Image forming apparatus

Abstract

To provide an image forming apparatus that can prevent the occurrence of an image defect by sufficiently stirring developer.SOLUTION: An image forming apparatus comprises a developing device, and a control unit 6 (control means) that controls the developing device. The developing device has a developer carrier, stirring means that stirs developer, and a concentration sensor 224 (measurement means) that measures the concentration of toner in the developer. The control unit 6 has a peripheral environment acquisition unit 70 (peripheral environment acquisition means) that acquires a peripheral environment of the developing device, and a determination unit 75 (determination means) that determines whether a measured value from the measurement means has become stable based on a predetermined condition. In a non-image forming period, the image forming apparatus can execute a stirring mode for causing the stirring means to stir the developer until the determination means determines that the measured value has become stable. The image forming apparatus acquires, with the peripheral environment acquisition unit 70, the peripheral environments before and after the time during which the stirring means is left standing, and executes the stirring mode based on the difference between the peripheral environments acquired by the peripheral environment acquisition unit 70 before and after the time during which the stirring means is left standing.SELECTED DRAWING: Figure 5

Description

【Technical Field】 【0001】 The present disclosure relates to an image forming apparatus such as a copying machine, a multifunction peripheral, a printer, and a facsimile machine. 【Background Art】 【0002】 Conventionally, a developing device that supports a two-component developer containing toner and a carrier on the surface of a developer carrier and develops an electrostatic latent image formed on an image carrier has been widely used. A toner image is formed on the image carrier by attaching the toner charged by friction with the carrier to the electrostatic latent image of the image carrier. 【0003】 If the charge amount of the toner in the developing device is too high, it becomes difficult for the toner to separate from the carrier and the image density decreases. On the other hand, if the charge amount of the toner in the developing device is too low, so-called toner fogging occurs where the non-image portion on the image carrier becomes dirty. For this reason, at the time of image formation, it is required to accurately control the charge amount of the toner in the developing device. In particular, when the image forming apparatus is left unused for a long time, the charge amount of the toner decreases due to natural discharge. Therefore, it is desirable to stir the developer to increase the charge amount of the toner before the image forming apparatus performs the image forming process again. As a technique for stirring the developer, for example, a technique is known in which the change in the charge amount of the toner is estimated based on the standing time and the humidity environment, and the developer is stirred for a stirring time corresponding to the change in the charge amount of the toner (see, for example, Patent Document 1). 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Laid-Open No. 11-212343 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 However, in the conventional technology described above, depending on conditions other than the standing time and humidity, the prediction of changes in the toner's charge may not be accurate, and consequently, the stirring time may not be sufficient to respond to the changes in the toner's charge. For example, the charge of toner changes with various conditions such as the deterioration of magnetic carriers, but the conventional technology described above does not take into account the deterioration conditions of magnetic carriers, and depending on the degree of deterioration of magnetic carriers, the developer may not be sufficiently stirred. If the developer is not sufficiently stirred, image defects such as toner fogging may occur. 【0006】 Furthermore, attempting to set the developer agitation time according to various conditions such as the degradation conditions of magnetic carriers could lead to complex control. 【0007】 This disclosure is made to solve the above-mentioned conventional problems and aims to provide an image forming apparatus that can suppress the occurrence of image defects by sufficiently stirring the developer. [Means for solving the problem] 【0008】 To achieve the above objective, the image forming apparatus disclosed herein is an image forming apparatus comprising a developing apparatus and control means for controlling the developing apparatus, wherein the developing apparatus comprises a developer carrier, a stirring means for stirring a developer supplied to the developer carrier, and a measuring means for measuring the concentration of toner in the developer stirred by the stirring means, the control means comprises a surrounding environment acquisition means for acquiring the surrounding environment of the developing apparatus and a determination means for determining whether the measured value of the measuring means has stabilized based on predetermined conditions, and during non-image forming, an stirring mode can be executed in which the stirring means stirs the developer until the determination means determines that the measured value has stabilized, the surrounding environment is acquired by the surrounding environment acquisition means before and after the standing time of the stirring means, and the stirring mode is executed based on the difference in the surrounding environment acquired by the surrounding environment acquisition means before and after the standing time. 【0009】 Other image forming apparatuses disclosed herein include an image forming apparatus comprising a developing apparatus and a control means for controlling the developing apparatus, wherein the developing apparatus comprises a developer carrier, a stirring means for stirring a developer supplied to the developer carrier, and a measuring means for measuring the concentration of toner in the developer stirred by the stirring means, the control means comprises a standing time acquisition means for acquiring the standing time of the stirring means, and a determination means for determining whether the measured value of the measuring means has stabilized based on predetermined conditions, and is capable of executing a stirring mode during non-image forming, in which the stirring means stirs the developer until the determination means determines that the measured value has stabilized, and is characterized in that the stirring mode is executed based on the standing time acquired by the standing time acquisition means. 【0010】 Further image forming apparatuses disclosed herein include an image forming apparatus comprising a developing apparatus and control means for controlling the developing apparatus, wherein the developing apparatus comprises a developer carrier, a stirring means for stirring a developer supplied to the developer carrier, and a measuring means for measuring the concentration of toner in the developer stirred by the stirring means, the control means comprises a surrounding environment acquisition means for acquiring the surrounding environment of the developing apparatus, a standing time acquisition means for acquiring the standing time of the stirring means, and a determination means for determining whether the measured value of the measuring means has stabilized based on predetermined conditions, and is capable of executing a stirring mode during non-image forming, in which the stirring means stirs the developer until the determination means determines that the measured value has stabilized, the surrounding environment is acquired by the surrounding environment acquisition means after the standing time, and the stirring mode is executed based on the surrounding environment acquired by the surrounding environment acquisition means after the standing time and the standing time acquired by the standing time acquisition means. 