JP2010002649A - Image forming apparatus, method of controlling image forming apparatus, and control program for image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that provides a suitable warning concerning toner. <P>SOLUTION: Based on a detection value of a toner concentration sensor that detects toner concentration in a developing device, determination is made whether the toner concentration is lower than a predetermined value (S103). If it is lower than the value and the estimated value of a quantity of toner remaining in a toner cartridge is smaller than the predetermined value, it is assumed that a trouble, which is an abnormally low toner concentration, is caused, and the apparatus is stopped (S105). If the toner concentration is lower than the predetermined value and the quantity of toner remaining in the toner cartridge is greater than the predetermined value, the possibility that the toner cartridge may not have been set correctly is high, and it is assumed that the toner cartridge is empty of toner. Accordingly, the apparatus is stopped (S104). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, a control method for the image forming apparatus, and a control program for the image forming apparatus, and more particularly to an image forming apparatus that uses a two-component developer composed of toner and carrier, a control method for the image forming apparatus, and The present invention relates to a control program for an image forming apparatus.

  An electrophotographic image forming apparatus (MFP (Multi Function Peripheral), facsimile apparatus, copying machine, printer, etc.) having a scanner function, a facsimile function, a copying function, a function as a printer, a data communication function, and a server function. A developing device for printing the toner image on a transfer member such as an intermediate transfer belt or paper is provided.

  In the image forming apparatus, it is necessary to grasp the remaining amount of toner for the convenience of maintenance such as toner replenishment. A dedicated toner remaining amount detecting device may be used for grasping the toner remaining amount, but an image forming apparatus that does not include a dedicated toner remaining amount detecting device is also known in order to reduce the cost of the device.

  In an image forming apparatus that does not include a toner remaining amount detecting device, when the developer to be used is a two-component developer, a method for detecting the remaining amount of toner using a result of toner density control is known.

  In the toner concentration control, the toner concentration in the developer is controlled to be constant by measuring the magnetic permeability of the developer. The two-component developer is obtained by mixing toner at a predetermined concentration (for example, about 7 to 8%) in a carrier made of iron powder or the like. Therefore, when the toner in the developer is consumed and the proportion of the carrier increases, the magnetic permeability of the developer increases. By detecting the magnetic permeability of the developer, the toner ratio in the developer can be grasped.

  When the magnetic permeability increases and exceeds the upper limit (corresponding to the lower limit of toner concentration), the toner is supplied from a toner supply source such as a toner cartridge (toner bottle) by rotating the replenishment motor for a predetermined time (or a predetermined number of rotations). There are techniques to replenish. Alternatively, a lower limit value of magnetic permeability (corresponding to an upper limit value of toner concentration) is set, and when the magnetic permeability increases and exceeds the upper limit value, the replenishing motor is rotated until the lower limit value is reached, and the toner supply source There are also methods for supplying toner.

  In any of the methods, when the remaining amount of toner in the toner supply source decreases, the influence appears on the toner density control. For this reason, it is possible to detect that the remaining amount of toner is less than the control result.

  That is, when the remaining amount of toner in the toner supply source decreases, the amount of replenishment per predetermined rotation time of the replenishment motor decreases, so that the toner replenishment is frequently repeated in the former method. From this, it is possible to detect that the remaining amount of toner is low. Further, in the latter method, when the remaining amount of toner in the toner supply source decreases, the replenishment amount per predetermined rotation time of the replenishment motor decreases, so that the replenishment time (the time required to reach the lower limit value) takes longer. become. From this, it is possible to detect that the remaining amount of toner is low. If the permeability does not return even when the replenishment motor is rotated for a predetermined time (for example, 3 seconds) (that is, the toner concentration does not increase), it is assumed that toner empty is detected.

  Note that the analog output of the sensor in toner density control has a certain amplitude. This is because the output fluctuates due to the stirring of the screw at the detection position of the toner concentration sensor. Therefore, in order to reliably determine the toner empty, it is necessary to reduce the toner density beyond a predetermined threshold.

  On the other hand, there is a technique for detecting the consumption or remaining amount of toner without using toner density control. This is a method of counting the number of printing dots based on the image signal and calculating the toner consumption from the result (a method based on dot counting).

  However, the above-described method for detecting the consumption or remaining amount of toner has advantages and disadvantages.

  In the method of detecting the remaining amount of toner using toner density control, the remaining amount of toner from full to empty cannot be detected over time. Therefore, the user cannot ensure a period for preparing the next toner. As a result, there is a problem that the operating rate of the image forming apparatus decreases.

  That is, in the toner density control, the toner replenishment is frequently repeated or the toner replenishment time per time becomes longer after the toner remaining amount is sufficiently reduced. For this reason, even when the user is notified that the remaining amount of toner is low when such a state is detected, before the user prepares the next toner, toner empty (out of toner) is reached and image formation is performed. There is a possibility that the device will stop.

  On the other hand, in the method of detecting the remaining amount of toner by dot count, the amount of toner to be used is accurately obtained by calculation based on the image signal, the pattern of the patch image, etc., and this is used as the toner consumption amount. By calculating the remaining amount of toner from the toner consumption thus obtained, it is possible to detect that the remaining amount of toner is low at an earlier stage than by the toner density control and notify the user.

  However, the amount of toner actually placed on the photoconductor is not necessarily a constant amount due to the environment and variations among devices. For this reason, no matter how much the accuracy is improved by performing a weighting calculation or the like, if the remaining toner amount is determined using only the result obtained by the calculation, the error becomes large. Therefore, even if it is set to notify the user that the remaining amount of toner is low while expecting a sufficient number of remaining printable sheets, the toner becomes empty before reaching the scheduled number of prints. On the other hand, there is a possibility that it is determined that the toner is empty when the toner still remains.

Patent Document 1 below detects the remaining amount of toner in the toner hopper, and when it is insufficient, issues a warning that the amount of toner supplied at the time of the shortage has reached a predetermined amount and then supplies the predetermined amount. An image forming apparatus is disclosed that issues a warning that there is no toner after being performed. After replenishing toner to the toner hopper, rotate the paddle in the hopper by a predetermined amount, supply the toner to the developer by a predetermined amount, detect the remaining amount of toner again, and reset the warning if the remaining amount is enough The
JP-A-8-87166

  In an image forming apparatus of a type in which toner is supplied from a toner cartridge to the two-component developing device and the toner cartridge is depleted, and it is determined that the toner is empty when the toner density is reduced, and printing is prohibited. Is replaced, forced toner replenishment for returning the lowered toner density to the normal control toner density is performed.

