JP2008125247A - Drive controller of a plurality of motors and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve stable starting load distribution of a plurality of electric motors without remarkably increasing power capacity. <P>SOLUTION: A driving controller of a plurality of motors includes a means 38 which starts a clock when a first motor 21 is started, repetitively detects a peak value Ap1, an average value Am1 or a standard deviation value As1 of motor current until they drop to less than or equal to set values Apt1, Amt1 and Ast1 and measures lapse time RMt1 until drop of the values is detected after starting, a means 38 setting delay time RRt1 from starting of the first motor to starting of a second motor 22, which corresponds to lapse time RMt1 in (6) on Fig. 4, and a starting control means (38) starting the first motor and then starting the second motor with a lapse of delay time RRt1. The first and second motors are brushless motors. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drive control device for a plurality of electric motors, and more particularly to a sequential start control device for a plurality of motors for preventing a power supply overload caused by the start of a plurality of electric motors. For example, it can be used in an image forming apparatus such as a printer, a copier, or a facsimile machine in which an image forming mechanism is driven by a plurality of electric motors.

JP 2004-138840 A JP 2004-343892 A JP-A-2005-300868.

  An image forming apparatus having a plurality of image forming units, for example, a black image forming unit, a magenta image forming unit, a cyan image forming unit, and a yellow image forming unit are arranged in this order from the upstream side in the moving direction along the intermediate transfer belt. In a tandem color copier, since there are many mechanical loads to be driven, a plurality of electric motors are often used (for example, Patent Documents 1 to 3). In order to reduce the operation sound and power consumption due to the mechanism drive of the electric motor, it has been proposed to drive the image forming unit and the intermediate transfer belt with separate DC brushless motors (Patent Document 3).

  Even when the drive of a mechanical load is shared by a plurality of electric motors, if the electric motors are started substantially simultaneously when the image forming apparatus is started up, the starting current value is high even in the individual electric motors. It may become extremely large, causing an abnormal load on the power supply, and the power supply may be automatically shut off. In order to avoid this and start smoothly, the starting timing of each electric motor is shifted to distribute the concentrated starting current in time series. However, the waiting time from the start of driving the mechanism to the start of printing increases. Cited Document 1 discloses a start control that measures the start current value of each electric motor, stores it in a memory, and individually determines the start timing of each electric motor so that the start current falls below the power supply capacity of the power source. ing.

  However, since the activation timing is determined based on the current value stored in the memory, the timing determination is complicated. In addition, the electric motor load of the electrophotographic image forming apparatus frequently fluctuates. For example, the variation range of the in-machine temperature of the image forming apparatus is wide, and the mechanical load varies with temperature. The load fluctuation due to the temperature change is not only a change in frictional resistance due to expansion and contraction of the motion mechanism, but also in an electrophotographic image forming apparatus that forms an electrostatic latent image and develops it with toner. The load fluctuates. For example, the fluidity of the toner changes due to changes in temperature and humidity, and the rotational load of the conveying agitating screw fluctuates due to fluctuations in the remaining amount of toner in the developing device. In the fixing device, the variation range of the fixing roller temperature (fixing temperature) is wide, and the starting load varies greatly depending on the fixing temperature. Therefore, there is a problem of how to set a highly reliable start timing that does not cause a start overload based on the current value stored in the memory.

  The first object of the present invention is to achieve stable start-up load distribution of a plurality of electric motors without significantly increasing the power supply capacity, and to shorten the waiting time from the start of mechanism drive to steady operation. It is a third object to sequentially start a plurality of electric motors at a highly reliable start timing that does not cause a start overload.

(1) When the first electric motor (21) is started, timing starts, and the peak value (Ap1) of the motor current of the first electric motor (21) within the set time (Tm) Means (38: on the top of FIG. 4) that repeatedly detects until it falls below the set value (Apt1), and measures the elapsed time (RMt1) from the start of the start until the fall of the peak value below the set value is detected 6);
Means (38) for setting a delay time (RRt1) from the start of the start of the first electric motor (21) to the start of the start of the second electric motor (22) corresponding to the elapsed time (RMt1);
Start control means (38) for starting the first electric motor (21) and starting the second electric motor (22) after the delay time (RRt1) has elapsed from the start of the start;
A drive control device for a plurality of motors.