【0011】 In the image forming apparatus, the stirring means is configured to include a rotating shaft and a helical blade formed on the outer circumference of the rotating shaft, which is capable of periodically changing the measured value of the measuring means, and the determination means may calculate a first average value representing the average value of the measured values ​​for each period of the measured value, and determine whether the measured value has stabilized based on the difference between the first average value calculated in the current period and the first average value calculated in the previous period. 【0012】 In the image forming apparatus, the stirring means includes a rotating shaft and a helical blade formed on the outer circumference of the rotating shaft, which is capable of periodically changing the measured value of the measuring means. The determination means may calculate a first average value representing the average value of the measured values ​​for each period of the measured value, and further calculate a second average value representing the average value of the first average value for N periods (where N is a natural number of 2 or more) prior to the current period, and determine whether the measured value has stabilized based on the difference between the second average value calculated in the current period and the second average value calculated in the previous period. 【0013】 In the image forming apparatus, the resting time may be the time from when the stirring means was last stopped until the image forming apparatus is turned off and then performs a warm-up. 【0014】 In the aforementioned image forming apparatus, the idle time may be the time from when the power to the image forming apparatus was last turned off until the image forming apparatus performs a warm-up. 【0015】 In the image forming apparatus, the control means may determine whether or not to perform the stirring mode when the image forming apparatus performs a warm-up. 【0016】 In the image forming apparatus, the control means may perform process control processing to adjust the image forming conditions of the image forming apparatus after the execution of the stirring mode. [Effects of the Invention] 【0017】 According to the present disclosure, the occurrence of image defects can be suppressed. 【Brief Description of the Drawings】 【0018】 [Figure 1] It is a schematic cross-sectional view showing the configuration of the image forming apparatus in Embodiment 1. [Figure 2] It is a schematic cross-sectional view showing the developing device and its surroundings in Embodiment 1. [Figure 3] It is a schematic perspective view showing the developing device in FIG. 2. [Figure 4A] It is a schematic diagram for explaining the relative positional relationship between the density sensor and the spiral blades in the stirring member. [Figure 4B] It is a diagram showing an example of the measured value of the density sensor. [Figure 5] It is a block diagram showing the control unit in Embodiment 1. [Figure 6] It is a diagram showing an example of the environmental zone table. [Figure 7] It is a flowchart showing an example of the processing procedure by the control unit in Embodiment 1. [Figure 8] It is a flowchart showing an example of the processing procedure in the stirring mode in Embodiment 1. [Figure 9] It is a diagram showing an example of the change in the second average value due to the execution of the stirring mode when the image forming apparatus is left in a high-temperature and high-humidity environment. [Figure 10] It is a diagram showing an example of the change in the second average value due to the execution of the stirring mode when the image forming apparatus is left in a low-temperature and low-humidity environment. [Figure 11] It is a block diagram showing the control unit in Embodiment 2. [Figure 12] It is a flowchart showing an example of the processing procedure by the control unit in Embodiment 2. [Figure 13] It is a block diagram showing the control unit in Embodiment 3. [Figure 14] It is a diagram showing an example of the placement time table. [Figure 15] This flowchart shows an example of the processing procedure by the control unit in Embodiment 3. [Modes for carrying out the invention] 【0019】 The embodiments of this disclosure will be described below with reference to the attached drawings. The same reference numerals will be used for identical components in each embodiment described below, and redundant descriptions of those components will be omitted. 【0020】 (Embodiment 1) -Overall configuration of the image forming apparatus- First, the overall configuration of the image forming apparatus A in Embodiment 1 will be described. 【0021】 Figure 1 is a schematic cross-sectional view showing the configuration of the image forming apparatus A in Embodiment 1. 【0022】 Image forming apparatus A is an electrophotographic image forming apparatus and is a color multifunction printer with an intermediate transfer method capable of printing full-color images. Image forming apparatus A comprises an image reading unit 10 and an image forming apparatus body 11 (see Figure 1). In this embodiment, yellow (Y), magenta (M), cyan (C), and black (K) toners are used for printing by image forming apparatus A. 【0023】 The image reading unit 10 reads images from the original document and is located at the top of the image forming apparatus A. The image reading unit 10 includes a document reading device 12, a document placement table 13, and an automatic document processing device 14 (see Figure 1). 【0024】 The document scanning device 12 illuminates the document with light and reads an image from the document based on the reflected light. The document scanning device 12 incorporates, for example, a light source for illuminating the document, a lens and an image sensor, and a mirror that guides the reflected light from the document to the lens. The reflected light from the document, which enters the image sensor via the lens, is photoelectrically converted by the image sensor to generate image data corresponding to the image of the document. The image data may be generated by the image reading unit 10 or supplied by an external device. 【0025】 The document tray 13 is the part on which the user places the document and is located above the document reader 12. The document tray 13 is made of transparent glass. The automatic document processing device 14 automatically and continuously transports the document inserted by the user to the document reader 12 and is located above the document tray 13. The image of the document is read by the document reader 12 either while it is placed on the document tray 13 or while it has been transported to the document reader 12 by the automatic document processing device 14. 【0026】 The image forming apparatus body 11 includes an image forming section 20, an intermediate transfer body 3, a secondary transfer section 40, a fixing device 42, a sheet storage section 43, a sheet roller group 5, and a sheet discharge section 44 (see Figure 1). The image forming apparatus A is provided with a sheet transport path S through which sheets are transported. 【0027】 The image forming unit 20 forms toner images of each color based on image data. The image forming unit 20 includes an exposure device 21, a developing device 22, a photoreceptor drum 23 (image carrier), a charger 24, and a cleaning device 25 (see Figure 1). There are four developing devices 22, four photoreceptor drums 23, four chargers 24, and four cleaning devices 25 for each color. 【0028】 The exposure apparatus 21 forms electrostatic latent images corresponding to each color on the photoreceptor drum 23 by exposing the surface of the photoreceptor drum 23 based on image data. The exposure apparatus 21 incorporates a light source that emits a laser beam, a polygon mirror that scans and reflects the laser beam, and optical elements (e.g., lenses and mirrors) for guiding the reflected laser light to the photoreceptor drum 23. The exposure apparatus 21 may also expose the surface of the photoreceptor drum 23 with an intensity corresponding to the density data included in the image data. 