JP5082664B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In an electrophotographic image forming apparatus, an electrostatic latent image formed on an image carrier is developed into a toner image by a developing device. Therefore, it is necessary to replenish the developing device with the toner consumed by the development. In general, in the case of a developing device that supplies a two-component developer composed of a toner and a carrier to a developing roll while stirring in a developing chamber, an auger for stirring (hereinafter also referred to as “stirring auger”) provided in the developing chamber. The developer (toner and carrier) is conveyed while being agitated by rotation. When toner is replenished to the developing device, the toner is replenished by driving a toner replenishing motor through a toner replenishing chamber and a toner replenishing path connected to the developing chamber of the developing device.

  In this type of image forming apparatus, in order to prevent image quality defects (BCO, fog, toner cloud, etc.) while stabilizing the image density, it is important to control the toner density in the developing chamber within a target range.

  Therefore, as a conventional technique related to toner density control, for example, Japanese Patent Application Laid-Open No. 2004-228561 solves a problem that a toner replenishment rate changes due to manufacturing variation and deterioration of a toner replenishment roller, a change in toner fluidity, and a change in toner amount. Therefore, an invention relating to an electrophotographic apparatus having means for changing the replenishment time per toner replenishment or the rotation speed of the toner replenishment roller per toner replenishment is disclosed.

  Patent Document 2 listed below is based on the density measurement value of a black reference patch formed by a black developer in a single color image formation mode (monochrome image formation mode) and a multicolor image formation mode (full color image formation mode). An invention relating to an image forming apparatus that controls the amount of toner replenished to the black developer is disclosed.

  Here, when the developing device driving source (hereinafter referred to as “developing device driving source”) and the toner replenishing driving source (hereinafter referred to as “toner replenishing driving source”) are configured as separate driving sources. When the operating speed of the developer drive source is changed in accordance with the processing speed of image formation (hereinafter referred to as “process speed”), the developer agitation in the developing chamber is caused by fluctuations in the rotational speed of the stirring auger. As a result, the developer transport speed (hereinafter also referred to as “developer transport speed”) by the rotation of the stirring auger and the toner transport speed by driving the toner supply drive source (toner supply motor) are changed. (Hereinafter also referred to as “toner replenishment conveyance speed”) is lost.

JP 2002-49234 A JP 2001-34018 A

  An object of the present invention is to provide an image forming apparatus capable of maintaining a balance between a developer conveyance speed and a toner replenishment conveyance speed even when the operation speed of the developing unit is changed.

An image forming apparatus according to a first aspect of the present invention includes an image carrier, a developing unit that develops an electrostatic latent image formed on the image carrier with toner, and a toner supply that replenishes the developing unit with the toner. And a speed control means for changing the operating speed of the toner replenishing means in accordance with the operating speed of the developing means, and the driving time of the toner replenishing means that could not be processed in the previous toner replenishing period. The toner replenishment control means for determining the next toner replenishment period by carrying over the toner replenishment period, and the toner replenishment time calculated based on the toner density control information for controlling the toner density of the developing means A value obtained by multiplying the first coefficient is used as an addition value, and a value obtained by multiplying the driving time of the toner replenishing means by a second coefficient is used as a first subtraction value. And a toner replenishment control means for switching the first coefficient and the second coefficient in accordance with the operating speed of the developing means when calculating the driving time of the toner replenishing means. .

An image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the toner replenishment control means includes an overrun of the toner replenishment means determined in addition to the first subtraction value. When the value obtained by multiplying the third coefficient by time is used as the second subtraction value, the third coefficient is switched according to the operating speed of the developing unit.

The image forming apparatus according to a third aspect of the present invention is characterized in that the toner replenishment control unit decreases the first coefficient as the operating speed of the developing unit increases.

The image forming apparatus according to claim 4 of the present invention is characterized in that the toner replenishment control means increases the second coefficient as the operating speed of the developing means increases.

The image forming apparatus according to claim 5 of the present invention is characterized in that the toner replenishment control means increases the third coefficient as the operating speed of the developing means increases.

According to the first aspect of the present invention, the driving time of the toner replenishing means that cannot be processed in the previous toner replenishing period is changed according to the operating speed of the developing means, and is carried over to the next toner replenishing period. Can do.
According to the second aspect of the present invention, the overrun time of the toner replenishing means can be changed according to the operating speed of the developing means and carried over to the next toner replenishing period.
According to the third to fifth aspects of the invention, the driving time of the toner replenishing unit can be changed according to the operating speed of the developing unit.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention. The illustrated image forming apparatus 1 employs a four-tandem machine configuration, and is roughly divided into four image forming units 2, 3, 4, and 5 and the four image forming units 2, 3, 4, and 4. 5 includes a common exposure device 6, an intermediate transfer member 7, and a secondary transfer device 8.

  The image forming apparatus 1 forms a full color image using four color toners such as yellow, magenta, cyan, and black in the multicolor image forming mode, and forms a black and white image using black toner in the single color image forming mode. To do. The image forming unit 2 forms a visible image using yellow toner, and the image forming unit 3 forms a visible image using magenta toner. The image forming unit 4 forms a visible image using cyan toner, and the image forming unit 5 forms a visible image using black toner. In the following description, a visible image formed using toner in each of the image forming units 2, 3, 4, and 5 will be referred to as a “toner image”.

  Each of the image forming units 2, 3, 4, 5 is arranged in order from the upstream side to the downstream side in the moving direction of the intermediate transfer body 7. That is, in the moving direction of the intermediate transfer body 7 (Y direction in the figure), the image forming unit 3 is disposed on the downstream side of the image forming unit 2, and the image forming unit 4 is disposed on the downstream side of the image forming unit 3. The image forming unit 5 is disposed on the downstream side of the image forming unit 4.

  The exposure device 6 emits laser light toward the corresponding image forming units 2, 3, 4, and 5 based on the image data separated into the color components of yellow, magenta, cyan, and black, and The laser beam is scanned in a predetermined direction (main scanning direction).

  The intermediate transfer member 7 is constituted by an endless belt member. The intermediate transfer body 7 is supported in a loop shape (partially omitted) by a plurality of support rolls 11, 12, 13, and 14. The plurality of support rolls 11 to 14 support the intermediate transfer body 7 with a predetermined tension and move (run) the intermediate transfer body 7 at a predetermined speed in the Y direction, which is an image forming process direction.

  The secondary transfer device 8 transfers the toner image transferred to the intermediate transfer body 7 to a sheet (not shown). The secondary transfer device 8 is arranged in a state where the intermediate transfer member 7 is sandwiched between the secondary transfer device 8 and the support roll 14 so as to be close to and opposed to the support roll 14. The sheet serving as the recording medium is conveyed so as to pass between the secondary transfer device 8 and the support roll 14, and the toner image is transferred from the intermediate transfer member 7 to the sheet during the conveyance. Further, the sheet on which the toner image is transferred is sent to a fixing device (not shown), where the toner image is fixed on the sheet by being heated and pressurized.