  In addition, in order to make an understanding easy, the code | symbol of the corresponding element or the corresponding matter of the Example which is shown in drawing and mentions later in a parenthesis was added as an example for reference. The same applies to the following.

(2) When the first electric motor (21) is started, the timing starts, and the average value (Am1) of the set period (Nt) of the motor current of the first electric motor (21) is set as the average value (Am1) Means (38: 6a on FIG. 7) that repeatedly detects until the value (Amt1) falls below, and measures the elapsed time (RMt1) from the start of the start until the fall of the average value below the set value is detected );
Means (38) for setting a delay time (RRt1) from the start of the start of the first electric motor (21) to the start of the start of the second electric motor (22) corresponding to the elapsed time (RMt1);
Start control means (38) for starting the first electric motor (21) and starting the second electric motor (22) after the delay time (RRt1) has elapsed from the start of the start;
A drive control device for a plurality of motors.

(3) When the first electric motor (21) is started, the timing starts, and the standard deviation value (As1) of the motor current of the first electric motor (21) for the set period (Nt) is changed to the standard deviation value (As1). Is repeatedly detected until the value falls below the set value (Ast1), and means for measuring the elapsed time (RMt1) from the start of the start until the drop of the standard deviation value below the set value is detected (38: FIG. 8). 6b) above;
Means (38) for setting a delay time (RRt1) from the start of the start of the first electric motor (21) to the start of the start of the second electric motor (22) corresponding to the elapsed time (RMt1);
Start control means (38) for starting the first electric motor (21) and starting the second electric motor (22) after the delay time (RRt1) has elapsed from the start of the start;
A drive control device for a plurality of motors.

  The present invention starts timing when the first electric motor (21) is started, and the process until the peak value (Ap1), average value (Am1) or standard deviation value (As1) of the motor current drops below the set value. Measure the time (RMt1) and set the delay time (RRt1) from the start of the first electric motor (21) to the start of the second electric motor (22) corresponding to the elapsed time (RMt1) Since the second electric motor (22) is started after the delay time (RRt1) has elapsed from the start of starting the first electric motor (21), the setting of the start timing is simple and reliable. Stable starting load distribution of a plurality of electric motors can be realized without significantly increasing the power supply capacity. It is possible to shorten the waiting time from the start of the mechanism drive to the steady operation. It is possible to sequentially start a plurality of electric motors at a highly reliable start timing that does not cause a start overload.

  (4) The means for measuring the elapsed time (RMt1) starts the repetitive detection when the rotational speed of the first electric motor (21) reaches a set value (Vt1) (8 in FIG. 4). A drive control apparatus for a plurality of motors according to any one of (1) to (3) above;

  (5) The means for measuring the elapsed time (RMt1) is responsive to the switching of the lock signal that switches from OFF to ON when the rotational speed of the first electric motor (21) reaches the set value (Vt1). Then, the repetitive detection is started (8 in FIG. 4); the multiple motor drive control device according to (4) above.

  (6) The means (38) for setting the delay time (RRt1) includes setting an average value of a plurality of (j) elapsed times (RMt1) adjacent to the first electric motor (21) as the delay time (RRt1). Set (20 in FIG. 4); The drive control apparatus for a plurality of motors according to any one of (1) to (5) above.

  (7) The means (38) for setting the delay time (RRt1) calculates a weighted average value of the measured elapsed time (RMt1) and the delay time (RRt1) to be held in a non-volatile manner. The drive control device for a plurality of motors according to any one of (1) to (5), wherein the delay time (RRt1) to be held in a nonvolatile manner is updated (20a in FIG. 9).

