JP2009116248A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that hardly causes the deterioration in image quality or toner soiling in a body due to fogging toner or scattering toner even in a toner cartridge for which many years have passed after manufacturing. <P>SOLUTION: A radio IC tag 30a, in which information related to manufactured date of toner is recorded, is stuck to a toner cartridge 11a. A control part 51 calculates the number of days which has passed up to the present date by reading the manufactured year, month and day from the radio IC tag through a communication part 50 and sets agitation time for developer when starting a developing unit 1a. Since the agitation time is increased as the number of days which has passed increases, image formation for a first sheet can be carried out in a state with the toner charged just like new toner even with the toner which has become old and hard to be charged. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus in which a developer replenishing container is mounted on an image forming apparatus so that the developer can be replenished with the replenishment developer. The present invention relates to control for adjusting stirring conditions.

  2. Description of the Related Art Toner cartridge type image forming apparatuses that replace toner cartridges or toner bottles that are detachable with respect to the developing device and supply toner to the image forming apparatus have been put into practical use. In addition, a process cartridge type image forming apparatus that replaces a new process cartridge that integrates an image carrier, a developing device, a cleaning device, and the like and supplies toner to the image forming apparatus has been put into practical use.

  An image forming apparatus in which a storage device (for example, a wireless IC tag) capable of data writing / reading wirelessly is attached to these developer supply containers and image forming conditions are adjusted according to read data has been put into practical use.

  Patent Document 1 discloses an image forming apparatus in which a memory element is attached to a process cartridge in which an image carrier, a developing device, a cleaning device, and the like are integrated. The memory element records the manufacturing date and quality assurance date of the process cartridge, and the image forming apparatus records the date until the quality assurance period based on the manufacturing date and the quality assurance date read from the memory element. Displays the remaining days.

  Japanese Patent Application Laid-Open No. H11-260260 shows that after the start of use of the process cartridge, the charging performance of the toner in the process cartridge is lowered and the toner may not be used in actual use before the toner is consumed up. Here, a wireless IC tag is attached to the process cartridge, and history information relating to toner quality degradation for each image formation is written. The history information is read from the wireless IC tag each time the printer is started, and the remaining life and replacement period of the process cartridge are read. Are displayed.

  Patent Document 3 shows a one-drum type full-color image forming apparatus provided with a rotary developing device. When a toner bottle connected to a developer supply device becomes empty, it is replaced with a new toner bottle. If the inventory period of the toner bottle is long, the charging performance of the toner will gradually decrease, causing an excessive density of the toner image, so here, if you connect a new toner bottle and enter the manufacturing date, the inventory period will be The corresponding process conditions are automatically set in the developing device.

JP-A-5-323716 JP 2005-178058 A JP 2006-251384 A

  If the stock period of the process cartridge, toner cartridge, and toner bottle from the time of shipment from the factory until it is actually attached to the developing device is long, the image quality is likely to deteriorate due to the fog toner or the scattered toner. found.

  According to our knowledge, the toner after many years has greatly deteriorated charging performance compared with a new toner, and applying the conventional control assuming a new toner with little deterioration over time, the non-image area of the image carrier is applied. Toner adhesion and toner scattering from the developing device are likely to occur. In particular, immediately after startup of the image forming apparatus that has been stopped for a long time, image formation is likely to be performed in a state where the amount of charge of toner is significantly insufficient, and the problem of fog toner and toner scattering becomes serious.

  For this reason, when image formation is started using a toner cartridge after many years, it is necessary to perform control different from that when a new toner cartridge is mounted.

  However, in the control of Patent Document 3, the final image density can be improved through adjustment of the development voltage and the like. However, since the charge amount of the toner in the developing device remains small, image defects caused by fog toner or toner scattering and The main body toner contamination cannot be prevented.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that is less likely to cause image quality deterioration and main body toner contamination due to fog toner and scattered toner even with a toner cartridge that has passed many years after manufacture.

  The image forming apparatus of the present invention supplies an image carrier, electrostatic image forming means for forming an electrostatic image on the image carrier, and a developer charged by stirring to the image carrier. And a developing means for developing the electrostatic image. And reading means for reading information related to the elapsed time from the date of manufacture of the replenishment developer, from the storage means attached to the developer replenishment container for replenishing the replenishment developer to the developing means, and the read And a control unit that controls the developing unit so that the amount of stirring of the developer increases as the elapsed time becomes longer based on the information.

  In the image forming apparatus of the present invention, it is necessary to increase the number of stirring of the developer in the developing unit for the replenishing developer whose charging amount is insufficient if it is normally stirred since the manufacturing date is long. Secure a sufficient amount of charge. The decrease in the amount of charge per number of frictions is compensated by the number of frictions so that a developer with an older production time can be handled in the same manner as a normal developer.

  Therefore, sufficient image quality can be ensured under normal image forming conditions without applying special image forming conditions as disclosed in Patent Document 3, and toner scattering can be suppressed to the same level as ordinary developers. For this reason, even in a toner cartridge or process cartridge that has passed many years after manufacture, image quality deterioration and main body toner contamination due to fog toner and scattered toner are less likely to occur.

  Further, since the developing unit is controlled according to the information read from the storage unit of the developer supply container, it is not necessary to actually detect the charge amount of the developer in the developing unit.

  Hereinafter, some embodiments of the present invention will be described in detail with reference to the drawings. The present invention can be implemented in another embodiment in which a part or all of the configuration of each embodiment is replaced with the alternative configuration as long as the developer supply container is older and the startup time of the developing device becomes longer. .

  Therefore, the present invention is not limited to an image forming apparatus that uses a recording material conveyance belt, but can also be implemented by an intermediate transfer type image forming apparatus that transfers a toner image carried on an intermediate transfer belt to a recording material by a secondary transfer unit. Not only a tandem type image forming apparatus using a plurality of image carriers having different development colors but also a one-drum type image forming apparatus using a single image carrier.

  Not only an image forming apparatus that replaces a toner bottle and a toner cartridge and replenishes toner, but also an image forming apparatus that replaces a process cartridge in which a photosensitive drum, a charging device, a developing device and the like are integrated to replenish toner.