  Each of the image forming units 2, 3, 4, and 5 has a common configuration. Therefore, here, the configuration of the image forming unit 2 will be described as a representative example. The image forming unit 2 is provided with an image carrier 201. The image carrier 201 is driven to rotate counterclockwise at a constant speed during image formation. Around the image holding member 201, a charger 202, a developing device 203, an image density sensor 204, a primary transfer roll 205, and the like are sequentially provided in accordance with the rotation direction of the image holding member 201.

  The charger 202 charges the surface of the image carrier 201 to a predetermined potential. The developing device 203 forms a toner image on the image carrier 201 by developing the electrostatic latent image formed on the surface of the image carrier 201 by the exposure device 6 with toner. A toner density sensor 206 is attached to the developing device 203. The toner concentration sensor 206 detects a toner concentration (TC) in the developing chamber. The image density sensor 204 detects the density of the toner image formed on the image carrier 201. The primary transfer roll 205 is for transferring the toner image formed on the surface of the image holding member 201 to the intermediate transfer member 7.

  A developing roll 207, a supply auger 208, and a stirring auger 209 are incorporated in the developing chamber of the developing device 203. The developing roll 207, the supply auger 208, and the stirring auger 209 rotate with the developing motor as a common driving source when, for example, a developing motor (not shown) is provided as a developing device driving source. The developing device 203 is provided as a developing means including the developing device driving source. Therefore, the operating speed of the developing means refers to the rotational speed of the developing roll 207, the supply auger 208, the stirring auger 209, etc., and the driving speed (rotational speed) of the developing motor that determines this.

  The developing roll 207 magnetically attracts and holds the two-component developer composed of toner and carrier, and conveys the developer in the circumferential direction by the rotation of the roll itself. The developing roll 207 is configured using, for example, a magnet roll, and is disposed close to a position facing the image holding member 201 (hereinafter referred to as “developing position”).

  The supply auger 208 supplies the two-component developer to the developing roll 207 while conveying the two-component developer in the rotation axis direction of the auger. The stirring auger 209 charges the toner with a predetermined polarity by friction with the carrier by transporting the toner and the carrier while stirring. The supply auger 208 and the stirring auger 209 are arranged in a developing chamber partitioned by a partition (not shown). The developing roll 207 is disposed facing the developing chamber on which the supply auger 208 is disposed.

  Similar to the image forming unit 2 configured as described above, the image forming unit 3 includes an image carrier 301, a charger 302, a developing unit 303, an image density sensor 304, a primary transfer roll 305, a toner density sensor 306, a developing roll 307, and a supply. An auger 308, a stirring auger 309, and the like are used. The image forming unit 4 uses an image carrier 401, a charger 402, a developing unit 403, an image density sensor 404, a primary transfer roll 405, a toner density sensor 406, a developing roll 407, a supply auger 408, a stirring auger 409, and the like. The image forming unit 5 includes an image carrier 501, a charger 502, a developing device 503, an image density sensor 504, a primary transfer roll 505, a toner density sensor 506, a developing roll 507, a supply auger 508, a stirring auger 509, and the like. It is comprised using.

  Of the four image forming units 2, 3, 4, and 5, the developing unit 203 of the image forming unit 2 is supplied with yellow toner from the toner cartridge 15 mounted in the apparatus corresponding thereto, and the image is formed. Corresponding to this, the developing unit 303 of the forming unit 3 is configured to be supplied with magenta toner from the toner cartridge 16 mounted in the apparatus. The developing unit 403 of the image forming unit 4 is supplied with cyan toner from the toner cartridge 17 mounted in the apparatus corresponding thereto, and the developing unit 503 of the image forming unit 5 corresponds to this. Thus, black toner is supplied from a toner cartridge 18 mounted in the apparatus. Among these, the size (volume) of the toner cartridge 18 is larger than the sizes of the other toner cartridges 15, 16, and 17.

  The yellow toner accommodated in the toner cartridge 15 is replenished to the developing device 203 by driving the toner replenishing motor 21, and the magenta toner accommodated in the toner cartridge 16 is replenished to the developing device 303 by driving the toner replenishing motor 21. Will be replenished. The cyan toner accommodated in the toner cartridge 17 is replenished to the developing device 403 by driving the toner replenishing motor 23, and the black toner accommodated in the toner cartridge 18 is developed by driving the toner replenishing motor 24. The vessel 503 is replenished.

  The toner replenishing motor 21 is provided as a toner replenishing drive source for yellow toner. The toner supply motor 21 serves as a drive source for rotating a toner supply member for supplying yellow toner (not shown). The toner supply motor 22 is provided as a toner supply drive source for magenta toner. The toner supply motor 22 is a drive source for rotating a toner supply member for supplying magenta toner (not shown). The toner replenishing motor 23 is provided as a toner replenishing drive source for cyan toner. The toner supply motor 23 is a drive source for rotating a toner supply member for supplying cyan toner (not shown). The toner replenishing motor 24 is provided as a toner replenishing drive source for black toner. The toner supply motor 24 serves as a drive source for rotating a toner supply member for black toner supply (not shown).

  The toner replenishing member for replenishing yellow toner is provided as toner replenishing means for replenishing the developing unit 203 with yellow toner including the toner replenishing motor 21. The toner supply member for supplying the magenta toner is provided as toner supply means for supplying the developing device 303 with magenta toner, including the toner supply motor 22. The toner replenishing member for replenishing cyan toner is provided as toner replenishing means for replenishing the developing unit 403 with cyan toner, including the toner replenishing motor 23. The toner replenishing member for black toner replenishment is provided as toner replenishing means for replenishing the developing device 503 with black toner including the toner replenishing motor 24. Therefore, in this embodiment, the operation speed of the toner replenishing means refers to the rotational speed of the toner replenishing member corresponding to each color and the driving speed (rotational speed) of the toner replenishing motors 21, 22, 23, and 24 that determine this. Say.

  The toner amount detection sensor 25 detects the amount (remaining amount) of toner stored in the toner cartridge 15. The toner amount detection sensor 26 detects the amount of toner contained in the toner cartridge 16. The toner amount detection sensor 27 detects the amount of toner contained in the toner cartridge 17. The toner amount detection sensor 28 detects the amount of toner contained in the toner cartridge 18.

