JP2015031827A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can effectively suppress the occurrence of a reduction in image quality due to supply fogging, even when a replaced toner storage container contains a toner having been left unused for a long time from the manufacture date.SOLUTION: An image forming apparatus includes an image carrier, a developing device, a toner storage container, and control means. The developing device develops an electrostatic latent image formed on the image carrier into a toner image. The toner storage container can be detachably attached to an image forming apparatus body, and accommodates unused toner to be supplied to the developing device. The control means restores the amount of toner in the developing device that has decreased below a reference amount immediately after the replacement of the toner storage container to the reference amount gradually within a predetermined period, and when a first manufacture date, which is the manufacture date of the toner filling the toner storage container after the replacement is prior to a second manufacture date, which is the manufacture date of the toner filling the toner storage container before the replacement, extends the restoration time to reach the reference amount as the difference in the number of days is larger between the first manufacture date and the second manufacture date.

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer using an electrophotographic process, and more particularly to an image forming apparatus including a detachable toner storage container for supplying toner to a developing device.

  In an image forming apparatus using an electrophotographic system such as a copying machine, a printer, or a facsimile, a powder developer is mainly used, and an electrostatic latent image formed on an image carrier such as a photosensitive drum is stored in the developing apparatus. In general, the toner image is visualized by the toner, and the toner image is transferred onto a recording medium directly or via an intermediate transfer member, and then a fixing process is performed. Developers are roughly classified into two-component developers composed of toner and carrier, and one-component developers composed of only magnetic toner components (hereinafter also simply referred to as toner).

  In order to reduce the size of the developing device, there is a system in which toner is supplied from the outside of the developing device according to the remaining amount of toner in the developing device using a replaceable toner container such as a toner container or a toner cartridge. Proposed. For example, a toner remaining amount sensor for detecting the amount of toner is attached to a magnetic one-component developing type developing device.

  FIG. 11 is a flowchart showing a toner replenishment procedure and a toner container replacement procedure in a conventional image forming apparatus equipped with a magnetic one-component developing type developing device. As shown in FIG. 11, when the output value of the toner remaining amount sensor falls below the first threshold L1 (YES in step S1), toner is supplied from the toner container (step S3). If the toner in the toner container runs out, replenishment is not performed and the sensor output value decreases.

  When the output value of the sensor continuously falls below the second threshold value L2 lower than the first threshold value L1 for a predetermined time t1 (YES in step S6), the control unit causes the toner in the toner container to be almost empty. And a display indicating that the toner is low (low display) is performed (step S8). At this time, the amount of toner in the developing device is smaller than usual. Thereafter, when the sensor output is accumulated and output for a certain printing rate M in a state where the sensor output is lower than the second threshold value L2, a display prompting replacement of the toner container (Replace display) is performed, and the printing operation is stopped ( Step S11).

  Thereafter, when the toner container is replaced with a new toner container, as shown in FIG. 12, toner replenishment is started, and the toner amount in the developing device has increased by a certain amount (exceeding the third threshold L3) (in step S4). YES) Replace display disappears and printing operation is allowed. However, when the toner production date in the replaced toner container is old, there is a problem that replenishment fog occurs.

  Therefore, in Patent Document 1, when using a toner whose production date is old, the developer agitation time when starting up the developing device is lengthened, thereby reducing the image quality caused by the fog toner or the scattered toner. A method for suppressing toner contamination has been proposed. Japanese Patent Application Laid-Open No. 2004-228561 proposes that the peak-to-peak value of the AC component of the developing bias is lowered when using toner whose production date is old.

JP 2009-116248 A JP 2009-265220 A

  However, the method of Patent Document 1 cannot obtain the effect of sufficiently suppressing the replenishment fog. The reason for this is that the charge amount of the replenished toner that has passed for a long time from the date of manufacture is not merely low, resulting in insufficient charging, but frictional charging between the toner already in the developing device and the replenished toner. This is because a part of newly supplied toner causes charging abnormality.

  In the case of the one-component developing method, the toner in the developing device is charged, for example, to the plus side by friction with the developing sleeve when passing through the regulating blade. Here, as the toner existing in the developing device continues to be used, the detachment and embedding of the external additive gradually proceeds, and the surface of the toner core (mother particles) is exposed and becomes easily charged. Go. On the other hand, the toner in the toner container becomes difficult to be charged with time from the date of manufacture due to exudation of wax, absorption of moisture, and the like.

  When toners having different frictional charging characteristics are mixed and stirred as described above, a part of the toner newly supplied from the toner container is charged to the negative side (reverse charging) due to frictional charging between the two. Although this reverse charging phenomenon is alleviated by passing through the regulating blade, it is considered that there are a large number of toners in the developing device that remain negative or have a low charge amount even when positive. . That is, when a large amount of toner that is difficult to be charged in a toner container is replenished in a short period of time to toner that is easily charged in the developing device, frictional charging occurs between these new and old toners, and toner with a reverse polarity or a low charge amount is generated. Many occur and replenishment fog occurs.

  In such a state, as proposed in Patent Document 1, even if the developer agitation time (aging time) is slightly increased, the charging abnormality due to frictional charging between the toners cannot be completely eliminated. In order to obtain the effect, a long aging time of several tens of minutes was required. Further, for the same reason as described above, the effect of sufficiently suppressing the replenishment fog is obtained even if the toner whose production date is older as in Patent Document 2, even if the peak-to-peak value of the AC component of the developing bias is lowered. There wasn't.

  In addition, in order to prevent a large amount of toner from being supplied in a short time immediately after the container replacement, the toner supply level (first threshold L1 or third threshold L3) immediately after the container replacement is lowered and constant from the replacement. A method of gradually returning the toner replenishment level to each original print number is conceivable. According to this method, the amount of toner in the developing device that has been reduced before replacement of the toner container can be slowly returned to the target toner amount over time, so that a large amount of toner can be replenished in a short period of time. Disappears. However, the period in which the amount of toner in the developing device is smaller than usual becomes longer, and triboelectric charging due to dropping or embedding of the toner external additive is promoted. As a result, when a toner that has passed for a long time from the date of manufacture is used at the next replacement of the toner container, replenishment fog is more likely to occur.

  Here, in the one-component development method, the occurrence of replenishment fog when the toner production time in the replaced toner container is old has been described, but two-component development using a two-component developer containing toner and magnetic carrier Also in this method, when the production time of the toner to be replenished is old, the charging characteristics of the toner are slightly lowered, so that there are problems similar to those in the one-component development method.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention provides an image forming apparatus capable of effectively suppressing the occurrence of image quality degradation due to replenishment fog even when the toner production time in the replaced toner container is old. For the purpose.