  (8) The means (38) for setting the delay time (RRt1) sets the maximum value of a plurality of (j) elapsed times (RMt1) adjacent to the first electric motor (21) as the delay time (RRt1). Set (20b in FIG. 10); The drive control apparatus for a plurality of motors according to any one of (1) to (5) above.

  (9) When the measured elapsed time (RMt1) is longer than the delay time (RRt1) held in a nonvolatile manner, the means (38) for setting the delay time (RRt1) The time (RRt1) is updated (20c in FIG. 11); the multiple motor drive control device according to any one of (1) to (5) above.

  (10) The means for measuring the elapsed time (RMt1) further measures the elapsed time (RMt2) of the second electric motor (22) similarly to the measurement of the elapsed time (RMt1); and the delay time (RRt1) Means for setting the delay time (RRt2) from the start of the start of the second electric motor (22) similarly to the setting of the delay time (RRt1); any one of (1) to (9) above A drive control apparatus for a plurality of motors according to one.

  (11) The means for measuring the elapsed time (RMt1) further measures the elapsed time (RMt3) of the third electric motor (23) similarly to the measurement of the elapsed time (RMt1); and the delay time (RRt1) Means for setting the delay time (RRt3) from the start of the start of the third electric motor (23) similarly to the setting of the delay time (RRt1); the start control means (38) The third electric motor (23) is started after elapse of the delay time (RRt2) from the start of starting of the electric motor (22); the drive control device for a plurality of motors according to (10) above.

(12) A rotating photoreceptor (5), a charging means (6) for charging the photoreceptor, a developing means (7) and a transfer means (8) for developing an electrostatic latent image on the photoreceptor into a toner image A plurality of image forming units arranged along the belt surface of the transfer belt (3), and exposing means (10) for exposing the charged surface of the photoreceptor (5) to form the electrostatic latent image. And an image forming apparatus provided with a fixing device (17) for fixing the paper onto which the toner image has been transferred,
A first electric motor (21) for driving the fixing device (17), the transfer belt (3), and at least one of the plurality of image forming units;
A second electric motor (22) for driving the plurality of image forming units excluding the image forming unit driven by the first electric motor (21); and
The multi-motor drive control device (38) according to any one of (1) to (8);
An image forming apparatus comprising:

  (13) The image forming unit driven by the first electric motor (21) is a black image forming unit, and the image forming unit driven by the second electric motor (22) is a magenta, cyan and yellow image forming unit. The drive control device (38) drives only the first electric motor (21) when there is a monochrome printing instruction, and drives the first electric motor (21) and starts it when there is a color printing instruction. The image forming apparatus according to (12), wherein the second electric motor (22) is driven after the delay time (RRt1) of the second electric motor (22) has elapsed from the start.

  (14) The image forming apparatus according to (12) or (13), wherein the first electric motor (21) is a brushless motor.

(15) A rotating photoreceptor (5), a charging means (6) for charging the photoreceptor, a developing means (7) and a transfer means (8) for developing an electrostatic latent image on the photoreceptor into a toner image A black image forming unit, and magenta, cyan and yellow color image forming units are arranged along the belt surface of the transfer belt (3), and the charged surface of the photoconductor (5) is exposed to light. An image forming apparatus provided with an exposure means (10) for forming the electrostatic latent image and a fixing device (17) for fixing the paper onto which the toner image has been transferred,
A first electric motor (21) for driving the black image forming unit (4k) and the transfer belt (3);
A second electric motor (22) for driving the color image forming units (4m, 4c, 4y);
A third electric motor (23) for driving the fixing device (17); and a drive control device for a plurality of motors according to (11);
An image forming apparatus comprising:

  (16) The activation control means (38) first activates the third electric motor (23) in response to the color printing instruction, starts the activation, and then starts activation of the third electric motor (23). The first electric motor (21) is started after the delay time (RRt3) has elapsed since the start of the first electric motor (21) and the delay time (RRt1) has elapsed since the start of the first electric motor (21). Later, the second electric motor (22) is started, and in response to the monochrome printing instruction, the first electric motor (21) is first started. After starting, the first electric motor (21) starts to start. The image forming apparatus according to (15), wherein the third electric motor (23) is started after the delay time (RRt1) from the time elapses.