  On the other hand, an ADC sensor 29 is disposed in the vicinity of the support roll 11 so as to face the intermediate transfer member 7 on the opposite side of the support roll 11. The ADC sensor 29 is provided to control the toner density by an ADC (Auto Density Control) method. The image density sensor 29 is a toner patch formed for the purpose of density control among toner images transferred to the intermediate transfer body 7 by primary transfer rolls 205, 305, 405, and 505 arranged in the Y direction at predetermined intervals. Is to detect the concentration of.

  The toner replenishment control unit 31 stores various types of information (hereinafter referred to as “toner density control information”) that is taken in each of the developing devices 203, 303, 403, and 503 of each color in order to stably control the toner density in the developing chamber. The toner replenishment time is calculated on the basis of the above, and the driving of the toner replenishment motors 21, 22, 23, 24 corresponding to each of the toner replenishment times is controlled.

  The toner supply control unit 31 includes, as an example of toner density control information, information from the toner density sensors 206, 306, 406, and 506, information from the toner amount detection sensors 25, 26, 27, and 28, and an ADC sensor. The information from 29, the information from the pixel counter 32, and the information from the temperature sensor 33 are taken in. The pixel counter 32 counts the number of pixels (effective number of pixels) of image data per page (one sheet of paper). For this reason, the information from the pixel counter 32 is information indicating the pixel count value per page. The temperature sensor 33 detects the temperature inside the apparatus (in-machine temperature).

  The toner density control information may be an image density per page (a value obtained by dividing the total number of pixels in one page by the number of effective pixels) or image density sensors 204, 304, 404, and 504. It may be information obtained by.

  However, in the embodiment of the present invention, out of various toner density control information, information from the pixel counter 32 (information indicating the pixel count value) and information from the ADC sensor 29 (information indicating the patch density) are used. The case of calculating the toner replenishment time with reference to will be described as an example.

  FIG. 2 is a block diagram showing a schematic configuration of a control system of the image forming apparatus according to the embodiment of the present invention. In addition to the ADC sensor 29 and the pixel counter 32 described above, a memory 34 is connected to the toner supply control unit 31. The memory 34 is used for storing various data and information related to toner supply control.

  The toner replenishing motor control unit 36 individually controls the driving of the toner replenishing motors 21, 22, 23, and 24 based on the motor driving command from the toner replenishing control unit 31. The developing motor control unit 37 individually controls driving of the developing motors 38, 39, 40, and 41 based on a motor driving command from an image forming control unit (not shown). The developing motor 38 is a driving source for the developing device 203, and the developing motor 39 is a driving source for the developing device 303. The developing motor 40 is a driving source for the developing device 403, and the developing motor 41 is a driving source for the developing device 503.

  FIG. 3 is a flowchart showing the toner replenishment motor speed setting process performed by the toner replenishment motor controller 36. First, the toner replenishing motor control unit 36 determines whether the driving speed of the developing motor is set to “high speed”, “medium speed”, or “low speed” (step S1). In this embodiment, as an example, the image forming process speed, the developing motor driving speed, and the toner replenishing motor driving speed are divided into three stages of “high speed”, “medium speed”, and “low speed”, respectively. Shall. Among these, “medium speed” is a normal (standard) speed, “high speed” is a speed faster than “medium speed”, and “low speed” is a speed slower than “medium speed”. The driving speed of the developing motor is defined by the motor rotation speed (rpm) per unit time. The driving speed of the developing motor depends on the image forming process speed. The image forming process speed depends on the peripheral speed of the image carrier (201, 301, 401, 501) at the developing position and the moving speed of the intermediate transfer member 7. It depends on. The peripheral speed of the developing roll is set so as to maintain a constant ratio with the peripheral speed of the image carrier. For this reason, the peripheral speed of the developing roll is proportional to the process speed. The driving speed of the developing motor and the peripheral speed of the developing roll determined thereby correspond to the “operating speed of the developing means”.

  Accordingly, for example, when there are a plurality of process speeds due to differences in image quality required (set) in image formation, the peripheral speed of the developing roll changes in proportion to the process speed applied to image formation. In the present embodiment, as an example, the image forming process speed (peripheral speed of the image carrier, etc.) is adjusted in three stages as described above according to image forming conditions such as image quality setting in an image forming control unit (not shown). Shall be switched to

  In such a case, when the process speed is set to “high speed” by the image forming control unit, the driving speed of the developing motor is set to “high speed” by the developing motor control unit 37 accordingly. When the process speed is set to “medium speed”, the development motor drive speed is set to “medium speed” accordingly, and when the process speed is set to “low speed”, the process speed is set accordingly. The driving speed of the developing motor is set to “low speed”. Incidentally, the process speed of image formation and the driving speed of the developing motor are set so as to maintain a constant ratio. For example, even if the same “high speed” setting is used, the speeds of both are not necessarily the same. .

  If it is determined in step S1 that the driving speed of the developing motor is set to “high speed”, the toner replenishing motor control unit 36 sets the driving speed of the toner replenishing motor to “high speed” accordingly. Set (step S2). If it is determined that the driving speed of the developing motor is set to “medium speed”, the toner replenishing motor control unit 36 sets the driving speed of the toner replenishing motor to “medium speed” accordingly. If it is determined that the driving speed of the developing motor is set to "low speed" (step S3), the toner replenishing motor control unit 36 sets the driving speed of the toner replenishing motor to "low speed" accordingly. (Step S4).

  Next, the toner replenishing motor control unit 36 sets each of the toner replenishing motors 21, 22, 23, and 24 in step S2, S3, or S4 based on the motor driving command given from the toner replenishing control unit 31. It is rotationally driven at the set drive speed (step S5). That is, when the driving speed of the toner replenishing motor is set to “high speed” in step S2, the toner replenishing motor control unit 36 rotates and drives the toner replenishing motor at “high speed” according to this speed setting. If the driving speed of the toner supply motor is set to “medium speed” in step S3, the toner supply motor control unit 36 drives the toner supply motor to rotate at “medium speed” according to this speed setting. When the driving speed of the toner supply motor is set to “low speed” in step S4, the toner supply motor control unit 36 drives the toner supply motor to rotate at “low speed” according to this speed setting.

  In the above processing flow, when the driving speed of the developing motor is set to “high speed”, the driving speed of the toner replenishing motor is set to “high speed” accordingly, and the driving speed of the developing motor is set. Is set to “medium speed”, the drive speed of the toner replenishing motor is set to “medium speed” and the drive speed of the developing motor is set to “low speed” accordingly. Accordingly, the driving speed of the toner replenishing motor is set to “low speed”.