【0029】 The developing device 22 visualizes the electrostatic latent images formed on the surface of each photoreceptor drum 23 by using toners of each color (Y, M, C, K) supplied from the toner cartridge T to create a toner image. The configuration of the developing device 22 will be explained in detail later. 【0030】 The photoreceptor drum 23 has an electrostatic latent image formed on its surface and is rotated in a predetermined direction by the drive of a main motor (not shown). 【0031】 The charger 24 uniformly charges the surface of the photoreceptor drum 23 to a predetermined potential (for example, around -600V). The charger 24 can be a contact-type charger (for example, a roller-type or brush-type charger) or a charger-type charger. 【0032】 The cleaning device 25 removes and recovers residues (such as residual toner) remaining on the surface of the photoreceptor drum 23 after development and image transfer. 【0033】 Through a series of operations based on the configurations of the image forming unit 20 described above, toner images of each color are formed on the surface of each photoreceptor drum 23. 【0034】 The intermediate transfer unit 3 is used for primary transfer and is positioned above the photoreceptor drum 23 (see Figure 1). Here, "primary transfer" refers to the transfer of the toner images of each color formed on the photoreceptor drum 23 onto the intermediate transfer belt 30. The intermediate transfer unit 3 includes the intermediate transfer belt 30, a drive roller 31, a driven roller 32, and primary transfer rollers 33 (see Figure 1). There are four primary transfer rollers 33, one for each color. 【0035】 The intermediate transfer belt 30 is an endless belt that rotates in a predetermined direction and is suspended by a drive roller 31 and a driven roller 32. The toner images of each color, which are visualized on the photoreceptor drum 23, are sequentially transferred onto the intermediate transfer belt 30 and transported to the secondary transfer section 40 by the rotation of the intermediate transfer belt 30. The intermediate transfer belt 30 is formed from, for example, a film with a thickness of about 100 μm to 150 μm. The drive roller 31 is a roller that is driven to rotate in a predetermined direction by a belt motor (not shown) and is provided on one end of the intermediate transfer body 3. The rotation of the drive roller 31 causes the intermediate transfer belt 30 to rotate. The driven roller 32 is a roller that is rotatably mounted along the intermediate transfer belt 30. The driven roller 32 rotates in accordance with the rotation of the intermediate transfer belt 30. The primary transfer rollers 33 are arranged in a row corresponding to the photoreceptor drum 23 via the intermediate transfer belt 30. By applying a transfer bias to the primary transfer roller 33, the toner image from the photoreceptor drum 23 is transferred to the intermediate transfer belt 30. 【0036】 The secondary transfer unit 40 is used for secondary transfer and is located on the sheet transport path S. Here, "secondary transfer" refers to the transfer of the toner images of each color transferred onto the intermediate transfer belt 30 to the sheet. The secondary transfer unit 40 has a secondary transfer roller 41 provided at the transfer area where the sheet and the intermediate transfer belt 30 face each other. A voltage is applied to the secondary transfer roller 41 to transfer the toner images of each color on the intermediate transfer belt 30 to the sheet. 【0037】 The fixing device 42 fixes the toner image onto the sheet by heating and melting the toner image that has been secondarily transferred onto the sheet, thereby fixing it onto the sheet, and is located downstream of the secondary transfer section 40 in the sheet transport path S. 【0038】 The sheet storage section 43 houses the sheets used for image formation and is located at the bottom of the image forming apparatus A. 【0039】 The sheet roller group 5 includes a pickup roller 5a, transport rollers 5b and 5c, and a registration roller 5d. The pickup roller 5a pulls out the top layer of sheets from the sheet storage section 43 and transports them to the sheet transport path S. The transport rollers 5b and 5c transport the sheets along the sheet transport path S. The registration roller 5d temporarily stops the sheets being transported from the sheet storage section 43 and aligns the leading edges of the sheets. Each of these sheet rollers 5 is rotated by a motor (not shown). 【0040】 The sheet ejection unit 44 is located at the top of the image forming apparatus A and loads the printed sheets face down. 【0041】 In addition to the configuration described above, the image forming apparatus A includes an environmental sensor 90 (for example, a temperature and humidity sensor) for measuring the surrounding environment of the developing apparatus 22, and a control unit 6 (control means) for controlling the developing apparatus 22. The configuration of the control unit 6 will be described in detail later. 【0042】 The image forming apparatus A described above performs printing on the sheet as follows: First, the image forming unit 20 forms a toner image on the photoreceptor drum 23 based on image data generated by the image reading unit 10 or supplied from an external device. The primary transfer roller 33 transfers this toner image to the intermediate transfer belt 30 of the intermediate transfer body 3. During this time, the pickup roller 5a pulls the sheet out of the sheet storage unit 43, the transport rollers 5b and 5c transport the sheet to the register roller 5d, and the register roller 5d transports the sheet to the secondary transfer unit 40. Subsequently, the secondary transfer unit 40 transfers the toner image that was primarily transferred onto the intermediate transfer belt 30 to the sheet. The fixing device 42 fixes the toner image that was secondarily transferred onto the sheet. After that, the sheet is discharged onto the sheet discharge unit 44, and printing on the sheet is completed. 【0043】 -Developing equipment- Next, the configuration of the developing apparatus 22 in this embodiment will be described. 【0044】 Figure 2 is a schematic cross-sectional view showing the developing apparatus 22 and its surroundings in Embodiment 1. Figure 3 is a schematic perspective view showing the developing apparatus 22 of Figure 2. In Figure 2, reference numeral R1 indicates the rotation direction of the developing roller 222, and reference numeral R2 indicates the rotation direction of the photoreceptor drum 23. Also, in Figures 2 and 3, in order to avoid making the drawings complicated, reference numerals for the rotating shaft 225 and the spiral blade 226 are only given to the stirring member 220. 【0045】 The developing apparatus 22 includes a developing tank 22a, two stirring members 220 and 221 (stirring means), a developing roller 222 (developer carrier), a regulating member 223, and a concentration sensor 224 (measuring means) (see Figure 2). 【0046】 The developing tank 22a is a container in which the developer is stored. The developer used is a two-component developer containing a non-magnetic toner and a magnetic carrier. 【0047】 The agitators 220 and 221 agitate the developer stored in the developing tank 22a and each comprises a rotating shaft 225 and a spiral blade 226 formed on the outer circumference of the rotating shaft 225 (see Figure 3). The agitators 220 and 221 are arranged in the developing tank 22a with their rotating shafts 225 facing each other in parallel, and the agitator 221 is positioned near the developing roller 222. In the developing tank 22a, a partition wall 22b extending in the axial direction of the rotating shaft 225 is formed between the agitators 220 and 221 to divide the internal space into two spaces in which the agitators 220 and 221 are respectively housed (see Figures 2 and 3). On the axial side of the rotating shaft 225, beyond the partition wall 22b of the developing tank 22a, there is a toner supply port 22c for supplying toner into the developing tank 22a and a developer discharge port 22d for discharging developer out of the developing tank 22a. 