JP2017049551A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that prevents an unnecessary increase in drive sound when recovering toner.SOLUTION: Detection parts 402 and 404 detect a load of toner acting on a motor through screws 133 and 136. A determination part 210 of a CPU 200 determines the duty of a drive signal according to the detected load. Motor drivers 401 and 403 create drive signals with the duty determined by the CPU 200 and supply the signals to the motor.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an image forming apparatus that forms an image using a developer such as toner.

  An image forming apparatus such as an electrophotographic system forms a toner image on a photosensitive drum or an intermediate transfer member, and transfers it to a sheet. A part of the toner constituting the toner image remains on the photosensitive drum and the intermediate transfer member without being transferred to the sheet. The image forming apparatus removes residual toner from the photosensitive drum and the intermediate transfer member and collects the toner in a toner box via a toner conveyance path. According to Patent Document 1, it is proposed to apply an AC voltage to an electrode arranged in the toner conveyance path in order to prevent toner clogging in the toner conveyance path.

Japanese Patent Laid-Open No. 08-30160

  However, if an electrode is provided in the toner conveyance path, the structure of the toner conveyance path becomes complicated. In addition, a power supply circuit for applying an AC voltage to the electrodes is required. As an alternative, the inventors tried to increase the number of rotations (rotational speed) of a screw for conveying toner. However, it has been found that increasing the number of rotations of the screw can suppress toner clogging, but increases the driving sound of the screw. In view of the above, an object of the present invention is to control the rotational speed of a drive unit that rotationally drives a rotating member to an appropriate rotational speed.

The present invention is, for example,
An image carrier;
Image forming means for forming a toner image using toner on the image carrier;
Transfer means for transferring the toner image to a sheet;
Fixing means for fixing the toner image to the sheet;
Removing means for removing toner remaining on the image carrier;
A collecting means for collecting the toner removed by the removing means;
Drive means for driving the recovery means;
Detecting means for detecting the rotational speed of the driving means;
An estimation means for estimating the load parameter corresponding to the rotation speed based on the rotation speed detected by the detection means and the amount of toner acting on the recovery means or the rotation torque of the drive means;
Determining means for determining a duty of a drive signal corresponding to the load parameter based on the load parameter estimated by the estimating means;
An image forming apparatus comprising: a generating unit that generates a driving signal having a duty determined by the determining unit and supplies the driving signal to the driving unit.

The present invention also provides:
An image carrier;
Image forming means for forming a toner image using toner on the image carrier;
Transfer means for transferring the toner image to a sheet;
Fixing means for fixing the toner image to the sheet;
Removing means for removing toner remaining on the image carrier;
A collecting means for collecting the toner removed by the removing means;
Drive means for driving the recovery means;
Detecting means for detecting a load caused by toner acting on the driving means through the collecting means;
Determining means for determining the duty of the drive signal according to the load detected by the detecting means;
An image forming apparatus comprising: a generating unit that generates a driving signal having a duty determined by the determining unit and supplies the driving signal to the driving unit.

  According to the present invention, it is possible to control the rotational speed of the driving unit that rotationally drives the rotating member to an appropriate rotational speed.

Sectional view showing configuration of image forming apparatus Cross section of toner transport path and toner box The figure which shows the transmission mechanism which transmits the driving force of a motor Block diagram showing the control system The figure which shows the relation of the duty of the motor, rotation speed and torque Diagram showing required motor speed Diagram showing variation in motor rotation speed The figure which shows the method of determining the duty of a conveyance motor The figure which shows the method of determining the duty of the stirring motor Flowchart illustrating a method for determining duty The figure which shows an example of the function implement | achieved by CPU

[Configuration of Image Forming Apparatus]
A schematic configuration of the image forming apparatus 100 will be described with reference to FIG. The image forming apparatus 100 may be an image forming apparatus that forms a single-color image, but here it is assumed to be an image forming apparatus that forms a multicolor image. The image forming apparatus 100 may be any of a printing apparatus, a printer, a copier, a multifunction machine, and a facsimile. The image forming apparatus 100 includes four stations that form toner images using yellow, magenta, cyan, and black developers. The developer includes a non-magnetic toner and a magnetic carrier. In FIG. 1, reference numerals are given only to the components of the yellow station, but the same configuration can be adopted for all four stations. Each station functions as an image forming unit that forms a toner image using toner on an image carrier such as the photosensitive drum 111 or the intermediate transfer belt 116.