  Thus, for example, in the developing device 203, when the rotation speed of the developing motor 38 that determines the rotation speed of the stirring auger 209 is relatively high, the rotation speed of the toner supply motor 21 that determines the rotation speed of the toner supply member is relatively high. If the rotational speed of the developing motor 38 is relatively slow, the rotational speed of the toner supply motor 21 is corrected to be relatively slow. Therefore, even if the image forming process speed changes, the balance between the developer conveying speed and the toner replenishing conveying speed is maintained. The same applies to the other developing devices 303, 403, and 503. However, in order to maintain the balance between the developer conveyance speed and the toner replenishment conveyance speed, the relationship between the speeds (speed ratio) is not necessarily constant.

  As a specific event when the balance between the developer conveyance speed and the toner replenishment conveyance speed is lost, for example, when the toner replenishment conveyance speed is too high compared to the developer conveyance speed, There is a risk of toner clogging, but such a concern disappears if the balance between the two is maintained.

  By the way, the toner replenishment control unit 31 predicts the toner consumption amount per page based on the pixel count value information fetched from the pixel counter 32, and develops an amount of toner corresponding to the toner consumption amount. The toner replenishment time required to replenish the chamber is calculated. Then, during the toner replenishment period corresponding to a period during which development is performed with any one developing device (hereinafter referred to as “development period”), the toner replenishment motor is referred to (used as a control parameter) with reference to the toner replenishment time. By rotating, toner supply to the developing device (developing chamber) is controlled. One development period is defined as a period during which the electrostatic latent image formed on the image holding member passes through a position facing the development roll, and one toner replenishment period is defined correspondingly. Within one toner replenishment period, the toner replenishment amount varies depending on the length of time for actually driving the toner replenishment motors (21 to 24). The toner replenishment control method based on the pixel count value described above is also called an ICDC (Image Count Dispense Control) method.

  The toner supply control unit 31 uses, in addition to ICDC toner density control using the pixel counter 32, ADC toner density control using the density detection sensor ADC sensor 29. When the ADC toner density control is used in combination, for example, the toner sensor density is detected by the ADC sensor 29 each time a toner image corresponding to a preset number of pages is developed, and the toner replenishment time is determined based on the detection result. Is calculated. The toner replenishment driving time calculated by the ADC method is a negative value corresponding to the density difference when the density of the toner patch detected by the ADC sensor 29 is higher than the target reference density, and the toner patch density is When the density is lower than the reference density, a positive value corresponding to the density difference is obtained.

When the toner supply time calculated by the ICDC method is defined as “ICDC toner supply time” and the toner supply time calculated by the ADC method is defined as “ADC toner supply time”, the toner supply control unit 31 (1) The toner replenishment time is obtained by the formula.
Toner replenishment time = ICDC toner replenishment time + ADC toner replenishment time (1)

  On the other hand, the amount of toner per unit time replenished to the developing device (development chamber) by the rotation of the toner replenishing motor, that is, the toner replenishing rate, depends on the driving speed of the toner replenishing motor. Specifically, the toner supply rate increases as the driving speed of the toner supply motor increases. Therefore, even if the toner replenishing motor is rotated by the same amount of time, the toner replenishing amount changes if the driving speed of the toner replenishing motor is changed in accordance with the driving speed of the developing motor as described above. The toner replenishment amount refers to the amount of toner replenished to the developing chamber of the developing device by driving toner replenishing means (equivalent to a toner replenishing motor).

Here, the time for actually driving the toner replenishing means is defined as the toner replenishing driving time, the unit of the toner replenishing driving time is millisecond (msec), the unit of the toner replenishing amount is milligram (mg), and the toner replenishing time. When the unit of the rate is milligram (mg) / second (sec), the relationship of the following equation (2) is established between them.
Toner replenishment amount = toner replenishment rate × 10 ⁻³ × toner replenishment drive time (2)

  In the above equation (2), if the toner replenishment drive time is constant, the toner replenishment amount increases as the toner replenishment rate increases, and conversely, the toner replenishment amount decreases as the toner replenishment rate decreases. As a specific example, if the toner replenishment drive time is constant at 1000 msec, the toner replenishment amount is 200 mg when the toner replenishment rate is 200 mg / sec, and the toner replenishment amount is 300 mg when the toner replenishment rate is 300 mg / sec. Become. For this reason, a difference of 100 mg occurs in the toner replenishment amount due to the difference in toner replenishment rate.

  On the other hand, in the image forming apparatus 1 according to the present invention, the developing motor is designed so that the toner replenishment amount does not change even when the driving speed of the toner replenishing motor is changed according to the driving speed of the developing motor. The toner supply control unit 31 performs processing (details will be described later) for changing the drive time (toner supply drive time) of the toner supply motor in accordance with the drive speed. In such processing, when the driving speed of the developing motor is relatively high, the driving time of the toner replenishing motor is changed to be relatively short, and when the driving speed of the developing motor is relatively slow, The driving time of the toner supply motor is changed so as to be relatively long. As a result, as compared with the case where the toner replenishment drive time is constant as described above, the difference in toner replenishment amount due to the difference in toner replenishment rate is reduced.

  As a specific example, assuming that the toner replenishment drive time applied when the toner replenishment rate = 200 mg / sec is 1000 msec, and the toner replenishment drive time applied when the toner replenishment rate = 300 mg / sec is 700 msec, the toner replenishment rate = 200 mg / sec, the toner supply amount is 200 mg, and when the toner supply rate = 300 mg / sec, the toner supply amount is 210 mg. Therefore, even if the toner replenishment rate is different, the difference in toner replenishment amount is 10 mg, which corresponds to 1/10 of the amount when the toner replenishment drive time is constant.

  FIG. 4 is a flowchart showing an example of the toner replenishment control process according to the embodiment of the present invention. First, the toner replenishment control unit 31 sets the development motor drive speed notified from the development motor control unit 37 (or the image formation control unit) to any one of “high speed”, “medium speed”, and “low speed”. It is determined whether it has been performed (step S11).

  If it is determined in step S11 that the driving speed of the developing motor is set to "high speed", the coefficient M1 stored in the memory 34 corresponding to the "high speed" speed setting is read (step S11). S12). When it is determined that the driving speed of the developing motor is set to “medium speed”, the coefficient M2 stored in the memory 34 corresponding to the “medium speed” speed setting is read (step S13). When it is determined that the driving speed of the developing motor is set to "low speed", the coefficient M3 stored in the memory 34 corresponding to the "low speed" speed setting is read (step S14). These three coefficients M1, M2, and M3 are set to have a magnitude relationship of “M1 <M2 <M3”.