  In the present embodiment, only main parts related to toner image formation / transfer will be described. However, the present invention includes a printer, various printing machines, a copier, a fax machine, a composite machine, in addition to necessary equipment, equipment, and a housing structure. It can be implemented in various applications such as a machine.

  In addition, about the general matter regarding the image forming apparatus and wireless IC tag shown by patent documents 1-3, illustration is abbreviate | omitted and the overlapping description is abbreviate | omitted. In the description, the reference symbols in parentheses attached to the component names used in the claims are examples for helping understanding of the invention, and are not intended to limit the configuration to the members of the embodiment. Absent.

<First Embodiment>
1 is an explanatory diagram of the configuration of the image forming apparatus according to the first embodiment, FIG. 2 is an explanatory diagram of the configuration of the image forming unit, and FIG. 3 is an explanatory diagram of the configuration of the developing device.

  As shown in FIG. 1, the image forming apparatus 100 according to the first embodiment is an image of a tandem direct transfer system in which four image forming units Pa, Pb, Pc, and Pd are arranged in a straight section of a recording material conveyance belt 21. Forming device.

  In the image forming portion Pa, a yellow toner image is formed on the photosensitive drum 3 a and transferred to the recording material P carried on the recording material conveyance belt 21. In the image forming portion Pb, a magenta toner image is formed on the photosensitive drum 3b, and transferred onto the yellow toner image of the recording material P. In the image forming portions Pc and Pd, a cyan toner image and a black toner image are formed on the photosensitive drums 3c and 3d, respectively, and are sequentially transferred onto the recording material P in the same manner.

  The recording material P on which the four color toner images are sequentially transferred on the recording material conveyance belt 21 is separated from the recording material conveyance belt 21 and fed to the fixing device 9 to fix the toner image on the surface. It is loaded on the discharge tray 20 later.

  The separation device 11 separates the recording material P drawn from the paper feed cassette 10 one by one and sends it out toward the registration roller 13. The registration roller 13 receives and waits for the recording material P in a stopped state, and delivers the recording material P to the recording material conveyance belt 21 in synchronization with the toner image carried on the photosensitive drum 3a.

  The recording material P is charged along with the transfer of the yellow toner image in the first image forming portion Pa, and is electrostatically attracted to the recording material conveyance belt 21. Then, after the transfer of the black toner image in the final image forming portion Pd, the recording material P is neutralized by the separation charger 23 and is separated from the recording material conveyance belt 21 by attenuating the electrostatic adsorption force.

  The recording material transport belt 21 is supported around the driven roller 15, the driving roller 14, the tension roller 16, and the transfer rollers 5a, 5b, 5c, and 5d, and is driven by the driving roller 14 to rotate in the direction of the arrow R2. As the recording material transport belt 21, an endless shape or a seamless belt (seamless) is used.

  The belt cleaning device 22 slides the tip of the urethane rubber blade on the recording material conveyance belt 21 to clean the fog toner, scattered toner, and the like adhering to the recording material conveyance belt 21.

<Electrostatic image forming means, developing means>
The image forming portions Pa, Pb, Pc, and Pd are substantially the same except that the color of toner used in the attached developing devices 1a, 1b, 1c, and 1d is different from yellow, magenta, cyan, and black. Hereinafter, the image forming unit Pa will be described, and the other image forming units Pb, Pc, and Pd will be described by replacing “a” at the end of the reference numerals with “b”, “c”, and “d”.

  As shown in FIG. 2, the image forming unit Pa includes a charging device 2a, an exposure device 6a, a developing device 1a, a transfer roller 5a, and a cleaning device 4a around the photosensitive drum 3a.

  The photosensitive drum 3a is configured by applying an organic photoconductor (OPC) having a negative charging property to an outer peripheral surface of an aluminum cylinder having an outer diameter of 30 mm, and a process speed of 130 mm / sec centering on a central support shaft. To rotate in the direction of arrow R1.

  The charging device 2a is driven to rotate by pressing a charging roller against the photosensitive drum 3a. The power source D3 applies a voltage obtained by superimposing a DC voltage and an AC voltage to the charging roller, and charges the surface of the photosensitive drum 3a to a uniform negative potential VD (−500 V) having a negative polarity.

  The exposure device 6a scans the scanning line image data obtained by developing the yellow separated color image with a rotating mirror, and writes an electrostatic image of the image on the surface of the charged photosensitive drum 3a. The potential of the exposed portion becomes the bright portion potential VL (−200 to −500 V).

  The developing device 1a stirs a two-component developer in which a magnetic carrier is mixed with toner to charge the toner negatively. The charged toner is carried in a stand-up state on a developing sleeve (developer carrying member) 41 that rotates around the magnet 40, and rubs the photosensitive drum 3a.

  The power supply D4 applies to the developing sleeve 41 a voltage obtained by superimposing a rectangular AC voltage having a frequency of 8.0 kHz and a peak-to-peak voltage Vpp = 1.8 kV on a negative DC voltage Vdev (−350 V). The toner moves to the electrostatic image on the photosensitive drum 3a that is more positive than the developing sleeve 41 by the DC voltage Vdev, and the electrostatic image on the photosensitive drum 3a is reversely developed.

  The developing sleeve 41 carries and rotates the two-component developer adjusted to a uniform layer thickness by the regulating member, and conveys the two-component developer to a portion (developing nip) facing the photosensitive drum 3a.

  The toner conveyed to the developing nip by the developing sleeve 41 receives an electric force due to the potential difference between the electrostatic latent image potential of the photosensitive drum 3a and the developing sleeve 41, and flies from the developing sleeve 41 toward the photosensitive drum 3a. The flying toner reciprocates between the developing sleeve 41 and the photosensitive drum 3a by the AC voltage applied to the developing sleeve 41.

  The toner having a negative charge moves according to the potential difference between the DC voltage Vdev applied to the developing sleeve 41 and the electrostatic image, and the toner returns to the developing sleeve 41 in the dark portion potential VD region and in the bright portion potential VL region. An amount of toner corresponding to the potential adheres to the photosensitive drum 3a.