  When forced toner supply is performed and the toner density returns, the toner cartridge is correctly replaced and the toner empty state is released. This enables printing. If the toner concentration does not increase, the toner cartridge may not be replaced, or even if it is replaced, the gear engagement with the main body of the cartridge is poor and the insertion is not performed correctly. When the toner density does not increase in this way, toner empty is not released.

  As described above, when the user inserts the toner cartridge, the way of inserting the toner cartridge is bad, and the engagement of the drive gear between the screw and the main body of the cartridge may be bad.

  At this time, even if the insertion is not performed correctly, the shutter between the main body and the cartridge provided on the toner cartridge side opens, so that some toner is replenished from the cartridge to the developing device by gravity. At this time, the toner concentration may be recovered in the forced toner replenishment sequence, and the toner empty may be released.

  At this time, since the toner empty is released, printing becomes possible. However, if printing is continued thereafter, the screw in the cartridge does not rotate and toner is not replenished even if the toner is replenished. As a result, a trouble that the toner density is low may be output. The determination that the toner is empty when the toner density becomes low is after the determination that the toner has been replenished by a predetermined value or more is made by integrating with a counter. For this reason, the fact that the toner concentration in the developing device has become low even though the toner has not been replenished more than a predetermined value is to determine that there is some trouble (toner concentration low abnormality).

  In this case, if the user inserts and removes the toner cartridge, correctly inserts the cartridge, and corrects the gear engagement between the main body and the cartridge, the trouble is solved. However, when the trouble of “low toner density abnormality” is output, an imaging unit in which the developing device and the photosensitive member are integrated, which is much more expensive than the toner cartridge, may be replaced. Since the toner density in the new imaging unit is appropriate, the trouble is fixed once, but the problem of the coupling between the toner cartridge and the main body has not been solved, and in the worst case, the toner density low abnormality may occur again.

  As described above, there is a possibility that the toner supply from the cartridge to the main body is not reliably performed even after the toner empty is released, and it is necessary to control the image forming apparatus in consideration thereof.

  The present invention has been made to solve such a problem, and provides an image forming apparatus, a control method for the image forming apparatus, and a control program for the image forming apparatus that can perform an appropriate warning regarding toner. The purpose is that.

  In order to achieve the above object, according to one aspect of the present invention, an image forming apparatus includes a developing unit using a two-component developing system, a toner cartridge that is replaceably attached to the apparatus main body, and toner from the toner cartridge to the developing unit. A replenishing means for replenishing, a sensor for detecting the toner density in the developing device, and a toner density detected by the sensor falls below the first density after a predetermined period has passed since the toner cartridge was replaced. A first stop means for indicating that a trouble has occurred and stopping the apparatus; and a toner concentration detected by the sensor falls below the first concentration within a predetermined period after the toner cartridge is replaced. And a second stop means for stopping the apparatus by performing a display different from the display.

  Preferably, the image forming apparatus includes a measuring unit that measures the remaining amount of toner in the toner cartridge, and a first unit that issues a warning of toner near empty when the remaining amount of toner in the toner cartridge falls below a predetermined value by the measuring unit. Warning means.

  Preferably, the image forming apparatus further includes a second warning unit that issues a toner empty warning when the toner density detected by the sensor is lower than the second density after the toner near empty warning is given. Prepare.

  Preferably, the predetermined period is a period until the remaining amount of toner in the toner cartridge measured by the measuring unit becomes equal to or less than a predetermined amount.

  Preferably, the predetermined period is a predetermined period after the toner empty is released.

  Preferably, the second stop unit displays the toner empty and stops the apparatus.

  According to another aspect of the present invention, an image forming apparatus includes a developing unit that uses a two-component developing system, a toner cartridge that is replaceably attached to the apparatus body, and a replenishing unit that replenishes toner from the toner cartridge to the developing unit. When the toner density detected by the sensor has risen as a result of toner replenishment by the replenishing means after the toner cartridge is replaced with the sensor for detecting the toner density in the developing device, the sensor detects the toner density. When the toner density is lower than the first density, the toner is supplied by the first stop means for displaying the trouble and stopping the apparatus, and the supply means after the toner cartridge is replaced. As a result, when there is no history of increase in the toner density detected by the sensor, the toner density detected by the sensor is the first. When the signal falls below the concentration, and a second stopping means for stopping the device performs a different display than the display.

  Preferably, the image forming apparatus includes a measuring unit that measures the remaining amount of toner in the toner cartridge, and a first unit that issues a warning of toner near empty when the remaining amount of toner in the toner cartridge falls below a predetermined value by the measuring unit. Warning means.

  Preferably, the image forming apparatus further includes a second warning unit that issues a toner empty warning when the toner density detected by the sensor is lower than the second density after the toner near empty warning is given. Prepare.

  Preferably, the second stop unit displays the toner empty and stops the apparatus.

  According to still another aspect of the present invention, a control method for an image forming apparatus includes: a developing unit that uses a two-component developing method; a toner cartridge that is replaceably mounted on the apparatus main body; and a toner supply from the toner cartridge to the developing unit. A method for controlling an image forming apparatus, comprising: a replenishing unit that detects a toner concentration in a developing device; and a toner concentration detected by a sensor after a predetermined period has elapsed since the toner cartridge was replaced When the toner concentration falls below the first concentration, a first stop step for displaying that a trouble has occurred and stopping the apparatus, and a toner detected by the sensor within a predetermined period after the toner cartridge is replaced And a second stop step for stopping the apparatus by performing a display different from the display when the density is lower than the first density.

  According to still another aspect of the present invention, a control method for an image forming apparatus includes: a developing unit that uses a two-component developing method; a toner cartridge that is replaceably mounted on the apparatus main body; and a toner supply from the toner cartridge to the developing unit. A method for controlling an image forming apparatus comprising a replenishing unit for replenishing and a sensor for detecting a toner density in the developing device, wherein the toner is replenished by the replenishing unit after the toner cartridge has been replaced. A first stop step for stopping the apparatus by displaying that a trouble has occurred when the toner density detected by the sensor falls below the first density in the case where there is a history of increased toner density. History of increase in toner density detected by the sensor as a result of toner replenishment after toner cartridge replacement In the absence, when the toner concentration detected by the sensor falls below the first concentration, and a second stop step of stopping the device performs a different display than the display.