  Next, the toner replenishment control unit 31 multiplies the ICDC toner replenishment time calculated by the ICDC method by the coefficient M1, M2 or M3 read in step S12, S13 or S14, thereby obtaining the ICDC toner replenishment time. Correction is performed (step S15). Specifically, when the driving speed of the developing motor is set to “high speed”, the ICDC toner supply time is multiplied by a coefficient M1. Further, when the driving speed of the developing motor is set to “medium speed”, the ICDC toner replenishment time is multiplied by the coefficient M2, and when the driving speed of the developing motor is set to “low speed”, The ICDC toner supply time is multiplied by a coefficient M3.

  Next, the toner replenishment control unit 31 multiplies the ADC toner replenishment time calculated in the ADC system by the coefficient M1, M2 or M3 read in step S12, S13 or S14, thereby obtaining the ADC toner replenishment time. Correction is performed (step S16). Specifically, when the driving speed of the developing motor is set to “high speed”, the ADC toner replenishment time is multiplied by a coefficient M1. Further, when the driving speed of the developing motor is set to “medium speed”, the ADC toner replenishment time is multiplied by the coefficient M2, and when the driving speed of the developing motor is set to “low speed”, The ADC toner supply time is multiplied by a coefficient M3.

  Next, the toner replenishment control unit 31 uses the ICDC toner replenishment time corrected in step S15 and the ADC toner replenishment time corrected in step S16 to determine the toner replenishment time to be applied to the toner replenishment operation (1). Calculation is performed according to the equation (step S17).

  Next, the toner replenishment control unit 31 gives a motor drive command to the toner replenishment motor control unit 36 based on the toner replenishment time calculated in step S17, thereby rotating the toner replenishment motor to perform the toner replenishment operation. This is executed (step S18). In this case, the toner replenishment motor control unit 36 is provided for each developing device (development color) from the toner replenishment control unit 31 in the toner replenishment period corresponding to the development period of each of the developing devices 203, 303, 403, and 503. Each toner replenishment motor is individually driven to rotate by the amount corresponding to the toner replenishment time included in the motor drive command.

  In the above processing flow, when the driving speed of the developing motor is set to “high speed”, the toner replenishment time (ICDC toner replenishment time + ADC toner replenishment time) is corrected using the smallest coefficient M1, and development is performed. When the driving speed of the motor is set to “low speed”, the toner replenishment time is corrected using the largest coefficient M3.

  For this reason, for example, assuming that the respective coefficients are set to M1 = 0.8, M2 = 1.0, and M3 = 1.2, the driving speed of the developing motor is set to “high speed”. In this case, correction is performed in a direction in which the toner replenishment time is shortened, and when the driving speed of the developing motor is set to “low speed”, correction is performed in a direction in which the toner replenishment time is increased. As a result, in the actual toner replenishment operation, when the drive speed of the developing motor is set to “high speed”, the toner replenishment drive time is made shorter than when it is set to “medium speed”. When the driving speed of the developing motor is set to “low speed”, the toner replenishment driving time is changed to be longer than when the driving speed is set to “medium speed”.

  As a specific example, when image data having a common ICDC toner replenishment time of 1000 msec calculated based on the number of pixels for one page is processed continuously for 10 pages with the same development color, The coefficient applied when the driving speed is set to “high speed” is set to M1 = 0.8, the coefficient applied to the setting of “medium speed” is set to M2 = 1.0, and the coefficient applied to the driving speed is set to “low speed”. Assume that the applied coefficient is set to M3 = 1.2.

  In such a case, if the drive speed of the developing motor is set to “medium speed”, the ICDC toner replenishment time is directly reflected in the toner replenishment drive time, so that toner for processing image data for 10 pages is used. The total replenishment drive time is 10,000 msec (an average of one page is 1000 msec). When the driving speed of the developing motor is set to “high speed”, a value obtained by multiplying the ICDC toner replenishment time by a coefficient M1 = 0.8 is reflected in the toner replenishment drive time. The total toner replenishment drive time for processing image data is 8000 msec (800 msec on an average per page). On the other hand, when the driving speed of the developing motor is set to “low speed”, the value obtained by multiplying the ICDC toner replenishment time by the coefficient M3 = 1.2 is reflected in the toner replenishment drive time. The total toner replenishment drive time when processing image data is 12000 msec (1 page average 1200 msec).

  Further, for convenience of explanation, the toner supply rate when the driving speed of the toner supply motor is set to “high speed” is 1.2 mg / sec, and the toner supply rate when the driving speed is set to “medium speed” is 1. It is assumed that the toner replenishment rate is 0.8 mg / sec when set to 0.0 mg / sec and “low speed”. In such a case, in the processing flow shown in FIG. 3, when the driving speed of the developing motor is set to “high speed”, the driving speed of the toner replenishing motor is also set to “high speed”, and the driving speed of the developing motor is set. Is set to “medium speed”, the driving speed of the toner replenishing motor is also set to “medium speed”, and when the driving speed of the developing motor is set to “low speed”, Since the drive speed is also set to “low speed”, in the above example, the total toner supply amount for 10 pages when the drive speed of the toner supply motor is set to “high speed” is 9.6 mg (average of one page) 0.96 mg), the total toner supply amount for 10 pages when the driving speed of the toner supply motor is set to “medium speed” is 10 mg (1 mg on an average per page), and the driving speed of the toner supply motor is “low speed”. At the time of setting Total amount of toner supplied 0 pages becomes 9.6 mg (0.96 mg on average for one page).

  On the other hand, for example, assuming that the coefficients M1, M2, and M3 are all set to 1.0, the total toner replenishment drive time when processing image data for 10 pages is calculated as follows. Regardless of the driving speed of the motor, all are 10,000 msec (one page average is 1000 msec). For this reason, when the driving speed of the developing motor is set to “high speed”, the total amount of toner replenishment for 10 pages is 12 mg (1.2 mg on an average per page), and when the driving speed of the developing motor is set to “medium speed” The total toner replenishment amount for 10 pages is 10 mg (1 page average is 1 mg), and the total toner replenishment amount for 10 pages when the developing motor drive speed is set to “low speed” is 8.0 mg (1 page average) 0.8 mg).

  Therefore, for example, when image data for one page having the same number of pixels counted by the pixel counter 32 is formed on a sheet by changing the driving speed condition of the developing motor, the toner is changed by changing the driving speed of the toner replenishing motor. Even if the replenishment rate changes, the toner replenishment drive time is changed based on the processing flow shown in FIG. 4 to equalize the toner replenishment amount per page regardless of the driving speed of the toner replenishment motor. It will be.

  By the way, the toner replenishing operation by driving the toner replenishing motor takes into account the agitation and charging properties of the toner, and the toner replenishment operation is performed up to n times (n is a maximum of n times) within one toner replenishing period. The natural number may be divided into two or more. In such a case, if the toner replenishment drive time t per one toner replenishment operation is defined as the toner replenishment drive unit time, the upper limit value of the toner replenishment drive time allowed in one toner replenishment period is defined by n × t hours. Will be.