  The transfer roller 5a is urged toward the photosensitive drum 3a and is brought into pressure contact with the recording material conveyance belt 21, and between the recording material P carried on the recording material conveyance belt 21 and the photosensitive drum 3a, the image forming portion Pa. A transfer portion Ta is formed. The transfer unit Ta sandwiches and conveys the recording material P over the toner image carried on the photosensitive drum 3a.

In the transfer roller 5a, an elastic layer is formed around a cored bar that also serves as a rotating shaft. The elastic layer is formed of an elastic material such as a rubber mixed with an ion conductive substance such as sodium perchlorate, a polymer elastomer material such as urethane or a polymer foam material, and the volume resistance value is 1 × 10 ⁶ Ω · cm (under 23 ° C / 50% RH environment).

  The power source Da applies a positive DC voltage to the transfer roller 5a, charges the negative polarity, and transfers the toner image carried on the photosensitive drum 3a to the recording material P carried on the recording material conveyance belt 21.

  The cleaning device 4a cleans the transfer residual toner remaining on the surface of the photosensitive drum 3a after passing through the transfer portion Ta.

<Developer supply container>
Next, the toner replenishment configuration and the toner remaining amount detection in the developing device 1a will be described.

  A toner cartridge 11a, which is an example of a developer supply container, supplies toner T, which is an example of a supply developer, to the developing device 1a via the sub hopper 61. In this configuration, since the sub-hopper 61 is always filled with a predetermined volume of toner, the pressure due to the weight of the toner is stable, and the amount of toner replenished to the developing device 1a by the replenishing screw 62 is easily stabilized.

  Inside the toner cartridge 11a, a stirring blade 64 made of PET resin having a thickness of 300 μm is disposed. Then, when the stirring blade 64 rotates in the direction of arrow A, the toner T in the toner cartridge 60 is stirred, and while preventing the toner T from settling or blocking, from the opening 65 to the sub hopper 61 below the gravity direction. Transports toner.

  Inside the sub hopper 61, a stirring blade 63 made of PET having a thickness of 300 μm is disposed. Then, the stirring blade 63 rotates in the direction of arrow B to stir the toner T and convey the toner to the replenishing screw 62.

  The supply screw 62 is controlled to rotate / stop in accordance with image information and T / D ratio (toner / developer weight ratio) information of the two-component developer in the developing device 1a, and the developer T in the developing device 1a. / D ratio is induced to a certain range.

  The toner T conveyed to the replenishing screw 62 falls to the stirring screw 43 in the developing device 1a through the opening 44 as the replenishing screw 62 rotates.

  Above the replenishing screw 62, a toner remaining amount detection sensor 66 is disposed in contact with the inner wall of the sub hopper 61. The toner remaining amount detection sensor 66 includes a piezo element, a transmission circuit, and a detection circuit, and outputs a natural frequency that changes according to the remaining amount of toner as a change in voltage. Based on the output of the remaining toner detection sensor 66, the remaining amount of toner in the toner cartridge 11a is determined. When the toner cartridge 11a becomes empty, a warning is displayed on the display unit of the image forming apparatus (100: FIG. 1) to replace the developer supply container 11a. Is done.

  The remaining toner detection sensor 66 is not limited to a piezo sensor, and may be replaced with an optical sensor that includes a light source and a light receiving element and detects transmitted light or reflected light to determine the presence or absence of toner. The remaining amount of toner in the toner cartridge 11a may be determined by detecting the number of rotations of the supply screw 62 and predicting the amount of toner used.

  As shown in FIG. 3, the toner is transported along a transport path 46 by a stirring screw (stirring transport member) 43, delivered to a transport path 45 as indicated by an arrow, and transported by a stirring screw (stirring means) 42. 45 is conveyed.

  While the toner is conveyed and circulated through the conveyance paths 45 and 46, the toner is agitated by the agitating screws 42 and 43 together with the two-component developer filled in the developing device 1 a to be charged to a predetermined charge amount. .

  A part of the two-component developer conveyed on the conveyance path 45 is carried on the developing sleeve 41 and is carried out of the developing device 1a and supplied to the photosensitive drum (1a: FIG. 1).

  The stirring screws 42 and 43 and the developing sleeve 41 are all connected by a gear 48 and are driven by one developing motor Ma for each image forming portion (Pa: FIG. 1). This is effective in simplifying the developing device 1a and reducing the size of the image forming apparatus 100.

  In the developing device 1a, the diameter of the developing sleeve 41 is set to Φ16 mm, and the peripheral speed of the developing sleeve 41 is set to 217 mm / sec.

  The outer diameter of the stirring screw 42 adjacent to the developing sleeve 41 is 14 mm, the screw pitch is 15 mm, and the rotational speed of the screw 42 is 327 rpm.

  The outer diameter of the stirring screw 43 on the opening 44 side of the developing device 1a is Φ14 mm, the screw pitch is 20 mm, and the rotational speed of the screw 43 is 392 rpm.

  The developer conveying speed by the stirring screw 43 is 30 mm / sec, and the distance from the opening 44 to the opening for delivering the developer from the stirring screw 43 to the stirring screw 42 is 210 mm.

  A magnetic permeability sensor 47 is disposed upstream of the opening 44. The magnetic permeability sensor 47 changes the output signal in accordance with the T / D ratio (toner / developer weight ratio) of the two-component developer. The replenishment screw (62: FIG. 2) is controlled using information obtained by averaging the output of the magnetic permeability sensor 47 with time.

<Control means>
4 is a block diagram of a control system of the image forming apparatus, FIG. 5 is a flowchart of reading information of the wireless IC tag, FIG. 6 is a flowchart of starting control of the developing apparatus, and FIG. 7 is a time chart of recovery control.

  As shown in FIG. 4, the control unit 51 estimates the date of manufacture of the toner cartridge 11 a read through the communication unit 50 as the date of manufacture of the toner.

  The control unit 51 estimates the number of days that have elapsed from the date of manufacture of the toner by subtracting the date of manufacture of the toner cartridge 11a from the current date stored in the time management unit 52.

  The controller 51 estimates that the charging performance of the toner decreases as the estimated number of elapsed days increases (see FIG. 8).