【0048】 The rotating shafts 225 of each agitator 220 and 221 receive rotational driving force from the agitator drive unit 95 via gears or the like (not shown) and rotate in opposite directions. As the agitator 220 and 221 rotate, the developer is agitated so that it circulates around the partition wall 22b. The rotation of the agitator 221 also transports the developer to the developer roller 222. The agitation by the agitator 220 and 221 creates friction between the toner contained in the developer and the magnetic carrier, and this friction causes the non-magnetic toner to become charged. 【0049】 The number of spiral blades 226 may be one or two or more. 【0050】 The developing roller 222 has a surface that carries a developer and is configured to include a sleeve portion 227 and a magnetic roll portion 228 (see Figure 2). The sleeve portion 227 is nonmagnetic, cylindrical in shape, and rotatably supported. The sleeve portion 227 receives rotational driving force from a drive unit (not shown) and rotates in the rotational direction R1. 【0051】 The magnetic roll section 228 is a cylindrical magnetic roll that possesses magnetism, and is housed within the sleeve section 227 such that its outer circumferential surface faces the inner circumferential surface of the sleeve section 227, while also being fixed independently of the sleeve section 227. In other words, the sleeve section 227 is responsible for the rotation of the developing roller 222. 【0052】 The developing roller 222 forms a nip section N with the photoreceptor drum 23. In the nip section N, a developing bias (for example, about -450V) is applied to the developing roller 222 by a bias power supply (not shown). As a result, toner is supplied from the developer supported on the surface of the developing roller 222 to the electrostatic latent image on the surface of the photoreceptor drum 23, and a toner image is formed on the photoreceptor drum 23. 【0053】 The regulating member 223 regulates the thickness of the developer layer being conveyed on the developing roller 222, and is positioned upstream of the developing roller 222 in the rotational direction R1 relative to the photoreceptor drum 23, with a gap between it and the outer surface of the sleeve portion 227 (see Figure 2). 【0054】 The density sensor 224 measures the concentration of toner in the developer agitated by the agitators 220 and 221, and is located near the agitator 220 and opposite the agitator 221 (see Figures 2 and 3). The density sensor 224 is composed of, for example, a permeability sensor capable of measuring the ratio of magnetic carriers in the developer as permeability. The higher the ratio of magnetic carriers, the higher the measurement value of the density sensor 224. Conversely, the lower the ratio of magnetic carriers, the lower the measurement value of the density sensor 224. In other words, the lower the toner concentration, the higher the measurement value of the density sensor 224, while the higher the toner concentration, the lower the measurement value of the density sensor 224. The density sensor 224 outputs the measurement value converted to 8 bits (256 gradations), for example. 【0055】 Figure 4A is a schematic diagram illustrating the relative positional relationship between the concentration sensor 224 and the helical blade 226 in the stirring member 220. In Figure 4A, the symbol D indicates the direction of movement of the helical blade 226. Figure 4B shows an example of a measurement value from the concentration sensor 224. 【0056】 In this embodiment, the measurement value of the concentration sensor 224 changes periodically depending on its relative position to the helical blade 226 on the stirring member 220. Specifically, as shown in Figure 4A, in the case of "time = T1", when the helical blade 226 approaches the concentration sensor 224 due to the rotation of the stirring member 220, the amount of developer present in the region where the concentration sensor 224 measures magnetic permeability inevitably decreases, as shown in Figure 4B, and the measurement value of the concentration sensor 224 decreases. Furthermore, as the stirring member 220 rotates and transitions from the state of "time = T1" to the state of "time = T2" shown in Figure 4A, and the helical blade 226 on the stirring member 220 moves away from the concentration sensor 224, the amount of developer present in the region where the concentration sensor 224 measures magnetic permeability increases, as shown in Figure 4B, and the measurement value of the concentration sensor 224 increases. Then, as shown in Figure 4A, the system transitions from the state where "time = T2" to the state where "time = T3" occurs, and the spiral blades 226 on the stirring member 220 approach the concentration sensor 224 again. As shown in Figure 4B, the amount of developer present in the region where the concentration sensor 224 measures permeability decreases again, causing the measured value of the concentration sensor 224 to decrease again. In this way, the measured value of the concentration sensor 224 changes periodically. The time width of one cycle of the measured value of the concentration sensor 224 depends on the number of spiral blades 226 on the stirring member 220. 【0057】 As will be explained later, the average value over one cycle of the measurements from the concentration sensor 224 is expressed as the first average value Mf (see Figure 4B). 【0058】 Incidentally, if the charge level of the toner in the developing tank 22a of the developing device 22 is too high, the toner will have difficulty separating from the carrier, resulting in a decrease in image density. On the other hand, if the charge level of the toner in the developing tank 22a is too low, so-called toner fogging will occur, where the non-image areas on the photoreceptor drum 23 become dirty. For this reason, it is necessary to precisely control the charge level of the toner in the developing device during image formation. In particular, if the agitators 220 and 221 have been left idle for a long time since they were last stopped, the charge level of the toner will decrease due to natural discharge. Therefore, it is necessary to thoroughly agitate the developer to restore the charge level of the toner before the image forming device A performs image forming processing again. 【0059】 However, the amount of charge in the toner changes with changes in the surrounding environment of the developing device 22. For example, in a high-temperature, high-humidity environment, the toner's charge tends to leak more easily, so the amount of charge in the toner tends to decrease. On the other hand, in a low-temperature, low-humidity environment, the toner tends to become electrostatically charged, so the amount of charge in the toner tends to increase. In particular, when the image forming apparatus A is left unattended for a long time, the changes in the surrounding environment of the developing device 22 become larger, and the changes in the amount of charge in the toner tend to become larger as well. Furthermore, the amount of charge in the toner changes with various conditions such as the deterioration of the magnetic carrier. For this reason, the stirring time of the developer required to restore the amount of charge in the toner can be influenced by various conditions, including changes in the surrounding environment of the developing device 22. 【0060】 Therefore, if we were to try to pre-set an appropriate agitation time according to the conditions under which the charge level of the toner changes, the control would become complicated. If we were to set a uniform agitation time, there is a risk that image defects such as toner fogging may occur due to insufficient agitation of the developer. 【0061】 Furthermore, changes in the charge level of the toner cause changes in the measurement values ​​of the density sensor 224, such as the value indicating the magnetic permeability of the developer. As the charge level of the toner increases, the developer particles repel each other, resulting in a lower bulk density and thus a lower measurement value from the density sensor 224. Conversely, as the charge level of the toner decreases, the developer particles attract each other, resulting in a higher bulk density and thus a lower measurement value from the density sensor 224. For this reason, if the surrounding environment of the developing device 22 changes, the measurement value from the density sensor 224 will change even if the toner concentration remains constant, making it difficult to accurately determine the toner concentration. 