  Further, when a toner replenishment time applied to a toner replenishment operation for a certain color toner exceeds the above upper limit (n × t time), toner replenishment may not be completed within one toner replenishment period. possible. In such a case, insufficient toner replenishment is performed for a certain color toner by performing the toner replenishment operation in the next toner replenishment period, taking into account the toner replenishment drive time that could not be processed in the previous toner replenishment period. Make up for the minute. In the following description, such processing is referred to as “toner supply buffer processing”.

  In the toner replenishment buffer process, the toner replenishment buffer time is stored in the memory 34 for each of the developing devices 203, 303, 403, and 503 of each color. That is, the toner replenishment buffer time is held in the memory 34 for each development color of yellow, magenta, cyan, and black. For the developer of the corresponding development color, the toner replenishment time calculated by the ICDC method, the ADC method, or the like is added to the toner replenishment buffer time, while the toner replenishment motor drive time (toner replenishment drive time) Is subtracted from the toner replenishment buffer time, and the toner replenishment buffer process described later is performed while sequentially updating the toner replenishment buffer time in the memory 34.

<Concept of toner supply buffer processing>
When the toner replenishment operation is performed n times (n is a natural number of 2 or more) every t time during one toner replenishment period, the number of toner replenishment operations is determined based on the toner replenishment buffer time in each toner replenishment period. To do. Specifically, the number of toner replenishment operations is determined based on the quotient (integer) and the remainder obtained by dividing the toner replenishment buffer time by the value of t, and the toner corresponding to the number of times is determined. The replenishment drive time is subtracted from the toner replenishment buffer time, and the remainder is set as the carry-over amount to the next time. Further, when the toner replenishment buffer time exceeds t × n time that is the upper limit value of the toner replenishment drive time, the excess amount is carried over to the next time, and when the toner replenishment buffer time is a negative value, The toner replenishment buffer time is used as the carry-over to the next time.

<Example of toner supply buffer processing>
Now, in a system configuration of a toner concentration control system capable of performing a toner replenishment operation for a maximum of 3000 msec (n = 6, t = 500 msec) in one toner replenishment period, it is stored in the memory 34 before entering this toner replenishment period. Assuming that the toner replenishment buffer time is 1000 msec, during this toner replenishment period, the toner replenishment operation by driving the toner replenishment motor is performed twice in 500 msec steps. For this reason, the toner replenishment buffer time stored in the memory 34 becomes 0 msec by subtracting 1000 msec reflected in the driving time of the toner replenishment motor in the current toner replenishment period.

  On the other hand, assuming that the toner replenishment buffer time is 800 msec before entering the current toner replenishment period, the toner replenishment operation by driving the toner replenishment motor is performed only once at 500 msec in the current toner replenishment period. . For this reason, the toner replenishment buffer time stored in the memory 34 is 300 msec by subtracting 500 msec reflected in the driving time of the toner replenishment motor in the current toner replenishment period. The 300 msec time that could not be processed in the current toner replenishment period is carried over to the next time. If the ICDC toner supply time calculated before the next toner supply period is 800 msec, this time is added to the carry-over from the previous time (300 msec) and the next toner supply period starts. Therefore, the toner replenishment buffer time before entering the next toner replenishment period is 1100 msec. Therefore, in the next toner replenishment period, the toner replenishment operation by driving the toner replenishment motor is performed twice in 500 msec.

  Further, when the toner replenishment buffer time stored in the memory 34 is 300 msec and the ADC toner replenishment time calculated before the current toner replenishment period is −500 msec, the addition processing is performed. As a result, the toner replenishment buffer time in the memory 34 becomes −200 msec. For this reason, the toner supply operation by driving the toner supply motor is not performed in the current toner supply period. On the other hand, when the toner supply buffer time stored in the memory 34 is 300 msec and the ADC toner supply time calculated before the current toner supply period is +200 msec, By the addition process, the toner replenishment buffer time in the memory 34 becomes 500 msec. For this reason, in the current toner supply period, the toner supply operation by driving the toner supply motor is performed only once in 500 msec.

  FIG. 5 is a flowchart showing another example of the toner supply control process according to the embodiment of the present invention. This process flow is applied when the above-described toner supply buffer process is performed. First, the toner replenishment control unit 31 sets the development motor drive speed notified from the development motor control unit 37 (or the image formation control unit) to any one of “high speed”, “medium speed”, and “low speed”. It is determined whether it has been performed (step S21).

  If it is determined in step S21 that the driving speed of the developing motor is set to “high speed”, the coefficient M11 stored in the memory 34 corresponding to the “high speed” speed setting is read (step S21). S22). If it is determined that the driving speed of the developing motor is set to “medium speed”, the coefficient M12 stored in the memory 34 corresponding to the speed setting of the “medium speed” is read (step S23). When it is determined that the driving speed of the developing motor is set to “low speed”, the coefficient M13 stored in the memory 34 is read corresponding to the “low speed” speed setting (step S24). These three coefficients M11, M12, and M13 are set to have a magnitude relationship of “M11> M12> M13”.

  Next, the toner replenishment control unit 31 sets the coefficients M11, M11 read in step S22, S23 or S24 to the driving time of the toner replenishing motor, which is the first subtraction value from the toner replenishing buffer time in the toner replenishing buffer process. The first subtraction value is corrected by multiplying by M12 or M13 (step S25). Specifically, when the driving speed of the developing motor is set to “high speed”, the first subtraction value (toner supply driving time) is multiplied by the coefficient M11, and the driving speed of the developing motor is set to “medium speed”. Is set to "1", the first subtraction value is multiplied by the coefficient M12. When the developing motor drive speed is set to "low speed", the first subtraction value is multiplied by the coefficient M13.

  Next, the toner replenishment control unit 31 performs the coefficient M11 read in step S22, S23 or S24 during the toner replenishment motor overrun time which is the second subtraction value from the toner replenishment buffer time in the toner replenishment buffer process. , M12 or M13 to correct the second subtraction value (step S26). Specifically, when the driving speed of the developing motor is set to “high speed”, the second subtraction value (overrun time) is multiplied by the coefficient M11, and the driving speed of the developing motor is set to “medium speed”. When the driving speed of the developing motor is set to “low speed”, the second subtraction value is multiplied by the coefficient M13.

  The toner replenishment motor overrun time is the actual toner replenishment motor after the toner replenishment motor controller 36 stops outputting the drive signal to the toner replenishment motor (21, 22, 23, 24). The time until the rotation of the toner stops, that is, the time during which the toner replenishment motor rotates excessively due to the inertial force of the rotation. This overrun time is a time experimentally obtained in advance. In the toner replenishment buffer process, this overrun time does not necessarily need to be included in the subtracted value from the toner replenishment buffer time, but the inclusion increases the accuracy in controlling the toner density.