  The photosensitive drum 111 is a cylindrical image carrier or photoconductor that carries an electrostatic latent image or a toner image. The charging device 112 uniformly charges the photosensitive drum 111 rotating in the direction of arrow A. The exposure device 113 outputs laser light modulated based on the image information, and scans the surface of the photosensitive drum 111 with the laser light. Thereby, an electrostatic latent image is formed. The developing device 114 develops the electrostatic latent image using toner to form a toner image. The primary transfer roller 117 primarily transfers the toner image on the photosensitive drum 111 to the intermediate transfer belt 116. Intermediate transfer belt 116 rotates in the direction indicated by arrow B. The sheet P is fed to the sheet conveyance path by the sheet feeding roller 120. The sheet P may be called recording paper, recording material, recording medium, paper, transfer material, transfer paper, or the like. The sheet P is skew-corrected by the registration roller 121 and is conveyed to the secondary transfer portion formed by the intermediate transfer belt 116 and the secondary transfer roller 119. In the secondary transfer portion, the toner image conveyed by the intermediate transfer belt 116 is secondarily transferred to the sheet P. Thus, the primary transfer roller 117 and the secondary transfer roller 119 function as a transfer unit that transfers the toner image to the sheet. The fixing device 140 applies heat and pressure to the toner image and fixes the toner image on the sheet P. Thereafter, the sheet P is discharged to the discharge tray by the discharge roller 122.

  The drum cleaner 115 removes (cleans) toner remaining on the surface of the photosensitive drum 111. The belt cleaner 118 removes (cleans) the toner remaining on the surface of the intermediate transfer belt 116. These removed (cleaned) toners are called recovered toners. The collected toner is conveyed through the toner conveyance path 131 and collected in the toner box 130. As described above, the drum cleaner 115 and the belt cleaner 118 function as a removing unit that removes the toner remaining on the image carrier.

[Configuration of Toner Collection Device]
The configuration of the toner recovery device 150 will be described with reference to FIG. The toner collecting device 150 functions as a collecting unit that collects the toner removed by the drum cleaner 115 and the belt cleaner 118. The toner conveyance path 131 has upward openings 134a to 134e as collected toner inflow ports on the upper wall surface. The openings 134a, 134b, 134c, and 134d are provided corresponding to the four stations, and the collected toner discharged from the drum cleaner 115 flows in. The opening 134 e is an inlet for collected toner discharged from the belt cleaner 118. The screw 136 is provided inside the toner conveyance path 131. The screw 136 is driven and rotated by the conveyance motor 206 to convey the collected toner flowing into the toner conveyance path 131 in one direction (from right to left in FIG. 2). Thus, the screw 136 is driven and rotated by the transport motor 206 to function as a transport member that transports toner in the toner transport path 131. The transport motor 206 is an example of a first motor that drives the screw 136. The collected toner is discharged to a toner box 130 provided at the end of the toner conveyance path 131.

  The toner box 130 is a container that collects toner, and is, for example, a rectangular container molded with a resin such as plastic. The toner box 130 has an opening 132 on the top wall. The opening 132 functions as an inlet for the collected toner. The opening 132 may be provided with a shutter that opens and closes in conjunction with the attaching / detaching operation of the toner box 130. In the vicinity of the opening 132 of the toner box 130, a screw 133 driven by the stirring motor 207 and rotating is provided. The screw 133 moves the collected toner that has accumulated near the opening 132 of the toner box 130 to disperse the collected toner substantially uniformly in the toner box 130. Thus, the screw 133 is driven and rotated by the agitation motor 207 to function as an agitation member for agitating the toner collected in the toner box 130. The stirring motor 207 is an example of a second motor that drives the stirring member.

  As described above, the toner recovery device 150 has two drive sources such as the conveyance motor 206 and the stirring motor 207. That is, the conveyance motor 206 and the agitation motor 207 function as a driving unit that drives the toner recovery device 150. The drive current applied to the transport motor 206 and the amount of toner transported by the screw 136 are generally proportional. Further, the drive current applied to the stirring motor 207 and the amount by which the screw 133 moves the toner are generally proportional. When the drive current supplied to the transport motor 206 decreases, the rotational speed of the transport screw 136 decreases, so that the collected toner is easily clogged in the toner transport path 131. When the drive current supplied to the transport motor 206 increases, the rotational speed of the transport screw 136 increases, so that the collected toner is less likely to be clogged in the toner transport path 131. However, if the drive current supplied to the transport motor 206 and the agitation motor 207 is increased more than necessary, the drive noise increases. In this embodiment, the number of rotations of the screw 136 is appropriately controlled in accordance with the amount of collected toner existing in the toner conveyance path 131, so that the drive sound does not increase more than necessary. Similarly, the number of rotations of the screw 133 is appropriately controlled according to the amount of collected toner present in the toner box 130, so that the drive sound is not increased more than necessary.

