JP2006163186A - Image forming method and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and image forming apparatus, by which unsatisfactory image quality due to insufficient toner is prevented even when images having heavy duty in high print proportion are continuously formed in an image forming apparatus such as a laser printer or a facsimile. <P>SOLUTION: The image forming apparatus detects the toner concentration of developer containing toner and carrier, and compares it with a toner density reference value recorded in advance, thereby controlling the supply of the toner to a developing mechanism. In the image forming apparatus, the number of times wherein image formation is performed within a prescribed time is counted each time the prescribed time elapses, and it is compared with an image formation count reference value recorded in advance. When it is judged that the counted number of times wherein image formation is carried out exceeds the image formation count reference value, the toner concentration reference value is corrected to increase the amount of toner to be supplied. When it is judged that the number of times wherein image formation is carried out is below the image formation count reference value, the toner concentration reference value is corrected to decrease the amount of toner to be supplied. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming method using an image forming apparatus such as a laser printer or a facsimile that forms an image on an image forming medium, and an image forming apparatus to which the image forming method is applied, and in particular, a developer containing toner and a carrier. Detecting the toner concentration of the developer stored in the developing mechanism that supplies the toner, and comparing the detected toner concentration with a pre-recorded toner concentration reference value to control the replenishment of toner to the developing mechanism; The present invention relates to an image forming method and an image forming apparatus for forming an image on an image forming medium with a developer supplied from a developing mechanism.

  A conventional image forming apparatus has a photosensitive drum for carrying an electrostatic latent image in the main body of the apparatus. After the surface of the photosensitive drum is uniformly charged by a charging mechanism, the surface is An electrostatic latent image is formed by exposure corresponding to image information. The electrostatic latent image formed on the surface of the photosensitive drum is developed by a developing mechanism to form a toner image (a visible image), and the toner image is transferred to a transfer material conveyed at a timing. . Next, the transfer material is peeled from the photosensitive drum by the peeling device, and the toner image on the transfer material is fixed by the fixing mechanism.

  In a developing mechanism used in such a conventional image forming apparatus, a two-component developer composed of a toner and a carrier is widely used as a developer, and the toner is formed by colored thermoplastic particles. The carriers are generally formed from ferromagnetic particles such as iron powder.

  Of the two-component developer composed of the toner and the carrier, the weight% of the toner is several percent, and the toner in the developer is consumed every time the electrostatic latent image on the photosensitive drum is developed. The Therefore, it is necessary to replenish the amount of toner consumed and maintain the toner weight percentage (that is, toner concentration) within a predetermined range.

  Therefore, the image forming apparatus is configured to detect the toner density and control the toner density to be appropriate. FIG. 31 is a block diagram illustrating a configuration of the image forming apparatus. The toner concentration of the developer stored in the developing mechanism 4 is detected by a magnetic type (magnetic permeability measurement type) toner concentration sensor (ATC sensor) 10, and the control circuit (Central Processing Unit) 13 is controlled by the ATC sensor 10. The toner supply from the toner cartridge 8 is controlled by driving the toner cartridge drive motor 21 serving as a toner supply unit corresponding to the detected toner density information.

  FIG. 32 is a graph showing the relationship between the toner concentration (wt%) and the output voltage value (V) of the ATC sensor. When the control circuit 13 detects from the output voltage value of the ATC sensor 10 that the toner density of the developer in the developing mechanism 4 has decreased, the control circuit 13 drives the toner cartridge drive motor 21 and passes the toner cartridge 8 through the toner cartridge 8. Is supplied to the developing mechanism 4. As a result of the replenishment, when the toner density increases and the output voltage value from the ATC sensor 10 falls below, for example, a reference value (reference output voltage value) V0 shown in FIG. 32, for example, 2.5 V, the control circuit 13 drives the toner cartridge. The motor 21 is stopped and the supply of toner from the toner cartridge 8 is stopped, and the toner concentration of the developer in the developing mechanism 4 is maintained at, for example, 4.0 wt% (reference value V0).

  As a technique for keeping the toner density constant, for example, it is described in Patent Document 1 below.

JP 2001-92237 A

  However, in the toner replenishment control by the toner density sensor, a delay occurs in the control. Therefore, if an image with a high printing rate, that is, an image of so-called heavy duty, continues, toner replenishment does not follow and image quality failure (insufficient density) due to toner shortage occurs. There is a problem that arises.

  The present invention has been made in view of such circumstances. For example, when the number of image formations is counted and it is determined that heavy duty image formation is continuous, the toner concentration standard is set to increase the amount of toner replenishment. To provide an image forming method capable of preventing the occurrence of image quality defects due to lack of toner, and an image forming apparatus to which the image forming method is applied, even when heavy duty images are consecutive by correcting values Objective.

  An image forming method according to the present invention detects a toner concentration of a developer housed in a developing mechanism that supplies a developer including toner and a carrier, and the detected toner concentration is a prerecorded toner concentration reference value. In the image forming method using the image forming apparatus that controls the replenishment of toner to the developing mechanism by comparison and forms an image on the image forming medium with the developer supplied from the developing mechanism, the image forming apparatus includes: The number of image formations is counted, and the counted number of image formations is compared with a pre-recorded formation number reference value. When the comparison determines that the image formation number exceeds the formation number reference value, The toner density reference value is corrected to increase the replenishment amount.

  In the image forming method according to the present invention, since the toner density reference value is corrected based on the number of image formations, the toner density reference value is corrected even when the toner replenishment control by the toner density sensor is delayed. Since toner replenishment can be followed, it is possible to prevent the occurrence of poor image quality due to lack of toner.

  An image forming apparatus according to the present invention detects a toner density of a developer housed in a developing mechanism that supplies a developer including toner and a carrier, and the detected toner density is a prerecorded toner density reference value. In the image forming apparatus that controls the replenishment of the toner to the developing mechanism and forms an image on the image forming medium with the developer supplied from the developing mechanism, the counting unit counts the number of image formations. A means for comparing the number of image formations with a pre-recorded formation number reference value, and a toner to increase the replenishment amount of toner when the comparison determines that the image formation number exceeds the formation number reference value. And correction means for correcting the density reference value.

  In the image forming apparatus according to the present invention, the toner density reference value is corrected even when the toner supply control by the toner density sensor is delayed by correcting the toner density reference value based on the number of image formations. Since toner replenishment can be followed, it is possible to prevent the occurrence of poor image quality due to lack of toner.

  The image forming apparatus according to the present invention further includes means for calculating a printing rate indicating a ratio occupied by an image formed on the image forming medium, wherein the counting unit has a printing rate exceeding a predetermined printing rate reference value. It is configured to count only images.

  In the image forming apparatus according to the present invention, it is easy to form a heavy duty image with a high printing rate by correcting the toner density reference value according to the number of images having a high toner consumption and a high printing rate. Thus, it is possible to easily cope with a heavy duty image in which toner supply control is delayed.

  In the image forming apparatus according to the present invention, the counting unit is configured to count the number of image formations within a predetermined time every time the predetermined time elapses, and the correction unit includes the number of image formations, The toner density reference value is corrected so that the replenishment amount of toner is increased step by step whenever the formation reference value is exceeded.

  In the image forming apparatus according to the present invention, the toner density reference value is corrected step by step whenever a predetermined time elapses, so that even when images are continuously formed, toner replenishment can be followed. It is possible to prevent the occurrence of poor image quality due to toner shortage.

  The image forming apparatus according to the present invention is characterized in that the toner density reference value has an upper limit value.

  In the image forming apparatus according to the present invention, by setting an upper limit on the toner density reference value, it is possible to prevent excessive toner replenishment even when image formation continues, so that stable image quality can be maintained. It is.

  The image forming apparatus according to the present invention is configured such that the correction unit corrects the toner density reference value so as to reduce the toner replenishment amount when it is determined that the number of image formations does not exceed the formation reference value. It is characterized by being.

  In the image forming apparatus according to the present invention, the toner density reference value is corrected so as to reduce the toner supply amount when the number of image formations is small, thereby preventing excessive toner supply when released from continuous image formation. Therefore, stable image quality can be maintained.

  The image forming apparatus according to the present invention is characterized in that the toner density reference value has a lower limit value.

  In the image forming apparatus according to the present invention, by providing a lower limit to the toner density reference value, it is possible to prevent insufficient toner replenishment when released from continuous image formation.

  The image forming apparatus according to the present invention further includes a means for detecting humidity and a means for comparing the detected humidity with a predetermined humidity reference value, and the correction means detects that the detected humidity exceeds the humidity reference value. When the determination is made, the correction of the toner density reference value is limited.

  In the image forming apparatus according to the present invention, it is possible to prevent excessive toner replenishment by limiting the toner density reference value so as not to be corrected when the relative humidity is medium humidity or high humidity greater than 40%. It is possible to maintain stable image quality. In the image forming apparatus, when the relative humidity is a low humidity of 40% or less, the charge amount of the developer becomes large, and the increase in the charge amount due to stirring becomes significant. In such a state, the charge amount due to image formation becomes large and correction is necessary. On the other hand, in the case of medium or high humidity, the increase in the developer charge amount due to discharge is suppressed, so the electrostatic force due to the charge is reduced and the developer is lost. Therefore, the toner density sensor detects a value lower than the actual toner density. In such a case, if the toner density reference value is corrected, the toner may be replenished excessively. In the present invention, excessive replenishment due to such a reason is prevented.

  An image forming apparatus according to the present invention includes means for counting the cumulative number of image formations and means for comparing the counted cumulative number with a cumulative number reference value recorded in advance. However, when it is determined that the cumulative number exceeds the reference value, the correction of the toner density reference value is limited.

  In the image forming apparatus according to the present invention, when the cumulative number of image formations exceeds the cumulative reference value, it is possible to prevent excessive toner replenishment by limiting the correction of the toner density reference value. Can be maintained. In the image forming apparatus, as the cumulative number of image formations increases, the developer deteriorates and the charge amount decreases, so that the bulk density increases and the toner density sensor detects a value lower than the actual toner density. become. In the present invention, excessive replenishment due to such a reason is prevented.

  An image forming method and an image forming apparatus of the present invention detect a toner concentration of a developer stored in a developing mechanism that supplies a developer including toner and a carrier, and the detected toner concentration is recorded in advance. In an image forming apparatus such as a laser printer or a facsimile that controls the replenishment of toner to the developing mechanism by comparing with the reference value and forms an image on the image forming medium with the developer supplied from the developing mechanism. The number of image formations is counted every time a predetermined time elapses, and the counted number of image formations is compared with a pre-recorded formation number reference value to determine that the image formation number exceeds the formation number reference value. In this case, the toner density reference value is corrected stepwise to increase the toner replenishment amount.

  With this configuration, even when the toner replenishment control by the toner concentration sensor is delayed, by correcting the toner concentration reference value, it is possible to follow the toner replenishment step by step. It has excellent effects such as being able to prevent. In addition, by providing an upper limit value for the toner density reference value, it is possible to prevent excessive toner supply even when image formation is continued, so that it is possible to maintain a stable image quality. Play.