【0062】 Therefore, even if the toner concentration is already at the appropriate level after stirring the developer, the image forming apparatus A may incorrectly determine that there is insufficient toner because the measurement value from the density sensor 224 does not correspond to the appropriate value for the toner concentration. This may lead to unnecessary toner being supplied to the developing tank 22a of the developing apparatus 22, potentially resulting in image defects such as toner fogging. 【0063】 Therefore, in order to suppress the occurrence of the above-mentioned image defects, the control unit 6 in this embodiment is characterized in that, when not forming an image, it triboelectrically charges the magnetic carrier and toner until the measurement value of the density sensor 224 reaches an appropriate value corresponding to the toner density, and also thoroughly stirs the developer. In other words, when stirring the developer when not forming an image, the control unit 6 is characterized in that it stirs the developer until the measurement value of the density sensor 224 is considered to have stabilized based on predetermined conditions. 【0064】 -Control Unit- Figure 5 is a block diagram showing the control unit 6 in Embodiment 1. 【0065】 The control unit 6 includes a processing unit 7, a storage unit 8, and an input / output unit 60 (see Figure 5). 【0066】 The processing unit 7 is implemented, for example, by a CPU (Central Processing Unit). Each part of the processing unit 7 is a part of the program 80 stored in the memory unit 8, and processes are executed when read under the control of the processing unit 7. The processing unit 7 includes a peripheral environment acquisition unit 70 (peripheral environment acquisition means) and a determination unit 75 (determination means). 【0067】 The ambient environment acquisition unit 70 acquires the ambient environment of the developing device 22 (for example, measured values ​​of temperature and humidity) from the ambient sensor 90 via the input / output unit 60. 【0068】 The determination unit 75 determines whether the measurement value from the concentration sensor 224 is stable based on predetermined conditions. The processing performed by the determination unit 75 will be explained later with reference to the flowchart. 【0069】 The storage unit 8 is implemented by memory such as an SSD (Solid State Drive) or HDD (Hard Disk Drive). The storage unit 8 stores the program 80 and the environment zone table 81. 【0070】 Figure 6 shows an example of an environmental zone table 81. 【0071】 The environmental zone table 81 divides the environment surrounding the developing device 22 into multiple environmental zones (zones 1 to 8) based on the temperature and humidity around the developing device 22 (see Figure 6). In the environmental zone table 81, the item "humidity" indicates the humidity conditions around the developing device 22, and the item "temperature" indicates the temperature conditions around the developing device 22. Based on the conditions of the items "humidity" and "temperature," the environment surrounding the developing device 22 is divided into zones 1 to 8. 【0072】 The input / output unit 60 is connected to the stirring member drive unit 95, the concentration sensor 224, and the environmental sensor 90 in a way that allows communication between them. 【0073】 Even when the power to the image forming apparatus A is turned off, the control unit 6 is supplied with power from the sub-power supply. 【0074】 -Control Unit Processing Procedure- Figure 7 is a flowchart showing an example of the processing procedure by the control unit 6 in Embodiment 1. 【0075】 Next, with reference to Figure 7, the processing procedure by the control unit 6 in this embodiment will be described. The processing described below is performed when the image forming apparatus A has recovered from the power-off state after being last turned off and is performing a warm-up, and is performed when no image is being formed. As a prerequisite for the following processing, the processing unit 7 of the control unit 6 acquires the surrounding environment of the developing apparatus 22 from the environment sensor 90 using the surrounding environment acquisition unit 70 before the image forming apparatus A is stopped and when the stirring members 220 and 221 of the developing apparatus 22 were last stopped. 【0076】 First, in step ST1, the processing unit 7 acquires the surrounding environment of the developing device 22 from the environmental sensor 90 using the surrounding environment acquisition unit 70. 【0077】 Next, in step ST2, the processing unit 7 compares the ambient environment acquired by the ambient environment acquisition unit 70 in step ST1 (ambient environment after standing) with the ambient environment acquired by the ambient environment acquisition unit 70 when the agitation members 220 and 221 of the developing device 22 were last stopped (ambient environment before standing). Specifically, the processing unit 7 refers to the ambient zone table 81 stored in the storage unit 8 and determines that the difference between the ambient environment before standing and the ambient environment after standing is greater than or equal to a predetermined change amount if the difference between the zone number of the ambient zone corresponding to the ambient environment before standing (for example, 3 for zone 3) and the zone number of the ambient zone corresponding to the ambient environment after standing (for example, 7 for zone 7) is greater than or equal to a predetermined number (for example, 3). 【0078】 If the difference between the surrounding environment before and after standing is greater than a predetermined amount, the process proceeds to step ST3. If the difference between the surrounding environment before and after standing is less than the predetermined amount, the process is terminated. In other words, in step ST2, the processing unit 7 determines whether or not to perform the stirring mode. 【0079】 Figure 8 is a flowchart showing an example of the processing procedure in the stirring mode in Embodiment 1. 【0080】 In step ST3, the processing unit 7 executes the stirring mode until the determination unit 75 of the processing unit 7 determines that the measurement value of the concentration sensor 224 has stabilized. The processing procedure for the stirring mode will be explained in detail with reference to the flowchart in Figure 8. 【0081】 In step ST30, the processing unit 7 causes the stirring member drive unit 95 to start rotating the stirring members 220 and 221. 【0082】 Steps ST31 to ST37 are the processing steps until the determination unit 75 determines whether or not the measurement value of the concentration sensor 224 has stabilized. In short, the determination unit 75 determines that the measurement value of the concentration sensor 224 has stabilized if the amount of change in the measurement value of the concentration sensor 224 has been within a predetermined range for a predetermined number of consecutive times. 【0083】 In step ST31, the determination unit 75 resets a counter (not shown) that counts the number of consecutive times the change in the measured value of the concentration sensor 224 has been determined to be within a predetermined range. 【0084】 In step ST32, the determination unit 75 obtains the measurement value for the current cycle from the concentration sensor 224. 【0085】 In step ST33, the determination unit 75 calculates a first average value Mf, which represents the average value of the measurements for the current cycle obtained in step ST32. The first average value Mf is temporarily stored in the storage unit 8. 【0086】 Although not shown in the diagram, the process from step ST32 to step ST33 is repeated until N+1 periods are reached (for example, if N is 10, then 11 periods). 【0087】 In step ST34, the determination unit 75 calculates a second mean value Ms, which represents the average of the first mean values ​​Mf for the N periods (for example, 10 periods) prior to the current period. For example, if the current period is the 11th period, the determination unit 75 calculates the second mean value Ms by adding up the first mean values ​​Mf from the 2nd to the 11th period and dividing by 10. 