  In order to achieve the above object, a first configuration of the present invention is an image forming apparatus including an image carrier, a developing device, a toner storage container, and a control unit. An electrostatic latent image is formed on the image carrier. The developing device develops the electrostatic latent image formed on the image carrier into a toner image. The toner container is detachable from the main body of the image forming apparatus, and stores unused toner for replenishing the developing device. The control means controls toner supply from the toner container to the developing device. The control means returns the toner amount in the developing device, which has decreased from the reference amount immediately after the replacement of the toner storage container, to the reference amount step by step within a predetermined period, and also controls the amount of toner filled in the replaced toner storage container. When the first manufacturing date, which is the manufacturing date, is before the second manufacturing date, which is the manufacturing date of the toner filled in the toner container before replacement, the first manufacturing date and the second manufacturing date. The return time to the reference amount is lengthened as the difference in days from the day is larger.

  According to the first configuration of the present invention, the first manufacturing date, which is the date of manufacture of the toner in the toner container after replacement, is the second date of manufacture of the toner in the toner container before replacement. When it is before the day, the period in which the amount of toner in the developing device is small can be lengthened as the difference between the first manufacturing date and the second manufacturing date is larger. Therefore, when replenishing toner with good chargeability, which has not passed much time since the date of manufacture, to a toner with an old production date and low chargeability, the amount of toner in the developing device is slowly stabilized over a long period of time. Since the transition amount (reference amount) is returned, the occurrence of replenishment fogging and toner scattering due to toner charging failure can be effectively suppressed. On the other hand, when replenishing a toner having an old production date and low chargeability with a toner having good chargeability that has not passed much time since the production date, or on the production date of the toner in the developing device and the toner in the toner container If there is not much difference, the toner amount in the developing device is returned to the stable transition amount in a relatively short time, so that it is possible to reliably suppress problems such as a decrease in density due to a decrease in the toner amount in the developing device. .

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus 100 according to an embodiment of the present invention. Schematic diagram showing the configuration of the photosensitive drum 1, the developing device 4, the toner container 5, and the cleaning device 7 in the image forming apparatus 100 of the present embodiment. Graph showing output waveform of remaining toner sensor 29 A graph showing a relationship between an output value of the toner remaining amount sensor 29 and a toner remaining amount in the developing device 4 A block diagram for explaining a control path of the image forming apparatus 100 of the present embodiment A flowchart showing a toner replenishment procedure and a replacement procedure of the toner container 5 in the image forming apparatus 100 of the present embodiment. 7 is a flowchart showing a return procedure from replacement of the toner container 5 in the image forming apparatus 100 of the present embodiment. The first threshold L1 immediately after the replacement of the toner container 5 is reduced to 0.7V, and the rate of increase of L1 per predetermined number of printed sheets when the L1 is returned to the reference value according to the accumulated number of printed sheets is set to the first value. Graph changed according to the number of days difference between the production date and the second production date The first threshold value L1 immediately after the replacement of the toner container 5 is set in a stepwise manner according to the difference in the number of days between the first manufacturing date and the second manufacturing date, and L1 is set at a constant rate according to the cumulative number of printed sheets. Graph restored to the reference value L1 immediately after the replacement of the toner container 5 is decreased from the reference value, and when L1 is returned to the reference value according to the accumulated number of printed sheets, the increasing ratio of L1 per predetermined number of printed sheets is the first production date and the second production. The amount of toner in the developing device 4 for each predetermined number of sheets, when changed according to the difference in the number of days (Examples 1 to 5) and when L1 was not decreased at the reference value (Comparative Example), Table showing comparison results of toner increase and fog occurrence A flowchart showing a toner replenishment procedure and a toner container replacement procedure in a conventional image forming apparatus A flowchart showing a return procedure from replacement of a toner container in a conventional image forming apparatus

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 according to an embodiment of the present invention. In the image forming apparatus (for example, a monochrome printer) 100, when performing a printing operation, an electrostatic latent image based on document image data transmitted from a personal computer (PC) (not shown) is displayed in the image forming unit P in the main body of the image forming apparatus 100. An image is formed, and toner is attached to a portion where the potential of the electrostatic latent image is reduced by the developing device 4 to form a toner image. In such an image forming apparatus 100, an image forming process for the photosensitive drum 1 is performed while rotating the photosensitive drum (image carrier) 1 in the clockwise direction in FIG.

  The image forming unit P includes a charging unit 2, an exposure unit 3, a developing device 4, a transfer roller 6, a cleaning device 7, and a charge eliminating device (not shown) along the rotation direction (clockwise direction) of the photosensitive drum 1. ) Is arranged. The photosensitive drum 1 is formed, for example, by laminating a photosensitive layer on an aluminum drum, and the charging unit 2 charges the surface. Then, an electrostatic latent image in which the charged charges are attenuated is formed on the surface that has received a laser beam from the exposure unit 3 described later. The photosensitive layer is not particularly limited. For example, amorphous silicon (a-Si) having excellent durability, or an organic photosensitive layer (OPC) that generates high-resolution images with little generation of ozone during charging. Etc.) are preferred.

  The charging unit 2 uniformly charges the surface of the photosensitive drum 1. For example, a corona discharge device that discharges by applying a high voltage using a thin wire or the like as an electrode is used as the charging unit 2. Instead of the corona discharge device, a contact-type charging device that applies a voltage to the charging member in a state where a charging member typified by a charging roller is in contact with the surface of the photoreceptor may be used. The exposure unit 3 irradiates the photosensitive drum 1 with a light beam (for example, a laser beam) based on the image data, and forms an electrostatic latent image on the surface of the photosensitive drum 1.

  The developing device 4 forms toner images by attaching toner to the electrostatic latent image formed on the photosensitive drum 1. The developing device 4 of the present embodiment is a one-component developing system that uses a magnetic one-component developer composed only of a toner component. The toner (one-component developer) is supplied to the developing device 4 from a toner container (toner container) 5. The transfer roller 6 transfers the toner image formed on the surface of the photosensitive drum 1 onto the paper (recording medium) transported through the paper transport path 11 without being disturbed. The cleaning device 7 includes a cleaning roller 16 and a cleaning blade 17 (see FIG. 2) that are in line contact with the longitudinal direction of the photosensitive drum 1 (direction perpendicular to the paper surface of FIG. 1), and the toner image is transferred to the paper. After that, the residual toner on the surface of the photosensitive drum 1 is removed.