  In addition, the image forming apparatus of the present invention corrects the toner density reference value so as to reduce the replenishment amount of toner when it is determined that the number of image formations does not exceed the formation reference value, thereby forming a continuous image. Since the toner can be prevented from being replenished when the toner is released from the toner, it is possible to maintain a stable image quality. In addition, by providing a lower limit to the toner density reference value, it is possible to prevent the toner from being insufficiently supplied when it is released from the continuous image formation.

  Furthermore, when the image forming apparatus of the present invention is operated in a medium or high humidity environment where the relative humidity is greater than 40%, the toner density reference value is limited so as not to be corrected, thereby preventing excessive toner replenishment. Therefore, it is possible to maintain an excellent effect such as being able to maintain a stable image quality. In the image forming apparatus, when the relative humidity is a low humidity of 40% or less, the charge amount of the developer becomes large, and the increase in the charge amount due to stirring becomes significant. In such a state, the charge amount due to image formation becomes large and correction is necessary. On the other hand, in the case of medium or high humidity, the increase in the developer charge amount due to discharge is suppressed, so the electrostatic force due to the charge is reduced and the developer is lost. Therefore, the toner density sensor detects a value lower than the actual toner density. In such a case, if the toner density reference value is corrected, the toner may be replenished excessively. In the present invention, excessive replenishment due to such a reason is prevented.

  Furthermore, the image forming apparatus of the present invention can prevent excessive toner replenishment by limiting the correction of the toner density reference value when the cumulative number of image formations exceeds the cumulative reference value. It is possible to maintain the image quality. In the image forming apparatus, as the cumulative number of image formation increases, the developer deteriorates and the charge amount decreases, so that the bulk density increases and the toner density sensor detects a value lower than the actual toner density. become. In the present invention, excessive replenishment due to such a reason is prevented.

  Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments for carrying out the invention.

Embodiment 1 FIG.
FIG. 1 is a cross-sectional view illustrating the image forming apparatus according to the first embodiment. 1, reference numeral 100 denotes an image forming apparatus of the present invention. The image forming apparatus 100 includes a photosensitive drum 1, a charging mechanism 2, an exposure mechanism 3, a developing mechanism 4, a transfer mechanism 5, a paper feeding unit 6, and a fixing mechanism 7. , A toner cartridge 8, a cleaning mechanism 9, an ATC sensor 10, a humidity sensor 11, and a photo sensor 12.

  FIG. 2 is a block diagram illustrating a configuration of the image forming apparatus 100 according to the first embodiment. A control circuit 13 that controls the entire apparatus includes an ATC sensor (toner concentration sensor) 10, a humidity sensor 11, and an A / D converter 14 that converts analog output voltage values of the photo sensor 12 into digital output voltage values, and a charger output. Control unit 15 for controlling drive circuit 19, development bias drive circuit 20, development mechanism drive motor 18 and toner cartridge drive motor 21, storage unit 17, information from each sensor, data stored in storage unit 17, etc. And an operation unit 16 that performs an operation using.

  The ATC sensor 10 detects the toner concentration in the developer in the developing mechanism 4 and outputs a voltage corresponding to the toner concentration to the control circuit 13 as a detection signal. The humidity sensor 11 is provided in the vicinity of the developing mechanism 4 and detects the relative humidity in the image forming apparatus 100. The storage unit 17 of the control circuit 13 stores in advance table data of toner density correction values (correction values of the reference output voltage value of the ATC sensor 10) for relative humidity as shown in FIG. The circuit 13 corrects the reference output voltage value based on the table data. The photosensor 12 detects the density of a toner patch image created in image density correction described later. The control circuit 13 controls the toner cartridge drive motor 21 based on the detection signal of the ATC sensor 10 during a copy or print job. Further, the charger output drive circuit 19 and the developing bias drive circuit 20 are controlled at the time of image density correction described later.

  Next, the operation of the image forming apparatus 100 configured as described above will be described. First, a monopolar charge is charged on the surface of the photosensitive drum 1 by corona discharge of the charging mechanism 2, and an electrostatic latent image is formed on the surface of the photosensitive drum 1 by irradiation of the exposure mechanism 3.

  Developer is supplied from the developing mechanism 4 to the surface of the photosensitive drum 1 on which the electrostatic latent image is formed, and the electrostatic latent image is visualized into a developer image. This developer image is transferred onto a sheet by the transfer mechanism 5. The sheet on which the developer image has been transferred is conveyed to the fixing mechanism 7, and the developer image is melted and fixed by heating and pressing. After the transfer of the developer image, the surface of the photosensitive drum 1 is charged again by the charging mechanism 2 after the residual toner is removed by the cleaning mechanism 9.

  Further, in the developing mechanism 4, the non-magnetic sleeve 41 is rotationally driven so as to face the photosensitive drum 1, and the stirring roller 42 stirs the toner and the carrier constituting the developer in the developing mechanism 4 and charges the toner. Is charged. The developer is conveyed by the action of a magnet fixed in the nonmagnetic sleeve 41, and only the toner in the developer moves to the surface of the photosensitive drum 1.

  Accordingly, only the toner in the developing mechanism 4 is consumed by executing the image forming process. Therefore, the ATC sensor 10 detects an output voltage value corresponding to the toner concentration in the developer in the developing mechanism 4 and compares it with a reference output voltage value as a toner concentration reference value stored in advance in the storage unit 17. Then, the toner supply motor is rotated, and the toner stored in the toner cartridge 8 is supplied to the developing mechanism 4. That is, the control circuit 13 controls the toner replenishment amount so that the toner density in the developing mechanism 4 detected by the ATC sensor 10 matches the toner density reference value.

  On the other hand, the control circuit 13 periodically interrupts the image forming process when the power is turned on and under predetermined conditions, and executes image density correction (process control). In this image density correction, a toner patch image is formed on the surface of the photosensitive drum 1, and the density of the toner patch image is detected by the photosensor 12. As described above, the output signal of the photosensor 12 is converted into digital data by the A / D converter 14. The control circuit 13 controls the charger output drive circuit 19 and the development bias drive circuit 20 based on the output data of the photosensor 12 to change the state of parameters that affect image formation.

  That is, by changing the output voltage value and the developing bias voltage value of the charging mechanism 2, a plurality of electrostatic latent images having different surface potentials are formed on the surface of the photosensitive drum 1 and visualized by the developing mechanism 4. Thus, a plurality of toner patch images having different densities are formed, and these densities are detected by the photosensor 12, and the development bias voltage value relating to the toner patch image that matches the reference value is determined as the development bias voltage in the subsequent image forming process. Adopt as a value.

  Note that the image forming conditions in the image forming process are not limited to the development bias voltage value that has a direct relationship with the toner density, but the exposure amount of the exposure unit 3, the charger output voltage value, and the like. It may be a transfer output voltage value of the transfer charger or the like.

  The storage unit 17 in the control circuit 13 stores the number of copies from the initial state such as when the developer is replaced and when the image forming apparatus is installed, and the developer agitation time. The control unit 15 causes the calculation unit 16 to calculate a correction value corresponding to the number of copies stored in the storage unit 17 and the developer agitation time, controls the reference output voltage value, and controls the humidity detected by the humidity sensor 11. Corresponding to the fluctuation, the calculation unit 16 calculates the correction value of the reference output voltage value of the ATC sensor 10 to control the reference output voltage value.

  The toner used in this embodiment is a non-magnetic powder obtained by mixing and dispersing a colorant such as carbon using a resin such as styrene acrylic as a main resin, and is hydrophobic to improve fluidity. A fluidizing agent such as alumina is externally added, and its volume average particle size is preferably 4 to 7 μm. When the volume average particle diameter is larger than 7 μm, the toner output is always controlled to an appropriate toner density by the reference output voltage value correction method according to the present embodiment. Not suitable for image quality image formation, the characters are crushed and the resolution is reduced. On the other hand, when the volume average particle size is smaller than 4 μm, high-quality image formation is maintained. However, since the particle size is too small, there is a problem of backside contamination due to toner scattering in the apparatus. Furthermore, since the specific surface area per unit weight is further increased as compared with the case where the volume average particle diameter is 4 to 7 μm, the behavior of the developer greatly changes with respect to the change of the humidity environment. Concentration management becomes difficult at the end of the developer life.

  On the other hand, the concentration (content) of a colorant (pigment) such as carbon in the toner used in the exemplary embodiment is preferably 8 to 20%. When the concentration of the pigment is lower than this, there is a problem that the toner consumption per copy becomes large and the unit price of the copy becomes high. On the other hand, if the concentration of the pigment exceeds 20%, the amount of resin in the toner decreases, so the fixability to a transfer material such as paper deteriorates, which is not preferable.

  In this embodiment, reversal development is performed to form a toner image on the exposed portion. Therefore, if the photosensitive drum 1 has a negative polarity, the charging polarity of the toner is negative. In addition, the charging polarity of the toner is not limited to negative, and the present invention can also apply a toner having a positive charging polarity.

  As the main resin, polyester, epoxy, polystyrene, acrylic resin, or the like can be used. Further, silica, titanium oxide or the like may be used as an external additive, and coloring may be performed with a pigment, a dye, or the like. Further, the toner may be produced not only by a pulverization method but also by a polymerization method or a microencapsulation method. Further, polyethylene or polypropylene wax may be added to improve the releasability in fixing.

  Hereinafter, a method for correcting the humidity of the toner density when the humidity changes in the image forming apparatus 100 described above will be described.

  FIG. 3 is a graph showing the correction value of the reference output voltage value in each humidity range. For example, when the humidity changes from a range of 50-60% to a range of 80-90%, toner replenishment is controlled with a value obtained by adding 0.3 V to the reference output voltage value. These values vary depending on the characteristics of the image forming apparatus 100, the toner and the carrier, and the corresponding numerical values are determined by a test or the like.

  Data corresponding to this graph is stored in the storage unit 17 in the control circuit 13, and each time the output voltage value of the humidity sensor 11 is monitored, a humidity correction value for the reference output voltage value can be obtained based on this data. it can.

  In the present embodiment, a toner patch image is formed on the photosensitive drum 1 under preset image forming conditions, and the image density is determined based on the density detection result of the photosensor 12 that detects the density of the toner patch image. The control unit 15 corrects the development bias voltage value so as to keep it constant, and the absolute value of the correction value of the development bias voltage value at the time of image density correction is greater than or equal to a predetermined value with respect to the initial installation value of the image forming apparatus 100. In this case, the above-described humidity correction is performed.

  FIG. 4 is a graph showing the relationship between the usage status (developer stirring time) of the image forming apparatus 100 and humidity, and FIG. 5 is the usage status (developer stirring time) of the image forming apparatus 100 and image density correction control. 6 is a graph showing the relationship between the developing bias voltage value (Vbias) and FIG. 6 is a graph showing the relationship between the usage status of the image forming apparatus (developer stirring time) and the reference output voltage value.