  As the estimated number of elapsed days increases, the control unit 51 increases the stirring time of the developer by the stirring screws 42 and 43 in the recovery control for starting up the developing device 1a as shown in FIG. As the stirring time becomes longer, the amount of developer stirring in the developing device increases, and the toner charge amount also increases. The developer is stirred by rotating the developing sleeve 41 or the stirring screws 42 and 43.

  By increasing the agitation time, the decrease in the charge amount per the number of friction of the toner is compensated for by the number of friction so that the toner having an old production time can be handled as a toner just before the production. As a result, the amount of toner charged to the opposite polarity that causes image defects called fogging is reduced, and the amount of toner that is insufficiently charged that scatters as the developing sleeve 41 rotates is also reduced.

  As shown in FIG. 4, in the image forming apparatus 100, toner cartridges 11a, 11b, 11c, and 11d are detachably attached to the image forming units Pa, Pb, Pc, and Pd, respectively. Wireless IC tags 30a, 30b, 30c, and 30d, which are examples of storage units, are affixed to the outer wall surfaces on the back side of the toner cartridges 11a, 11b, 11c, and 11d, respectively.

  The communication unit 50, which is an example of a reading unit, is connected to the wireless IC tags 30a, 30b, 30c, and 30d via an antenna (not shown) disposed on the image forming apparatus 100 side. Read and write.

  The wireless IC tags 30a, 30b, 30c, and 30d record information related to the toner cartridges 11a, 11b, 11c, and 11d, the date of manufacture of the toner, and the elapsed time from the date of manufacture of the replenishment developer at the manufacturing factory. ing.

  This storage means stores information on the date of manufacture of the toner or the date of manufacture of the developer supply container (toner cartridge) filled with the toner. Such information is information related to the elapsed time from the date of manufacture of the replenishment developer to the date and time until actual use. Usually, in the manufacturing stage, the process from the production of the toner to the filling of the container is managed. Therefore, the information related to the toner cartridge manufacturing date is also related to the elapsed time from the toner manufacturing date.

  After starting use of the toner cartridges 11a, 11b, 11c, and 11d, the communication unit 50 updates the estimated supply amount of each color toner and the estimated remaining amount of each color toner recorded in the wireless IC tags 30a, 30b, 30c, and 30d as needed. Record.

  The control unit 51 includes hardware having a calculation function and software defining the calculation operation, and controls the image forming units Pa, Pb, Pc, and Pd to execute toner image formation / transfer.

  The control unit 51 controls the developing motors Ma, Mb, Mc, and Md to start up the developing devices 1a, 1b, 1c, and 1d, and receives information from the communication unit 50, the time management unit 52, and the storage unit 53. Process.

  The time management unit 52 has a calendar function and outputs the current date and time.

  The storage unit 53 is configured by a semiconductor memory, a hard disk, or the like, and stores various data and programs.

  As shown in FIG. 5 with reference to FIG. 4, the date of manufacture of the toner is read from the wireless IC tag 30a attached to the toner cartridge 11a. FIG. 5 is a flowchart illustrating a process of using the toner cartridges 11a, 11b, 11c, and 11d and the wireless IC tags 30a, 30b, 30c, and 30d.

  At the stage where the toner cartridge 11a is manufactured, the wireless IC tag 30a stores information related to the manufacturing date and other manufacturing lots (S11). Thereafter, the toner cartridge 11a is hermetically sealed and shipped as a product (S12).

  When using the new toner cartridge 11a, the user of the image forming apparatus 100 or the maintenance manager of the image forming apparatus 100 opens the toner cartridge 11a and attaches it to the developing device 1a of the image forming unit Pa (see FIG. S13).

  At this time, if the main body power supply of the image forming apparatus 100 is ON (YES in S14), the communication unit 50 receives the toner from the wireless IC tag 30a as a trigger when the replacement door of the toner cartridge 11a is closed (S16). The date of manufacture is read (S17). The replacement door is always opened and closed when the toner cartridge 11a is replaced.

  When the main body power supply is OFF (NO in S14), the communication unit 50 reads the date of manufacture of toner from the wireless IC tag 30a (S17) using the start-up after the main body power supply is turned on as a trigger (S15). When the main body power is turned on, the communication unit 50 reads the date of manufacture of the toner from the wireless IC tag 30a regardless of whether or not a new toner cartridge 30a is mounted before that (S17).

<Setting of stirring time in developing device>
As shown in FIG. 4, when the power is turned on, the control unit 51 causes the developing devices 1a, 1b, 1c, and 1d to perform recovery control corresponding to the age of the toner cartridges 11a, 11b, 11c, and 11d.

  The control unit 51 sets different rotation times of the developing motors Ma, Mb, Mc, and Md for the developing devices 1a, 1b, 1c, and 1d according to the elapsed days of the toner cartridges 11a, 11b, 11c, and 11d, respectively. .

  As a result, when the recovery control is finished and image formation is started, the difference in the charge amount of the toner carried on each developing sleeve 41 is small in the developing devices 1a, 1b, 1c, and 1d. For example, even when only the toner cartridge 11a is extremely old, by adding only the stirring time of the developing device 1a, the fogged image and the toner scattering amount in the image forming unit Pa are suppressed to the same level as the developing devices 11b, 11c, and 11d. The

  As shown in FIG. 6 with reference to FIG. 4, when the power is turned on (S21), the temperature of the fixing device (9: FIG. 1) is detected (S22).

  When the temperature of the fixing device (9: FIG. 1) is less than 100 degrees C (YES in S23), the idling time t1 is set according to the number of days elapsed from the date of manufacture of the toner cartridge 11a (S24), and recovery control is performed. Perform (S25).

  Since the temperature adjustment temperature of the fixing device (9: FIG. 1) at the time of image formation is 180 ° C., when the temperature is less than 100 ° C. (YES in S23), the toner charge amount decreases due to being left for several hours or more. Therefore, recovery control is performed (S25).

  However, when the temperature is 100 ° C. or higher (NO in S23), it is estimated that the time has not passed so much since the previous power-off and the charge amount of the toner has not decreased, so the recovery control is not performed. This is because unnecessary agitation of the developer causes a new problem such as advancing deterioration of the developer or an excessive increase in the charge amount of the toner to lower the image density.