[Gear mechanism]
A gear mechanism including a worm 301 and the like press-fitted into the rotation shaft of the transport motor 206 will be described with reference to FIG. The gear mechanism (transmission mechanism) functions as a transmission unit that transmits the driving force of the conveyance motor 206 and the agitation motor 207 to the toner recovery device 150. The worm 301 is engaged with the worm wheel 302. A first gear 303 is fixed to the rotation shaft of the worm wheel 302, and the first gear 303 rotates as the worm wheel 302 rotates. The first gear 303 meshes with the second gear 304, and the second gear 304 rotates as the first gear 303 rotates. A third gear (not shown) is fixed to the rotation shaft of the second gear 304, and the third gear rotates as the second gear 304 rotates. A fourth gear 305 is engaged with the third gear. As the third gear rotates, the fourth gear 305 rotates. A screw 136 is connected to the rotation shaft of the fourth gear 305. The driving force of the transport motor 206 is transmitted to the screw 136 through such a gear mechanism, and the screw 136 rotates. The combination of gears constituting the driving force transmission mechanism (gear mechanism) shown in FIG. 3 is merely an example, and can be appropriately changed according to the reduction ratio and the rotation direction of the screw 136. A similar driving force transmission mechanism may be employed for the stirring motor 207 and the screw 133.

  The direction of the force acting on the drive shaft (rotation shaft) of the transport motor 206 changes according to the rotation direction of the worm gear constituted by the worm 301 and the worm wheel 302. For example, when the rotation shaft of the conveyance motor 206 rotates to the right, a force may be received from the worm gear in the direction in which the rotation shaft of the conveyance motor 206 is pushed (from right to left in FIG. 3). On the other hand, when the rotation shaft of the conveyance motor 206 rotates counterclockwise, a force may be received from the worm gear in the direction in which the rotation shaft of the conveyance motor 206 is drawn (from left to right in FIG. 3). Depending on the direction of the force received by the rotation shaft of the transport motor 206, the magnitude of the drive sound may change. Therefore, by selecting the rotation direction in which the vibration is relatively small from the two rotation directions of the transport motor 206, it is possible to reduce the drive sound. In this embodiment, the rotation direction in which a force is applied in the pushing direction with respect to the rotation axis is selected. However, depending on the structure of the motor, driving sound and vibration may be reduced when a force is applied in the pull-in direction. In this case, the rotation direction in which force is applied in the pull-in direction is selected. For the stirring motor 207 as well, a rotation direction in which the driving sound is relatively small is selected. Thus, the rotation direction of each motor may be selected in advance as the rotation direction in which the drive sound generated from each motor is relatively reduced. The transmission mechanism includes a plurality of gears that are combined so that the toner collecting device 150 collects toner as the motor rotates in a selected rotation direction.

[Control system]
A control system of the image forming apparatus 100 will be described with reference to FIG. The CPU 200 detects the rotational speed (rotational speed) of the transport motor 206 using the detection unit 402, and from the motor driver 401 so that the rotational speed (rotational speed) of the transport motor 206 becomes the target rotational speed (target rotational speed). A drive current to be supplied to the transport motor 206 is controlled. The CPU 200 detects the rotation speed (rotation speed) of the agitation motor 207 using the detection unit 404, and from the motor driver 403 so that the rotation speed (rotation speed) of the agitation motor 207 becomes the target rotation speed (target rotation speed). The drive current to be supplied to the stirring motor 207 is controlled. The target rotation speed (target rotation speed) may be referred to as a necessary rotation speed that is necessary for conveying or stirring the toner without aggregating the toner. Note that the rotational speed (rotational speed) of the motor changes according to the duty ratio (hereinafter simply referred to as duty) of the drive current (drive signal) supplied to the motor. The detection units 402 and 404 are an encoder, a photo interrupter, a magnetic detection element, and the like. The detection unit 402 may be a sensor that detects the rotational speed of the transport screw 136, for example. Similarly, the detection unit 404 may be a sensor that detects the rotation speed of the stirring screw 133, for example. A control program executed by the CPU 200 and data used for controlling the motors 206 and 207 are stored in the ROM 201 in advance. The ROM 201 stores a correction coefficient for correcting the control of the transport motor 206 and the like. The ROM 201 is a nonvolatile memory such as an EEPROM that can hold information even when power is not supplied to the image forming apparatus 100. An operation unit 203 is a user interface for a user to operate the image forming apparatus 100, and includes an input device and a display device. When a copy button provided on the operation unit 203 is pressed, the CPU 200 starts an image forming operation.