  In FIG. 5, the initial value of the developing bias voltage value is set to 575V, and α is set to 110V. In FIG. 6, the reference output voltage value is set to 2.5V. It goes without saying that these values are set to appropriate values by each image forming apparatus 100.

  When the printing operation is performed, the correction value by the process control operation when the initial value of the developing bias voltage value is 0 becomes −α or less when the developing stirring time has passed 13 Ksec. Since the humidity at this point is in the range of 80 to 90%, the correction value 0.3V is added to the reference output voltage value from FIG. 3, and the reference output voltage value thereafter is controlled at 2.8V.

  Next, when 35 Ksec is passed, the development bias voltage correction value exceeds + α. Since the humidity at this time is in the range of 50 to 60% as in the initial time, the correction value is 0 V and the reference output voltage value is reset to 2.5 V from FIG.

  Next, when 53 Ksec has passed, the correction value of the development bias voltage value in the process control operation becomes −α or less. Since the humidity at this time is in the range of 60 to 70%, the correction value 0.1V is added to the reference output voltage value from FIG. 3, and thereafter, the reference output voltage value is controlled at 2.6V.

  When 75 Ksec has passed, the correction value of the development bias voltage value in the process control operation becomes −α or less. Since the humidity at this time is in the range of 90 to 100%, the correction value 0.4V is added to the reference output voltage value from FIG. 3, and thereafter, the reference output voltage value is controlled at 2.9V.

  Table 1 below summarizes whether or not the humidity correction processing is executed.

  As shown in Table 1, when the humidity range does not change, humidity correction is not performed regardless of the correction value of the development bias voltage value in the process control operation. Further, when the correction value of the developing bias voltage value is within the range of + α to −α, humidity correction is not performed regardless of the change in humidity. On the other hand, when the humidity changes to the humidity range on the high humidity side, the control differs depending on the correction value of the development bias voltage value in the process control operation.

  For example, when the correction value of the development bias voltage value in the process control operation is larger than + α, the humidity correction is not performed when the range changes to the high humidity side. The correction in the direction of increasing the development bias voltage value in the process control operation is correction for increasing the current image density because the current image density is low. However, as shown in FIG. 3, the correction when changing to the high humidity side is a correction to increase the reference output voltage value, and when this is done, the toner density is corrected in the direction of decreasing the toner density. Since the correction is performed in the direction in which the image density decreases due to the decrease in the toner density, the effect of the correction of the developing bias voltage value in the process control operation is offset. In order to avoid such a contradiction, humidity correction is not performed in this case.

  On the other hand, when the development bias correction value in the process control operation is −α or less and the range changes to the high humidity side, humidity correction is performed. Since the image density is high, the correction in the direction of decreasing the developing bias is correction for reducing the developing density. Further, the correction when the humidity is changed to the high humidity side is also a correction to increase the reference output voltage value. When this is performed, the correction is performed in a direction in which the toner density decreases. The decrease in toner density works in the direction of lowering the image density, and the correction policy is consistent between the two, so humidity correction is performed in such a case.

  When the development bias correction value for the process control operation is between + α and −α, as described above, no humidity correction is performed regardless of which humidity range is changed.

  When the correction value of the development bias voltage value in the process control operation is larger than + α, the humidity correction is performed when the range changes to the low humidity side. The correction in the direction of increasing the development bias voltage value is correction for increasing the image density because the image density is low. Further, the correction when the humidity is changed to the low humidity side is also a correction that lowers the reference output voltage value. The increase in toner density works in the direction of increasing the image density. Since the correction policy is consistent between the two, humidity correction is performed in such a case.

  On the other hand, when the correction value of the developing bias voltage value in the process control operation is −α or less and the range is changed to the low humidity side, humidity correction is not performed. Since the image density is high, the correction in the direction of decreasing the developing bias is a correction for reducing this. However, the correction when it changes to the low humidity side is a correction that lowers the reference output voltage value, and when this is done, the correction is performed in the direction of increasing the toner density. The increase in toner density works in the direction of increasing the image density. Therefore, since the effect of the correction of the developing bias voltage value in the process control control operation is canceled out by the humidity correction, the humidity correction is not performed in this case in order to avoid such a contradiction.

  7 and 8 are flowcharts showing the processing procedure for correcting the reference output voltage value of the control unit 15 according to the first embodiment. When the process is started by turning on the power or the like, first, the control circuit 13 of the image forming apparatus 100 determines whether or not it is time to perform process control (step S1). The process control execution time is a time when control such as a preset timing such as when the power is turned on, after a predetermined time elapses after the power is turned on, or after the predetermined number of copies is finished, is necessary. If it is determined in step S1 that the process control execution time is not reached, the normal copy operation is repeated until the execution time (step S2). If it is determined in step S <b> 1 that the process control timing has been reached, charging, exposure, and development processes are performed on the photosensitive drum 1 to create a toner patch image for density measurement on the photosensitive drum 1. (Step S3). A plurality of electrostatic latent images having different surface potentials are formed on the surface of the photosensitive drum 1 by changing the charging output voltage value, the developing bias voltage value, and the like. Toner patch images of different densities are formed.

  Next, the optical density of the created toner patch image is measured by the photosensor 12 (step S4). These densities are detected by the photosensor 12, and the development bias voltage value (Vbias) relating to the toner patch image that matches the reference value is adopted as the development bias voltage value in the subsequent image forming process.

  Next, a difference between the adopted process control development bias voltage value and the initial value of the development bias voltage value stored in the storage unit 17, that is, a correction amount (ΔVbias) is calculated (step S5). Next, it is determined whether or not ΔVbias is larger than a predetermined amount + α (step S6). The correction in the direction of increasing the developing bias voltage is a correction to increase the image density because it is low.

  If it is determined in step S6 that ΔVbias is greater than + α, the process proceeds to step S7, and the reference output voltage value in which the output voltage value of the ATC sensor 10 has been changed after the reference output voltage value has been changed previously. It is determined whether or not it has been reached. If it is determined in step S7 that the reference output voltage value has not been reached, the reference output voltage value is not changed, the process returns to step S2, and the normal copy operation is repeated until the next process control execution time. If it is determined in step S7 that the reference output voltage value has been reached, the output voltage value of the humidity sensor 11 is detected (step S8), and the detected output voltage value is the output voltage value in the humidity range on the low humidity side. It is determined whether or not it has changed to (step S9).

  In step S9, when the detected output voltage value has changed to the output voltage value in the humidity range on the low humidity side, a correction value is determined based on the humidity correction table stored in the storage unit 17 (step S10), and the reference The correction value is added to the output voltage value to calculate a new reference output voltage value (step S11), and the process returns to step S2. In this case, since the correction value is a negative value, the correction is made so as to decrease the reference output voltage value. In step S9, when the output voltage value in the humidity range on the low humidity side has not changed, the process returns to step S2.

  If it is determined in step S6 that ΔVbias is smaller than + α, the process proceeds to step S12, and it is determined whether or not ΔVbias is equal to or less than a predetermined value −α. If it is determined in step S12 that ΔVbias is −α or less, for example, if −α is set to −100 V, or if ΔVbias is −110 V, the process proceeds to step S13. For example, if ΔVbias is −90 V and is between + α and −α, the reference output voltage value is not corrected and the process returns to step S2.

In step S13, it is determined whether or not the output voltage value of the ATC sensor 10 has reached the changed reference output voltage value before the reference output voltage value has been changed.
If it is determined in step S13 that the reference output voltage value has not been reached, the reference output voltage value is not changed, the process returns to step S2, and the normal copy operation is repeated until the next process control execution time. If it is determined in step S13 that the reference output voltage value has been reached, the output voltage value of the humidity sensor 11 is detected (step S14), and the detected output voltage value is the output voltage value in the humidity range on the high humidity side. It is determined whether or not it has changed to (step S15).

  If it is determined in step S15 that the detected output voltage value has changed to an output voltage value in the humidity range on the high humidity side, a correction value is determined based on the humidity correction table stored in the storage unit 17 (step S15). S16) The humidity correction value is added to the reference output voltage value to calculate a new reference output voltage value (step S17), and the process returns to step S2. In this case, since the correction value is a positive value, it is corrected in the direction of increasing the reference output voltage value. If it is determined in step S15 that the output voltage value in the humidity range on the high humidity side has not been changed, the process returns to step S2.

  When executing the image density correction, the control circuit 13 detects the output voltage value of the humidity sensor 11, compares the humidity at the time of the previous correction of the reference output voltage value with the current humidity, and whether there has been a humidity change over a predetermined range. Judge whether or not. If there is no change in humidity exceeding the predetermined range, naturally, humidity correction is not executed.

  When the humidity change is changed to the high humidity side, the charge amount of the normal toner is decreased and the developability is increased. Therefore, in the image density correction, the development bias voltage value is decreased to decrease the developability. In this embodiment, when the developing bias voltage value is lowered by −αV or less from the initial value, the correction value obtained from the humidity correction table is added to the reference output voltage value. However, when the correction value of the developing bias voltage value is within −αV or when the developing bias voltage value is increased, the humidity correction is not executed.

  When the humidity change is changed to the low humidity side, the charge amount of the normal toner is increased and the developability is decreased. Therefore, the image density correction increases the developing bias voltage value in order to improve developability. In this embodiment, when the developing bias voltage value is increased by + αV or more with respect to the initial value, the correction value obtained from the humidity correction table is added to the reference output voltage value. However, when the correction value of the developing bias voltage value is within + αV or when the developing bias voltage value is corrected to decrease, the humidity correction is not executed.

  In the present embodiment, the humidity correction is performed when the developing bias voltage value is lowered by −αV or less with respect to the initial value, or when it is raised by + αV or more with respect to the initial value. Although the magnitude of α is determined by various experiments, the magnitude of α may be changed between correction for increasing the reference output voltage value and correction for decreasing the reference output voltage value. Thereby, the execution timing of the correction of the reference output voltage value becomes more appropriate, and stable and high-quality image formation becomes possible.

  In the present embodiment, even when there is little change in developability due to humidity change, the humidity of the reference output voltage value is corrected, the toner density is always kept at an appropriate value, and the image density is kept constant. An image can be obtained. With this configuration, it is possible to prevent a time when the reference output voltage value needs to be corrected from being overlooked or performing the correction of the reference output voltage value more than necessary.

  In the present embodiment, when the reference output voltage value is corrected once and the reference output voltage value is changed, it is newly added until the output voltage value of the ATC sensor 10 reaches the changed reference output voltage value. The reference output voltage value is not corrected. When a new reference output voltage value correction is performed before the output voltage value of the ATC sensor 10 reaches the reference output voltage value, the toner density is optimized and the image density is made uniform. This is an excessive correction, and on the contrary, the toner density is inappropriate and the image quality is deteriorated.