  Then, the exposure unit 3 emits a laser beam (light beam) on the photosensitive drum 1 based on image data inputted in advance, thereby forming an electrostatic latent image based on the image data on the surface of the photosensitive drum 1. Thereafter, the developing device 4 attaches toner to the electrostatic latent image to form a toner image.

  A sheet is conveyed from the sheet storage unit 10 through the sheet conveyance path 11 and the registration roller pair 13 at a predetermined timing toward the image forming unit P on which the toner image is formed as described above. The toner image on the surface of the photosensitive drum 1 is transferred onto the sheet by the transfer roller 6. The sheet on which the toner image has been transferred is separated from the photosensitive drum 1, conveyed to the fixing unit 8, and heated and pressurized to fix the toner image on the sheet. The paper that has passed through the fixing unit 8 passes through the discharge roller pair 14 and is discharged to the paper discharge unit 15.

  FIG. 2 is a schematic diagram illustrating the configuration of the photosensitive drum 1, the developing device 4, the toner container 5, and the cleaning device 7 in the image forming apparatus 100 of the present embodiment. The cleaning device 7 includes a cleaning roller 16 and a cleaning blade 17. The cleaning roller 16 is pressed against the photosensitive drum 1 with a predetermined pressure, and is driven to rotate in the same direction as the photosensitive drum 1 on a contact surface with the photosensitive drum 1 by a driving unit (not shown).

  A cleaning blade 17 is fixed in contact with the photosensitive drum 1 on the surface of the photosensitive drum 1 downstream of the contact surface with the cleaning roller 16 in the rotation direction. The material, hardness and dimensions of the cleaning blade 17, the amount of biting into the photosensitive drum 1, the pressure contact force, and the like are appropriately set according to the specifications of the photosensitive drum 1. Waste toner recovered from the photosensitive drum 1 by the cleaning device 7 is stored in a recovery container (not shown).

  An IC chip (IC tag) 27 is mounted on the side surface of the toner container 5. On the image forming apparatus 100 side, a reader / writer module 30 for reading and writing information to and from the IC chip 27 is provided. In the present invention, various information stored in the IC chip 27 by the reader / writer module 30. The wireless automatic identification (Radio Frequency Identification, hereinafter referred to as RFID) for performing reading and rewriting is used to determine individual identification information such as the date of manufacture of toner in the toner container 5 and the remaining amount of toner. Note that when the used toner container 5 is refilled with new toner, the IC chip 27 is overwritten with the production date of the refilled toner.

  In addition, since the toner container 5 is normally filled in a short period after the toner is manufactured, the toner filling date information in the toner container 5 is stored in the IC chip 27 instead of the toner manufacturing date information. May be. Accordingly, “toner production date” in the following description includes both the toner production date and the toner filling date.

  A toner remaining amount sensor 29 is disposed in the developing device 4. As the toner remaining amount sensor 29, a magnetic permeability sensor that detects the magnetic permeability of toner (magnetic one-component developer) in the developing device 4 is used. In this embodiment, the toner remaining amount sensor 29 detects the magnetic permeability of the toner, and a voltage value corresponding to the detection result is output to a control unit 90 (see FIG. 5) described later. 90, the toner remaining amount is determined from the output value of the toner remaining amount sensor 29.

  FIG. 3 is a graph showing an output waveform of the toner remaining amount sensor 29. As shown in FIG. 3, the sensor output value changes according to the remaining amount of toner, and the output value increases as the remaining amount of magnetic toner increases, and the output value decreases as the remaining amount of toner decreases. The control unit 90 transmits a control signal to the toner supply motor 33 (see FIG. 5) according to the determined remaining toner amount, drives the toner supply roller 5a of the toner container 5 for a predetermined time, and places it in the developing device 4. Supply a fixed amount of toner. Thereby, the sensor output value changes in the range of 0.1 with 1.2 as the median value. The sensor output value indicates an average value for 1 second.

  FIG. 4 is a graph showing the relationship between the output value of the remaining toner sensor 29 and the amount of toner in the developing device 4. As shown in FIG. 4, when the sensor output value falls below 1.1 V, which is the first threshold value L <b> 1 (broken line in FIG. 4), toner is supplied from the toner container 5. At this time, the toner amount (thick line in FIG. 4) in the developing device 4 changes at about 180 g. When the toner in the toner container 5 runs out, replenishment is not performed, so that the sensor output value decreases and the toner amount in the developing device 4 gradually decreases. When the sensor output value decreases to 0.9 V, which is the second threshold value L2 (dotted line in FIG. 4), the toner amount in the developing device 4 decreases to about 160 g.

  When the sensor output value is continuously lower than the second threshold value L2 for a certain time (when Low is displayed), or even when the sensor output value is lower than the second threshold value L2, the output is performed for a certain printing rate. The toner container 5 is replaced later (when Replace is displayed). After replacement with a new toner container 5, the toner supply is resumed, and the Replace display disappears when the toner amount in the developing device 4 exceeds the third threshold value L3 (the one-dot chain line in FIG. 4) 1.0 V, and printing is performed. It becomes possible. As a result, the toner amount in the developing device 4 is recovered to about 170 g.

  As the toner remaining amount sensor 29, in addition to the magnetic permeability sensor described above, a piezoelectric sensor that takes out as an electric signal that pressure has been applied to the detection surface, a detection filler that rotates by the pressure of the toner, and a rotation of the detection filler An optical sensor or the like having a detection sensor (photo interrupter) for detecting that the optical path is opened or closed by movement can also be used.

  FIG. 5 is a block diagram for explaining a control path of the image forming apparatus 100 of the present embodiment. Portions common to FIG. 1 are denoted by the same reference numerals and description thereof is omitted. It should be noted that since various control of each part of the apparatus is performed when the image forming apparatus 100 is used, the control path of the entire image forming apparatus 100 becomes complicated. Therefore, here, the portions necessary for detecting the remaining amount of toner in the toner container 5 and controlling the notification of the replacement timing of the toner container 5 will be described mainly. Further, the description of the parts that have already been described is omitted or simplified.