  Next, the toner supply control unit 31 updates the toner supply buffer time by applying the first subtraction value corrected in step S25 and the second subtraction value corrected in step S26 (step S27). Specifically, the first subtraction value corrected in step S25 and the second subtraction value corrected in step S26 are added, and this addition value is supplied to the toner stored in the memory 34 at that time. By subtracting from the buffer time, the toner supply buffer time applied to the toner supply operation is updated in the next toner supply period, and the updated toner supply buffer time is held in the memory 34.

  In the above processing flow, when the driving speed of the developing motor is set to “high speed”, the first subtraction value and the second subtraction value are corrected using the largest coefficient M11, and the developing motor is corrected. Is set to “low speed”, the first subtraction value and the second subtraction value are corrected using the smallest coefficient M13.

  For this reason, for example, assuming that each coefficient is set to M11 = 1.2, M12 = 1.0, and M13 = 0.8, the driving speed of the developing motor is set to “high speed”. In this case, each subtraction value is corrected in the direction of increasing, and when the driving speed of the developing motor is set to “low speed”, the subtraction value is corrected in a decreasing direction. As a result, in the actual toner replenishment operation, when the drive speed of the developing motor is set to “high speed”, the toner replenishment drive time is made shorter than when it is set to “medium speed”. When the driving speed of the developing motor is set to “low speed”, the toner replenishment driving time is changed to be longer than when the driving speed is set to “medium speed”.

  As a specific example, when image data having a common ICDC toner replenishment time of 1000 msec calculated based on the number of pixels for one page is processed continuously for 10 pages with the same development color, the development is performed as described above. The coefficient applied when the motor driving speed is set to “high speed” is set to M11 = 1.2, the coefficient applied to the setting of “medium speed” is set to M12 = 1.0, and “low speed” is set. It is assumed that the coefficient applied when setting is set to M13 = 0.8.

  In such a case, when the process speed is set to “medium speed”, the ICDC toner supply time is directly reflected in the toner supply drive time in the toner supply buffer process, and therefore, when image data for 10 pages is processed. The total toner replenishment drive time is 10,000 msec.

  On the other hand, when the driving speed of the developing motor is set to “high speed” or “low speed”, the toner replenishment buffer process is performed according to the flow of numerical processing as shown in FIG. It is. For example, when the driving speed of the developing motor is set to “high speed”, the toner replenishment buffer time is 1000 msec by adding the ICDC toner replenishment time for the image data of the first page. The replenishment operation is performed twice in 500 msec. Therefore, the toner replenishment drive time is 1000 msec, and the subtraction value (buffer subtraction value) from the toner replenishment buffer time is 1200 msec by multiplication with the coefficient M11 = 1.2. Therefore, the carry-over time to the next time is −200 msec.

  For the image data of the second page when the driving speed of the developing motor is set to “high speed”, the toner supply buffer is obtained by adding the ICDC toner supply time for one page to the carry-over time from the previous time. Since the time is 800 msec, based on this, the toner replenishment operation is performed only once at 500 msec. For this reason, the toner replenishment drive time is 500 msec, and the subtracted value from the toner replenishment buffer time is 600 msec by multiplication with the coefficient M11 = 1.2. Therefore, the carry-over time to the next time is +200 msec.

  On the other hand, when the driving speed of the developing motor is set to “low speed”, the toner replenishment buffer time is 1000 msec by adding the ICDC toner replenishment time for the image data of the first page. The replenishment operation is performed twice in 500 msec. For this reason, the toner replenishment drive time is 1000 msec, and the subtracted value from the toner replenishment buffer time is 800 msec by multiplication with the coefficient M13 = 0.8. Therefore, the carry-over time to the next time is +200 msec.

  For the image data of the second page when the driving speed of the developing motor is set to “low speed”, the toner supply buffer is obtained by adding the ICDC toner supply time for one page to the carry-over time from the previous time. Since the time is 1200 msec, based on this, the toner replenishment operation is performed twice in 500 msec. For this reason, the toner replenishment drive time is 1000 msec, and the subtracted value from the toner replenishment buffer time is 800 msec by multiplication with the coefficient M13 = 0.8. Therefore, the carry-over time to the next time is +400 msec.

  As a result, when the driving speed of the developing motor is set to “high speed”, the total toner replenishing driving time for 10 pages is 8500 msec (an average of 850 msec per page), and the driving speed of the developing motor is “medium” The total toner replenishment drive time for 10 pages when “speed” is set is 10000 msec (average of 1000 msec per page), and 10 pages when the developing motor drive speed is set to “low”. The total toner replenishment drive time is 12000 msec (one page average is 1200 msec).

  Further, for convenience of explanation, the toner supply rate when the driving speed of the toner supply motor is set to “high speed” is 1.2 mg / sec, and the toner supply rate when the driving speed is set to “medium speed” is 1. It is assumed that the toner replenishment rate is 0.8 mg / sec when set to 0.0 mg / sec and “low speed”. In such a case, in the processing flow shown in FIG. 3, when the driving speed of the developing motor is set to “high speed”, the driving speed of the toner replenishing motor is also set to “high speed”, and the driving speed of the developing motor is set. Is set to “medium speed”, the driving speed of the toner replenishing motor is also set to “medium speed”, and when the driving speed of the developing motor is set to “low speed”, Since the driving speed is also set to “low speed”, in the above example, the total toner supply amount for 10 pages when the process speed is set to “high speed” is 10.2 mg (1.02 mg on an average for one page), The total toner supply amount for 10 pages when the process speed is set to “medium speed” is 10 mg (1 mg on an average per page), and the total toner supply amount for 10 pages when the process speed is set to “low speed” is The .6mg (0.96mg on average for one page).

  On the other hand, for example, assuming that the above coefficients M11, M12, and M13 are all set to 1.0, the total toner replenishment drive time when processing 10 pages of image data is Regardless of the driving speed of the motor, all are 10,000 msec (one page average is 1000 msec). For this reason, when the driving speed of the developing motor is set to “high speed”, the total amount of toner replenishment for 10 pages is 12 mg (1.2 mg on an average per page), and when the driving speed of the developing motor is set to “medium speed” The total toner replenishment amount for 10 pages is 10 mg (1 page average is 1 mg), and the total toner replenishment amount for 10 pages when the developing motor drive speed is set to “low speed” is 8.0 mg (1 page average) 0.8 mg).