  When the reference output voltage value is corrected as described above, the reference output voltage value is changed by the correction amount, but the actual output voltage value of the ATC sensor 10 naturally does not reach the reference output voltage value immediately. .

  FIG. 9 is a graph showing the transition between the output voltage value of the ATC sensor 10 and the reference output voltage value when correction for increasing the reference output voltage value is executed in the first embodiment. When performing humidity correction to increase the reference output voltage value, the reference output voltage value is changed at once.

  The correction for increasing the reference output voltage value is a correction for decreasing the toner density. Therefore, the toner in the developer is consumed by printing, and the output voltage value of the ATC sensor 10 gradually increases. Then, when several prints are processed, the output voltage value of the ATC sensor 10 reaches the corrected reference output voltage value, and normal toner supply control is performed.

  Alternatively, the image density correction may be performed again when the output voltage value of the ATC sensor 10 reaches the changed reference output voltage value. By this image density correction, the optimum print image density is obtained when the changed developability is achieved.

  FIG. 10 is a graph showing the transition between the output voltage value of the ATC sensor 10 and the reference output voltage value in this case. The toner in the developer is consumed by printing, the output voltage value of the ATC sensor 10 gradually rises, and the output voltage value of the ATC sensor 10 is corrected when several sheets of printing are processed. At this time, the image density correction is performed again, and the optimum image forming conditions are changed. Thereafter, regular toner replenishment control is performed.

  FIG. 11 is a graph showing the transition between the output voltage value of the ATC sensor 10 and the reference output voltage value when correction for lowering the reference output voltage value is executed in the first embodiment. When executing humidity correction to lower the reference output voltage value, the reference output voltage value is gradually changed. The correction for decreasing the reference output voltage value is correction for increasing the toner density. Therefore, the toner is further replenished in the developer, and the toner is replenished while the printing operation is executed. The output voltage value of the ATC sensor 10 reaches the reference output voltage value, and the normal toner concentration replenishment control is performed. Is done.

  Alternatively, the image density correction may be performed again when the output voltage value of the ATC sensor 10 reaches the changed reference output voltage value. By this image density correction, the optimum print image density is obtained when the changed developability is achieved.

  FIG. 12 is a graph showing the transition between the output voltage value of the ATC sensor 10 and the reference output voltage value in this case. The toner is replenished while executing the printing operation, and the output voltage value of the ATC sensor 10 reaches the reference output voltage value. At this time, the image density correction is performed again, and the image forming conditions are changed to the optimum image forming conditions. . Thereafter, regular toner concentration replenishment control is performed.

  In the present embodiment, the case where the present invention is applied to the single-color image forming apparatus 100 has been described. However, the present invention is also applicable to the case where a multi-color developing mechanism 4 such as a color image forming apparatus is provided. Is applicable. In the image forming apparatus 100 having the image density correction function including the multi-color developing mechanism 4, when the reference output voltage value is corrected corresponding to the change in humidity, the development bias voltage value is set to the initial value at the time of image density correction. The configuration is such that the reference output voltage value is corrected only when the change is greater than a predetermined value for all colors and the average value of the change amount of the development bias voltage value for all colors is equal to or greater than the predetermined value. Can do. With this configuration, it is possible to effectively perform toner density correction only when the correction of the reference output voltage value is actually necessary. Therefore, when minor correction is necessary for only some of the multiple color developers, the correction of the reference output voltage value is executed for all colors, resulting in unnecessary developer agitation and reduction in operating rate. Invitation can be prevented.

Further, in the image forming apparatus 100 having the image density correction function, when the correction of the reference output voltage value is executed in response to the humidity change, the correction of the reference output voltage value is simultaneously executed for all colors. Also good. In the multi-color image forming apparatus 100, color balance is important, and it is possible to maintain good color balance by executing correction of reference output voltage values for all colors simultaneously.

  On the other hand, for a color that is difficult for humans to see (for example, Y), the number of corrections of the reference output voltage value may be reduced, and the maximum effect can be achieved by correcting the minimum reference output voltage value. .

Embodiment 2. FIG.
Depending on the frequency of use of the device by copying or printing by the user, a difference occurs in the agitation stress on the developer per predetermined time. The difference in the agitation stress to the developer per unit time causes a difference in toner charge amount. As a result, a difference occurs in the output voltage value of the ATC sensor 10 despite the same toner concentration. In a developer with a frequency of use of an apparatus with a little agitation stress, the toner density increases, the charge amount decreases, toner scattering and background fogging, image collapse, and the like occur, resulting in a decrease in image quality. On the other hand, in a developer with a high usage frequency of agitation stress per unit time, the toner density decreases, the charge amount increases, the image density decreases, for example, character blurring occurs, and the image quality decreases. Will be. According to the present embodiment, it is possible to eliminate a toner density control failure caused by a difference in developer charge amount caused by a difference in usage frequency of a user's apparatus.

  As in the humidity correction according to the first embodiment, the correction of the reference output voltage value based on the difference in the usage frequency of the device is performed in advance in order to determine whether or not the correction of the reference output voltage value is necessary. A controller 15 forms a toner patch image on the photosensitive drum 1 under the set image forming conditions, and maintains the image density constant based on the result of detecting the density of the toner patch image by the photosensor 12. When the developing bias voltage value is corrected, it is determined whether or not the developing bias voltage value has changed by a predetermined value or more with respect to the initial value when the apparatus is installed. When the developing bias voltage value changes by a predetermined value or more with respect to the initial value at the time of installation, the reference output voltage value is corrected by a predetermined amount.

  FIGS. 13 and 14 are flowcharts illustrating a processing procedure for correcting the reference output voltage value based on the difference in humidity of the control unit 15 and the usage frequency of the apparatus according to the second embodiment. When the process is started by turning on the power or the like, first, the control circuit 13 of the image forming apparatus 100 determines whether it is time to execute process control (step S21). The process control execution time is a time when control is required, such as a preset timing such as when the power is turned on, after a predetermined time elapses after the power is turned on, or after the predetermined number of copies is completed. If it is determined in step S21 that it is not the process control execution time, the normal copying operation is repeated until the execution time (step S22). If it is determined in step S21 that the process control timing has been reached, charging, exposure, and development processes are performed on the photosensitive drum 1 to create a toner patch image for density measurement on the photosensitive drum 1 ( Step S23). A plurality of electrostatic latent images having different surface potentials are formed on the surface of the photosensitive drum 1 by changing the charging output voltage value, the developing bias voltage value, and the like. Toner patch images of different densities are formed.

  Next, the optical density of the created toner patch image is measured by the photosensor 12 (step S24). These densities are detected by the photosensor 12, and the development bias voltage value (Vbias) relating to the toner patch image that matches the reference value is adopted as the development bias voltage value in the subsequent image forming process.

  Next, the difference between the adopted process control developing bias voltage value and the initial value of the developing bias voltage value stored in the storage unit 17, that is, the correction amount (ΔVbias) is calculated (step S25). Next, it is determined whether or not ΔVbias is larger than a predetermined amount + α (step S26). The correction in the direction of increasing the development bias voltage value is a correction for increasing the image density because the image density is low.

  If it is determined in step S26 that ΔVbias is greater than + α, the process proceeds to step S27. After the reference output voltage value has been changed before, the output voltage value of the ATC sensor 10 is changed to the changed reference output voltage value. It is determined whether or not it has been reached (step S27). If it is determined in step S27 that the reference output voltage value has not been reached, the reference output voltage value is not changed, the process returns to step S22, and the normal copy operation is repeated until the next process control execution time. If it is determined in step S27 that the reference output voltage value has been reached, the output of the humidity sensor 11 is detected (step S28), and the detected output voltage value changes to an output voltage value in the humidity range on the low humidity side. It is determined whether or not it has been done (step S29).

  If it is determined in step S29 that the detected output voltage value has changed to an output voltage value in the humidity range on the low humidity side, a correction value is determined based on the humidity correction table stored in the storage unit 17 (step S31). ), The correction value is added to the reference output voltage value to calculate a new reference output voltage value (step S32), and the process returns to step S22. In this case, since the correction value is a negative value, the correction is made so as to decrease the reference output voltage value. If it is determined in step S29 that the output voltage value in the humidity range on the low humidity side has not changed, the reference output voltage value is changed to (currently set reference output voltage value-A) (step S30). The process returns to step S22. This A is determined in advance according to the frequency of use of the apparatus by performing various aging tests and the like, and is stored in the storage unit 17.

  If it is determined in step S26 that ΔVbias is smaller than + α, the process proceeds to step S40, and it is determined whether or not ΔVbias is equal to or less than a predetermined amount −α. If it is determined in step S40 that ΔVbias is equal to or less than −α, for example, if −α is set to −100V and the correction value is −110V, the process proceeds to step S41. If ΔVbias is −90 V and is between + α and −α, the reference output voltage value is not corrected, and the process returns to step S22.

  In step S41, after the reference output voltage value has been changed, it is determined whether or not the output voltage value of the ATC sensor 10 has reached the changed reference output voltage value. If it is determined in step S41 that the output voltage value has not reached the changed reference output voltage value, the reference output voltage value is not changed, and the process returns to step S22 until the next process control execution time. Repeat the normal copy operation. If it is determined in step S41 that the output voltage value has reached the changed reference output voltage value, the output of the humidity sensor 11 is detected (step S42), and the detected output voltage value is within the humidity range on the high humidity side. It is determined whether or not the output voltage value has changed (step S43).

  If the detected output voltage value has changed to an output voltage value in the humidity range on the high humidity side in step S43, a correction value is determined based on the humidity correction table stored in the storage unit 17 (step S45), The correction value is added to the reference output voltage value to calculate a new reference output voltage value (step S46), and the process returns to step S22. In this case, since the correction value is a positive value, it is corrected in the direction of increasing the reference output voltage value.

  If it is determined in step S43 that the output voltage value in the humidity range on the high humidity side has not changed, the reference output voltage value is changed to (currently set reference output voltage value + A) (step S44), The process returns to step S22. This A is determined in advance according to the frequency of use of the apparatus by performing various aging tests and the like, and is stored in the storage unit 17. In addition, the magnitude of α is determined in advance by performing various aging tests or the like, but it is not necessary to make the correction equal when the reference output voltage value is increased and when it is decreased.

  When the frequency of use of the apparatus is extremely low, the charge amount of the toner is lowered and the developability is high. In such a case, the appropriate development bias voltage value obtained by the image density correction has an absolute value larger than the initial value by a predetermined value or more in the minus direction (in the direction of decreasing the image density). Therefore, the reference output voltage value is corrected to the plus side as the usage frequency correction, and correction in the direction of decreasing the toner density is performed. As a result, the problem of toner density increase, toner scattering, and ground fog does not occur.

  On the contrary, when the frequency of use of the apparatus is extremely high, the charge amount of the toner increases and the developability is low. In such a case, the appropriate development bias voltage value obtained by the image density correction has an absolute value larger than the initial value by a predetermined value or more in the plus direction (in the direction of increasing the image density). Accordingly, the reference output voltage value is corrected to the minus side as the usage frequency correction, and correction in the direction of increasing the toner density is performed. As a result, the problem of toner density reduction and image fading does not occur.