  The control unit 90 includes a central processing unit (CPU) 91 as a central processing unit, a read only memory (ROM) 92 that is a read-only storage unit, a random access memory (RAM) 93 that is a read / write storage unit, A plurality of (two in this case) I / Os that temporarily transmit control signals to and receive input signals from the operation unit 50. F95 is provided at least.

  The ROM 92 stores a control program for the image forming apparatus 100, numerical values necessary for control, and the like that are not changed during use of the image forming apparatus 100. The RAM 93 stores necessary data generated during the control of the image forming apparatus 100, data temporarily required for controlling the image forming apparatus 100, and the like. The ROM 92 is provided with a message storage table that stores a plurality of messages for each state of the toner container 5.

  In the message storage table, various character messages corresponding to the state of the apparatus are stored as data. Here, message data that prompts the user to perform exchange work is stored. The CPU 91 selects message data based on detection signals from the toner remaining amount sensor 29 and the reader / writer module 30 and displays the message data on the liquid crystal display unit 51 in the operation unit 50.

  For example, when the output value of the toner remaining amount sensor 29 is equal to or lower than the second threshold value L2 (see FIG. 4), the toner in the toner container 5 is reduced, but image formation is possible for a while. Therefore, the message “Low toner” is selected, saying “Toner is low. It is recommended to replace the toner container.”

  Further, when the output value of the toner remaining amount sensor 29 is continuously equal to or lower than the second threshold value L2 for a predetermined time or when the sensor output value is lower than the second threshold value L2, the output is performed for a certain printing rate. In this case, it is determined that the toner in the toner container 5 is empty. Therefore, a message (Replace display) that requests replacement of the toner container 5 “Toner is out. Please replace the toner container.” Is selected.

  In addition, the control unit 90 transmits a control signal from the CPU 91 to the respective units and apparatuses in the image forming apparatus 100 through the I / F 95. In addition, a signal indicating the state and an input signal are transmitted from each part or device to the CPU 91 through the I / F 95. For example, detection signals from the toner remaining amount sensor 29 and the reader / writer module 30 are transmitted to the CPU 91 in the control unit 90 via the I / F (interface) 95.

  The operation unit 50 is provided with a liquid crystal display unit 51 and LEDs 52 that indicate various states, and displays the state of the image forming apparatus 100 and displays the image forming status and the number of copies to be printed. Various settings such as printing conditions of the image forming apparatus 100 are made from a printer driver of a personal computer.

  In addition, the operation unit 50 includes a start button that the user instructs to start image formation, a stop / clear button that is used when image formation is stopped, and various settings of the image forming apparatus 100 that are in a default state. A reset button or the like is provided for use.

  The reader / writer module 30 faces the IC chip 27 of the toner container 5 in a state where the toner container 5 is accommodated in the image forming apparatus 100 (the state shown in FIG. 2). When data is written to the memory of the IC chip 27, the reader / writer module 30 generates an electromagnetic wave including a write command and data, and the IC chip 27 is activated by receiving the electromagnetic wave, and sends data to the memory according to the write command. Data is written. When reading data from the memory of the IC chip 27, the reader / writer module 30 generates an electromagnetic wave including a read command. The IC chip 27 is activated by receiving the electromagnetic wave and stores it in the memory according to the read command. The read data is transmitted to the reader / writer module 30.

  By the way, when the conventional toner replenishment procedure and the toner container 5 replacement procedure shown in FIGS. 11 and 12 are executed, the toner container 5 is replaced because the output value of the toner remaining amount sensor 29 is the second value. When the threshold value L2 is continuously lower than a certain time (when Low is displayed), or when the output value is lower than the second threshold value L2 and the cumulative printing rate is M% or more (when Replace is displayed) Therefore, after replacement with a new toner container 5, a large amount of toner is replenished at a time until the sensor output value exceeds the third threshold value L3. When printing is resumed thereafter, the toner is replenished in a relatively short time until the sensor output value changes at a level higher than the first threshold value L1.

  For example, as shown in FIG. 4, the first threshold L1 is 1.1V, the second threshold L2 is 0.9V, the third threshold L3 is 1.0V, and the low display determination time t1 = 30 seconds, Assuming that the replacement display release determination time t2 = 120 seconds, Table 1 shows an example of the toner amount in the developing device 4, the increased amount of toner since the replacement of the toner container 5, and the toner replenishment amount. In Table 1, the amount of increase in toner is smaller than the amount of toner replenished because part of the replenished toner is consumed by printing.

  As can be seen from Table 1, in the conventional toner replenishment procedure, as much as 62 g of toner is replenished while only 500 sheets are printed after the toner container 5 is replaced. Therefore, when the toner container 5 filled with toner that has passed for a long time from the date of manufacture is replaced, the toner that is not easily charged in the toner container 5 is added to the easily charged toner remaining in the developing device 4. A large amount of toner is replenished in a short period of time, a large amount of toner having a reverse polarity or low charge is generated, and replenishment fog occurs.

  Therefore, in the image forming apparatus 100 according to the present embodiment, the toner production date in the toner container 5 after the replacement (hereinafter referred to as the first production date) and the toner container before the replacement that has been attached to the image forming apparatus 100. The toner replenishment level (toner replenishment amount per unit time) after replacement is changed according to the difference in the number of days from the toner production date (hereinafter referred to as the second production date). Specifically, when the first manufacturing date is earlier than the second manufacturing date, the toner supply level after replacement is lowered as the difference in the number of days between the first manufacturing date and the second manufacturing date increases. , So that a large amount of toner is not supplied immediately after replacement. Then, as the difference in the number of days between the first manufacturing date and the second manufacturing date becomes smaller, the decrease in the toner replenishment level after the container replacement is reduced, and the decrease in the toner amount in the developing device 4 is suppressed.

  On the other hand, if the first manufacturing date is later than the second manufacturing date, the toner supply level after container replacement is not changed, or the difference in the number of days between the first manufacturing date and the second manufacturing date is small. The toner replenishment level after replacement is lowered so that a large amount of toner is not supplied immediately after replacement. Then, as the difference in the number of days between the first manufacturing date and the second manufacturing date increases, the decrease in the toner replenishment level after the container replacement is reduced, and the decrease in the toner amount in the developing device 4 is suppressed. This is because when the first manufacturing date is later than the second manufacturing date and the difference in the number of days between the first manufacturing date and the second manufacturing date is large, the toner in the toner container 5 before replacement is changed. This is because the toner replenished from the toner container 5 after replacement due to frictional charging with the toner in the toner container 5 before replacement is difficult to be negatively charged (reversely charged).