  According to still another aspect of the present invention, a control program for an image forming apparatus includes a developer that uses a two-component development method, a toner cartridge that is replaceably attached to the apparatus body, and replenishes toner from the toner cartridge to the developer. A control program for an image forming apparatus, comprising a replenishing means for detecting a toner concentration in a developing device, and a toner concentration detected by the sensor after a predetermined period of time has elapsed since the toner cartridge was replaced When the toner concentration falls below the first concentration, a first stop step for displaying that a trouble has occurred and stopping the apparatus, and a toner detected by the sensor within a predetermined period after the toner cartridge is replaced A second stop step for stopping the apparatus by performing a display different from the display when the density is lower than the first density; To be executed by a computer.

  According to still another aspect of the present invention, a control program for an image forming apparatus includes a developer that uses a two-component development method, a toner cartridge that is replaceably attached to the apparatus body, and replenishes toner from the toner cartridge to the developer. A control program for an image forming apparatus comprising a replenishing unit for replenishing and a sensor for detecting the toner density in the developing device, and is detected by the sensor as a result of toner replenishment performed by the replenishing unit after the toner cartridge is replaced. A first stop step for stopping the apparatus by displaying that a trouble has occurred when the toner density detected by the sensor falls below the first density in the case where there is a history of increased toner density. As a result of toner replenishment performed after the toner cartridge is replaced, the toner density detected by the sensor is When there is no history of rising, when the toner density detected by the sensor falls below the first density, the computer is caused to execute a second stop step for stopping the apparatus by performing a display different from the display. .

  According to these inventions, it is possible to provide an image forming apparatus, an image forming apparatus control method, and an image forming apparatus control program capable of providing an appropriate warning regarding toner.

  The image forming apparatus according to the embodiment of the present invention is an apparatus for forming a toner image such as an electrophotographic copying machine or a laser beam printer, and in particular, an apparatus using a two-component developer composed of toner and a carrier.

  To detect the remaining amount of toner, a dot count value and / or a measured value of the cumulative rotation amount (rotation speed, rotation time, etc.) of the toner supply motor is used. For detection of toner empty, a value obtained by toner density control is used.

  Further, the image forming apparatus does not include a dedicated toner remaining amount detecting device. The image forming apparatus includes a toner remaining amount predicting unit that predicts a toner remaining amount based on a calculation result of a toner consumption amount based on a measurement result of a dot count of an image signal (and / or a cumulative rotation amount of a toner supply motor), a toner remaining amount And a determination unit that makes a toner empty determination based on toner concentration detection by a toner concentration (toner concentration control) sensor that measures the toner concentration in the developing device at a time when the amount of toner is reduced to a predetermined value or less.

  That is, it is determined that the toner is empty when the toner density decreases. After a toner empty has occurred and the toner cartridge has been replaced and the empty has been released, the following determination (and a warning to the user) is made when there is a problem with the toner.

  (1) If a toner density (TC) low abnormality is detected shortly after empty is released, it is determined that the toner is empty, and a warning to that effect is given to the user (first embodiment).

  (2) After canceling empty, the toner density (TC) low abnormality when the toner density never increases is determined to be toner empty, and the user is warned to that effect (second embodiment).

  This is to monitor whether the cartridge is properly mounted without resetting the warning inside the apparatus for a while after the toner empty warning is once reset.

  By performing such processing, even if a problem such as a decrease in toner density of the developing device due to incomplete replacement operation by the user occurs immediately after replacement of the toner cartridge, the user can appropriately cope with it.

  Hereinafter, one embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. In the following description, it is necessary to clarify whether the device or member to be described is yellow (Y), magenta (M), cyan (C), or black (K). Is described by adding the characters “(Y)”, “(M)”, “(C)”, and “(K)” to the reference numerals, and otherwise omitting those characters.

  [First Embodiment]

  <Overall configuration of image forming apparatus>

  FIG. 1 is a diagram showing an overall configuration of an image forming apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, the image forming apparatus has four color image forming portions 105Y, 105M, 105C, and 105K of cyan, magenta, yellow, and black, and an exposure portion 107 that exposes a photosensitive member with a laser beam. is doing. Each color image forming unit includes a photoconductor and a scanning unit for scanning and exposing a laser beam from the exposure unit with a polygon mirror.

  Inside the apparatus main body, an intermediate transfer member (intermediate transfer belt) 103, four toner cartridges 101Y, 101M, 101C, and 101K, and four transport pipes that connect each toner cartridge and each developing device are provided. Yes. A toner image is formed by a photoreceptor, a charging device, a developing device, a cleaner device, and the like.

  The intermediate transfer member 103 has an endless belt shape formed of an insulating resin sheet material, and is arranged around a plurality of rollers (not shown). By rotating one of the rollers by a driving member (not shown), the intermediate transfer member 103 is rotationally driven.

  The four photoconductors are arranged in series in the order of (Y), (M), (C), and (K) at predetermined intervals along the intermediate transfer member 103 so as to face the intermediate transfer member 103. ing.

  The toner image formed on the photosensitive member is transferred to the intermediate transfer member 103 and further transferred to the transfer target (paper) by the secondary transfer roller. In the case of color printing, four color toner images are transferred in a multiple manner, and in the case of monochrome printing, a black toner image is transferred.

  The transferred object onto which the toner image has been transferred is conveyed to the fixing roller 401. When the transfer medium passes through the fixing roller 401, the toner on the transfer medium is thermally melted by the heat of the fixing roller 401. As a result, the toner image is fixed on the transfer target. The transfer medium on which the image is formed in this manner is discharged onto a paper discharge tray provided inside the apparatus main body.

  Note that toner remaining on the intermediate transfer member 103 without being transferred to the transfer member is collected by an intermediate transfer member cleaner provided on the downstream side of the secondary transfer position. The collected waste toner is stored in a waste toner bottle.

  An IDC sensor is disposed on the most downstream side of the intermediate transfer member 103. The IDC sensor is a reflective photoelectric sensor that includes a light emitting element such as a light emitting diode and a light receiving element such as a photodiode. The IDC sensor is used to detect a toner pattern formed on the intermediate transfer member 103 when performing image stabilization control.

  A sheet as a transfer medium is stored in the sheet feeding unit 301. A scanner 201 that reads an image from a document is provided on the upper part of the image forming apparatus.