  And the correction | amendment by the usage frequency of this apparatus is not performed simultaneously with humidity correction | amendment. By configuring in this way, you can overlook the time when the reference output voltage value correction that is caused by the difference in the usage frequency of the device, not the correction due to humidity change, is necessary, or execute the reference output voltage value correction more than necessary. Can be prevented. Further, the execution timing of the correction of the determined reference output voltage value is the same as that in the first embodiment.

  In this embodiment, the case where the present invention is applied to the single-color image forming apparatus 100 has been described. However, the present invention can also be applied to a case where the developing mechanism 4 has a plurality of colors such as a color image forming apparatus. . When an image forming apparatus having an image density correction function including a multi-color developing mechanism 4 performs a correction of a reference output voltage value corresponding to a difference in user's apparatus usage frequency, a developing bias voltage value for image density correction is The reference output voltage value may be corrected only when a predetermined value or more is changed for all colors with respect to the initial value, or when an average value of all colors is changed by a predetermined value or more.

Embodiment 3 FIG.
FIGS. 15, 16 and 17 are flowcharts showing a processing procedure for correcting the reference output voltage value based on the humidity change of the control unit 15 and the frequency of use of the apparatus according to the third embodiment. When the control circuit 13 of the image forming apparatus 100 starts when the power is turned on or the like, first, it is determined whether or not it is time to perform process control (step S51). The process control execution time is a time when control is required, such as a preset timing such as when the power is turned on, after a predetermined time elapses after the power is turned on, or after the predetermined number of copies is completed. If it is determined in step S51 that it is not the process control execution time, the normal copy operation is repeated until the execution time (step S52). If it is determined in step S51 that the process control timing has been reached, charging, exposure and development processes are performed on the photosensitive drum 1, and a toner patch image for density measurement is created on the photosensitive drum 1. (Step S53). By changing the charging voltage value, the developing bias voltage value, and the like, a plurality of electrostatic latent images having different surface potentials are formed on the surface of the photosensitive drum 1, and the developing mechanism 4 visualizes the latent images. Toner patch images of different densities are formed.

  Next, the optical density of the created toner patch image is measured by the photosensor 12 (step S54). These densities are detected by the photosensor 12, and the development bias voltage value (Vbias) relating to the toner patch image that matches the reference value is adopted as the development bias voltage value in the subsequent image forming process.

  Next, a difference between the adopted process control development bias voltage value and the initial value of the development bias voltage value stored in the storage unit 17, that is, a correction amount (ΔVbias) is calculated (step S55). Next, it is determined whether or not this ΔVbias is larger than a predetermined amount + α (step S56). The correction for increasing the developing bias voltage value is a correction for increasing the image density because the image density is low.

  If it is determined in step S56 that ΔVbias is greater than + α, the process proceeds to step S57, and after the reference output voltage value has been changed before, the reference output voltage value in which the output voltage value of the ATC sensor 10 has been changed. It is determined whether or not it has been reached (step S57). If it is determined in step S57 that the output voltage value has not reached the reference output voltage value, the reference output voltage value is not changed, the process returns to step S52, and normal copying is performed until the next process control execution time. Repeat the operation. If it is determined in step S57 that the reference output voltage value has been reached, the output voltage value of the humidity sensor 11 is detected (step S58), and the detected output voltage value is the output voltage value in the humidity range on the low humidity side. It is determined whether or not it has changed to (step S59).

  If it is determined in step S59 that the detected output voltage value has changed to an output voltage value in the humidity range on the low humidity side, a correction value is determined based on the humidity correction table stored in the storage unit 17 (step S62). ), The correction value is added to the reference output voltage value to calculate a new reference output voltage value (step S63), and the process returns to step S52. In this case, since the correction value is a negative value, the correction is made so as to decrease the reference output voltage value. If it is determined in step S59 that the output voltage value in the humidity range on the low humidity side has not changed, it is determined whether or not ΔVbias is greater than + α2 (step S60).

  If it is determined in step S60 that ΔVbias is not greater than + α2, the process returns to step S52 without changing the reference output voltage value. If it is determined in step S60 that ΔVbias is greater than + α2, the reference output voltage value is changed to (currently set reference output voltage value−A) (step S61), and the process returns to step S52. This A is determined in advance according to the frequency of use of the apparatus by performing various aging tests and the like, and is stored in the storage unit 17.

  If it is determined in step S56 that ΔVbias is smaller than + α, the process proceeds to step S70 to determine whether ΔVbias is equal to or less than a predetermined amount −α. If it is determined in step S70 that ΔVbias is −α or less, for example, if −α is set to −100V and the correction value is −110V, the process proceeds to step S71. For example, when the correction value is −90 V and is between + α and −α, the reference output voltage value is not corrected, and the process returns to step S52.

  In step S71, after the reference output voltage value has been changed, it is determined whether or not the output voltage value of the ATC sensor 10 has reached the changed reference output voltage value. If it is determined in step S71 that the output voltage value has not reached the changed reference output voltage value, the reference output voltage value is not changed, and the process returns to step S52 until the next process control execution time. Repeat the normal copy operation. If it is determined in step S71 that the output voltage value has reached the changed reference output voltage value, the output voltage value of the humidity sensor 11 is detected (step S72), and the detected output voltage value is on the high humidity side. It is determined whether or not the output voltage value in the humidity range has been changed (step S73).

  If it is determined in step S73 that the detected output voltage value has changed to an output voltage value in the humidity range on the high humidity side, a correction value is determined based on the humidity correction table stored in the storage unit 17 (step S73). In step S76, the correction value is added to the reference output voltage value to calculate a new reference output voltage value (step S77), and the process returns to step S52. In this case, since the correction value is a positive value, it is corrected in the direction of increasing the reference output voltage value. If it is determined in step S73 that the output voltage value in the humidity range on the high humidity side has not changed, it is determined whether or not ΔVbias is −α2 or less (step S74).

  If it is determined in step S74 that ΔVbias is not less than −α2, the process returns to step S52 without changing the reference output voltage value. If it is determined in step S74 that ΔVbias is −α2 or less, the reference output voltage value is changed to the currently set reference output voltage value + A) (step S75), and the process returns to step S52. This A is determined in advance according to the frequency of use of the apparatus by performing various aging tests and the like, and is stored in the storage unit 17. Note that the magnitude of α2 is determined in advance by performing various aging tests or the like, but it is not necessary to make the same when the reference output voltage value is raised or lowered. In the present embodiment, the degree of agitation stress is recognized based on the correction value of the setting value of the image forming condition and is corrected based on this value, so that the use frequency can be corrected more appropriately.

Embodiment 4 FIG.
FIG. 18 is a graph showing the relationship between the output voltage value of the ATC sensor 10 and the developer stirring time. In contrast to the phenomenon in which the output voltage value of the ATC sensor 10 increases as the developer stirring time increases as shown in FIG. 18, if the apparatus is used without correcting the reference output voltage value, the developer stirring time increases. Replenishment of toner increases the toner concentration, reduces the toner charge amount, and causes problems such as toner scattering and ground fogging. In the present embodiment, for this problem, table data that is corrected step by step as a life correction value of the reference output voltage value with respect to the developer stirring time is set in advance to the reference output voltage value in the initial developer. Is stored in the storage unit 17 and referred to as a life correction value with respect to the developing stirring time at the present time, and the correction added to the reference output voltage value is the correction based on the humidity change of the first embodiment, the second or third embodiment. The correction is performed in parallel with the correction based on the humidity change and the use frequency difference of the apparatus. Thereby, developability can be stabilized against deterioration of the developer due to spent toner or the like.

  Therefore, as a control method for the reference output voltage value, humidity correction performed for humidity change, usage frequency correction performed for a difference in the usage frequency of the apparatus, and developer deterioration performed by developer stirring time. Correction considering the correction is performed on the reference output voltage value. The reference output voltage value that controls the replenishment of toner in the developing mechanism 4 is a total value that takes all three corrections into consideration. With the recent development of high image quality technology, the trend toward smaller toner particles is progressing, and toners with an average particle size of 8 μm or less and a sharper particle size distribution have been developed. The carrier also tends to have a smaller particle size, and as the toner and carrier have a smaller particle size, the specific surface area per unit weight increases, and accordingly the humidity environment changes and the use of the device. In the present embodiment, the reference output voltage value is corrected with a correction value that takes all three changes into consideration, in order to solve the problem that the behavior of the developer changes greatly with respect to the difference in frequency and the difference in developer agitation stress. It becomes possible to always control the toner density to an appropriate level, and high-quality image formation is maintained.

Embodiment 5. FIG.
When the elapsed time since the previous execution of a print job, which is a series of processing instructions for forming an image, is long, phenomena such as settling and aggregation of the developer occur in the developing mechanism 4 and the developer In some cases, the density becomes non-uniform, a value deviating from the true toner density value is detected, and the toner density is controlled to an incorrect value.

  In the case of the present embodiment, when a long time has passed since the end of the print job, a phenomenon such as sedimentation and aggregation of the developer occurs, causing a malfunction in which the toner density is controlled to an incorrect value. This can be prevented. Further, in realizing the present embodiment, a malfunction prevention table showing the relationship between the elapsed time and the correction coefficient necessary for preventing malfunction shown in Table 2 below is stored in the storage unit 17 in advance.

  As shown in Table 2, in the malfunction prevention table stored in the storage unit 17, correction coefficients K (t) corresponding to the elapsed time t from 0 seconds to 50 seconds are recorded. In this embodiment, when the correction value of the toner density reference value Vref is TS1, the correction value TS1 of the toner density reference value is an output value before the toner density, which is 1. Based on the toner density output value TS2 after 5 seconds and the elapsed time t, it is determined by the following equations 1 and 2.

When TS2> Vref TS1 = (TS2−Vref) × K (t) + Vref Equation 1
When TS2 ≦ Vref TS1 (t) = Vref …… Equation 2
Vref: Toner density reference value
TS1: Correction value
TS2: Previous output value of toner density
t: Elapsed time
K (t): Correction coefficient

  Next, the processing procedure of this embodiment will be described. FIG. 19 is a flowchart illustrating a processing procedure of the image forming apparatus according to the fifth embodiment. In the image forming apparatus 100, the execution of the print job is started based on the control of the control circuit 13, and when the image formation is completed along with the execution of the print job, the elapsed time t is measured with the initial value t = 0. Start (step S81).

  When a new print job is received, the toner density reference value Vref indicated as the reference output voltage value is detected by the method described in the first to fourth embodiments (step S82), and the detection should be stabilized. After waiting for a predetermined time such as 1.5 seconds (step S83), the toner density output value TS2 is detected (step S84).

