplitude of the pump portion 3a is made relatively smaller in the initial stage, and in the subsequent the stage after the start of the discharge of the developer, the amplitude is made relatively large, by which the reduction of the initial drive load and the discharging stability can both be accomplished. Therefore, the developer can be stably discharged by a small drive load from the initial stage you to the subsequent stage.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2014-228138 filed on Nov. 10, 2014, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-228138 | Nov 2014 | JP | national |
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