  When the toner supply level after replacement of the toner container 5 is low and the amount of toner in the developing device 4 is low, the first manufacturing date is before the second manufacturing date. In this case, the difference in the number of days between the first manufacturing date and the second manufacturing date is large. In this case, since the toner in the developing device 4 has been manufactured for a long time and the charging property is low, the toner in the developing device 4 can be used in the developing device 4 even if the toner capacity in the developing device 4 is low. Little increase in charging. For this reason, even if the toner replenishment level is lowered, replenishment fog hardly occurs at the next replacement of the toner container 5.

  FIG. 6 is a flowchart showing a toner supply procedure and a replacement procedure of the toner container 5 in the image forming apparatus 100 of the present embodiment, and FIG. 7 is a flowchart showing a return procedure from the replacement of the toner container 5. The procedure for replacing the toner container 5 and the procedure for setting the toner replenishment level after the toner container 5 is replaced will be described with reference to FIGS.

  When printing is started by the user, it is determined whether or not the output value of the toner remaining amount sensor 29 becomes smaller than the first threshold value L1 during printing (step S1). If the output value of the toner remaining amount sensor 29 is equal to or greater than L1 (NO in step S1), sufficient toner is present in the developing device 4, so that toner supply is not performed (step S2) and printing is continued. And do it. On the other hand, when the output value is smaller than L1 (YES in step S1), intermittent toner replenishment for replenishing an appropriate amount of toner from the toner container 5 based on the detection result of the toner remaining amount sensor 29 is started (step S3). ).

  Next, it is determined whether or not the output value of the remaining toner sensor 29 has become smaller than the second threshold value L2 (step S4). If the output value is L2 or more (NO in step S4), the process returns to step S1, and if the output value is restored to L1 or more, the intermittent toner supply is stopped (step S2). On the other hand, when the output value is smaller than L2 (YES in step S4), the elapsed time from the time when the output value falls below L2 is counted (step S5). And it is judged whether elapsed time is t1 or more (step S6).

  If the elapsed time does not exceed t1 (NO in step S6), the process returns to step S4 again to determine whether the output value is smaller than L2. If the output value becomes equal to or greater than L2 due to toner supply, the elapsed time count is reset (step S7), and the process returns to step S1.

  When the elapsed time is t1 or more (YES in step S6), the toner supply from the toner container 5 to the developing device 4 is not performed, so the controller 90 is in a state where the remaining toner in the toner container 5 is low. And the low display is performed on the liquid crystal display unit 51. Further, LOW information is written to the IC chip 27 mounted on the toner container 5 using the reader / writer module 30 (step S8). In this state, since toner remains in the toner container 5 and the developing device 4, printing can be continued.

  Then, the cumulative printing rate after performing the Low display is calculated (step S9), and it is determined whether or not the cumulative printing rate is equal to or higher than the predetermined printing rate M (step S10). Until the cumulative printing rate becomes M or more (NO in step S10), the process returns to step S1 to continuously detect whether the output value of the toner remaining amount sensor 29 is restored to L1 or more.

  If the output value recovers to L1 before the cumulative printing rate becomes M or more (NO in step S1), the intermittent toner supply is stopped and the time count and printing rate calculation are reset. Further, when the output value falls below L2, it is determined that the toner remaining amount sensor 29 is erroneously detected, and the low information in the IC chip 27 and the low display on the liquid crystal display unit 51 are erased (step S2). Further, when the output value of the toner remaining amount sensor 29 is recovered to L2 or more by intermittent toner replenishment (NO in step S4), the elapsed time count is reset. Further, if the output value falls below L2, it is determined that the toner remaining amount sensor 29 is erroneously detected, and the low information in the IC chip 27 and the low display on the liquid crystal display unit 51 are erased (step S7).

  If the cumulative printing rate is equal to or greater than M (YES in step S10), the control unit 90 determines that the replenishment toner in the toner container 5 is empty and the toner in the developing device 4 is also consumed. Then, the Replace display is performed on the liquid crystal display unit 51, and the printing operation is stopped (Step S11). Further, the LOW information of the IC chip 27 mounted on the toner container 5 is rewritten to Empty information using the reader / writer module 30 (step S12). Further, the production date information (second production date) of the toner is read from the individual identification information in the toner container 5 recorded on the IC chip 27 using the reader / writer module 30 and stored in the RAM 93 (step S13). .

  As shown in FIG. 7, when the power of the image forming apparatus 100 displaying the Replace display is turned on (step S1), it is determined whether or not the toner container 5 has been replaced (step S2). If the toner container 5 has been replaced (YES in step S2), the individual identification information of the IC chip 27 mounted on the toner container 5 is read using the reader / writer module 30 (step S3).

  Then, it is determined whether or not the individual identification information read from the IC chip 27 includes “Low information” or “Empty information” (step S4). If neither the “Low information” nor the “Empty information” is included (NO in step S4), the toner container 5 contains a sufficient amount of toner, so that the Replace display is canceled and printing is possible. A state is set (step S5).

  Next, the manufacturing date information (first manufacturing date) of the toner in the toner container 5 read from the IC chip 27 and the manufacturing date information (first date) of the toner in the toner container 5 before replacement stored in the RAM 93 are stored. 2), the first threshold value L1 and the second threshold value L2 within a predetermined period from immediately after the replacement of the toner container 5 are changed (step S6).

  On the other hand, when the toner container 5 has not been replaced (NO in step S2), or when the individual identification information of the IC chip includes either “Low information” or “Empty information” (NO in step S4). Continuously displays the Replace display prompting the replacement of the toner container 5 on the liquid crystal display unit 51, and continues the stop of the printing operation (step S7).

  Next, a specific method for changing the first threshold value L1 and the second threshold value L2 in step S6 of FIG. 7 will be described. For example, the values of L1 (= 1.1V) and L2 (= 0.9V) before container replacement are set as reference values, and L1 and L2 immediately after replacement are reduced to 0.7V and 0.5V, respectively. Then, as the cumulative number of printed sheets increases, L1 and L2 are gradually raised to the reference value. At this time, the rate of increase (increase rate) of L1 and L2 is changed according to the difference in the number of days between the first manufacturing date and the second manufacturing date.