【0088】 Next, in step ST35, the determination unit 75 determines whether the amount of variation of the second mean value Ms is within a predetermined range. Specifically, the determination unit 75 determines whether the difference between the second mean value Ms calculated in the current cycle and the second mean value Ms calculated in the previous cycle is within a predetermined range (for example, within plus or minus 1 level when the measurement value of the concentration sensor 224 is converted to 8 bits (256 levels)). 【0089】 If the difference between the second mean Ms calculated in the current cycle and the second mean Ms calculated in the previous cycle is within a predetermined range, proceed to step ST36. On the other hand, if the difference between the second mean Ms calculated in the current cycle and the second mean Ms calculated in the previous cycle is not within a predetermined range, return to step ST31. 【0090】 In step ST36, the determination unit 75 increments the value of the counter by one. 【0091】 In step ST37, the determination unit 75 determines whether the counter value has reached a predetermined value (for example, 10). That is, the determination unit 75 determines whether the change in the measured value of the concentration sensor 224 has been within a predetermined range for a predetermined number of consecutive times (for example, 10 times). 【0092】 If the change in the measured value of the concentration sensor 224 remains within a predetermined range for a predetermined number of consecutive times (for example, 10 times), the measurement value of the concentration sensor 224 is considered stable, and the process proceeds to step ST38. On the other hand, if the number of consecutive times the change in the measured value of the concentration sensor 224 has remained within the predetermined range has not yet reached the predetermined number, the process returns to step ST32. The determination unit 75 repeats the processing of steps ST31 to ST37 until the value of the counter reaches the predetermined number of times. 【0093】 As described in steps ST31 to ST37 above, the determination unit 75 determines whether the measurement value of the concentration sensor 224 is stable or not based on the difference between the second average value Ms calculated in the current cycle and the second average value Ms calculated in the previous cycle. This makes it possible to determine whether the measurement value of the concentration sensor 224 is stable or not with a simple calculation. 【0094】 In step ST38, the processing unit 7 stops the rotational drive of the stirring members 220 and 221 by the stirring member drive unit 95, and completes the execution of the stirring mode. 【0095】 As described above, the processing unit 7 executes the stirring mode until the determination unit 75 of the processing unit 7 determines that the measurement value of the density sensor 224 has stabilized. This allows the magnetic carrier and toner to be triboelectrically charged until the measurement value of the density sensor 224 reaches an appropriate value corresponding to the toner concentration, and the developer is also sufficiently stirred. This suppresses the occurrence of image defects as described above. 【0096】 Figure 9 shows an example of the change in the second mean value Ms due to the execution of the stirring mode when the image forming apparatus A is left in a high temperature and high humidity environment. Figure 10 shows an example of the change in the second mean value Ms due to the execution of the stirring mode when the image forming apparatus A is left in a low temperature and low humidity environment. 【0097】 For example, as shown in Figure 9, even if the image forming apparatus A is left in a high-temperature, high-humidity environment, causing the toner charge to decrease and the second average value Ms of the density sensor 224 to rise, the execution of the stirring mode described above will cause the second average value Ms of the density sensor 224 to reach an appropriate value corresponding to the toner concentration. Also, as shown in Figure 10, even if the image forming apparatus A is left in a low-temperature, low-humidity environment, causing the toner charge to increase and the second average value Ms of the density sensor 224 to decrease, the execution of the stirring mode described above will cause the second average value Ms of the density sensor 224 to reach an appropriate value corresponding to the toner concentration. Note that when left in a low-temperature, low-humidity environment, the toner charge tends to be higher compared to when left in a high-temperature, high-humidity environment, and therefore the toner charge tends to be higher after the execution of the stirring mode. 【0098】 The determination unit 75 may repeat the process from step ST31 to step ST37 until the counter value reaches a predetermined value (for example, 10), or it may proceed to step ST38 and terminate the process after repeating the process a predetermined number of times (for example, 8 times). 【0099】 Returning to Figure 7, in step ST4, the processing unit 7 performs process control processing to adjust the image forming conditions of the image forming apparatus A. This allows the image forming conditions of the image forming apparatus A to be appropriately adjusted when the measurement value of the density sensor 224 is an appropriate value corresponding to the toner density. 【0100】 The process control process includes adjusting various image formation conditions, such as the exposure amount of the exposure apparatus 21, the charging potential of the photoreceptor drum 23, and the development bias of the developing roller 222. The process control process may be performed, for example, in response to the output of the density sensor 224. In this way, the processing by the control unit 6 is completed. 【0101】 As described in step ST2 above, the determination unit 75 of the control unit 6 determines whether or not to perform the stirring mode when the image forming apparatus A warms up. This allows the toner charge to be restored before the image forming apparatus A performs image forming processing again. 【0102】 As described in steps ST2 to ST3 above, the processing unit 7 of the control unit 6 executes the stirring mode based on the difference in the surrounding environment acquired by the surrounding environment acquisition unit 70 before and after the standing time. As a result, when the change in the surrounding environment of the developing device 22 is relatively large, that is, when the change in the charge amount of the toner is relatively large, the magnetic carrier and toner are appropriately triboelectrically charged by executing the stirring mode, thereby efficiently suppressing the occurrence of the image defects described above. 【0103】 Alternatively, the process in step ST34 may be omitted, and in step ST35, the determination unit 75 may determine whether the measurement value of the concentration sensor 224 is stable based on the difference between the first average value Mf calculated in the current period and the first average value Mf calculated in the previous period by determining whether the amount of fluctuation of the first average value Mf is within a predetermined range. This allows the stability of the measurement value of the concentration sensor 224 to be determined with a simple calculation. In this case, if the difference between the first average value Mf calculated in the current period and the first average value Mf calculated in the previous period is within a predetermined range (for example, within plus or minus 1 level when the measurement value of the concentration sensor 224 is converted to 8 bits (256 levels)), the process proceeds to step ST36. On the other hand, if the difference between the first average value Mf calculated in the current period and the first average value Mf calculated in the previous period is not within a predetermined range, the process returns to step ST31. 