  The carry motor 206 is a DC brushless motor driven by a motor driver 401. The motor driver 401 controls the rotation speed (rotational speed) of the carry motor 206 by controlling the duty of the pulse-shaped drive signal output to the carry motor 206. Such control is generally called PWM (pulse width modulation) control. The drive signal may be referred to as a PWM signal, a pulse signal, or a control signal. The CPU 200 estimates the load (the amount of toner present in the toner conveyance path 131) based on the rotation speed of the conveyance motor 206 detected by the detection unit 402, and determines the duty of the drive signal according to the load. As described above, since the rotational speed of the motor is controlled according to the amount of collected toner, it is possible to suppress the rotational speed from increasing more than necessary. Therefore, the volume of the drive sound does not increase more than necessary.

  Agitation motor 207 is a DC brushless motor driven by motor driver 403. The motor driver 403 controls the number of rotations (number of rotations) of the stirring motor 207 by controlling the duty of the pulsed drive signal output to the stirring motor 207. The CPU 200 estimates the load (the amount of toner present in the toner box 130) based on the rotation speed of the stirring motor 207 detected by the detection unit 404, and determines the duty of the drive signal according to the load. As described above, the motor drivers 401 and 403 function as a generation unit that generates a drive signal having a duty determined by the CPU 200 and supplies the drive signal to the motors 206 and 207.

[Relationship between duty, rotation speed and torque]
The relationship among the motor duty, the number of rotations (rotation speed) and the torque will be described with reference to FIG. The horizontal axis represents the rotational torque of the motor. The vertical axis represents the number of rotations (number of rotations) of the motor. FIG. 5 shows the rotational speed and torque characteristics for each duty. The motor rotation speed Y and the torque X have a substantially linear relationship. Further, FIG. 5 shows the relationship between the rotational speed Y and the torque X when the duty is 100%, 80%, 60%, and 40%. When the duty Z of the drive signal (pulse signal) is changed in this way, the relationship between the rotational speed Y and the torque X moves in parallel. From the relationship between the duty Z, the rotational speed Y, and the torque X shown in FIG.

Y = −800 × X + 8000− (100−Z) × 50 (1)
X = (− Y + 8000− (100−Z) × 50) ÷ 800 (2)
Z = (800 × X + Y−3000) ÷ 50 (3)
In addition, each coefficient is an example and is calculated | required by experiment or simulation.

[Number of rotations required to transport / stir toner]
The required rotational speed (rotational speed) with respect to the load torque of the motor will be described with reference to FIG. The horizontal axis indicates the motor load torque. If the amount of toner in the toner transport path 131 increases, the load torque of the transport motor 206 increases. Similarly, as the amount of toner in the toner box 130 increases, the load torque of the agitation motor 207 also increases. The vertical axis represents the motor rotation speed (rotation speed). Y1 indicates the required rotation speed (required rotation speed) of the transport motor 206. Y2 indicates the required rotation speed (required rotation speed) of the stirring motor 207.

  There is a correlation between the rotational torque (load torque) of the transport motor 206 and the amount of toner present in the toner transport path 131. Therefore, the CPU 200 can estimate the amount of toner in the toner conveyance path 131 from the rotational torque of the conveyance motor 206. For example, the CPU 200 obtains the load torque based on the duty of the drive current supplied to the conveyance motor 206 and the rotation speed (rotation speed) of the conveyance motor 206, and obtains the relationship between the load torque and the amount of toner in the conveyance path 131. Based on the data shown, the amount of toner in the transport path 131 is estimated. Similarly, since the rotational torque (load torque) of the stirring motor 207 and the amount of toner existing in the toner box 130 are correlated, the CPU 200 determines the amount of toner present in the toner box 130 from the rotational torque of the stirring motor 207. The amount can be estimated. For example, the CPU 200 obtains the load torque based on the duty of the drive current supplied to the stirring motor 207 and the rotation speed (rotation speed) of the stirring motor 207, and the relationship between the load torque and the amount of toner in the toner box 130. The amount of toner in the toner box 130 is estimated based on the data indicating the above.