  The image forming apparatus 100 reads the measured elapsed time t (step S85), and determines whether or not the read elapsed time t exceeds a predetermined time such as 50 seconds stored in advance in the storage unit 17, for example. If it is determined (step S86) and it is determined that the predetermined time is not exceeded (step S86: NO), the toner density output value TS2 detected in step S83 is compared with the toner density reference value Vref (step S87). When it is determined in step S87 that the toner density output value TS2 is greater than the toner density reference value Vref (step S87: YES), the correction coefficient corresponding to the elapsed time t read from the malfunction prevention table shown in Table 2 K (t) is read (step S88), and the correction value TS1 is calculated based on the toner density output value TS2, the toner density reference value, the correction coefficient K (t), and the toner density reference value Vref using the above-described equation 1. Calculate (step S89). The calculated correction value TS1 is used as a correction value when toner is supplied.

  Then, the image forming apparatus 100 executes the newly accepted print job (step S90), determines whether or not processing such as image formation based on all print jobs has been completed (step S91), and print job. If it is determined that the process has not been completed (step S91: NO), the process returns to step S85 and the subsequent processes are repeated.

  When it is determined in step S86 that the read elapsed time t exceeds the predetermined time (step S86: YES), the image forming apparatus sets the toner density reference value Vref as the correction value TS1 (step S92), and proceeds to step S90. The subsequent processing is performed.

When it is determined in step S87 that the toner density output value TS2 is equal to or lower than the toner density reference value Vref (step S87: NO), the image forming apparatus sets the toner density reference value Vref as the correction value TS1 (step S92). Proceeding to step S90, the subsequent processing is performed.
If it is determined in step S91 that the print job has been completed (step S91: YES), the process ends.

  As described above, in the present embodiment, when the elapsed time t from the previous image formation based on the execution of the print job is within 50 seconds that is set in advance as a predetermined time, it is recorded in the malfunction prevention table. The correction value TS1 of the toner density reference value Vref is determined based on the correction coefficient K (t) corresponding to the elapsed time t and the toner density output value TS2 detected previously. When the elapsed time t exceeds 50 seconds set in advance as a predetermined time, the correction value TS1 for correcting the toner density reference value Vref based on the elapsed time t is set regardless of the toner density output value TS2. decide.

  FIG. 20 is a graph showing the relationship between the elapsed time t and the corrected toner density reference value according to the fifth embodiment. As shown in FIG. 20, the corrected toner density reference value is corrected based on the correction coefficient K (t) recorded in the malfunction prevention table until the predetermined time of 50 seconds is reached. It changes with time and takes a constant value after reaching a predetermined time of 50 seconds.

Embodiment 6 FIG.
In the present embodiment, when an image with a high printing rate is formed, the toner supply is not performed when the image is deteriorated because toner replenishment cannot follow and the images with a low printing rate are continuously formed. The object is to prevent the deterioration of image quality that occurs when the toner replenishment time lasts for a long time.

  21 and 22 are flowcharts showing the processing procedure of the image forming apparatus according to the sixth embodiment. The image forming apparatus 100 receives a print job that is a series of processing instructions for forming an image, and stabilizes the detection value based on the control of the control circuit 13 when performing an image forming process based on the received print job. In order to achieve this, the idling operation is performed for 1.5 seconds, the toner density indicated as the output voltage value is detected by the method described in the first to fourth embodiments (step S101), and the detected toner density is used as the toner density. Comparison with the reference value (step S102).

  If the comparison in step S102 determines that the detected toner density is equal to or lower than the toner density reference value (step S102: YES), the image forming apparatus turns off the near-end flag set to indicate the remaining amount of toner. (Step S103), a continuous replenishment time counter for measuring the continuous replenishment time that has been continuously replenished since the start of toner replenishment is initialized (Step S104), and the toner density is set to the toner reference value 0 A state monitoring counter for counting the number of times of continuation of the state that is equal to or greater than the value obtained by adding 3 V is initialized (step S105).

  In the image forming apparatus 100, as the toner non-supply time, the cumulative elapsed time required for the image forming process after the previous toner supply is measured using the cumulative elapsed time counter. It is determined whether or not the accumulated elapsed time is 30 seconds or more set as the predetermined time (step S106), and when it is determined that the accumulated elapsed time is equal to or longer than the predetermined time (step S106: YES) The output value is compared with the value obtained by subtracting 0.1 V from the toner density reference value (step S107), and when it is determined that the output value of the toner density is greater than the value obtained by subtracting 0.1 V from the toner density reference value (step S107). (S107: YES), toner is replenished, for example, for 1 second (step S108), and an accumulated elapsed time counter that measures the toner non-replenishment time being measured is initialized (step S108). Flop S109).

  By replenishing toner in step S108, image quality deterioration at a low printing rate can be prevented.

  Then, the image forming apparatus 100 determines whether or not the print job has been completed (step S110). If it is determined that the print job has been completed (step S110: YES), the process ends.

  If it is determined in step S106 that the accumulated elapsed time does not exceed the predetermined time (step S106: NO), the process proceeds to step S110, and it is determined whether the print job is completed.

  In step S107, when it is determined that the output value of the toner density is smaller than the value obtained by subtracting 0.1 V from the toner density reference value (step S107: NO), for the purpose of preventing excessive toner supply. The toner replenishment process is not performed, and the process proceeds to step S109 to execute the subsequent processes. If it is determined in step S110 that the print job has not been completed (step S110: NO), the process returns to step S101 and the subsequent processing is repeated.

  If it is determined in step S102 that the detected toner density is equal to or higher than the toner density reference value (step S102: NO), the image forming apparatus 100 adds the toner density output value to the toner density reference value by 0.3V. If the toner density output value is less than the value obtained by adding 0.3 V to the toner density reference value (step S111: YES), the toner is replenished, for example, for 1 second (step S111). In step S112, a cumulative elapsed time counter that measures the measured toner non-supply time is initialized (step S113).

  Then, the image forming apparatus 100 determines whether or not the near end flag set to indicate the remaining amount of toner is ON (step S114), and determines that the near end flag is ON. (Step S114: YES), it is determined whether or not the value of the continuous supply time counter that measures the continuous supply time is a predetermined time, for example, 3 minutes or more (Step S115).

  If it is determined in step S115 that the continuous replenishment time is 3 minutes or longer (step S115), it is assumed that the remaining amount of toner in the toner cartridge 8 is low, and the print job is interrupted (step S116). Toner empty processing for requesting replenishment by cartridge replacement is performed (step S117). After completion of the toner empty process, the process returns to step S101 and the subsequent processes are repeated.

  If it is determined in step S115 that the continuous replenishment time is less than 3 minutes (step S115: NO), the process returns to step 102 and the subsequent processing is repeated.

  If it is determined in step S114 that the near-end flag is OFF (step S114: NO), the image forming apparatus uses the continuous replenishment time counter to measure the continuous replenishment time for a predetermined time, for example, 1 minute. When it is determined whether or not it is above (step S118), and when it is determined that it is 1 minute or longer (step S118: YES), it is considered that toner replenishment does not follow, and a process of feeding an image to form an image Is interrupted (step S119), and toner supply processing for supplying toner is performed (step S120).

  If it is determined in step S118 that the continuous replenishment time is less than 1 minute (step S118: NO), the process returns to step S101 and the subsequent processing is repeated.

  In step S111, when it is determined that the output value of the toner density is larger than the value obtained by adding 0.3 V to the toner density reference value (step S111: NO), in the image forming apparatus 100, the value of the state monitoring counter is 3 or more. It is determined whether or not there is (step S121), and when it is determined that the value of the state monitoring counter is 3 or more (step S121: YES), it is further determined whether or not the near end flag is ON ( In step S122), when it is determined that the near-end flag is ON (step S122: YES), the print job is interrupted (step S123) and toner empty processing is performed (step S124). After completion of the toner empty process, the process returns to step S101 and the subsequent processes are repeated.

  When it is determined in step S122 that the near-end flag is OFF (step S122: NO), the image forming apparatus interrupts the process of feeding paper and forming an image (step S125), and supplying toner. Toner replenishment processing for replenishment is performed (step S126).

  When it is determined in step S121 that the value of the state monitoring counter is less than 3 (step S121: NO), the image forming apparatus adds 1 to the value of the state monitoring counter (step S127), and returns to step S101. The subsequent processing is repeated.

  Next, the toner supply process executed in steps S120 and S126 of FIG. 22 will be described. 23 and 24 are flowcharts illustrating toner supply processing of the image forming apparatus 100 according to the sixth embodiment. As a toner replenishment process executed in steps S120 and S126 in FIG. 22 in order to prevent image deterioration caused by image formation at a high printing rate and toner replenishment not being able to follow, in the image forming apparatus 100, a control circuit Based on the control of No. 13, information indicating that the toner replenishing process is being executed is displayed from a display means such as a liquid crystal panel provided on the outer surface of the image forming apparatus 100 (step S131). The continuous replenishment counter that measures the continuous replenishment time that has been continuously replenished since the start is initialized (step S132), and the state in which the toner density is equal to or greater than the value obtained by adding 0.3 V to the toner reference value is continued. A state monitoring counter for counting the number of times is initialized (step S133).

  Then, the image forming apparatus 100 performs idling for 30 seconds to stabilize the detection value in the developing mechanism 4 based on the control of the control circuit 13, and then detects the output value of the toner density (step S134). The detected output value of the toner density is compared with the toner density reference value (step S135). If the toner density output value is equal to or less than the toner density reference value (step S135: YES), the toner supply process is terminated, and FIG. In order to restart the process interrupted in step S119 or S125, the process returns to step S101 in FIG. 21 and the subsequent processes are executed.

  In step S135, when the output value of the detected toner density is larger than the toner density reference value (step S135: NO), the image forming apparatus replenishes toner for 1 second, for example (step S136), and measures the toner non-replenishment time. The accumulated elapsed time counter is initialized (step S137), the output value of the toner density after replenishment is detected (step S138), and the detected toner density output value is compared with a value obtained by adding 0.1 V to the toner density reference value. If the toner density output value detected after replenishment is smaller than the value obtained by adding 0.1 V to the toner density reference value (step S139: NO), the cumulative value of toner replenishment time in step S136 is a predetermined time. It is determined whether or not it is 2 minutes 30 seconds or more (step S140), and the accumulated value is less than 2 minutes 30 seconds Step S140: NO), the process returns to step S134, and repeats the subsequent processing.

  If it is determined in step S140 that the cumulative value of the toner replenishment time in step S136 is 2 minutes 30 seconds or more (step S140: YES), the image forming apparatus 100 detects the output value of the detected toner density and the toner density reference. When the output value of the detected toner density is equal to or lower than the toner density reference value (step S141: YES), the toner supply process is terminated, and the process proceeds to step S119 or step S125 in FIG. In order to resume the processing that has been interrupted, the processing returns to step S101 in FIG. 21 and the subsequent processing is executed.