【0104】 Furthermore, the processing unit 7 of the control unit 6 may acquire the above-mentioned surrounding environment before the device was left idle when the power to the image forming apparatus A was last turned off. 【0105】 (Embodiment 2) The following description of Embodiment 2 will focus only on the differences between it and Embodiment 1. 【0106】 Figure 11 is a block diagram showing the control unit 6 in Embodiment 2. 【0107】 In Embodiment 2, the processing unit 7 of the control unit 6 includes a waiting time acquisition unit 71 (waiting time acquisition means) and a determination unit 75 (determination means) (see Figure 11). 【0108】 The resting time acquisition unit 71 acquires the resting time of the stirring members 220 and 221. The resting time may be the time from when the image forming apparatus A returned from the previous stopped state, or it may be the time from when the stirring members 220 and 221 were previously stopped until the image forming apparatus A returned after going through the stopped state. The resting time acquisition unit 71 may acquire the resting time by timing it itself, or it may acquire the resting time from the control means (not shown) of the image forming apparatus A. 【0109】 Figure 12 is a flowchart showing an example of the processing procedure by the control unit 6 in Embodiment 2. 【0110】 Next, with reference to Figure 12, the processing procedure by the control unit 6 in Embodiment 2 will be described. Note that the processing in steps ST3 and ST4 is the same as the processing in steps ST3 and ST4 in Embodiment 1, respectively, so their explanation will be omitted. 【0111】 First, in step ST1, the processing unit 7 acquires the standing time of the stirring members 220 and 221 using the standing time acquisition unit 71. 【0112】 Next, in step ST2, the processing unit 7 determines whether the standing time of the stirring members 220 and 221, as obtained by the standing time acquisition unit 71 in step ST2, is equal to or greater than a predetermined time (for example, 6 hours). 【0113】 If the standing time of the stirring members 220 and 221 is longer than a predetermined time, the process proceeds to step ST3. If the standing time of the stirring members 220 and 221 is less than a predetermined time, the process ends. In other words, in step ST2, the processing unit 7 determines whether or not to perform the stirring mode. 【0114】 In this way, by having the processing unit 7 execute the stirring mode based on the standing time acquired by the standing time acquisition unit 71, when the standing time of the stirring members 220 and 221 is relatively long, that is, when the change in the surrounding environment of the developing device 22 is relatively large and the change in the charge amount of the toner is relatively large, the magnetic carrier and toner are appropriately triboelectrically charged by executing the stirring mode, thereby efficiently suppressing the occurrence of the image defects described above. 【0115】 (Embodiment 3) The following description of Embodiment 3 will focus only on the differences between it and Embodiment 1. 【0116】 Figure 13 is a block diagram showing the control unit 6 in Embodiment 3. 【0117】 In Embodiment 3, the processing unit 7 of the control unit 6 includes a surrounding environment acquisition unit 70 (surrounding environment acquisition means), a standing time acquisition unit 71 (surrounding environment acquisition means), and a determination unit 75 (determination means) (see Figure 13). The standing time acquisition unit 71 is the same as that in Embodiment 2. 【0118】 In Embodiment 3, the storage unit 8 stores a program 80, an environment zone table 81, and a idle time table 82 (see Figure 13). 【0119】 Figure 14 shows an example of a waiting time table 82. 【0120】 The resting time table 82 relates the surrounding environment of the developing device 22 to the resting time of the agitators 220 and 221 (see Figure 14). In the resting time table 82, the item "Environmental Zone" indicates the conditions of multiple environmental zones (zones 1 to 8) classified by the Environmental Zone Table 81, and the item "Resting Time" indicates the conditions for the resting time of the agitators 220 and 221. The resting time table 82 shows the conditions for the execution of the agitation mode corresponding to each condition of the item "Environmental Zone" and the item "Resting Time" as values ​​(e.g., "0" and "1"). In Embodiment 3, the value "1" indicates that the agitation mode is executed, and the value "0" indicates that the agitation mode is not executed. 【0121】 Figure 15 is a flowchart showing an example of the processing procedure by the control unit 6 in Embodiment 3. 【0122】 Next, with reference to Figure 15, the processing procedure by the control unit 6 in Embodiment 3 will be described. Note that the processing of steps ST1, ST4, and ST5 is the same as the processing of steps ST1, ST3, and ST4 in Embodiment 1, respectively, so their explanation will be omitted. Also, the processing of step ST2 is the same as step ST1 in Embodiment 2, so its explanation will be omitted. 【0123】 In step ST3, the processing unit 7 obtains conditions for executing the stirring mode based on the surrounding environment (surrounding environment after standing) obtained by the surrounding environment acquisition unit 70 in step ST1 and the standing time of the stirring members 220 and 221 obtained by the standing time acquisition unit 71 in step ST2. If the value indicating the conditions for executing the stirring mode is "1", the process proceeds to step ST4. On the other hand, if the value indicating the conditions for executing the stirring mode is "0", the process ends. In other words, in step ST3, the processing unit 7 determines whether or not to execute the stirring mode. 【0124】 For example, if the ambient environment after standing, as acquired by the ambient environment acquisition unit 70 in step ST1, is zone 8, and the standing time of the stirring members 220 and 221, as acquired by the standing time acquisition unit 71 in step ST2, is long (for example, 6 hours), then the value indicating the conditions for executing the stirring mode is "1", and the stirring mode is executed. 【0125】 On the other hand, if the surrounding environment after standing, as acquired by the surrounding environment acquisition unit 70 in step ST1, is zone 4, then regardless of the standing time of the stirring members 220 and 221 acquired by the standing time acquisition unit 71 in step ST2, the value indicating the conditions for executing the stirring mode is "0", and therefore the stirring mode is not executed. 【0126】 In this way, the processing unit 7 executes the stirring mode based on the ambient environment after the standing period acquired by the ambient environment acquisition unit 70 and the standing period acquired by the standing period acquisition unit 71. When the ambient environment after the standing period is relatively hot and humid, and the standing period of the stirring members 220 and 221 is relatively long, the magnetic carrier and toner are appropriately triboelectrically charged by executing the stirring mode, thereby efficiently suppressing the occurrence of the image defects described above. 【0127】 The order of steps ST1 and ST2 described above is irrelevant. 【0128】 The conditions for executing the stirring mode shown in the standing time table 82 are not limited to those described above. For example, the conditions for the counter value to be reached in step ST37 for the measurement value of the density sensor 224 to be considered stable may also be the number of times the counter value should be reached. This makes it possible to adjust the rotational driving time of the stirring members 220 and 221, i.e., the stirring time of the developer, according to the surrounding environment of the developing apparatus 22 and the standing time of the stirring members 220 and 221. 【0129】 In all of the above embodiments, the waiting time for the developing device 22 is suitable whether the waiting time is the time from when the power to the image forming apparatus A was last turned off until the image forming apparatus A performs a warm-up, or whether the waiting time is the time from when the stirring members 220 and 221 were last stopped until the image forming apparatus A performs a warm-up after being in a state where the power to the image forming apparatus A was turned off. 【0130】 The embodiments and examples described above are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of this disclosure is not construed solely by the embodiments and examples described above, but is defined by the claims. This includes all modifications within the meaning and scope of the claims. [Explanation of symbols] 【0131】 A Image forming apparatus 20 Image forming unit 21 Exposure apparatus 22 Developing equipment 220,221 Agitation member (agitation means) 222 Developing roller (developer carrier) 223 Regulating member 224 Concentration sensor (measuring means) 225 Rotation axis 226 Helical feather 23 Photoconductor drum 24 Chargers 6. Control Unit (Control Means) 7 Processing Unit 70. Surrounding Environment Acquisition Unit (Means for Acquiring Surrounding Environment) 71 Idle time acquisition unit (Idle time acquisition means) 75 Judgment unit (judgment means) 8 Memory section 80 Programs 81 Environmental Zone Table 82. Table of idle time 60 Input / output section 90 Environmental Sensors 95 Stirring member drive unit Mf 1st mean Ms. 2nd Average Value