  In the control of FIG. 6, the temperature of the fixing device (9: FIG. 1) is detected to estimate the stop time of image formation. However, the duration time of the power OFF state is directly determined based on the output of the time management unit 52. It may be determined whether or not recovery control is necessary.

  As shown in FIG. 7, in the recovery control, only the developing motor Ma is first driven for the idling time t1. Subsequently, the photosensitive drum 3a and the recording material conveying belt 21 shown in FIG. 2 are started and driven together with the developing motor Ma for the rear idling time t2, and formed on the photosensitive drum (3a: FIG. 2) through the idling time t1. Eliminate electrostatic images.

  At the post-idling time t2, the rotation of the photosensitive drum 3a is performed with the same voltage as that of normal charging applied to the charging device 2a shown in FIG. 2 and the same voltage as that of normal development applied to the developing sleeve 41 of the developing device 1a. And the development motor Ma are driven.

  The developing means (1a) has a developer carrier (41) that carries a developer on a cylindrical surface and rotates to supply the developer to the image carrier (3a).

  The control means (51) stirs the developer over the stirring time (t1) while rotating the developer carrier (41) with the image carrier (3a) stopped.

  Following the stirring time (t1), the control means (51) rotates the image carrier (3a) over a plurality of rotations (t2) while rotating the image carrier (3a) to a uniform potential (-) having the same polarity as the toner charging polarity (-) -) Is charged.

  The control means (51) maintains the direct current component of the potential of the developer carrier (41) at a potential having an absolute value lower than the charging potential of the image carrier (3a) through a plurality of rotations (t2).

<Change over time of developer for replenishment>
FIG. 8 is an explanatory diagram of a change in charging performance according to the number of days elapsed after the manufacture of the toner, and FIG.

  As shown in FIG. 2, in the developing device 1a, the magnetic carrier and the toner are mixed at a predetermined mixing ratio so that the non-magnetic toner (toner) in the developer becomes a weight ratio T / D = 7%. Two-component developer is filled. The developing device 1a is filled with a developer after outputting 50000 original images with an image ratio of 5%.

The magnetic carrier has a saturation magnetization of 24 Am ² / kg for an applied magnetic field of 240 kA / m, a resistivity of 1 × 10 ⁷ to 1 × 10 ⁸ Ω · cm at a field strength of 3000 V / cm, and a ferrite magnetism having a weight average particle size of 50 μm. A carrier was used. The particle size was measured with a laser diffraction particle size distribution measuring device HEROS (manufactured by JEOL Ltd.) in the range of 0.5 to 350 μm divided into 32 logarithms and defined as a median diameter of 50% by weight.

  The method for producing the magnetic carrier is not particularly limited, and a resin magnetic carrier produced by a polymerization method using a binder resin, a magnetic metal oxide, and a nonmagnetic metal oxide as starting materials may be used.

  As the toner, a negatively chargeable polyester resin toner having a weight average particle diameter of 7.2 μm in which hydrophobic colloidal silica is externally added to colored resin particles was used. As the toner, a styrene acrylic resin toner may be used.

  As shown in FIG. 8, as the number of days elapsed from the date of manufacture increases, the charging performance of the toner deteriorates. It cannot be secured.

  FIG. 8 shows the results of measuring the charge amount of toner of the same specification with different elapsed days after manufacture, with the environment and charging conditions (magnetic carrier, external additive, agitation time, etc.) aligned in the developing device 1a. is there.

  The amount of charge is reduced to about half with toner whose elapsed days have passed 3,000 days compared to toner whose elapsed days after manufacture are almost 0 days. Specifically, the charge amount measured for the toner immediately after manufacture was about −25 μC / g, whereas the toner whose elapsed days passed 3000 days was about −10 μC / g.

  The specific mechanism by which the charging performance of the toner decreases with the number of days elapsed after manufacture, in other words, the charging mechanism becomes difficult due to friction with the magnetic carrier, is not well understood.

  However, possible causes include deterioration of charging performance due to oxidation of the external additive and the toner itself, or oil components inside the toner are deposited on the toner surface, and the surface of the external additive is coated to cause frictional charging. To prevent. In addition, the external additive attached to the toner is peeled off, and the chance of friction with the magnetic carrier in a state where the external additive is held on the toner side in the developing device 1a is reduced.

  When the toner developing device 1a having such a large number of elapsed days after manufacture is replenished, the toner cannot be sufficiently frictionally charged with the carrier, and toner with a low charge amount increases. Immediately after the start of image formation, a large amount of low-charge toner or toner charged to the opposite polarity adheres to the white image portion of the photosensitive drum 3a, causing an image defect called white background fog.

  As shown in FIG. 2, the toner scraped by the cleaning device 4a without being transferred at the transfer portion Ta increases, and the waste toner increases. The amount of toner scattered by the rotation of the developing sleeve 41 increases and the toner scattering deteriorates.

  Therefore, in the recovery control, the developer agitation time at the start-up of the developing device (1a: FIG. 2) is set according to the number of days elapsed after manufacture. Specifically, a stirring time of 30 seconds (t1: FIG. 7) is set for new toner that has passed 20 days after manufacture, and a stirring time of 120 seconds is set for old toner 3000 days after manufacture. is doing.

  By the way, the charging performance of the toner varies depending not only on the leaving time in units of months and years but also on the leaving time in units of hours and days.

  FIG. 9 shows the toner charge amount distribution in the developing device 1a when the developing device 1a is started up with a stirring time of 30 seconds (t1: FIG. 7) after changing the standing time after the image forming apparatus 100 is stopped. Is shown.

  The charge amount distribution is measured by using an E-spart analyzer (registered trademark) manufactured by Hosokawa Micron Corporation. The toner taken out from the developing device 1a is blown off with nitrogen gas, and the measurement portion (measurement cell) of the measuring device is passed through the sampling hole. It was done by introducing.

  Measurements a to c in the figure were carried out using toner having elapsed days of 20 days after production until 3000 toner particles were counted. The measurement of d in the figure was performed in the same manner using a toner having elapsed days of 3000 days after production.