  If the detected toner density output value is larger than the toner density reference value in step 141 (step S141: NO), the image forming apparatus 100 sets the toner density output value and the value obtained by adding 0.3 V to the toner density reference value. (Step S142), and if the toner density output value is less than the value obtained by adding 0.3 V to the toner density reference value (step S142: YES), the near-end The flag is turned on (step S143), the toner supply process is terminated, and the process after step S101 in FIG. .

  In step S142, when the output value of the toner density is equal to or greater than the value obtained by adding 0.3V to the toner density reference value (step S142: NO), the image forming apparatus 100 uses the toner empty requesting replenishment by replacing the toner cartridge. Processing is performed (step S144).

  In step S139, when the output value of the toner density detected after replenishment is larger than the value obtained by adding 0.1 V to the toner density reference value (step S139: YES), the image forming apparatus 100 stabilizes the detected value in the developing mechanism 4. After the idling for 30 seconds, the toner density output value is detected (step S145), and the detected toner density output value is compared with the toner density reference value (step S146). If the toner density is not more than the reference value of the toner density (step S146: YES), the toner supply process is terminated and the process returns to step S101 in FIG. 21 to restart the process interrupted in step S119 or step S125 in FIG. The subsequent processing is executed.

  In step S146, when the detected output value of toner density is larger than the toner density reference value (step S146: NO), the image forming apparatus 100 replenishes toner for, for example, 1 second (step S147), and measures the toner non-replenishment time. The accumulated elapsed time counter is initialized (step S148), and it is determined whether the accumulated value of the toner replenishment time in steps S136 and S146 is a predetermined value of 3 minutes or more (step S149). If it is less than a minute (step S149: NO), the process returns to step S145 and the subsequent processing is repeated.

  In step S149, when it is determined that the cumulative value of the toner replenishment time in steps S136 and S146 is 3 minutes or more (step S149: YES), the process proceeds to step S140, and the subsequent processing is executed.

  In step S149, when it is determined that the accumulated value of the toner replenishment time in steps S136 and S146 is less than 3 minutes (step S149: NO), the process returns to step 145 and the subsequent processing is repeated.

  In this way, when the correction value of the toner density reference value is positive, an accumulated elapsed time counter that measures a toner non-replenishment time indicating the time required for image formation processing after the previous toner replenishment is initialized. Therefore, excessive toner replenishment is prevented. Rather than initializing the accumulated elapsed time counter, after the toner is replenished based on the toner density reference value, the measurement of the accumulated elapsed time is interrupted until the toner density reaches the corrected toner density reference value. You may make it do.

  Note that the sixth embodiment is used in combination with the first to fifth embodiments described above as appropriate, and therefore, the same portions as those described in the first to fifth embodiments described above are used. Shall refer to Embodiments 1 to 5 described above, and a description thereof will be omitted.

Embodiment 7 FIG.
Since the toner density in the developing mechanism 4 may be non-uniform when starting, restarting, or returning from the standby state, a malfunction may occur if the toner density is detected and controlled immediately after startup or the like. There is a risk of inviting.

  In the present embodiment, in order to prevent malfunction due to erroneous detection due to non-uniform toner density in the developing mechanism 4, the developing mechanism 4 is idled without toner replenishment. This shows a preparatory operation before process control and toner density correction for equalizing the density.

  FIG. 25 is a flowchart illustrating a processing procedure of the image forming apparatus according to the seventh embodiment. In the image forming apparatus 100, the relative humidity in the image forming apparatus 100 is determined by a humidity sensor provided in the vicinity of the developing mechanism 4 based on the control of the control circuit 13 at the time of starting, restarting, or returning from the standby state. In accordance with the detected humidity, the idle time is calculated using the calculation formula or correspondence table stored in the storage unit 17 (step S152), and the toner is supplied for the calculated idle time. First, the developing mechanism 4 is idled (step S153), and the toner density and the charge amount are made uniform.

Then, after performing the idling operation for the calculated idling time, process control correction processing is performed (step S154), and further toner correction processing is performed (step S155).
Thus, the preparation operation for executing the print job is completed.

Embodiment 8 FIG.
FIG. 26 is a block diagram schematically illustrating a toner cartridge provided in the image forming apparatus 100 according to the eighth embodiment. As shown in FIG. 26, the toner cartridge 8 according to the eighth embodiment of the present invention has a recording unit 81 such as an IC memory and an interface unit 82 serving as an interface for recording information in the recording unit 81. Information relating to the usage status of the toner cartridge 8 is recorded in the section 81.

  The image forming apparatus 100 includes an access unit that accesses the interface unit 82 to record information in the recording unit 81 and read information when the toner cartridge 8 is attached.

  The information on the usage status of the toner cartridge 8 recorded in the recording unit 81 is information such as unused, in use, and used, and is not used in the recording unit 81 of the toner cartridge 8 before being attached. Is recorded, and when the attached toner cartridge 8 starts to be used, it is rewritten to information indicating that it is in use, and is rewritten to information indicating that it has been used when executing the toner empty process. The information on the usage status is not only rough information such as unused, in use, and used, but also information indicating the detailed usage status, the accumulated time required for replenishment using the toner cartridge 8, Specifically, the cumulative driving time of the toner cartridge driving motor 21 is measured, and the cumulative driving time obtained by the measurement is recorded.

  Further, at the time of starting, restarting, or returning from the standby state, a preparatory operation for changing the operating condition according to the usage state of the toner cartridge 8 is performed.

  FIG. 27 is a flowchart showing a processing procedure of the image forming apparatus 100 according to Embodiment 8 of the present invention. In the image forming apparatus 100, use indicating information on the use status recorded in the recording unit 81 of the toner cartridge 8 based on the control of the control circuit 13 at the time of starting, restarting, or returning from the standby state. The status information is read (step S161), and it is determined whether the read usage status information is unused (step S162). If it is determined that it is not used (step S162: YES), toner serving as toner replenishing means is used. The operating conditions are changed so that the drive frequency of the drive power source of the cartridge drive motor 21 is 50 Hz (step S163), and the usage status information is updated to information indicating that it is in use (step S164).

  If it is determined in step S162 that it is not unused (step S162: NO), the operating condition is changed so that the driving frequency of the driving power source of the toner cartridge driving motor 21 is 62.5 Hz (step S165).

  Thus, when the toner cartridge 8 is unused, the torque of the toner cartridge drive motor 21 is improved by lowering the drive frequency, and torque due to toner blocking that is likely to occur during storage of the unused toner cartridge 8 is achieved. It is possible to prevent trouble caused by shortage.

  When the cumulative drive time of the toner cartridge drive motor 21 is recorded in the recording unit 81 as usage status information, the unused toner cartridge 8 is used when the cumulative drive time is a predetermined value, for example, 120 seconds or less. to decide. When the accumulated driving time is used as the usage status information, the image forming apparatus 100 measures the accumulated time required for toner supply (step S166), and uses the measured usage time based on the measured accumulated time, in this case, information indicating the accumulated time. A process of recording in the recording unit 81 of the toner cartridge 8 (step S167) is required.

Embodiment 9 FIG.
28 and 29 are flowcharts showing the processing procedure of the image forming apparatus 100 according to the ninth embodiment. When performing heavy duty printing that requires a large amount of toner such as continuous printing, the toner replenishment control by the ATC sensor (toner concentration sensor) 10 causes a delay in the control, so the toner replenishment does not follow and the toner concentration does not follow. Insufficient image quality (insufficient density) occurs. In the ninth embodiment, the toner density reference value is corrected in order to maintain a stable image quality without causing a supply delay due to a delay in the toner supply control system.

  When receiving a print request (step S171), the image forming apparatus 100 performs an initialization process using the toner density reference value recorded in the storage unit 17 as an initial value (step S172). Is detected (step S173), and the detected humidity is compared with a humidity reference value previously stored in the storage unit 17 such as 40% (step S174).

  When it is determined that the humidity detected in step S174 is equal to or lower than the humidity reference value (step S174: YES), the image forming apparatus 100 counts the number of images formed on the image forming medium related to the stored developer, that is, copies. The cumulative number of sheets is counted (step S175), and the counted cumulative number is compared with the cumulative number reference value stored in advance in the storage unit 17 such as 50000 sheets (step S176). If it is determined that the humidity detected in step S174 exceeds the humidity reference value (step S174: NO), the process for correcting the toner density reference value described below is limited. Here, the process is performed so that the correction is not performed. finish.

  When it is determined that the cumulative number counted in step S175 is equal to or less than the cumulative reference value (step S176: YES), the image forming apparatus 100 sets the storage unit 17 to count the number of corrections of the toner density reference value. The value of the correction counter is initialized, that is, set to “0” (step S177). If it is determined that the cumulative number counted in step S175 exceeds the cumulative reference value (step S176: NO), the processing for correcting the toner density reference value shown below is limited. Here, the correction is not performed. The process ends.

  Further, the image forming apparatus 100 starts an interval timer and starts measuring a predetermined time such as 10 minutes (step S178), and sets an image forming number counter set in the storage unit 17 to count the number of image formings within the predetermined time. Is initialized, that is, set to "0" (step S179).

  Then, each time an image is formed, the image forming apparatus 100 prints a print rate indicating a ratio occupied by an image formed on the image forming medium, specifically, a print obtained by dividing the number of black pixels by the total number of pixels. The rate is calculated (step S180), and the calculated printing rate is compared with a printing rate reference value stored in advance in the storage unit 17 such as 15% (step S181).

  If it is determined in step S181 that the calculated printing rate is equal to or higher than the printing rate reference value (step S181: YES), the image forming apparatus 100 increases the value of the image forming number counter that counts the number of image forming by “1”. The counting process is performed (step S182), and it is determined whether or not the time indicated by the interval timer has reached a predetermined time (step S183). If it is determined in step S181 that the printing rate is less than the printing rate reference value (step S181: NO), the counting process in step S182 is not performed, the process proceeds to step S183, and the subsequent processes are performed.

  When it is determined in step S183 that the predetermined time has been reached (step S183: YES), the image forming apparatus 100 stores the value of the image formation number counter for counting the number of image formations in advance, such as 200 sheets. Is compared with the formation number reference value stored in (step S184). If it is determined in step S183 that the predetermined time has not been reached (step S183: NO), the process returns to step S180, and the subsequent processing is repeated.

  If it is determined in step S184 that the number of image formations exceeds the formation number reference value (step S184: YES), the image forming apparatus 100 performs a counting process for increasing the value of the correction number counter for counting the number of corrections by “1”. (Step S185), and the value of the correction number counter is compared with the upper limit value of the correction number stored in the storage unit 17 in advance such as five times (step S186), and it is determined that the correction number exceeds the upper limit value of the correction number. In this case (step S186: YES), the correction number upper limit value is set as the value of the correction number counter (step S187). If it is determined in step S186 that the number of corrections is less than or equal to the upper limit of corrections (step S186: NO), the process of step S187 is not performed. That is, setting is performed so that the number of corrections does not exceed the upper limit of corrections by the processing of steps S186 to S187.