  (17) The image forming apparatus according to any one of (12) to (16), wherein the first and second electric motors are brushless motors.

(18) A rotating photoreceptor (5), a charging means (6) for charging the photoreceptor, a developing means (7) and a transfer means (8) for developing an electrostatic latent image on the photoreceptor into a toner image A black image forming unit, and magenta, cyan, and yellow color image forming units are arranged along the belt surface of the transfer belt (3); exposing the charged surface of the photoconductor (5) An exposure unit (10) for forming the electrostatic latent image, a fixing unit (17) for fixing the sheet on which the toner image is transferred, a fixing temperature detecting unit (39) for detecting a fixing temperature of the fixing unit, and Immediately after turning on the main power switch, set the operation mode in which the operating voltage is applied to each part of the image forming apparatus, and set the energy saving mode to stop the power supply to the circuit part with large power consumption if there is no print instruction for the set time If there is a print instruction when in the energy saving mode, the operation mode is set. An image forming apparatus for energy-saving control means (33), is provided,
A first electric motor (21) for driving the black image forming unit and the transfer belt (3);
A second electric motor (22) for driving the color image forming units;
A third electric motor (23) for driving the fixing device (17);
The drive control apparatus for a plurality of motors according to (11) above;
When the image forming apparatus is started by turning on the original power switch, if the fixing temperature is lower than a set value, the first electric motor is started first, and then the first electric motor (21) is started. The second electric motor is started after the delay time (RRt1) from the start of the start of the motor, and after the start of the start, the delay time (RRt2) from the start of the start of the second electric motor (22) The third electric motor is started later, and when the fixing temperature is equal to or higher than the set value, the third electric motor is first started, and the delay time (RRt3) from the start of the third electric motor (23) is started. A main power-on start control means (38) for starting the first electric motor after the elapse of time and starting the second electric motor after the delay time (RRt1) from the start of the start of the first electric motor (21); and,
When the operation mode is set in response to the print instruction in the energy saving mode, the third electric motor is started first when it is a color print instruction, and the delay time from the start of the start of the third electric motor (23). The first electric motor is started after the lapse of (RRt3), the third electric motor is started after the delay time (RRt1) from the start of the start of the first electric motor (21), and the monochrome print instruction is first The first electric motor is activated at the same time, and the start-up control means for starting the third electric motor after the delay time (RRt1) from the start of the activation of the first electric motor (21) is started after the start of the first electric motor. (38);
An image forming apparatus comprising:

  (19) The image forming apparatus according to (18), wherein each of the first, second, and third electric motors is a brushless motor.

  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

  FIG. 1 shows an outline of an image forming mechanism of a laser printer PTR according to the first embodiment of the present invention. Reference numerals 1 and 2 denote a driving roller and a tension roller on which the transfer belt 3 is stretched. The image forming mechanism includes known color electrophotographic forming process elements, and includes image forming units 4k to 4y for printing each color of K (black), C (cyan), M (magenta), and Y (yellow). ing. Each image forming unit is provided with a charging roller 6, a toner developing device 7 and a cleaner around a drum-shaped photoconductor 5, and these image forming units 4 k to 4 y are moved in the moving direction of the transfer belt 3. They are arranged in tandem at a predetermined pitch along y (sub-scanning direction). Above the image forming units 4k to 4y, there is a laser scanner 10, which projects each laser beam modulated by image data for each color image exposure onto each photosensitive drum 5 charged by the charging roller 6, and The scanning is repeated in the main scanning direction x orthogonal to the moving direction y of the transfer belt 3. As a result, an electrostatic latent image is formed on the photosensitive drum 5. The electrostatic latent image is visualized as a toner image by the developing unit 7. The intermediate transfer belt 3 to which the black toner image is transferred by the black developing device 7 is conveyed to the next image forming unit 4m when a color printing request is made. In the image forming unit 4m, a magenta toner image is formed on the photoreceptor 5m by a process similar to the image forming process in the image forming unit 4k, and the toner image is converted into a black image formed on the intermediate transfer belt 3. Superimposed and transferred.