  FIG. 8 is a graph showing the relationship between the cumulative number of printed sheets immediately after the replacement of the toner container 5 and the increase in the first threshold value L1 for each day difference between the first manufacturing date and the second manufacturing date. . Note that the second threshold L2 is a value obtained by subtracting 0.2V from L1, and the graph is the same as that in FIG. 8 except that the value immediately after the replacement is 0.5V, and thus the description thereof is omitted here. In FIG. 8, the first threshold value L1 immediately after the replacement of the toner container 5 is lowered to 0.7 V, and L1 is returned to the reference value according to the cumulative number of printed sheets. Then, the increasing rate of L1 per predetermined number of printed sheets is changed according to the difference in the number of days between the first manufacturing date and the second manufacturing date. Here, (day difference) = (first production date) − (second production date), and when the day difference is negative, the first production date is before the second production date ( In this case, the toner in the toner container 5 after replacement is older than the toner in the toner container 5 before replacement.

  For example, when the difference in the number of days between the first manufacturing date and the second manufacturing date is 60 days or more (indicated by a solid line in FIG. 8), the value of L1 is changed from 0.7V immediately after replacement to the 200th sheet after replacement. The voltage is increased at a rate of 0.2V per 100 sheets. That is, 0.8V for the 50th sheet, 0.9V for the 100th sheet, 1.0V for the 150th sheet, 1.1V for the 200th sheet, and then 1.1V until the next container replacement.

  Similarly, when the difference in the number of days between the first manufacturing date and the second manufacturing date is -60 days to 60 days (indicated by a dotted line in FIG. 8), the value of L1 is changed from 0.7 V immediately after the replacement. After the 400th sheet, the voltage is increased at a rate of 0.1 V per 100 sheets. That is, 0.8V for the 100th sheet, 0.9V for the 200th sheet, 1.0V for the 300th sheet, 1.1V for the 400th sheet, and then 1.1V until the next container replacement.

  When the difference in the number of days between the first manufacturing date and the second manufacturing date is −180 days to −60 days (indicated by a broken line in FIG. 8), the value of L1 is changed from 0.7 V immediately after replacement to 800 after replacement. The voltage is increased at a rate of 0.05 V per 100 sheets. That is, 0.8V for the 200th sheet, 0.9V for the 400th sheet, 1.0V for the 600th sheet, 1.1V for the 800th sheet, and then 1.1V until the next container replacement.

  When the difference in the number of days between the first manufacturing date and the second manufacturing date is -360 days to -180 days (indicated by a one-dot chain line in FIG. 8), the value of L1 is changed from 0.7 V immediately after the replacement. It increases at a rate of 0.02V per 100 sheets over the 2000th sheet. That is, 0.8V for the 500th sheet, 0.9V for the 1000th sheet, 1.0V for the 1500th sheet, 1.1V for the 2000th sheet, and then 1.1V until the next container replacement.

  When the difference in days between the first manufacturing date and the second manufacturing date is -730 days to -360 days (indicated by a two-dot chain line in FIG. 8), the value of L1 is changed from 0.7 V immediately after the replacement. After that, the voltage is increased at a rate of 0.01 V per 100 sheets over the 4000th sheet. That is, 0.8V for the 1000th sheet, 0.9V for the 2000th sheet, 1.0V for the 3000th sheet, 1.1V for the 4000th sheet, and then 1.1V until the next container replacement.

  When the difference in the number of days between the first manufacturing date and the second manufacturing date is −730 days or less (indicated by a thick line in FIG. 8), the value of L1 is changed from 0.7V immediately after replacement to 8000th after replacement. Increase at a rate of 0.005V per 100 sheets. That is, 0.8V for the 2000th sheet, 0.9V for the 4000th sheet, 1.0V for the 6000th sheet, 1.1V for the 8000th sheet, and then 1.1V until the next container replacement.

  By performing the above control, the difference in the number of days between the first manufacturing date and the second manufacturing date is larger on the minus side, that is, the toner in the toner container 5 after replacement is in the toner container 5 before replacement. The older the toner is, the longer the period in which the amount of toner in the developing device 4 is small can be delayed by delaying the return of the first threshold value L1 and the second threshold value L2 to the reference value.

  As a result, when replenishing toner with good chargeability that has not passed much time since the date of manufacture, to a toner with an old production date and low chargeability, the amount of toner in the developing device 4 is slowly increased over a long period of time. Since it is returned to the stable transition amount (reference amount), it is possible to effectively suppress the occurrence of replenishment fog and toner scattering due to toner charging failure.

  By the way, when the amount of toner in the developing device 4 decreases, mechanical stress due to the stirring of the toner increases, so that the toner easily deteriorates. Further, when the amount of toner in the developing device 4 is returned to the stable transition amount over time, L2 is also lowered together with L1. When L2 is lowered, the toner is replenished when the toner in the developing device 4 becomes less than normal. Therefore, when an image with a high printing rate is continuously printed immediately before the sensor output value falls below L2, the developing device 4 The amount of toner in the toner may be lower than the printable amount, and there is a possibility that a white-out image or a decrease in image density may occur.

  Therefore, when there is not much difference between the production dates of the toner in the developing device 4 and the toner in the toner container 5 (the difference in days between the first production date and the second production date is on the negative side, the difference in days is If the toner is old and has a low manufacturing date, and a toner with good charging property that has not passed much time since the manufacturing date is supplied (the number of days between the first manufacturing date and the second manufacturing date) When the difference is on the plus side), the toner amount in the developing device 4 is returned to the stable transition amount in a relatively short time, so that the toner is deteriorated, the white image or the image density is lowered, and the remaining amount of toner is erroneously detected. Etc. can be reliably suppressed.

  Further, if the period in which the amount of toner in the developing device 4 is low is lengthened, for example, when the toner container 5 is replaced with a toner having a small amount of toner, the toner container before the output value of the toner density sensor 29 returns to L2. 5 may run out of toner. In this state, the toner in the developing device 4 is less than that in the normal Replace display, but the values of L1 to L3 remain unchanged. For this reason, if the toner container 5 is replaced with a toner container 5 in which the difference in days between the first manufacturing date and the second manufacturing date is large on the minus side at the next Replace display, the toner is output until the sensor output value is restored to L3 immediately after the start of printing. Will be replenished, and there is a possibility that replenishment fogging may occur although the probability is low. Therefore, when the difference in the number of days between the first manufacturing date and the second manufacturing date is negative but small, or when the toner container 5 is replaced with a toner container 5 with a positive difference in the number of days, the amount of toner in the developing device 4 By returning to the stable transition amount in a relatively short time, it is possible to suppress the occurrence of replenishment fog at the next replacement of the toner container 5.