  As shown in FIG. 9, as the stirring stop time (leaving time) of the developing device 1a increases in the order of b after being left for 16 hours and c after being left for 60 hours with respect to a immediately after image formation, The amount of charge decreases. As a result of an increase in the amount of toner having a small charge amount that cannot be electrostatically restrained by the developing sleeve 41 and a toner having a reversed charge polarity, the amount of toner scattered from the developing sleeve 41 increases.

  In the case of a time-degraded toner that has passed 3000 days after production, the charge amount decreases greatly even if the leaving time is the same, and after being left for 60 hours, which is equal to c, the charge amount distribution is as shown in d. . As a result of a marked increase in the amount of toner with a small charge amount and a toner whose charge polarity is reversed, the amount of toner scattered from the developing sleeve 41 increases significantly.

  In addition, this is measurement data at a temperature of 23 ° C. and a relative humidity of 50%. However, when the temperature is high and the humidity is high, the change in charge amount according to the standing time is further increased.

  Accordingly, when the temperature of the fixing device 9 that cannot be regarded as immediately after image formation is 100 degrees or less, recovery control is performed to restore the toner charge amount distribution in the developing device 1a even immediately after the start of image formation.

<Example 1>
FIG. 10 is an explanatory diagram of the relationship between the stirring time and the toner charge amount distribution in the new toner.

  FIG. 10 shows the result of measuring the toner charge amount distribution in the developing device after the recovery control by changing the stirring time (t1) shown in FIG. 7 in four stages. The method for measuring the toner charge amount distribution is the same as in the experiment of FIG.

  As shown in FIG. 2, the development motor Ma is driven for a predetermined time t1 with a new toner having passed 20 days after manufacture, with a stop of 60 hours, and the agitating screws 42 and 43, the developing sleeve 41, and the like. Stirring of the developer was performed.

  As shown in FIG. 10, in the case of a new toner having passed 20 days after manufacture, the charge amount distribution is negative in the order of a stirring time of 10 seconds, b of 30 seconds, c of 30 seconds, and d of 40 seconds. It moves to the sex side and the variation is also reduced. There is almost no difference in the charge amount distribution between c of 30 seconds and d of 40 seconds.

  As shown in FIG. 10, when there is a large amount of toner charged to the opposite polarity, a large amount of toner is insufficiently charged. As described above, the toner charged to the opposite polarity adheres to the white image portion to generate a fogged image, and the toner with insufficient charge amount causes toner scattering because the electrostatic binding force is weak.

  Accordingly, the number of positive toners charged to the opposite polarity among the 3000 toner particles measured by the above-described method was evaluated as parameters for fog image and toner scattering. Table 1 shows the measurement results of the average toner charge amount and the number of positive toners.

  In the case of the image forming apparatus 100 shown in FIG. 1, it has been confirmed that the fog is deteriorated when the number of positive toners is 20/3000 or more.

  Therefore, as shown in Table 1, when new toner that has passed 20 days after manufacture is used, 30 seconds may be secured as the idling time t1 of the recovery control shown in FIG.

  As shown in FIG. 2, it was found that if the developing motor Ma is driven for 30 seconds, the positive toner and the toner with insufficient charge amount are eliminated, and the fogged image and the toner scattering do not occur.

  Here, even if the idling time t1 is longer than 30 seconds, fog images and toner scattering can be prevented. However, if the idling time t1 is increased more than necessary, the deterioration of the developer is promoted.

  For this reason, it is necessary to set the shortest time during which fog images and scattering can be prevented. When a new toner is introduced, the idling time t1 is set to 30 seconds.

<Example 2>
As shown in FIG. 3, the developing device 1 a has a configuration in which only the stirring screws 42 and 43 are driven by removing the gear 48 connecting the stirring screw 42 and the developing sleeve 41. Then, an experiment was conducted in which the idling time t1 of the recovery control was set to 10 seconds, 30 seconds, 60 seconds, and 90 seconds with the same conditions as in Example 1.

  The developer was collected from around the stirring screw 42 immediately after the recovery control, and the average toner charge amount and the number of positive toners were measured. The measurement results are shown in Table 2.

  As shown in Table 2, the average toner charge amount and the number of positive toners for the same idling time t1 are worse than those in Table 1.

  From the comparison between Examples 1 and 2, when the developing sleeve 41 is not driven and only the stirring screws 42 and 43 are driven, the idling time is about three times as long as the same effect as when the developing sleeve 41 is driven. It was found that t1 was required. By simultaneously driving the developing sleeve 41, the effect of imparting a charge amount by frictional charging to the toner is enhanced, the downtime of the image forming apparatus 100 accompanying the recovery control can be reduced, and the stirring deterioration of the developer can be suppressed.

<Example 3>
As shown in FIG. 7 with reference to FIG. 2, in the recovery control, the developer is stirred by the stirring screws 42 and 43 and the developing sleeve 41 for the idling time t1, and then the photosensitive drum 3a facing the developing sleeve 41 is moved back. Rotate only for idling time t2.

  At this time, a fog removal potential (Vback) is secured between the dark portion potential VD of the photosensitive drum 3a not exposed and the DC voltage Vdev applied to the developing sleeve 41. For example, when using negative toner charged to negative polarity, if the DC voltage (Vdev) is set to a positive potential from the dark portion potential (VD) of the white image portion, the negative toner does not adhere to the white image portion of the photosensitive drum 3a as fog toner. .

  The dark portion potential (VD) and the DC voltage (Vdev) in the recovery control are set for each of the image forming portions Pa, Pb, Pc, and Pd by the control unit 51.

  When the fog removal potential (Vback) is small, the force to attract the toner to the developing sleeve 41 becomes weak, and the fog toner easily adheres to the white image portion of the photosensitive drum 3a.

  When the fog removal potential (Vback) is large, the toner is charged to a negative polarity, so that the Coulomb force acting on the magnetic carrier charged to a positive polarity is increased, and the magnetic carrier is likely to adhere to the white image portion of the photosensitive drum 3a. Become.