  <Functional configuration of image forming apparatus>

  FIG. 2 is a block diagram illustrating the configuration of the control unit of the image forming apparatus.

  The image forming apparatus 1 mainly includes an engine control unit 501 that controls the image forming unit and a controller 513 that controls the engine control unit 501.

  The engine control unit 501 includes a YMCK replenishment motor 503 serving as a member that outputs a signal from the engine control unit 501, and a toner replenishment door open / closed state sensor serving as a member to which the engine control unit 501 inputs a signal. 505, a front door open / close state sensor 507, a toner density sensor 153 of each YMCK developer, and a memory 511 of each YMCK toner cartridge are connected.

  The engine control unit 501 and the controller 513 are connected by communication means. The controller 513 transmits a print command, and the engine control unit 501 transmits various toner empty information.

  The controller 513 is connected to the operation panel 515 through communication, accepts user input, and notifies the user of various information.

  The toner concentration sensor 153 is a sensor that detects the magnetic permeability of the developer in the developing device.

  The engine control unit 501 detects the remaining amount of toner in each color toner cartridge. That is, the amount of toner consumed by forming an image is calculated based on the image information. Here, it is assumed that the toner consumption amount is calculated based on the dot count result obtained by counting the dots of the image.

  The engine control unit 501 controls the toner concentration in the developer to be constant based on the magnetic permeability of the developer in the developing device detected by the toner concentration sensor 153. As already described, in an image forming apparatus using a two-component developer, toner is replenished from the toner cartridge to the developer based on the magnetic permeability of the developer in the developer. Thereby, control is performed to keep the toner density in the developing device constant. Here, when the magnetic permeability increases and the toner density falls below the lower limit value, the engine control unit 501 replenishes toner from the toner cartridge to the developing device by rotating the toner replenishing motor corresponding to the color for a predetermined time T1.

  When the toner supply motor is rotated and the toner density is equal to or less than a threshold value for determining that the toner is empty even after a predetermined time T2 (for example, 5 seconds) has elapsed, it is determined that the toner has run out.

  Information on the remaining amount of toner in the toner cartridge is notified using the operation panel 515 based on the detection result of the remaining amount of toner. For example, according to the detected toner remaining amount, information such as the toner remaining rate, the time to prepare a replacement toner cartridge, and information indicating that the toner cartridge has become empty is notified in a timely manner.

  <Configuration of toner cartridge>

  FIG. 3 is a perspective view of one of the toner cartridges 101.

  As shown in FIG. 3, the toner cartridge 101 that stores each developer includes a storage unit 21, a discharge port 22, and an operation unit 23.

  The storage unit 21 is filled with toner to be supplied to the corresponding developing device, that is, the same type of toner as the developer used in the corresponding developing device.

  The transport pipe is disposed between the developing device and the toner cartridge, and an upper end portion thereof is connected to the toner cartridge, and a lower end portion thereof is connected to the developing device.

  The toner cartridge 101 is configured to be detachable from the apparatus main body. For example, when the developer in the storage unit 21 runs out, the user takes out the empty toner cartridge 101 from the apparatus main body, and installs a new toner cartridge 101 instead. As a result, the toner cartridge can be easily replaced.

  The toner cartridge 101 is attached / detached by the user opening the exterior cover and holding the operation unit 23 to push the toner cartridge 101 into the back of the apparatus or pull it out toward the front of the apparatus. Of course, it is not limited to such a configuration as long as it is detachable.

  A shutter mechanism is provided at the discharge port 22 of the toner cartridge 101. This is to prevent toner spillage when the toner cartridge is detached. When the toner cartridge 101 is attached to the apparatus main body, the shutter is opened. When the toner cartridge 101 is removed from the apparatus main body, the shutter is closed.

  FIG. 4 is a perspective view of a part of the toner cartridge 101 as seen from the opposite direction to that of FIG.

  When the toner cartridge 101 is inserted into the main body, the screw gear is coupled to the main body, and the shutter mechanism is further opened. When the toner replenishing motor 503 is rotated in this state, the conveying screw (stirring blade) 151 of the cartridge rotates, and the toner is replenished to the developing device.

  When the toner cartridge is replaced after the occurrence of toner empty, the forced toner replenishment sequence operates. The shutter opens even when the drive gear of the main body and the screw of the cartridge are not meshed during the forced toner supply. For this reason, even if the replenishment mechanism on the cartridge side is not operating (even if the conveying screw 151 does not rotate), some toner falls to the developing device.

  The toner cartridge 101 is provided with an EEPROM substrate (memory, storage unit) 511 and stores the remaining amount of toner, color, type, and the like.

  <Developer configuration>

  FIG. 5 is a diagram illustrating a configuration of a developing device included in the image forming unit 105.

  The developing device 109 includes a developing roller 161 that attaches toner to the photosensitive member 157, conveying screw portions 159a and 159b that stir and convey the toner, and a toner concentration (TCR) sensor 153 that detects the toner concentration in the developing device. And a mylar 155 that rotates with the rotation of the stirring member 159a and cleans the surface of the toner concentration sensor 153.

  The toner density sensor 153 is a magnetic toner density sensor attached below each color developing device. The toner concentration sensor 153 detects the mixing ratio (toner concentration) of toner and carrier. By this detection, the toner replenishment amount is determined.

  In detecting the toner density, the magnetic permeability of iron contained in the carrier per unit volume around the magnetic toner density sensor installed on the bottom surface in the developing device is read. Accordingly, the toner density decreases as the AD conversion value (resolution 10 bits) of the analog signal read by the sensor increases. In order to clean the surface of the toner concentration sensor 153, the mylar 155 provided in the conveying screw portion 159a scrapes off the toner of the toner concentration sensor 153. Since the toner density sensor 153 is integrated with the imaging unit (image forming unit), it is necessary to replace the imaging unit in order to replace the toner density sensor.

  As a trouble detection, when the toner concentration obtained from the toner concentration sensor 153 is abnormally high or low, the machine is stopped as a trouble of the toner concentration sensor 153 abnormality. In the event of an abnormal trouble with the toner density sensor 153, the imaging unit must be replaced.

  <About trouble detection>

  It is necessary to prevent smoke and carrier consumption when the toner concentration in the developing device cannot be detected normally due to a failure of the toner concentration sensor 153 or when normal toner replenishment is not performed correctly due to a failure of the replenishment mechanism. For this reason, when the input from the toner concentration sensor 153 deviates greatly from the normal use region, the engine control unit 501 detects the toner concentration sensor abnormality and stops the apparatus.