  That is, according to the configuration of the present embodiment in which the inclination of the toner increase amount in the developing device 4 is corrected using the difference in days between the first manufacturing date and the second manufacturing date as a parameter, the toner that has passed for a long time from the manufacturing date. The above-described problems can be effectively suppressed regardless of whether the toner container 5 filled with the toner container 5 or the toner container 5 filled with the toner whose time has not elapsed since the date of manufacture is used.

  Further, in FIG. 8, the value of L1 is determined from the difference in the number of days between the first manufacturing date and the second manufacturing date. However, even if the L1 value is corrected by adding the parameter of the replacement date of the toner container 5 to this value. Good. As shown in FIG. 8, the correction value K is set so that the relationship B = AK is established when the inclination until L1 returns to the reference value is A and the new inclination after correction is B. An example of the correction value K is shown in Table 2.

  In this way, by correcting the value of L1 based on the difference in days between the replacement date of the toner container 5 and the second manufacturing date, the toner in the developing device 4 becomes older as the toner in the toner container 5 before replacement is older. The time when the amount is small can be shortened. As a result, it is possible to suppress toner deterioration, prevent white spots due to erroneous detection and high-density continuous printing, and to prevent the toner in the toner container 5 from running out before L1 returns to the normal level.

  If the toner in the toner container 5 runs out before L1 returns to the normal level, L2 has also returned to the normal level. Therefore, when the Replace display is displayed, the inside of the developing device 4 is more than in the normal Replace display. The toner amount is reduced. In this case, since the value of L1 after the replacement of the toner container 5 remains as shown in Table 7, more toner than usual is supplied into the developing device 4 immediately after the replacement of the toner container 5. As a result, although the probability of occurrence is low, replenishment fog is more likely to occur than in normal times. On the other hand, when the inclination is corrected in consideration of the replacement date parameter, the return to the normal level of L1 and L2 can be accelerated, and the occurrence of replenishment fog due to the toner being replenished more than usual. There is an effect to suppress.

  In FIG. 8, the first threshold L1 immediately after the replacement of the toner container 5 is set to a constant value (0.7 V) regardless of the difference in the number of days between the first manufacturing date and the second manufacturing date. The amount of toner in the developing device 4 immediately after replacement is made the same, but the value of L1 (and L2) may be determined by other methods.

  For example, in the graph shown in FIG. 9, the first threshold L1 immediately after the replacement of the toner container 5 is set to be lower stepwise in accordance with the difference in the number of days between the first manufacturing date and the second manufacturing date. Specifically, when the difference in the number of days between the first manufacturing date and the second manufacturing date is 60 days or more (indicated by a solid line in FIG. 9), the value of L1 immediately after the replacement is 0.95V.

  Similarly, when the difference in the number of days between the first manufacturing date and the second manufacturing date is −60 days to 60 days (indicated by the dotted line in FIG. 9), −180 days to −60 days (the broken line in FIG. 9). ), -360 days to -180 days (displayed with a one-dot chain line in FIG. 9), -730 days to -360 days (displayed with a two-dot chain line in FIG. 9), and -730 days or less (displayed with a one-dot chain line) In FIG. 9, the values of L1 immediately after the replacement are 0.9V, 0.85V, 0.8V, 0.75V, and 0.7V, respectively. And L1 is raised by the same rate (rate of 0.005V per 100 sheets) irrespective of the difference in the number of days between the first production date and the second production date.

  By determining L1 and L2 using FIG. 9 instead of FIG. 8, the developing device 4 immediately after the replacement of the toner container 5 is larger as the difference in the number of days between the first manufacturing date and the second manufacturing date is larger on the minus side. Control may be performed so that the amount of toner in the toner is reduced. In this case, when the toner container 5 is replaced with a toner container 5 in which the difference in the number of days between the first manufacturing date and the second manufacturing date is large on the minus side, toner supply is not performed immediately after the replacement. On the other hand, if the difference in the number of days between the first manufacturing date and the second manufacturing date is small or the toner container 5 is replaced with a larger one on the plus side, toner supply is performed.

  Further, the toner amount in the developing device 4 can be controlled using the flowchart shown in FIG. 12 instead of the flowchart shown in FIG. In that case, the value of the third threshold L3 (see FIG. 4) is changed according to the difference in the number of days between the first manufacturing date and the second manufacturing date. Specifically, the value of L3 is decreased as the difference in the number of days between the first manufacturing date and the second manufacturing date is larger on the minus side. As a result, the older the toner in the toner container 5 after replacement is compared to the toner in the toner container 5 before replacement, the smaller the amount of toner in the developing device 4 when the Replace display disappears and printing is possible. Therefore, the same effect as described above can be obtained.

  In the control of FIG. 7, the presence / absence of toner in the toner container 5 is detected by reading the individual identification information in the IC chip 27. However, the remaining amount of toner is detected using the conventional control shown in FIG. The presence or absence of toner in the toner container 5 may be detected by comparing the output value of the sensor 29 with the third threshold value L3. Specifically, if the output value of the remaining toner sensor 29 does not exceed L3 within a predetermined time t2 from the start of toner supply from the toner container 5, it is determined that the toner container 5 is empty, and the Replace display is performed again. The toner container 5 is urged to be replaced again.

  Alternatively, immediately after the toner container 5 is replaced, an aging operation for driving the agitating / conveying member in the developing device 4 for a certain period of time may be executed to stabilize the amount of toner in the developing device 4 and enable the printing operation.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above-described embodiment, it is determined whether or not new toner remains in the toner container 5 based on the toner remaining amount level in the developing device 4 detected by the toner remaining amount sensor 29 in the developing device 4. However, for example, it may be configured to directly detect the remaining amount of toner in the toner container 5. In that case, it can also be determined whether or not new toner remains in the toner container 5 based on the amount of toner replenished from the toner container 5 to the developing device 4 (integrated rotation speed of the toner supply motor 33).

  The present invention is not limited to the developing device 4 that uses a magnetic one-component developer, but can also be applied to an image forming apparatus that includes a two-component developing type developing device that uses a two-component developer containing toner and a magnetic carrier. is there. In the two-component developing type developing device, when a magnetic permeability sensor is used as the toner remaining amount sensor, the smaller the amount of toner in the developing device, the larger the percentage of magnetic carrier, and the larger the sensor output value. Therefore, the relationship between the sensor output value and the first threshold value L1 to the third threshold value L3 is opposite to that of the magnetic one-component development method of the above embodiment.