  The fog removal potential is set to an appropriate value based on the magnetic flux density of the portion where the developing sleeve 41 faces the photosensitive drum 3a and the charging characteristics of the toner and the carrier, but 150 V is appropriate in the image forming apparatus 100. .

  The post idling time t2 in the recovery control was determined as follows.

  When the developing sleeve 41 is driven in a state where the driving of the photosensitive drum 3a is stopped, only the portion of the photosensitive drum 3a facing the developing sleeve 41 comes into contact with the developer carried on the developing sleeve 41, and the potential due to frictional charging. Will remain. For this reason, when an image having a uniform latent image potential such as a halftone image is output thereafter, an image defect such as a drum memory having a different image density only in a frictionally charged portion occurs.

  In Example 3, the photosensitive drum 3a was rotated with the charging device 2a applying a normal charging bias voltage in which a DC voltage and an AC voltage were superimposed, and the number of rotations at which the surface potential of the photosensitive drum 3a became uniform was obtained. . It was found that when the photosensitive drum 3a is rotated more than 10 times, the surface potential of the photosensitive drum 3a becomes uniform, and the drum potential at the portion facing the developing sleeve 41 is eliminated.

  When a charging bias is applied, the AC voltage tends to focus the surface potential of the photosensitive drum 3a, which is effective in eliminating the surface potential due to frictional charging. In Example 3, the outer diameter of the photosensitive drum 3a is Φ30 mm, and the peripheral speed of the photosensitive drum 3a is 130 mm / sec. Therefore, it is sufficient to secure 7.3 seconds or more in the rear idling time t2 by 10 rotations.

  Based on the experimental results of Examples 1, 2, and 3, recovery control was determined as follows for a new toner having a small number of days after manufacture.

  First, only the developing motor Ma is driven for 30 seconds to rotate the developing sleeve 41, and then the photosensitive drum 3a and the developing motor Ma are driven for 10 seconds while applying a fog removal potential. When the recovery control ends, the image forming apparatus 100 enters a standby state in which image output is possible.

  Conventionally, the image forming apparatus 100 is the first image output in the morning when left for 16 hours in a stopped state using new toner on the 20th day after manufacture. When there is no recovery control, the fog image density is 1 when the entire white background image is output. It was 6%.

  On the other hand, when such recovery control was performed, the density of the fogged image was improved to 0.7%. The density of the fog image is the difference between the reflectance of the blank paper before the image formation and the reflectance of the entire white background image on which the image is formed. The reflectance was measured using DENITOMETER TC-6MC-D manufactured by Tokyo Denshoku.

<Example 4>
FIG. 11 is an explanatory diagram of the relationship between the stirring time and the toner charge amount distribution in the old toner.

  FIG. 11 shows the result of measuring the toner charge amount distribution in the same manner as in Example 1, using the same conditions as those in Example 1 and using old toner that has passed 3000 days after manufacture. .

  As shown in FIG. 11, in the case of an old toner that has passed 3000 days after manufacture, the charge amount is critically insufficient at the idling time t1 of 30 seconds when the stirring time is applied to a new toner. With the stirring time of 90 to 120 seconds, finally, the charge amount distribution obtained by stirring the new toner for 30 seconds is close.

  Table 3 shows the measurement results of the average toner charge amount when the stirring time is b: 60 seconds, c: 90 seconds, and d: 120 seconds, and the number of positive toners charged to the opposite polarity in 3000 toner particles.

  As shown in Table 3, if the developing motor (Ma: FIG. 2) is driven for 90 seconds or more, even if the toner is 3000 days old after manufacture, the new toner 20 days after manufacture is positively charged to the level of stirring for 30 seconds. It was found that fog images and toner scattering can be prevented.

  Based on the result of Example 4, in the case of old toner that has passed 3000 days after manufacture, the idling time t1 in the recovery control after replacement of the toner cartridge (11a: FIG. 2) was set to 90 seconds. First, only the developing motor Ma is driven for 90 seconds, and then, while applying the anti-fogging potential, the photosensitive drum 3a and the developing motor Ma are driven for 10 seconds, and a standby state in which image output is possible comes.

  As shown in FIG. 2, when the toner cartridge 11a on the 20th day after manufacture is replaced with the toner cartridge 11a on the 3000th day after manufacture, the toner remaining in the developing device 1a is new toner on the 20th day after the manufacture. .

  Therefore, in the first recovery control after replacement, a sufficient charge amount can be secured even if the idling time t1 is set to 30 seconds. However, the developer deterioration due to unnecessary idling is only “90 seconds−30 seconds = 60 seconds” immediately after the replacement of the toner cartridge 11a, and therefore the idling time t1 is set to 90 seconds for control.

  Conventionally, the image forming apparatus 100 is the first image output in the morning when it is left for 16 hours in a stopped state using 3000-year-old toner after manufacture. When there is no recovery control, the fog image density is 2 when an entire white background image is output. It was 6%.

  On the other hand, when such recovery control was performed, the density of the fogged image was improved to 0.7%. The toner scattering in the image forming apparatus 100 was kept small, and an increase in waste toner could be prevented.

<Example 5>
FIG. 12 is an explanatory diagram of the time coefficient of toner, and FIG. 13 is an explanatory diagram of the relationship between the number of days elapsed after the toner production and the idling time required for recovery control.

  In the fifth embodiment, an appropriate idling time t1 in the toner cartridge 11a between the 20th and 3000th days after the manufacture is set.

  As shown in FIG. 12 with reference to FIG. 4, the control unit 51 reads the date of manufacture of the toner cartridge 11a from the wireless IC tag 30a attached to the toner cartridge 11a, and determines the toner from the difference from the current date and time. Calculate the number of days that have elapsed since the manufacture of the product.

  The control unit 51 controls the developing device 1a so that the developer agitation amount increases when the elapsed time after the toner production exceeds a specified time (500 days).