  If it is determined in step S184 that the number of image formations is equal to or less than the formation number reference value (step S184: NO), the image forming apparatus 100 performs a counting process of decreasing the value of the correction number counter that counts the number of corrections by “1”. (Step S188), the value of the correction number counter is compared with the lower limit value of correction number stored in the storage unit 17 in advance such as zero (step S189), and the correction number is less than the lower limit value of correction number When the determination is made (step S189: YES), the correction number lower limit value is set as the value of the correction number counter (step S190). If it is determined in step S189 that the number of corrections is equal to or greater than the correction number lower limit (step S189: NO), the process of step S190 is not performed. That is, setting is performed so that the number of corrections does not fall below the lower limit value of corrections by the processing of steps S189 to S190.

  Then, the image forming apparatus 100 adds the product of a predetermined coefficient previously stored in the storage unit 17 such as 0.25% and the number of corrections indicated by the correction number counter to the initial toner density value. Thus, the toner density reference value is calculated (step S191), and the toner density reference value correction process for setting the calculated toner density reference value in the storage unit 17 is performed (step S192).

  Toner density reference value (correction value) = initial value of toner density + coefficient × number of corrections ...... Formula 3

  Since the toner supply amount increases as the toner density reference value increases, the processing in steps S184 to S187 and S191 to S192 is performed in order to increase the toner supply amount when the image formation number exceeds the formation number reference value. It can be said that this is a process for correcting the toner density reference value, and the correction of the toner density reference value has an upper limit value by setting the upper limit value of the number of corrections. Conversely, the processing in steps S184 to S192 can be said to be processing for correcting the toner density reference value to reduce the amount of toner replenishment when the number of image formations does not exceed the formation number reference value. By setting the lower limit value, the correction of the toner density has the lower limit value.

  Then, the image forming apparatus 100 determines whether or not the printing for which the request has been received is completed (step S193). When the image forming apparatus 100 determines that the printing has been completed (step S193: YES), the correction number counter indicating the number of corrections indicates “ It is determined whether it is “0” (step S194), and when it is determined that the correction number counter is “0” (step S194: YES), the process is terminated.

  If it is determined in step S193 that printing has not been completed (step S193: NO), the process returns to step S178, and the subsequent processing is repeated. If it is determined in step S194 that the number of corrections is not “0” (step S194: NO), the process returns to step S178, and the subsequent processing is repeated. The reason why the process is repeated when the correction count is not “0” in step S194 is to return the correction count to “0”.

  More stable image quality can be maintained by performing the processing of the first to eighth embodiments based on the toner density reference value corrected as described above. Various reference values such as the humidity reference value, the cumulative reference value, the printing rate reference value, and the formation number reference value described above can be set as appropriate. For example, in the example shown in the ninth embodiment, assuming that the image forming apparatus 100 has an image forming speed of 45 sheets / minute, the formation number reference value is set to 200 sheets. However, for example, the image forming apparatus 100 has 30 sheets / minute. May be used, the formation number reference value may be set to 150 sheets.

  FIG. 30 is a graph showing an example of processing for correcting the toner density reference value according to the ninth embodiment. In FIGS. 30A and 30B, the horizontal axis represents time and the vertical axis represents the toner density reference value, and the relationship is shown. 30A and 30B show a case where the toner density reference value is corrected to increase the amount of toner replenishment when the number of image formations exceeds 200 sheets in a predetermined time of 10 minutes, and the number is less than 200 sheets. Is an embodiment under conditions where the toner density reference value is corrected to reduce the toner replenishment amount. In FIG. 30A and FIG. 30B, the toner density reference value is shown as a level for convenience. When the toner density initial value is set to level “0” and the toner supply amount is increased, the toner density is shown. When the reference value changes in the “+” direction and the toner supply amount is decreased, the toner density reference value changes in the “−” direction. The upper limit value of the toner density reference value is level “4”, and the lower limit value is set to level “0”, which is the initial value of toner density. As apparent from FIGS. 30A and 30B, the toner density reference value is obtained by executing the process of correcting the density reference value according to the ninth embodiment described with reference to FIGS. Changes between levels “0” to “4” based on the number of image formations.

  In the first to ninth embodiments, the case where the correction value of the reference output voltage value of the ATC sensor 10 is added has been described. However, the present invention is not limited to this, and the correction is made to the reference output voltage value of the ATC sensor 10. You may comprise so that a value may be multiplied.

  In the first to ninth embodiments, the case where the reference output voltage value of the ATC sensor 10 is used as the toner density reference value is described. However, the present invention is not limited to this, and the toner density is used as the toner density reference value. Also good.

1 is a cross-sectional view showing an image forming apparatus according to Embodiment 1. FIG. 1 is a block diagram illustrating a configuration of an image forming apparatus according to a first embodiment. It is a graph which shows the correction value of the reference output voltage value in each humidity range. 6 is a graph showing the relationship between the usage status of the image forming apparatus (developer stirring time) and humidity. 6 is a graph showing the relationship between the usage status of the image forming apparatus (developer stirring time) and the developing bias voltage value by image density correction control. 5 is a graph showing the relationship between the usage status of the image forming apparatus (developer stirring time) and the reference output voltage value. 4 is a flowchart illustrating a processing procedure for correcting a reference output voltage value of a control unit according to the first embodiment. 4 is a flowchart illustrating a processing procedure for correcting a reference output voltage value of a control unit according to the first embodiment. 6 is a graph showing a transition between the output voltage value of the ATC sensor and the reference output voltage value when correction for increasing the reference output voltage value is executed in the first embodiment. 6 is a graph showing a transition between the output voltage value of the ATC sensor and the reference output voltage value when correction for increasing the reference output voltage value is executed in the first embodiment. 5 is a graph showing a transition between an output voltage value of an ATC sensor and a reference output voltage value when correction for lowering a reference output voltage value is executed in the first embodiment. 5 is a graph showing a transition between an output voltage value of an ATC sensor and a reference output voltage value when correction for lowering a reference output voltage value is executed in the first embodiment. 6 is a flowchart illustrating a processing procedure for correcting a reference output voltage value based on a difference in humidity of a control unit and a use frequency of the apparatus according to the second embodiment. 6 is a flowchart illustrating a processing procedure for correcting a reference output voltage value based on a difference in humidity of a control unit and a use frequency of the apparatus according to the second embodiment. 10 is a flowchart showing a processing procedure for correcting a reference output voltage value based on humidity change of a control unit and frequency of use of the apparatus according to the third embodiment. 10 is a flowchart showing a processing procedure for correcting a reference output voltage value based on humidity change of a control unit and frequency of use of the apparatus according to the third embodiment. 10 is a flowchart showing a processing procedure for correcting a reference output voltage value based on humidity change of a control unit and frequency of use of the apparatus according to the third embodiment. It is a graph which shows the relationship between the output voltage value of an ATC sensor, and developer stirring time. 10 is a flowchart illustrating a processing procedure of the image forming apparatus according to the fifth embodiment. 10 is a graph showing a relationship between an elapsed time t and a corrected toner density reference value according to the fifth embodiment. 15 is a flowchart illustrating a processing procedure of the image forming apparatus according to the sixth embodiment. 15 is a flowchart illustrating a processing procedure of the image forming apparatus according to the sixth embodiment. 14 is a flowchart illustrating toner supply processing of the image forming apparatus according to the sixth embodiment. 14 is a flowchart illustrating toner supply processing of the image forming apparatus according to the sixth embodiment. 15 is a flowchart illustrating a processing procedure of the image forming apparatus according to the seventh embodiment. FIG. 10 is a block diagram schematically illustrating a toner cartridge provided in an image forming apparatus according to an eighth embodiment. 18 is a flowchart illustrating a processing procedure of the image forming apparatus according to the eighth embodiment. 20 is a flowchart illustrating a processing procedure of the image forming apparatus according to the ninth embodiment. 20 is a flowchart illustrating a processing procedure of the image forming apparatus according to the ninth embodiment. 20 is a graph showing an example of processing for correcting a toner density reference value according to Embodiment 9. 1 is a block diagram illustrating a configuration of an image forming apparatus. It is a graph which shows the relationship between a toner density | concentration (wt%) and the output voltage value (V) of an ATC sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 1 Photoconductor drum 2 Charging mechanism 3 Exposure mechanism 4 Developing mechanism 5 Transfer mechanism 7 Fixing mechanism 10 ATC sensor 11 Humidity sensor 12 Photo sensor 13 Control circuit 15 Control unit 16 Calculation unit 17 Storage unit

Claims (9)

By detecting the toner density of the developer housed in the developing mechanism that supplies the developer including the toner and the carrier, and comparing the detected toner density with a pre-recorded toner density reference value, In an image forming method using an image forming apparatus that controls replenishment of toner and forms an image on an image forming medium with a developer supplied from a developing mechanism.
The image forming apparatus includes:
Count the number of images formed,
Compare the number of image formations counted with the reference number of formations recorded in advance,
An image forming method comprising: correcting the toner density reference value so as to increase a toner replenishment amount when it is determined by the comparison that the number of formed images exceeds a formation number reference value. By detecting the toner density of the developer housed in the developing mechanism that supplies the developer including the toner and the carrier, and comparing the detected toner density with a pre-recorded toner density reference value, In an image forming apparatus that controls replenishment of toner and forms an image on an image forming medium with a developer supplied from a developing mechanism.
A counting means for counting the number of image formations;
Means for comparing the counted number of image formations with a pre-recorded formation number reference value;
An image forming apparatus comprising: a correction unit that corrects the toner density reference value so as to increase the toner replenishment amount when it is determined by the comparison that the number of image formations exceeds the formation number reference value. A means for calculating a printing ratio indicating a ratio occupied by an image formed on the image forming medium;
The image forming apparatus according to claim 2, wherein the counting unit is configured to count only images whose printing rate exceeds a predetermined printing rate reference value. The counting means is configured to count the number of image formations within a predetermined time every time the predetermined time elapses,
The correction means is configured to correct the toner density reference value so as to increase the toner replenishment amount step by step whenever the number of image formations exceeds the formation reference value. The image forming apparatus according to claim 3.   The image forming apparatus according to claim 4, wherein the toner density reference value has an upper limit value.   The correction means is configured to correct the toner density reference value so as to decrease the toner replenishment amount when it is determined that the number of image formations does not exceed the formation reference value. The image forming apparatus according to claim 4 or 5.   The image forming apparatus according to claim 6, wherein the toner density reference value has a lower limit value. Means for detecting humidity;
Means for comparing the detected humidity with a predetermined humidity reference value;
8. The correction unit is configured to limit correction of the toner density reference value when it is determined that the detected humidity exceeds the humidity reference value. 8. The image forming apparatus according to any one of the above. Means for counting the cumulative number of image formations;
Means for comparing the counted cumulative number with a pre-recorded cumulative number reference value;
9. The toner density reference value correction is limited when it is determined by the comparison that the accumulated number exceeds the accumulated number reference value. The image forming apparatus according to one.

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