  The intermediate transfer belt 3 is further conveyed to the next image forming units 4c and 4y, and a cyan toner image formed on the photoconductor 5c and a yellow toner image formed on the photoconductor 5y by the same operation. Are superimposed and transferred onto the intermediate transfer belt 3. Thus, a full color image is formed on the intermediate transfer belt 3. The intermediate transfer belt 3 on which the full-color superimposed image is formed is conveyed to the position of the secondary transfer roller 11, and the full-color image on the intermediate transfer belt 3 is transferred to a sheet. After the transfer of the toner image is completed, the intermediate transfer belt 3 waits for the next image formation after unnecessary toner remaining without being transferred to the sheet is removed by a cleaning device near the drive roller 1. .

  The fixing device 17 heat-seals the toner image transferred to the paper and fixes the toner image to the paper. There is a heater inside the fixing roller of the fixing device 17, which is energized by a fixing heater driver (not shown) to generate heat and heat the fixing roller. The paper that has passed through the fixing unit 17 passes through the paper discharge path 18 and is sent out by the paper discharge roller 19 onto the paper discharge tray 19 outside the paper discharge port Pout.

  In the image formation, in the case of black-only printing (monochrome printing), the photoconductor 5m, photoconductor 5c, and photoconductor 5y are retracted to positions separated from the intermediate transfer belt 3, and the above-described image forming process is performed in black. Only if you do.

  FIG. 2 shows driving sources of the fixing device 17, the paper feeding roller 13, the intermediate transfer belt 3, and the image forming units 4k to 4y shown in FIG. In the printer PTR of this embodiment, a first electric motor 21 for driving the paper feed roller 13, the fixing device 17, the image forming unit 4k, and the driving roller 1 that supports the intermediate transfer belt 3, and the first And a second electric motor 22 for driving an image forming unit (4m, 4c, 4y in FIG. 2) other than the image forming unit 4k driven by the electric motor 21. Note that the paper feed roller 13 is connected to the first electric motor via a clutch only during paper feed, so that it is not driven when the first electric motor is started, and does not become a starting load for the first electric motor 21. The first and second electric motors 21 and 22 are brushless motors.

  FIG. 3 shows an outline of the image processing system of the printer PTR shown in FIG. A print command is given to the printer controller 33 via the communication interface 31 from a directly connected personal computer PC or a personal computer PC connected to a LAN, Ethernet (registered trademark) or other network. The print command includes paper size, color printing / monochrome printing and other printing conditions, and document information.

  The printer controller 33 develops the document information of the received print command into image data and outputs it to the image processing 34. The image processing 34 converts the image data into each color image data suitable for printing by the image forming mechanism shown in FIG. 1 and outputs it to the writing I / F 35 according to the image forming process control of the process controller 38. The writing I / F 35 lights (ON / OFF) or modulates and drives each color recording laser diode of the laser scanner 10 according to each color image data.

  The actuator (electric motor, solenoid) in the mechanism of the printer PTR in FIG. 1 is connected to the driver in the block 39 of the “mechanism driver & sensor” shown in FIG. The fixing temperature sensor for detecting the temperature of the fixing roller and various other sensors in the mechanism of the printer PTR are located in a block 39 together with a detection circuit for processing those signals. The driver and the detection circuit are connected to an input / output interface 37, and the process controller 38 reads detection signals of various sensors through the input / output interface 37, and the image forming unit through the input / output interface 37. 36 actuators are driven. The operation timing and signal input / output timing of the image processing 34 and the writing I / F 35 are controlled via the input / output interface 37.