  Therefore, for example, when image data for one page having the same number of pixels counted by the pixel counter 32 is formed on a sheet by changing the driving speed condition of the developing motor, the toner is changed by changing the driving speed of the toner replenishing motor. Even if the replenishment rate changes, the toner replenishment drive time is changed based on the processing flow shown in FIG. 5 to equalize the toner replenishment amount per page regardless of the driving speed of the toner replenishment motor. It will be.

<Application example of the present invention>
As an application example of the present invention, when the toner replenishment control unit 31 performs the toner replenishment buffer process based on the processing flow shown in FIG. 5, the toner replenishment period is allowed depending on the driving speed of the developing motor. The upper limit value of the toner replenishment drive time to be performed may be changed. For example, as described above, the upper limit value of the toner replenishment drive time is the value of t when the toner replenishment operation is performed at maximum n times (n is a natural number of 2 or more) every t time within one toner replenishment period. And / or by changing the value of n.

  That is, if the value of t is a fixed value and the value of n is relatively large, the upper limit value of the toner replenishment drive time is changed. In contrast, if the value of n is relatively small, the toner replenishment drive is performed. It is changed in the direction that the upper limit of time becomes smaller. Further, if the value of n is fixed and the value of t is relatively increased, the upper limit value of the toner replenishment drive time is changed. In contrast, if the value of t is relatively decreased, the toner replenishment drive is performed. It is changed in the direction that the upper limit of time becomes smaller. Further, when both the value of t and the value of n are relatively increased, the upper limit value of the toner replenishment drive time is changed so as to increase. Conversely, when both the values of t and n are relatively decreased. The upper limit value of the toner replenishment drive time is changed in the direction of decreasing.

  FIG. 7 is a flowchart showing a procedure of a toner replenishment control process applied when the upper limit value of the toner replenishment drive time is changed according to the drive speed of the developing motor. First, the toner replenishment control unit 31 sets the development motor drive speed notified from the development motor control unit 37 (or the image formation control unit) to any one of “high speed”, “medium speed”, and “low speed”. It is determined whether it has been performed (step S31).

  If it is determined in step S31 that the developing motor drive speed is set to "high speed", the toner replenishment operation limit count stored in the memory 34 corresponding to the "high speed" speed setting is set. The value N1 is read (step S32). If it is determined that the driving speed of the developing motor is set to “medium speed”, the value of the toner replenishment operation limit number stored in the memory 34 corresponding to the “medium speed” speed setting. When N2 is read out (step S33) and it is determined that the driving speed of the developing motor is set to “low speed”, the toner replenishment operation stored in the memory 34 corresponding to the “low speed” speed setting. The limit number N3 is read (step S34). These three values N1, N2, and N3 are all natural numbers and are set to have a magnitude relationship of “N1 <N2 <N3”.

  Next, the toner replenishment control unit 31 substitutes the value N1, N2 or N3 read in step S31, S32 or S33 for the value of n (step S35). With the above processing flow, the value of n is changed according to the driving speed of the developing motor.

  In the processing flow shown in FIG. 7, since the three values N1, N2, and N3 are set to have a magnitude relationship of “N1 <N2 <N3”, the driving speed of the developing motor is set to “high speed”. If it is set to “medium speed”, the toner replenishment operation limit count is less than if it is set to “medium speed”. If the drive speed of the developing motor is set to “low speed”, it is set to “medium speed”. The number of toner replenishment operation restriction times is larger than that of Therefore, when the driving speed of the developing motor is set to “high speed”, the upper limit value of the toner replenishing driving time is changed to be smaller than when the driving speed is set to “medium speed”. When the driving speed is set to “low speed”, the upper limit value of the toner replenishment driving time is changed in a direction in which the upper limit value becomes larger than when the driving speed is set to “medium speed”.

  In the processing flow shown in FIG. 7, the value of n is changed according to the driving speed of the developing motor. However, the value of t may be changed instead of the value of n. . The processing flow in that case is the procedure of steps S41 to S45 in FIG. However, when changing any of the values of n and t, the upper limit value of the toner replenishment drive time is changed as the developing motor drive speed increases. Therefore, in the processing flow of FIG. 8, the values T1, T2, and T3 of the toner replenishment unit driving time read from the memory 34 in step S42, S43, or S44 are set to a magnitude relationship of “T1 <T2 <T3”. It will be.

1 is a schematic diagram illustrating an example of an overall configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of a control system of an image forming apparatus according to an embodiment of the present invention. 6 is a flowchart illustrating a speed setting process of a toner supply motor. 6 is a flowchart illustrating an example of a toner supply control process according to an embodiment of the present invention. 7 is a flowchart illustrating another example of toner supply control processing according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a flow of numerical processing in toner supply buffer processing. It is a figure which shows the processing flow which concerns on the application example of this invention. It is a figure which shows the processing flow which concerns on the application example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2, 3, 4, 5 ... Image forming part, 6 ... Exposure apparatus, 7 ... Intermediate transfer body, 8 ... Secondary transfer apparatus, 15-18 ... Toner cartridge, 21-24 ... For toner replenishment Motor 29... ADC sensor 31. Toner replenishment control unit 32. Pixel counter 36. Toner replenishment motor control unit 37 37 Development motor control unit 38 to 41 Development motor 201, 301, 401, 501... Image carrier 2, 203, 303, 403, 503.

Claims (5)

An image carrier,
Developing means for developing the electrostatic latent image formed on the image carrier with toner;
Toner replenishing means for replenishing the developing means with the toner;
A speed control means for changing the operating speed of the toner replenishing means according to the operating speed of the developing means ;
A toner replenishment control means for determining the next toner replenishment period by carrying over the drive time of the toner replenishment means for the amount not processed in the previous toner replenishment period to the next toner replenishment period, A value obtained by multiplying the toner replenishment time calculated based on the toner density control information for controlling the toner density by the first coefficient is used as an addition value, and the driving time of the toner replenishing means is multiplied by the second coefficient. By setting the value as the first subtraction value, the first coefficient and the second coefficient are calculated when the driving time of the toner replenishing means that cannot be processed in the previous toner replenishing period is calculated. An image forming apparatus comprising: a toner replenishment control unit that switches according to an operation speed of the developing unit . The toner replenishment control means, in addition to the first subtraction value, when a value obtained by multiplying a predetermined overrun time of the toner replenishment means by a third coefficient is used as the second subtraction value, The image forming apparatus according to claim 1, wherein the third coefficient is switched according to an operation speed of the developing unit. The image forming apparatus according to claim 1, wherein the toner replenishment control unit decreases the first coefficient as an operation speed of the developing unit increases. The image forming apparatus according to claim 1, wherein the toner replenishment control unit increases the second coefficient as an operation speed of the developing unit increases. The image forming apparatus according to claim 2, wherein the toner replenishment control unit increases the third coefficient as an operation speed of the developing unit increases.

Images