  There are two types of toner density sensor abnormality, high abnormality and low abnormality, and these are detected individually for YMCK.

  The toner density sensor abnormality detection is performed during the printing operation and when the developing device is rotating.

  [Detection method for abnormal toner concentration]

  The toner density (Tc) in the developing device determined by the toner replenishment amount determination control is

  Tc [%] ≧ 12 [%]

  Is detected 20 times consecutively, it is determined that the abnormality is high, and the higher-level controller 513 is notified. In this way, a high toner density abnormality is detected.

  [Detection method for low toner concentration abnormality]

  The toner density (Tc) in the developing device determined by the toner replenishment amount determination control is

  Tc [%] ≦ 6 [%]

  Is detected 20 times consecutively, it is determined that the abnormality is low, and the higher-level controller 513 is notified. In this way, a low toner density abnormality is detected.

  [Near empty state, abnormal condition immediately after cartridge replacement]

  However, when a low toner concentration abnormality is detected in the near empty state and immediately after the replacement of the toner cartridge, a transition to the toner empty state is made without causing the trouble of the low toner concentration.

  This is because when the toner concentration is low in the near empty state, it is considered that the toner has actually run out. Further, when the toner concentration becomes low immediately after the cartridge replacement, there is a high possibility that the toner is not sent from the cartridge to the developing device due to a cartridge mounting error.

  <Operation Performed by Image Forming Apparatus>

  The following control is performed as detection / removal of the toner cartridge and detection of the life.

  (A) Toner cartridge detection / new article detection timing

  As toner cartridge detection control, when the front door sensor 507 detects that the front door is closed, data is confirmed by accessing an EEPROM (memory substrate) 511 of each toner cartridge unit.

  Based on the data, it is determined whether or not a cartridge is mounted. After the cartridge is detected, it is determined whether or not the cartridge is new based on the data on the memory board.

  (B) Toner remaining amount detection control

  The state of the remaining amount of toner is divided into three states: (a) normal, (b) near empty, and (c) empty. (A) Normal means that the number of printable sheets is 1K (1000 sheets) or more. (A) Near empty means a state where the number of printable sheets is less than 1K. (C) Empty means a state in which the remaining amount of toner is zero.

  (C) Toner near empty detection control

  When a new toner cartridge is set, toner remaining amount information is set on the EEPROM substrate. The toner replenishment amount is calculated from the rotation time (or dot count) of the toner replenishment motor, and the toner remaining amount information is subtracted. Thereafter, when the toner is subtracted to a predetermined toner remaining amount, a toner near empty is displayed on the operation panel 515.

  (D) Toner empty control

  After the near empty detection, the toner density detected by the toner density sensor 153 is compared with the target toner density at every toner density detection timing to detect a density difference. When the toner density detection sensor 153 detects that the toner density in the developing device is (target toner density-1%) 30 times continuously, it is determined as toner empty, and this is displayed on the operation panel 515. At this time, printing is prohibited.

  FIG. 6 is a flowchart showing control of toner empty detection.

  In step S1, when a new toner cartridge is set, the normal state is set. At this time, the toner replenishment amount to the developing device is integrated. If the remaining amount of toner in the toner cartridge becomes equal to or less than a predetermined value based on the integration result, the process proceeds to step S3 and a near empty state is set.

  FIG. 7 is a diagram showing a display on the operation panel 515 in the toner near empty state.

  In addition to the normal operation panel 515 display, a message “Toner cartridge (Y) is about to be replaced soon” is displayed on the screen. In response to this, the user prepares a Y toner cartridge. A message is displayed for each color of toner that is in a nearly empty state.

  When the near empty state is reached in step S3 of FIG. 6, if the toner density is detected by the toner density sensor and the toner density remains below the predetermined value even if the toner is supplied to the developing device, the process proceeds to step S5, where the toner is Empty (print prohibited state).

  FIG. 8 is a diagram showing a display on the operation panel 515 in the toner empty state.

  Here, instead of the normal operation panel 515 display, a message indicating that there is no toner of a certain color and a procedure for replacing the toner cartridge are displayed on the screen (in this case, a message indicating that the Y color toner is used up is displayed). Have been). In response to this, the user replaces the Y toner cartridge. A message is displayed for each toner color that has become empty.

  FIG. 9 is a diagram showing the state of the apparatus in three cases of normal, near empty, and empty.

  In the normal state, the printing is permitted. The panel is displayed normally (no indication about empty). This is a state in which the toner cartridge and the sub hopper are sufficiently filled with toner.

  In toner near empty, a print permission state is entered. The panel displays “Toner cartridge replacement time soon” as a one-line message. This is a state where the toner in the toner cartridge is low.

  In the case of toner empty, printing is prohibited. A full-screen warning is displayed on the panel, “Toner is out. Please replace the toner cartridge and close the toner supply door”. This is a state in which the toner in the toner cartridge is emptied, and the toner density further decreases, so that printing cannot be continued.

  FIG. 10 is a flowchart showing the forced toner supply process, and FIG. 11 is a diagram showing the numerical values in FIG.

  This is a process for performing forced toner replenishment for canceling toner empty. The forced toner supply process is started when the user opens the front door of the image forming apparatus, replaces the toner cartridge, and closes the front door. Hereinafter, each step will be described.

  (Step 1)

  This sequence is started when the toner cartridge is replaced and the front door is closed.

  For example, when only K color toner is supplied, only the sequence for the K photoconductor is started. In other cases, a sequence for all color photoconductors is started. For colors other than the color for which the empty is to be canceled, the drive around the photosensitive member is started, but the replenishment control is not performed. The charging and developing bias DC output settings in the photoreceptor startup sequence are set to values determined in the immediately preceding image stabilization process.

  (Step 2)

  When all the developing sleeves have reached stable rotation by starting up the photosensitive member, the process proceeds to Step 3.

  (Step 3)

  If the number of times that the processing from Step 3 to Step 8 is performed for the color for which toner supply is specified is less than N3 times, the developing device is agitated for a period of time T1 and then proceeds to Step 4 (specific values such as T1). See FIG. 11 for an example).

  For colors for which toner replenishment is not specified, the process proceeds to Step 9 as completion of replenishment.

  Steps 4 to 8 are processes performed only with the supply designation color.

  (Step 4)

  After completion of stirring at time T1, sampling of the toner density sensor output is started. The sampling period is T2, and the number of samplings is N1. An arithmetic average of all the sampling results is taken and used as an output value of the toner density sensor.