  The motor drivers for driving and energizing the first electric motor 21 and the second electric motor 22 each have a motor current detection circuit, and are in the block 39 of “mechanism driver & sensor” shown in FIG. The current detection signal of the motor current detection circuit is output to the peak hold circuit in the “input / output interface” 37 shown in FIG. When obtaining the maximum current value of the first electric motor 21, the process controller 38 turns on the peak hold circuit (an operation state in which the hold signal is updated to the peak value) and then turns off (holds) after the set time Tm has elapsed. State) and hold signal (level) is A / D converted and read. Then, the peak hold circuit is reset (erasure of the hold signal: initialization of the hold level).

  The printer controller 33 is a computer system mainly composed of a CPU, a ROM, a RAM, and an interface, and further includes a memory device for recording document information and a nonvolatile RAM for holding various data. The data group of the nonvolatile RAM also includes data that is referred to by the process controller 38 in image forming mechanism control. When the printer controller 33 sets the “operation mode” in which the operation voltage for image formation is applied to each part by turning on (contacting) the original power switch or returning from the “energy saving mode” to the printer PTR. The data referred to by the process controller 38 in the image forming mechanism control, which must be held in a non-volatile state even when the operating voltage is not applied to the process controller 38, is read from the non-volatile RAM of the printer controller 33, and the process controller 38 Written to the RAM. Each data write area of the RAM is called a register individually. Data in the register that must be held in a nonvolatile manner is overwritten in the nonvolatile RAM of the process controller 38 when the “operation mode” is switched to the “energy saving mode”, while the printer PTR is in the “energy saving mode”. It is held in the nonvolatile RAM while the original power switch is turned off.

  4 and 5 show an outline of printer control executed by the printer controller 33 using the process controller 38. FIG. When an original power switch (not shown) is turned on and the operating voltage is supplied to the printer PTR, the controller 33 resets itself and sets each part of the printer to an initial state (steps 1 and 2), and performs image forming operation on each part. The power supply circuit is set to the “operation mode” in which the operation voltage necessary for the operation is applied, and the timer Td1 whose time limit value is Td1 is started (step 3). In the following, the word “step” is omitted, and only the step number is written in parentheses.

  Next, the process controller 38 instructs a fixing heater driver (not shown) to start temperature control using the fixing temperature as a target temperature (4), and blocks the drive of the first electric motor 21 via the input / output interface 37. The motor driver for the first electric motor 21 at 39 is instructed (5), and “measurement of the startup time RMt1 of the first electric motor 21” (6) is executed.

  That is, the time t (measurement of the elapsed time t) is started (7), and the LOCK signal is turned on (8). Here, the lock signal is a signal generated by the motor driver for the first electric motor 21 and is turned off when the rotation speed of the first electric motor 21 reaches a threshold value Vt1 that is a set speed around the target speed. (OFF: high speed H in this embodiment) is a speed detection signal that is switched from ON (ON: L), and the motor driver drives the first electric motor 21 when the lock signal is switched from OFF to ON. The energization is switched from the start mode for increasing the motor speed to the constant speed control mode for stabilizing the target speed. When the motor driver performs motor drive control employing PLL control, a speed detection pulse (feedback) proportional to the rotational speed of the first electric motor 21 with respect to a pulse (finger speed pulse) designating a target speed. When the frequency of (pulse) becomes substantially the same frequency and within a predetermined phase difference range, the lock signal is switched from OFF to ON. At this time, the rotational speed of the first electric motor 21 is substantially the same as the target speed (the threshold value Vt1 that is the set speed). In the case of feedback control that does not employ PLL control, in order to reduce motor speed overshoot, the rotational speed signal representing the rotational speed of the first electric motor 21 reaches a threshold value Vt1 that is a set speed that is slightly lower than the target speed. Then, the lock signal is switched from OFF to ON, and in response to this, the motor driver is switched from the start mode to the constant speed control mode.