  Further, the present invention is not limited to the monochrome printer as shown in FIG. 1, and detachable toner storage such as a tandem or rotary color copier and printer, a monochrome copier, a digital multifunction machine, a facsimile machine, etc. Of course, the present invention can be applied to various image forming apparatuses having containers. Hereinafter, the effects of the present invention will be described in more detail with reference to examples.

  The relationship between the difference in the number of days between the first manufacturing date and the second manufacturing date, the amount of toner in the developing device 4 immediately after the replacement of the toner container 5 and the occurrence of replenishment fog was investigated. As a test method, as shown in FIG. 8, the first threshold value L1 immediately after the replacement of the toner container 5 is lowered from the reference value, and a predetermined value when returning L1 to the reference value according to the accumulated number of printed sheets. When the increasing rate of L1 per number of printed sheets is changed according to the difference in the number of days between the first manufacturing date and the second manufacturing date (Examples 1 to 5), the first immediately after the replacement of the toner container 5 is performed. When the threshold value L1 was not lowered at the reference value (comparative example), the amount of toner in the developing device 4 for each predetermined number of sheets, the amount of toner increase, and the occurrence of replenishment fog were compared.

  For the occurrence of replenishment fog, the reflectance of the paper before printing and the reflectance of the paper after white solid printing are measured by a reflection densitometer (Macbeth RD912), respectively, and the fog value = (reflection of the paper after white solid printing) Rate)-(reflectance of paper before printing). The results are shown in FIG. It should be noted that when the fogging value exceeds 0.01, the occurrence of replenishment fogging is at a level visually recognized, and when the fogging value is 0.01 or less, the level is not visually recognized.

  As is apparent from FIG. 10, L1 immediately after replacement of the toner container 5 is set to 0.7 V, and the rate of increase of L1 when L1 is returned to the reference value (1.1 V) is expressed as the first manufacturing date and the second production date. In Examples 1 to 5 changed according to the number of days difference from the production date, the number of days difference between the first production date and the second production date is 30 days, -120 days, -200 days, -500 days. Even when the toner container 5 was replaced, no replenishment fog was observed from immediately after the replacement of the toner container 5 until printing 10,000 sheets.

  On the other hand, in the comparative example in which L1 immediately after the replacement of the toner container 5 is not lowered from the reference value (1.1V), the difference in the number of days between the first manufacturing date and the second manufacturing date is −500 days. When the container 5 was replaced, occurrence of replenishment fogging was recognized from the first printed sheet to about 600 sheets.

  The present invention can be used in an image forming apparatus including a detachable toner container that replenishes toner to a developing device. By utilizing the present invention, it is possible to provide an image forming apparatus capable of effectively suppressing the occurrence of image quality degradation due to replenishment fogging even when the production time of the toner in the replaced toner container is old.

1 Photosensitive drum (image carrier)
4 Developing device 5 Toner container (toner container)
7 Cleaning device 27 IC chip (memory means)
29 Toner level sensor 30 Reader / writer module 33 Toner supply motor 50 Operation unit 51 Liquid crystal display unit 90 Control unit (control means)
100 Image forming apparatus P Image forming unit

Claims (10)

An image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image formed on the image carrier into a toner image;
A removable toner storage container for storing unused toner for replenishing the developing device;
Control means for controlling toner replenishment from the toner container to the developing device;
With
The control means returns the toner amount in the developing device, which has decreased from the reference amount immediately after the replacement of the toner storage container, to the reference amount step by step within a predetermined period, and fills the toner storage container after the replacement. When the first production date that is the production date of the toner that has been used is earlier than the second production date that is the production date of the toner filled in the toner container before replacement, the first production date The image forming apparatus characterized in that the return time to the reference amount is lengthened as the difference in the number of days between the date and the second manufacturing date increases.   A reader / writer module for reading and writing information to and from a non-volatile storage means mounted on the toner container is provided, and the control means is the storage means read by the reader / writer module The image forming apparatus according to claim 1, wherein a difference in days between the first manufacturing date and the second manufacturing date is calculated based on manufacturing date information.   A toner remaining amount sensor for detecting the toner remaining amount in the developing device is provided, and the control means estimates the toner remaining amount in the toner containing container based on a detection result of the toner remaining amount sensor. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The developing device is a one-component developing system that develops an electrostatic latent image into a toner image using a one-component developer composed only of magnetic toner, and the toner remaining amount sensor has an output value that increases as the remaining amount of toner increases. The image forming apparatus according to claim 1, wherein the image forming apparatus is a magnetic permeability sensor that increases.   The control means starts supplying toner to the developing device when the output value of the toner remaining amount sensor falls below a first threshold L1, and the output value of the toner remaining amount detecting means continues for a predetermined time. When the value falls below a threshold value L2 (L1> L2) of 2, it is determined that the remaining amount of toner in the toner container is empty, and according to the number of days difference between the first manufacturing date and the second manufacturing date. The image forming apparatus according to claim 4, wherein the L1 and L2 are changed within a predetermined period after the toner container is replaced.   The control means sets L1 and L2 immediately after replacement of the toner container to a constant value lower than a reference value, then raises L1 and L2 to return to the reference value, and the first manufacturing date 6. The image forming apparatus according to claim 5, wherein the increase rate of the L <b> 1 and L <b> 2 is decreased as the difference in the number of days between the first manufacturing date and the second manufacturing date increases.   7. The image forming apparatus according to claim 6, wherein the control unit corrects the increasing ratio of the L <b> 1 and L <b> 2 according to the number of days elapsed from the second manufacturing date to the replacement date of the toner container. .   The control means sets the L1 and L2 immediately after the replacement of the toner storage container to be lower stepwise as the number of days difference between the first manufacturing date and the second manufacturing date is larger, and the L1 and L2 The image forming apparatus according to claim 5, wherein the image forming apparatus is raised at a constant rate and returned to a reference value.   The control means allows a printing operation when the output value of the toner remaining amount sensor becomes equal to or higher than a third threshold value L3 (L1> L3> L2) after the replacement of the toner container, and the first manufacture. 9. The image forming apparatus according to claim 5, wherein the L <b> 3 is decreased as the difference in the number of days between the date and the second manufacturing date increases.   The image forming apparatus according to claim 1, wherein an aging operation for stirring and mixing the toner in the developing device is performed immediately after replacement of the toner container.

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