The control unit 51 refers to the table prepared in the storage unit 53 in terms of the number of elapsed days, and sets a time coefficient k corresponding to the number of elapsed days. As shown in the following equation, the time constant changes to k = 0 in the case of a new toner, and changes to a maximum k = 1 as the elapsed days progress.
k = 0 (0 ≦ t <500)
k = 0.004 × (t−500) (500 ≦ t <3000)
k = 1 (t ≧ 3000)

In the fifth exemplary embodiment, the idling time t1 of the elapsed toner days t is calculated by the following equation.
t1 = t1 (t = 0) + k × α
t1 (t = 0): idling time when new toner is used α: idling time offset value

  In Example 5, t1 (t = 0) = 30 seconds and α = 60 seconds.

  Thus, the idling time t1 is set as shown in FIG. 13 with respect to the number of days that have passed since the toner cartridge 11a was manufactured. For example, when t = 1500 days, the idling time t1 is 54 seconds, and when t = 3000 days or more, the idling time t1 is 90 seconds.

  By performing the recovery control as described above, it is possible to set an appropriate idling time t1 corresponding to the aging deterioration even when the old aging toner whose number of days elapsed from the manufacturing date is several years is used. As a result, even with the toner deteriorated with time, the fogged image and the toner scattering can be suppressed to reduce the image defect and the main body toner contamination.

Second Embodiment
FIG. 14 is an explanatory diagram of a configuration of the image forming apparatus according to the second embodiment. In FIG. 14, configurations common to the configuration of the first embodiment exclude a, b, d, and d that indicate the distinction between the image forming portions Pa, Pb, Pc, and Pd from the reference numbers assigned to the configuration of FIG. 1. The same reference numerals are attached and redundant explanations are omitted.

  As shown in FIG. 1, the image forming apparatus 100 according to the first embodiment includes a tandem type in which yellow, magenta, cyan, and black image forming portions Pa, Pb, Pc, and Pd are arranged along a recording material conveyance belt 21. This is an image forming apparatus.

  On the other hand, as shown in FIG. 14, the image forming apparatus 200 of the second embodiment is provided with yellow, magenta, cyan, and black developing means on one image carrier, and collects toner images of a plurality of colors at once. 1-drum type image forming apparatus.

  Note that a monochrome image forming apparatus that directly transfers a monochrome toner image to a recording material may be used.

<Third Embodiment>
FIG. 15 is an explanatory diagram of a configuration of the image forming apparatus according to the third embodiment. In FIG. 15, the same reference numerals as those in the configuration of FIG.

  As shown in FIG. 1, the image forming apparatus 100 according to the first embodiment directly transfers yellow, magenta, cyan, and black image forming portions Pa, Pb, Pc, and Pd along a recording material conveyance belt 21. This is an image forming apparatus of the type.

  In contrast, as shown in FIG. 15, the image forming apparatus 300 according to the third embodiment includes yellow, magenta, cyan, and black image forming portions Pa, Pb, Pc, and Pd along the intermediate transfer belt 21C. An intermediate transfer type image forming apparatus is disposed.

  The intermediate transfer belt 21C may be an intermediate transfer drum.

It is explanatory drawing of a structure of the image forming apparatus of 1st Embodiment. It is explanatory drawing of a structure of an image formation part. It is explanatory drawing of a structure of a developing device. 2 is a block diagram of a control system of the image forming apparatus. FIG. It is a flowchart of the information reading of a wireless IC tag. It is a flowchart of starting control of a developing device. It is a time chart of recovery control. FIG. 6 is an explanatory diagram of a change in charging performance according to the number of days that have elapsed since the toner was manufactured. It is explanatory drawing of the change of the charging performance according to the leaving time after stirring stop. FIG. 10 is an explanatory diagram of a relationship between a stirring time and a toner charge amount distribution in new toner. FIG. 6 is an explanatory diagram of a relationship between agitation time and toner charge amount distribution in old toner. FIG. 7 is an explanatory diagram of a time coefficient of toner. FIG. 10 is an explanatory diagram of a relationship between the number of days elapsed after the toner production and the idling time required for recovery control. It is explanatory drawing of a structure of the image forming apparatus of 2nd Embodiment. It is explanatory drawing of a structure of the image forming apparatus of 3rd Embodiment.

Explanation of symbols

1a, 1b, 1c, 1d Developing means (developing device)
2a, 2b, 2c, 2d Electrostatic image forming means (charging device)
3a, 3b, 3c, 3d Image carrier (photosensitive drum)
6a, 6b, 6c, 6d Electrostatic image forming means (exposure device)
11a, 11b, 11c, 11d Developer supply container (toner cartridge)
21 Recording material conveying belts 30a, 30b, 30c, 30d Storage means (wireless IC tag)
41 Developer carrier (developing sleeve)
42, 43 Stirring means (stirring screw)
50 Reading means (communication part)
51 Control means (control unit)
52 Time management unit 100, 200, 300 Image forming apparatus T Replenishment developer (toner)

Claims (6)

An image carrier;
Electrostatic image forming means for forming an electrostatic image on the image carrier;
An image forming apparatus comprising: a developer that is stirred and charged to the image carrier to develop the electrostatic image;
Reading means for reading information relating to the elapsed time from the date of manufacture of the replenishment developer from the storage means attached to the developer replenishment container for replenishing the developer for replenishment;
An image forming apparatus comprising: a control unit that controls the developing unit so that the amount of developer agitation increases as the elapsed time becomes longer based on the read information.   2. The image forming apparatus according to claim 1, wherein the control unit sets a developer agitation time when the developing unit is started up before starting image formation based on the read information.   The image forming apparatus according to claim 2, wherein the control unit sets the stirring time shorter when the elapsed time after the stirring of developer is stopped is shorter than when the time is long. The developing means has a developer carrier that carries a developer on a cylindrical surface and rotates to supply the developer to the image carrier,
4. The image forming apparatus according to claim 3, wherein the control unit rotates the developer carrier while the image carrier is stopped throughout the stirring time.   The control means, following the stirring time, charges the image carrier to a uniform potential having the same polarity as the charging polarity of the toner while rotating the image carrier for a plurality of rotations, and the developer carrying is carried through the plurality of rotations. 5. The image forming apparatus according to claim 4, wherein the direct current component of the body potential is maintained at a potential whose absolute value is lower than the charging potential of the image carrier.   The image forming apparatus according to claim 1, wherein the developer supply container is attached and detached at least integrally with the developing unit.

Images