  (Step 5)

  Based on the sampled toner density sensor output, the toner density in the developing device is calculated. When the toner density in the developing device is smaller than the target toner density N4 [%], the process proceeds to Step 6. If the target toner density is N4 [%] or more, the process proceeds to Step 9) as completion of replenishment (or the process ends normally).

  If the replenishment to sampling process is performed N2 times or more, the process proceeds to Step 9 as completion of replenishment.

  (Step 6)

  The toner replenishing motor is driven to replenish toner for each color for a time T3.

  (Step 7)

  After completion of the toner supply operation, the inside of the developing device is stirred for a time T4.

  (Step 8)

  The process of Step 6 and Step 7 is repeated N2 times, and when completed, the process proceeds to Step 9.

  (Step 9)

  During time T5, the inside of the developing device is stirred, and then the process proceeds to Step 10.

  (Step 10)

  Perform sampling processing. This is the same as the processing in Step 4. After the sampling process, the process proceeds to Step 11.

  (Step 11)

  The toner density is determined. This is the same as the processing in Step 5. When the toner density in the developing device is smaller than the target toner density, the process proceeds to Step 12. When the toner density is not less than the target toner concentration, the process proceeds to normal end (Step 13) as completion of replenishment.

  (Step12)

  If the number of replenishment to sampling processes is less than N3, the process returns to the replenishment process (Step 6). In the case of N3 times or more, the process proceeds to the abnormal end process (Step 13).

  (Step 13)

  When all the replenishing operations are completed, the photosensitive member falling-down sequence is started. If the forced toner supply during the initial engine operation ends abnormally (the toner concentration does not reach the target toner concentration), the state transits to the toner empty state. When abnormal termination occurs N5 times in succession, a trouble (toner density (TC) low abnormality) is notified.

  The forced toner replenishment sequence in FIG. 10 determines that the toner has been correctly replenished from the toner cartridge and the toner density has been restored, and the empty state is canceled. When the shutter mechanism of the toner cartridge is opened, the toner falls, and the toner density may be recovered even if the screw in the cartridge is not rotating well.

  <Control after toner cartridge replacement>

  In the present embodiment, after the toner cartridge is replaced and the toner empty is released, the toner concentration low abnormality immediately after the toner empty is processed as a toner empty. Here, when the estimated toner remaining amount of the cartridge is between 500 (new) and 450 g, even if the toner concentration by the sensor is less than 6%, no trouble occurs and it is empty.

  FIG. 12 is a flowchart showing toner density detection processing during printing.

  When the printing operation is started (S100), the toner density of each color developer is detected by the toner density sensor (S101). The developing device having a toner concentration of 8% or less performs toner replenishment by driving the replenishment motor 503 (S102). When toner is replenished, the remaining amount counter of the toner cartridge is subtracted at the same time. The value of the remaining amount counter is written in the nonvolatile memory of the cartridge. The initial value of the remaining amount counter (when new) is assumed to be 500 g. In a developing device having a toner density exceeding 8%, the processing in step S102 is skipped.

  Next, it is determined whether or not the toner density is low (S103). The determination algorithm for low toner density abnormality is as described above. When the condition of low toner concentration is satisfied, the remaining amount counter is referred to, and when 500 to 450 g, the toner is empty (S104), and when it is 449 g or less, a trouble is caused (S105).

  If the value of the remaining amount counter is large and the toner concentration decreases, there is a high possibility that the drive gear of the main body and the screw of the cartridge are not coupled when the cartridge is replaced. For this reason, the toner empty (S104) is temporarily set. By doing so, it is considered that the user checks the insertion of the toner cartridge, so that there is a high possibility that the poor connection will be released.

  Note that instead of the processing in step S104, the apparatus may be stopped and a message prompting inspection of the insertion of the toner cartridge may be displayed.

  The process of FIG. 6 is performed in preference to the process of FIG. 12. When the remaining amount counter is 100 g or less, it is determined that the toner is near empty, and the toner density by the sensor is less than a predetermined value (7%) in the near empty state. It shall be made to shift to an empty state when it becomes.

  FIG. 13 is a diagram showing control relating to the toner of the image forming apparatus according to the first embodiment in comparison with the prior art.

  In the prior art, the state of the apparatus is determined based on the detection result of the toner remaining amount sensor when the estimated remaining amount in the cartridge by the cartridge remaining amount counter is 500 to 100 g and when it is 100 g or less.

  When the estimated remaining amount in the cartridge is 500 to 100 g, if the toner concentration in the developing device detected by the toner concentration sensor is 7% or more, it is determined to be normal. Even if it is 6% -7%, it determines with it being normal. If it is 6% or less, it is determined that there is a trouble (toner density low abnormality).

  When the estimated remaining amount in the cartridge is 100 g or less, if the toner concentration in the developing device detected by the toner concentration sensor is 7% or more, it is determined that the cartridge is near empty. If it is 6% to 7%, it is determined that the toner is empty.

  On the other hand, in the present embodiment, the remaining toner amount when the estimated remaining amount in the cartridge by the remaining cartridge counter is 500 to 450 g, 450 to 100 g, and 100 g or less. The state of the apparatus is determined from the detection result of the sensor.

  When the estimated remaining amount in the cartridge is 500 to 450 g, if the toner concentration in the developing device detected by the toner concentration sensor is 7% or more, it is determined to be normal. Even if it is 6% -7%, it determines with it being normal. If it is 6% or less, it is determined that the toner is empty (or the toner cartridge is not normally mounted).

  When the estimated remaining amount in the cartridge is 450 to 100 g, if the toner concentration in the developing device detected by the toner concentration sensor is 7% or more, it is determined to be normal. Even if it is 6% -7%, it determines with it being normal. If it is 6% or less, it is determined that there is a trouble (toner density low abnormality).

  When the estimated remaining amount in the cartridge is 100 g or less, if the toner concentration in the developing device detected by the toner concentration sensor is 7% or more, it is determined that the cartridge is near empty. If it is 6% to 7%, it is determined that the toner is empty.

  By the above processing, even if the connection between the main body and the toner cartridge is bad and the toner density is lowered, it is possible to prevent the imaging unit from being mistakenly replaced. That is, by removing and inserting the toner cartridge, the error can be canceled, so that the user can perform appropriate abnormality processing. In addition, it is possible to eliminate unnecessary service costs.