  FIG. 6 shows the rotational speeds Y1 and Y2 of the motor that can reliably convey / stir the estimated amount of toner. Here, the number of rotations that can be reliably conveyed / stirred is the number of rotations that is two to three times the limit of the number of rotations that can be conveyed / stirred, as determined by experiments. By taking such a margin into consideration, it is possible to reduce toner clogging due to toner aggregation even if there is an estimation error or the like. The necessary rotational speeds Y1 and Y2 shown in FIG. 6 are expressed by the following equations. X1 is the rotational torque of the transport motor 206, X2 is the rotational torque of the stirring motor 207, Y1 is the required rotational speed of the transport motor 206, and Y2 is the required rotational speed of the stirring motor 207.

Y1 = 1600 × X1 (4)
Y2 = 750 × X2 (5)
In addition, each coefficient is an example and is calculated | required by experiment or simulation.

[Correction method specific to motor]
With reference to FIG. 7, a method for correcting variations inherent in the motor will be described. Since DC brushless motors have individual differences in products, there are variations in the number of rotations. That is, even if the load and applied voltage of a plurality of DC brushless motors are shared, the rotational speed varies by 10% to 15%. For this reason, it is necessary to correct variations in the rotational speed of the motor. Therefore, when the motor or the image forming apparatus 100 is shipped from the factory, a correction coefficient is obtained for each motor and stored in the ROM 201. The correction coefficient is read by the CPU 200 and multiplied by the duty. The correction coefficient A is determined, for example, so as to drive the motor with a constant load and a constant duty, detect the rotational speed of the motor, and correct the rotational speed to the center value.

  FIG. 7 shows an example of the characteristics of the motor. The horizontal axis represents the motor rotational torque. The vertical axis represents the motor speed. As shown in FIG. 7, assuming that the center value of the rotational speed at no load (torque is 0 [mN · m]) is 8000 [rpm], the correction coefficient A is calculated from the following equation.

A = 8000 ÷ Y3 (6)
Y3 is the number of rotations for each product actually measured at no load. The correction coefficient A is stored in the ROM 201. Thus, the correction coefficient A is obtained for each of the transport motor 206 and the agitation motor 207 and stored in the ROM 201. When the timing for transporting the toner comes, the CPU 200 reads the correction coefficient A from the ROM 201 and multiplies the duty by correcting the variation due to individual differences.

Z ′ = Z × A (7)
Z ′ represents the duty corrected by the correction coefficient A.

[Duty determination method]
The duty determination method will be described with reference to FIGS. 8A, 8B, 9A, 9B, and 10. FIG. Although the conveyance motor 206 will be described here, the duty of the stirring motor 207 is determined by the same method. Note that the flowchart shown in FIG. 10 is started in response to the CPU 200 instructing execution of an image forming operation.

  In S100, the CPU 200 sets an initial value for the duty of the drive signal supplied to the transport motor 206. The duty is set in the motor driver 401. The initial value is a duty that enables the conveyance motor 206 to convey the toner even at the maximum load (maximum toner amount) assumed in the toner conveyance path 131. It is assumed that the initial value is determined at the time of factory shipment and stored in the ROM 201. As described above, by setting a large duty in the motor driver 401 when the transport motor 206 is started, it is possible to detect the load caused by the collected toner on the transport motor 206. In this embodiment, it is assumed that the initial value of the duty with respect to the assumed maximum load is 60%.

  In step S <b> 101, the CPU 200 instructs the motor driver 401 to activate the transport motor 206. The motor driver 401 generates a drive signal with a duty of 60% and supplies it to the transport motor 206. The detection unit 402 detects the number of rotations of the transport motor 206 and outputs a detection signal indicating the number of rotations to the CPU 200.

  In S <b> 102, the CPU 200 recognizes the number of rotations of the transport motor 206 based on the detection signal output from the detection unit 402. FIG. 8A shows an example of the rotation speed detection result. a shows the rotation speed detected when the initial value is set to the duty.

  In S <b> 103, the CPU 200 calculates torque based on the number of rotations detected by the detection unit 402. This torque correlates with the amount of toner present in the toner conveyance path 131. The CPU 200 calculates torque X by substituting a for Y and substituting 60% for Z in equation (2).

  In S104, the CPU 200 calculates the required rotational speed Y1 from the torque X. For example, the CPU 200 determines the necessary rotational speed Y1 by substituting the torque X obtained from the equation (2) into X1 in the equation (4).