Claims

[Claim 1] An image forming apparatus comprising a developing device and control means for controlling the developing device, The developing apparatus is Developer carrier and A stirring means for stirring the developer supplied to the developer carrier, The system includes a measuring means for measuring the concentration of toner in the developer that is stirred by the stirring means, The control means is A means for acquiring the surrounding environment of the developing device, The measurement means includes a determination means for determining whether the measurement value of the measurement means is stable based on predetermined conditions, During non-image formation, an agitation mode can be performed in which the agitation means agitates the developer until the determination means determines that the measured value has stabilized. The surrounding environment is acquired by the surrounding environment acquisition means before and after the standing time of the stirring means, and the stirring mode is executed based on the difference in the surrounding environment acquired by the surrounding environment acquisition means before and after the standing time. The stirring means comprises a rotating shaft and a helical blade formed on the outer circumference of the rotating shaft, which is capable of periodically changing the measured value of the measuring means. The determination means calculates a first average value representing the average value of the measured values ​​for each period of the measured values, and further calculates a second average value representing the average value of the first average value for N periods (where N is a natural number of 2 or more) prior to the current period for each period of the measured values, and determines whether the measured values ​​have stabilized based on the difference between the second average value calculated for the current period and the second average value calculated for the previous period. An image forming apparatus characterized by the following. [Claim 2] An image forming apparatus comprising a developing device and control means for controlling the developing device, The developing apparatus is Developer carrier and A stirring means for stirring the developer supplied to the developer carrier, The system includes a measuring means for measuring the concentration of toner in the developer that is stirred by the stirring means, The control means is A means for obtaining the standing time of the stirring means, The measurement means includes a determination means for determining whether the measurement value of the measurement means is stable based on predetermined conditions, During non-image formation, an agitation mode can be performed in which the agitation means agitates the developer until the determination means determines that the measured value has stabilized. Based on the standing time acquired by the standing time acquisition means, the stirring mode is executed. The stirring means comprises a rotating shaft and a helical blade formed on the outer circumference of the rotating shaft, which is capable of periodically changing the measured value of the measuring means. The determination means calculates a first average value representing the average value of the measured values ​​for each period of the measured values, and further calculates a second average value representing the average value of the first average value for N periods (where N is a natural number of 2 or more) prior to the current period for each period of the measured values, and determines whether the measured values ​​have stabilized based on the difference between the second average value calculated for the current period and the second average value calculated for the previous period. An image forming apparatus characterized by the following. [Claim 3] An image forming apparatus comprising a developing device and control means for controlling the developing device, The developing apparatus is Developer carrier and A stirring means for stirring the developer supplied to the developer carrier, The system includes a measuring means for measuring the concentration of toner in the developer that is stirred by the stirring means, The control means is A means for acquiring the surrounding environment of the developing device, A means for obtaining the standing time of the stirring means, The measurement means includes a determination means for determining whether the measurement value of the measurement means is stable based on predetermined conditions, During non-image formation, an agitation mode can be performed in which the agitation means agitates the developer until the determination means determines that the measured value has stabilized. After the aforementioned standing time, the surrounding environment is acquired by the surrounding environment acquisition means, and the stirring mode is executed based on the surrounding environment acquired by the surrounding environment acquisition means after the standing time and the standing time acquired by the standing time acquisition means. The stirring means comprises a rotating shaft and a helical blade formed on the outer circumference of the rotating shaft, which is capable of periodically changing the measured value of the measuring means. The determination means calculates a first average value representing the average value of the measured values ​​for each period of the measured values, and further calculates a second average value representing the average value of the first average value for N periods (where N is a natural number of 2 or more) prior to the current period for each period of the measured values, and determines whether the measured values ​​have stabilized based on the difference between the second average value calculated for the current period and the second average value calculated for the previous period. An image forming apparatus characterized by the following. [Claim 4] An image forming apparatus according to any one of claims 1 to 3, The aforementioned standing time is characterized by being the time from when the stirring means was last stopped until the power to the image forming apparatus was turned off and the image forming apparatus performed a warm-up. [Claim 5] An image forming apparatus according to any one of claims 1 to 3, The aforementioned waiting time is characterized by being the time from when the power to the image forming apparatus was last turned off until the image forming apparatus performs a warm-up. [Claim 6] An image forming apparatus according to any one of claims 1 to 3, The control means is characterized by determining whether or not to perform the stirring mode when the image forming apparatus performs a warm-up. [Claim 7] An image forming apparatus according to any one of claims 1 to 3, The control means is characterized by performing a process control process to adjust the image forming conditions of the image forming apparatus after the execution of the stirring mode.

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