  [Second Embodiment]

  Hereinafter, the difference between the image forming apparatus according to the second embodiment of the present invention and that according to the first embodiment will be described.

  FIG. 14 is a flowchart illustrating toner density detection processing during printing performed by the image forming apparatus according to the second embodiment.

  When the printing operation is started (S200), the toner density of each color developer is detected by the toner density sensor (S201). The developing device having a toner concentration of 8% or less performs toner supply by driving the supply motor 503 (S202). When toner is replenished, the history of toner replenishment for the developing device is stored at the same time (S202). The information on the history of toner supply is cleared when the toner cartridge is replaced.

  In a developing device having a toner density exceeding 8%, it is determined whether there is a history of toner replenishment by the developing device. If there is, the fact that there has been a tendency to increase the toner density is stored (S203). This indicates that the toner concentration has exceeded 8% after the toner concentration once becomes 8% or less and toner replenishment (S202) is performed. Therefore, it is recorded that the toner concentration has increased even once due to toner replenishment. Is.

  Next, it is determined whether or not the toner density is low (S204). The determination algorithm for low toner density abnormality is as described above. When the condition of abnormal toner density is satisfied, it is referred to whether or not there is a tendency for the toner density to rise. If not, the toner is empty (S205), and if it is, a trouble is caused (S206).

  Even if the toner replenishing operation is performed, if there is no history of increase in toner density, there is a high possibility that the drive gear of the main body and the screw of the cartridge are not coupled when the cartridge is replaced. For this reason, toner empty (S205) is temporarily set. By doing so, it is considered that the user checks the insertion of the toner cartridge, so that there is a high possibility that the poor connection will be released.

  Note that, instead of the processing in step S205, the apparatus may be stopped and a message prompting inspection of insertion of the toner cartridge may be displayed.

  The process in FIG. 6 is performed in preference to the process in FIG. 14. When the remaining amount counter is 100 g or less, it is determined that it is near empty, and in the near empty state, the toner density by the sensor is less than a predetermined value (7%). It shall be made to shift to an empty state when it becomes.

  FIG. 15 is a diagram illustrating control relating to the toner of the image forming apparatus according to the second embodiment in comparison with the related art.

  In the prior art, the state of the apparatus is determined based on the detection result of the toner remaining amount sensor when the estimated remaining amount in the cartridge by the cartridge remaining amount counter is 500 to 100 g and when it is 100 g or less. This is the same as that described in FIG.

  On the other hand, in the present embodiment, the state of the apparatus is determined by the detection result of the toner remaining amount sensor when the estimated remaining amount in the cartridge by the cartridge remaining amount counter is 500 to 100 g and when it is 100 g or less. Is determined.

  When the estimated remaining amount in the cartridge is 500 to 100 g, the toner replenishment operation is performed, but when the toner concentration detected by the sensor has never increased, the toner concentration in the developing device by the toner concentration sensor detection Is 7% or more, it is determined to be normal. Even if it is 6% -7%, it determines with it being normal. If it is 6% or less, it is determined that the toner is empty (or the toner cartridge is not normally mounted).

  When the estimated remaining amount in the cartridge is 500 to 100 g, when the toner replenishment operation is performed and the toner concentration detected by the sensor has increased even once, the toner concentration in the developing device detected by the toner concentration sensor is If it is 7% or more, it is determined to be normal. Even if it is 6% -7%, it determines with it being normal. If it is 6% or less, it is determined that there is a trouble (toner density low abnormality).

  When the estimated remaining amount in the cartridge is 100 g or less, if the toner concentration in the developing device detected by the toner concentration sensor is 7% or more, it is determined that the cartridge is near empty. If it is 6% to 7%, it is determined that the toner is empty.

  As a result of the above processing, it is determined that the toner concentration low abnormality when the toner concentration does not increase even once the toner is replenished after the toner empty is canceled is toner empty. Thereby, even if the connection between the main body and the toner cartridge is bad and the toner density is lowered, it is possible to prevent the imaging unit from being mistakenly replaced. That is, by removing and inserting the toner cartridge, the error can be canceled, so that the user can perform appropriate abnormality processing. In addition, it is possible to eliminate unnecessary service costs.

  [Effects of the embodiment]

  According to the above-described image forming apparatus, a toner empty is generated, a toner cartridge is replaced, and after the toner empty is released, the toner density low abnormality that has just been released is regarded as toner empty (first embodiment). Form).

  In addition, a toner density low abnormality when the toner density never increases after the cancellation of empty is regarded as toner empty (second embodiment).

  That is, according to the image forming apparatus described above, when the toner cartridge is replaced, the toner concentration in the developing device decreases when the connection between the drive gear of the main body and the screw of the toner cartridge is poor and the replenishment mechanism is not operating properly. At this time, the low toner density abnormality is not detected. Thereby, the user can cancel the error by inserting and removing the toner cartridge without replacing the imaging unit by mistake. Since the user can perform an appropriate abnormality process, it is possible to eliminate unnecessary service costs.

  [Others]

  The image forming apparatus may be a monochrome / color copying machine, a printer, a facsimile machine, or a multifunction machine (MFP) thereof.

  Further, the processing in the above-described embodiment may be performed by software or by using a hardware circuit.

  In addition, a program for executing the processing in the above-described embodiment can be provided, and the program is recorded on paper such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, and a memory card and provided to the user. You may decide. The program may be downloaded to the apparatus via a communication line such as the Internet.

  In addition, it should be thought that the said embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment of the present invention. 2 is a block diagram illustrating a configuration of a control unit of the image forming apparatus. FIG. 2 is a perspective view of one of the toner cartridges 101. FIG. FIG. 4 is a perspective view in which a part of a toner cartridge 101 is seen from a direction opposite to that in FIG. 3. 2 is a diagram illustrating a configuration of a developing device included in an image forming unit 105. FIG. 6 is a flowchart illustrating control of toner empty detection. FIG. 10 is a diagram showing a display on an operation panel 515 in a toner near empty state. FIG. 10 is a diagram illustrating a display on an operation panel 515 in a toner empty state. It is a figure which shows the state of the apparatus in three normally, near empty and empty. 10 is a flowchart illustrating forced toner supply processing. It is a figure which shows the numerical value in FIG. 6 is a flowchart illustrating toner density detection processing during printing. FIG. 6 is a diagram illustrating control related to toner of the image forming apparatus according to the first embodiment in comparison with the related art. 10 is a flowchart illustrating toner density detection processing during printing performed by the image forming apparatus according to the second embodiment. FIG. 10 is a diagram illustrating control related to toner of an image forming apparatus according to a second embodiment in comparison with a conventional technique.