  In S105, the CPU 200 calculates the duty Z from the necessary rotational speed Y1. For example, the CPU 200 calculates the duty Z by substituting X1 into X and substituting Y1 into Y in equation (3). In the example shown in FIG. 8A, the duty is determined to be 20%. The CPU 200 sets the duty to 20% for the motor driver 401. In step S106, the CPU 200 corrects the duty Z by multiplying the duty Z by the correction coefficient A read from the ROM 201. S106 is a process for reducing individual differences between motors. In this case, the corrected duty is set in the motor driver 401.

  In step S107, the CPU 200 determines whether printing of all images included in the image data has been completed. The CPU 200 sets the flag to 1 while an image included in the image data is formed, and sets the flag to 0 when the image formation is completed. Therefore, the CPU 200 can determine whether or not printing of all the images included in the image data has been completed by referring to the flag. If printing of all the images included in the image data has not been completed, the process returns to S102. In the case shown in FIG. 8B, the CPU 200 sets the duty to 20% in S102, and the detection unit 402 detects the rotation speed. The rotation speed immediately after the duty is changed to 20% is b.

  As shown in FIG. 8B, when the rotation speed changes from b to c due to the change in the amount of toner, the CPU 200 executes the processing from S103 to S106 to change the duty. That is, in S103, the CPU 200 determines the torque X by substituting 20% for Z in equation (2) and substituting c for Y. Further, in S104, the CPU 200 substitutes the torque X into the equation (4) to obtain the rotational speed Y1. Further, in S105, the CPU 200 calculates the duty Z by substituting the torque X and the rotational speed Y1 into the equation (3). The CPU 200 executes the adjustment processing from step S102 to step S107 every predetermined time until printing of all images included in the image data is completed. The predetermined time is, for example, 3 seconds. When printing of all the images included in the image data is completed, the CPU 200 advances to S108. In step S108, the motor driver 401 is controlled to stop the transport motor 206.

  The duty of the stirring motor 207 is similarly determined. In S100, the CPU 200 sets the duty of the stirring motor 207 to an initial value. The initial value is determined at the time of shipment from the factory and stored in the ROM 201 so that the screw 133 in the toner box 130 can stir the toner even at the assumed maximum load (maximum toner amount). Here, when power is not supplied to the image forming apparatus 100, there is a possibility that a user or a service person touches the toner box 130. For example, the toner in the toner box 130 may be discarded. Therefore, there is a possibility that the state of toner in the toner box 130 (the amount of accumulation or density) may change. Therefore, a large duty is set in the motor driver 403 when the stirring motor 207 is started. For example, the initial value is 80%.

  In S101, the CPU 200 activates the stirring motor 207. For example, the CPU 200 causes the motor driver 403 to generate a drive signal with an 80% duty and supply it to the stirring motor 207. The detection unit 404 detects the rotation speed of the stirring motor 207 and outputs a detection signal indicating the rotation speed to the CPU 200. In S <b> 102, the CPU 200 recognizes the rotation speed of the agitation motor 207 based on the detection signal output from the detection unit 404. FIG. 9A shows an example of the detection result of the rotation speed of the stirring motor 207. Here, the detected rotation speed is d.

  In S103, the CPU 200 calculates the torque X from the rotation speed and the duty using the equation (2). In S104, the CPU 200 calculates the necessary rotational speed Y2 from the torque X using the equation (5). In S105, the CPU 200 calculates the duty Z from the torque X and the necessary rotational speed Y2 using the equation (3). Here, it is assumed that the duty Z is calculated as 40%. The CPU 200 changes the duty to 40% and continuously detects the rotational speed. The rotation speed immediately after changing the duty to 40% is e. Note that the duty Z of the stirring motor 207 may be corrected in S106. If it is determined in S107 that printing of all images included in the image data has not been completed, the process returns to S102.

  As shown in FIG. 9B, when the rotation speed changes from e to f, the CPU 200 again determines the duty Z using the equations (2), (5), and (3). The adjustment processing from step S102 to step S107 is repeatedly executed at predetermined intervals until printing of all the images included in the image data is completed. When printing of all the images included in the image data is completed, the agitation motor 207 is stopped in S108.