Explanation of symbols

22 Discharge port (shutter)
101Y, 101M, 101C, 101K Toner cartridge 103 Intermediate transfer member 105Y, 105M, 105C, 105K Image forming unit 107 Exposure unit 109 Developer 151 Transport screw (stirring blade)
153 Toner density sensor 157 Photoconductor 159a, 159b Conveying screw unit 161 Developing roller 201 Scanner 301 Paper feeding unit 401 Fixing roller 501 Engine control unit 503 Replenishing motor 505 Toner replenishing door opening / closing state sensor 507 Front door opening / closing state sensor 511 Memory 513 Controller 515 control panel

Claims (14)

A developing device using a two-component developing system;
A toner cartridge that is replaceably attached to the apparatus body;
Replenishment means for replenishing toner from the toner cartridge to the developer;
A sensor for detecting a toner concentration in the developing unit;
After a predetermined period of time has passed since the toner cartridge was replaced, when the toner concentration detected by the sensor falls below the first concentration, a first error is displayed indicating that a trouble has occurred and the device is stopped. Stopping means,
A second stop for stopping the apparatus by performing a display different from the display when the toner density detected by the sensor falls below the first density within a predetermined period after the toner cartridge is replaced. And an image forming apparatus. Measuring means for measuring the remaining amount of toner in the toner cartridge;
2. The image forming apparatus according to claim 1, further comprising a first warning unit that issues a warning of toner near empty when the toner remaining in the toner cartridge becomes equal to or less than a predetermined value by the measuring unit.   3. The apparatus according to claim 2, further comprising: a second warning unit that issues a toner empty warning when the toner density detected by the sensor falls below a second density after the toner near empty warning. The image forming apparatus described in 1.   The image forming apparatus according to claim 2, wherein the predetermined period is a period until the remaining amount of toner in the toner cartridge measured by the measuring unit becomes equal to or less than a predetermined amount.   The image forming apparatus according to claim 1, wherein the predetermined period is a predetermined period after the toner empty is released.   The image forming apparatus according to claim 1, wherein the second stopping unit stops the apparatus by displaying toner empty. A developing device using a two-component developing system;
A toner cartridge that is replaceably attached to the apparatus body;
Replenishment means for replenishing toner from the toner cartridge to the developer;
A sensor for detecting a toner concentration in the developing unit;
When there is a history in which the toner concentration detected by the sensor has increased as a result of toner replenishment after the toner cartridge has been replaced, the toner concentration detected by the sensor is greater than the first concentration. A first stopping means for displaying that a trouble has occurred and stopping the apparatus when
When there is no history in which the toner density detected by the sensor has increased as a result of toner replenishment after the toner cartridge has been replaced, the toner density detected by the sensor is greater than the first density. An image forming apparatus comprising: a second stop unit that stops the apparatus by performing a display different from the display when the display is lowered. Measuring means for measuring the remaining amount of toner in the toner cartridge;
The image forming apparatus according to claim 7, further comprising: a first warning unit that issues a warning of toner near empty when the toner remaining amount of the toner cartridge becomes a predetermined value or less by the measuring unit.   9. The apparatus according to claim 8, further comprising: a second warning unit that issues a toner empty warning when the toner density detected by the sensor falls below a second density after the toner near empty warning. The image forming apparatus described in 1.   The image forming apparatus according to claim 7, wherein the second stopping unit stops the apparatus by displaying toner empty. A developing device using a two-component developing system;
A toner cartridge that is replaceably attached to the apparatus body;
Replenishment means for replenishing toner from the toner cartridge to the developer;
A control method of an image forming apparatus comprising a sensor for detecting a toner concentration in the developing unit,
After a predetermined period of time has passed since the toner cartridge was replaced, when the toner concentration detected by the sensor falls below the first concentration, a first error is displayed indicating that a trouble has occurred and the device is stopped. Stopping step,
A second stop for stopping the apparatus by performing a display different from the display when the toner density detected by the sensor falls below the first density within a predetermined period after the toner cartridge is replaced. And a method for controlling the image forming apparatus. A developing device using a two-component developing system;
A toner cartridge that is replaceably attached to the apparatus body;
Replenishment means for replenishing toner from the toner cartridge to the developer;
A control method of an image forming apparatus comprising a sensor for detecting a toner concentration in the developing unit,
When there is a history in which the toner concentration detected by the sensor has increased as a result of toner replenishment after the toner cartridge has been replaced, the toner concentration detected by the sensor is greater than the first concentration. A first stop step for indicating that a trouble has occurred and stopping the device when
When there is no history in which the toner density detected by the sensor has increased as a result of toner replenishment after the toner cartridge has been replaced, the toner density detected by the sensor is greater than the first density. And a second stop step for stopping the apparatus by performing a display different from the display when the image is lowered. A developing device using a two-component developing system;
A toner cartridge that is replaceably attached to the apparatus body;
Replenishment means for replenishing toner from the toner cartridge to the developer;
A control program for an image forming apparatus comprising a sensor for detecting a toner density in the developing unit;
After a predetermined period of time has passed since the toner cartridge was replaced, when the toner concentration detected by the sensor falls below the first concentration, a first error is displayed indicating that a trouble has occurred and the device is stopped. Stopping step,
A second stop for stopping the apparatus by performing a display different from the display when the toner density detected by the sensor falls below the first density within a predetermined period after the toner cartridge is replaced. And a step of causing the computer to execute the steps. A developing device using a two-component developing system;
A toner cartridge that is replaceably attached to the apparatus body;
Replenishment means for replenishing toner from the toner cartridge to the developer;
A control program for an image forming apparatus comprising a sensor for detecting a toner density in the developing unit;
When there is a history in which the toner concentration detected by the sensor has increased as a result of toner replenishment after the toner cartridge has been replaced, the toner concentration detected by the sensor is greater than the first concentration. A first stop step for indicating that a trouble has occurred and stopping the device when
When there is no history in which the toner density detected by the sensor has increased as a result of toner replenishment after the toner cartridge has been replaced, the toner density detected by the sensor is greater than the first density. A program for controlling the image forming apparatus to cause the computer to execute a second stop step for stopping the apparatus by performing a display different from the above display.

Images