[Summary]
FIG. 11 is a functional block diagram of the CPU 200 and a schematic diagram showing the relationship between the detection unit, the motor driver, and the ROM. FIG. 11 shows a function realized by the CPU 200 executing the control program 260. All or some of these functions may be realized by a logic circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Array). The detection units 402 and 404 detect a load caused by toner acting on the motor through the screws 133 and 136. For example, as described in connection with S102, the detection units 402 and 404 output information (detection signal) regarding the number of rotations of the motor. The determination unit 210 determines the duty of the drive signal according to the detected load. For example, as described with respect to S103 and S104, the estimation unit 211 estimates a load parameter corresponding to the rotation speed based on the detected rotation speed. The load parameter may be the amount of toner that acts on the screws 133, 136, or the like, or the rotational torque (load torque) of the motor. For example, as described with respect to S103, the torque calculation unit 212 may calculate the load torque (toner amount) from the rotation speed and the duty. The determination unit 210 determines the duty of the drive signal according to the detected load torque (load parameter). More specifically, the determination unit 210 may determine the duty of the drive signal corresponding to the load parameter based on the load parameter estimated by the estimation unit 211. For example, as described with respect to S104, the rotation speed calculation unit 220 may calculate the required rotation speed from the load torque. Further, as described with respect to S105, the duty calculation unit 230 may calculate the duty from the load torque and the required rotational speed. The motor drivers 401 and 403 function as a generation unit that generates a drive signal having a duty determined by the CPU 200 and supplies the drive signal to the motor. In this embodiment, the duty of the drive signal supplied to the motor is controlled according to the amount of toner (load torque) present in the toner conveyance path 131 and the toner box 130. For this reason, the driving sound when collecting the toner does not increase more than necessary.

  As described above, the estimation unit 211 may estimate the amount of toner present in the toner conveyance path 131 or the rotational torque of the conveyance motor 206 that drives the screw 136 as the load parameter. Further, the estimation unit 211 may estimate the amount of toner present in the toner box 130 or the rotational torque of the stirring motor 207 that drives the screw 133 as the load parameter. The rotational torque is a load torque that correlates with the amount of toner, and is convenient for obtaining a necessary rotational speed corresponding to the amount of toner.

  Although the conveyance motor 206 and the agitation motor 207 have been described as separate motors in the above-described embodiment, they may be the same motor. As a result, the number of motors, motor drivers and detection units can be reduced, and the manufacturing cost can be reduced. In this case, the driving force output from the single motor is transmitted to the screws 133 and 136 through a transmission mechanism such as a gear or a clutch. On the other hand, the number of rotations detected by the detection unit correlates with both loads of the screws 133 and 136. In other words, the necessary rotation speed determined in S104 is determined to be a rotation speed at which the toner inside the toner conveyance path 131 can be conveyed and the toner inside the toner box 130 can be stirred.

  As described with reference to FIG. 3, the rotation direction of the motor may be selected in advance so that the drive sound generated from the motor is relatively small. This will further reduce drive noise. The transmission mechanism includes a plurality of gears that are combined so that the toner is collected by the rotation of the motor in the selected rotation direction. Since the stirring motor 207 only needs to be able to rotate the toner, the rotation direction of the stirring motor 207 and the stirring ability will not be related. On the other hand, regarding the transport motor 206, if the rotation direction changes, the toner transport direction changes. Therefore, the configuration of the transmission mechanism itself, such as a combination of gears, is changed according to the rotation direction of the selected motor.

  As described with respect to S103 and S104, the estimation unit 211 may estimate the load parameter using a conversion equation or a table that converts the detected number of rotations into the load parameter. For example, equation (2) may be used. Furthermore, the determination unit 210 may determine the duty using a conversion formula or a table for converting the load parameter into the duty. For example, the rotational speed calculation unit 220 may calculate the necessary rotational speed using the formula (4) or the formula (5). Moreover, the duty calculating part 230 may calculate a duty using (3) Formula.

  The ROM 201 may function as a storage unit that stores a correction coefficient A based on individual motor differences. The correction unit 240 may function as a correction unit that corrects the duty determined by the duty calculation unit 230 with the correction coefficient A and sets the duty in the motor drivers 401 and 403. This will reduce the variation in the number of rotations based on individual differences in the motor.

  As described with respect to S100, when starting the motor, the CPU 200 may cause the motor drivers 401 and 403 to generate and supply a duty drive signal corresponding to the maximum toner load assumed for the motor. As a result, it will be possible to accurately determine the toner amount (rotational torque and required rotational speed) even when the motor is started.

  DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 150 ... Toner collection apparatus, 111 ... Photosensitive drum, 116 ... Intermediate transfer belt, 115 ... Drum cleaner, 118 ... Belt cleaner, 130 ... Toner box, 131 ... Toner conveyance path, 206 ... Conveyance motor, 401 ... Motor driver, 402 ... Detector, 200 ... CPU

Claims (11)

An image carrier;
Image forming means for forming a toner image using toner on the image carrier;
Transfer means for transferring the toner image to a sheet;
Fixing means for fixing the toner image to the sheet;
Removing means for removing toner remaining on the image carrier;
A collecting means for collecting the toner removed by the removing means;
Drive means for driving the recovery means;
Detecting means for detecting the rotational speed of the driving means;
An estimation means for estimating the load parameter corresponding to the rotation speed based on the rotation speed detected by the detection means and the amount of toner acting on the recovery means or the rotation torque of the drive means;
Determining means for determining a duty of a drive signal corresponding to the load parameter based on the load parameter estimated by the estimating means;
An image forming apparatus comprising: a generating unit that generates a driving signal having a duty determined by the determining unit and supplies the driving signal to the driving unit. The recovery means includes
A transport path for transporting the toner removed by the removing means;
A conveyance member that conveys the toner inside the conveyance path by being driven and rotated by the driving unit;
The image forming apparatus according to claim 1, wherein the estimation unit estimates, as the load parameter, an amount of toner existing in the conveyance path or a rotational torque of the driving unit that drives the conveyance member. apparatus. The recovery means includes
A container for collecting the toner removed by the removing means;
An agitating member that agitates the toner collected in the container by being driven and rotated by the driving means;
The image forming apparatus according to claim 1, wherein the estimation unit estimates, as the load parameter, an amount of toner existing inside the container or a rotational torque of the driving unit that drives the stirring member. . The recovery means includes
A transport path for transporting the toner removed by the removing means;
A conveying member that conveys the toner inside the conveying path by being driven and rotated by the driving means;
A container for collecting the toner conveyed through the conveyance path;
An agitating member that agitates the toner collected in the container by being driven and rotated by the driving means;
The driving means includes
A first motor for driving the conveying member;
A second motor for driving the stirring member,
The estimation means estimates the amount of toner present in the conveyance path or the rotational torque of the first motor as a load parameter for the first motor, and the container as a load parameter for the second motor. Estimating the amount of toner present in the interior or the rotational torque of the second motor,
The determining means determines a duty of a drive signal supplied to the first motor based on a load parameter for the first motor estimated by the estimating means, and for the second motor estimated by the estimating means Determining the duty of the drive signal supplied to the second motor based on the load parameter of
The generation unit generates a drive signal having a duty determined by the determination unit for the first motor and supplies the drive signal to the first motor, and a drive signal having a duty determined by the determination unit for the second motor. The image forming apparatus according to claim 1, wherein the image forming apparatus is generated and supplied to the second motor.   The image forming apparatus according to claim 4, wherein the first motor and the second motor are the same motor. A transmission means for transmitting the driving force of the driving means to the collecting means;
The rotation direction of the driving means is selected in advance as a rotation direction in which the driving sound generated from the driving means is relatively small, and the transmission means is configured so that the driving means rotates in the selected rotation direction. The image forming apparatus according to claim 1, wherein the collecting unit includes a plurality of gears combined so as to collect the toner.   The said estimation means estimates the said load parameter using the conversion type | formula or table which converts the rotation speed detected by the said detection means into the said load parameter, It is any one of Claim 1 thru | or 6 characterized by the above-mentioned. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the determining unit determines the duty using a conversion formula or a table for converting the load parameter into the duty. Storage means for storing correction coefficients based on individual differences of the drive means;
9. The image forming apparatus according to claim 1, further comprising a correcting unit that corrects the duty determined by the determining unit with the correction coefficient and sets the duty in the generating unit.   The generation unit generates and supplies a drive signal having a duty corresponding to a maximum toner load assumed for the drive unit when the drive unit is activated. The image forming apparatus according to claim 9. An image carrier;
Image forming means for forming a toner image using toner on the image carrier;
Transfer means for transferring the toner image to a sheet;
Fixing means for fixing the toner image to the sheet;
Removing means for removing toner remaining on the image carrier;
A collecting means for collecting the toner removed by the removing means;
Drive means for driving the recovery means;
Detecting means for detecting a load caused by toner acting on the driving means through the collecting means;
Determining means for determining the duty of the drive signal according to the load detected by the detecting means;
An image forming apparatus comprising: a generating unit that generates a driving signal having a duty determined by the determining unit and supplies the driving signal to the driving unit.

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