  When the lock signal is switched on, the process controller 38 turns on the peak hold circuit in the input / output interface 37 connected to the motor current detection circuit in the motor driver (operation state in which the hold signal is updated to the peak value). (9), then, after the set time Tm has elapsed, it is turned OFF (holding state) (10-12), and the holding signal (level), that is, the peak value Ap1 is A / D converted and read (13). Then, the peak hold circuit is reset (erasure of the hold signal: initialization of the hold level) (14). If the peak value Ap1 is not less than or equal to a threshold value (set value) Aptl that is slightly higher than the motor current during steady constant speed rotation, the peak value is detected during the set time Tm (15, 9 to 14). When the peak value Ap1 becomes equal to or less than the threshold value Apt1, the time count t at that time is written in the register RMt1 (15, 16).

  FIG. 6 shows the relationship between the current transition of the first electric motor 21, the switching of the lock (LOCK) signal, and the peak value detection period Tm. FIG. 6 shows that the peak value Ap1 of the motor current becomes equal to or lower than the threshold value Apt during 3 Tm after the lock signal is switched from OFF to ON.

  Refer to FIG. 4 again. Next, the process controller 38 determines whether or not the measured value t has reached the start time RRt1 of the first electric motor 21 (starting delay timing value of the second electric motor 22 that starts after starting) in the register RRt1. If it has not reached RRt1 (17), when it reaches RRt1, the second electric motor 22 is driven via the input / output interface 37 to drive the second electric motor 22 in the block 39. The driver is instructed (18), and “measurement of the startup time RMt2 of the second electric motor 22” (19) is executed. This content is the same as the content of “Measurement of Start Time RMt1 of First Electric Motor 21” (6) described above, and after starting the second electric motor 22, the motor current of the second electric motor 22 is measured. The elapsed time t until the peak value Ap2 becomes equal to or less than the threshold value Apt2 is written in the register RMt1.

  While waiting for the lock signal to switch from OFF to ON in the “measurement of the startup time RMt2 of the second electric motor 22” (19) described above (in a step corresponding to step 8), the process controller 38 Perform. In the upper part of FIG. 4, “RRt1 update” (20) is shown next to “measurement of start-up time RMt2 of second electric motor 22” (19).

  In “Update of RRt1” (20), the process controller 38 assigns the data of the addresses 2 to j of the RMt1 memory for reading / writing a plurality of j pieces of data allocated to one area of the internal RAM to the addresses 1 to (j −1), the data address is shifted (21), and the starting time RMt1 (register RMt1 of the register RMt1) obtained in the above-mentioned “measurement of the starting time RMt1 of the first electric motor 21” (6) is set to the vacant address j. Data) is written (22). Then, the average value of the data at the addresses 1 to j is calculated and overwritten in the register RRt1 (23). The data 1 to j of the RMt1 memory and the data of the register RRt1 are held in a nonvolatile manner.

  When the start time RRt2 of the second electric motor 22 is measured and written in the register RRt2 in “Measurement of start time RMt2 of the second electric motor 22” (19), the process controller 38 starts the second electric motor 22. After that, it is determined whether the measured time t has reached the start time (image formation start delay time) RRt2 of the second electric motor 21 in the register RRt2, and if not, wait until it reaches RRt2 (24) When RRt2 is reached, "RRt2 update" (25) is executed to start the timer Td1 for measuring the timing of energy saving mode transition (26), and the process proceeds to "input reading" (27).

  The contents of “update RRt2” (25) are the same as the contents of “update RRt1” (20), and the data of addresses 2 to j in the RMt2 memory are moved to addresses 1 to (j−1). The address shift is performed, and the start time RMt2 (data in the register RMt2) obtained in the above-mentioned “measurement of the start time RMt2 of the second electric motor 22” (19) is written to the free address j, and the addresses 1 to j are written. The average value of data is calculated and overwritten in the register PRt2. The data 1 to j of the RMt2 memory and the data of the register RRt2 are also held in a nonvolatile manner.

  Please refer to FIG. While waiting for a print instruction in “input reading” (27), when there is no print instruction and the timer Td1 times out, the printer controller 33 detects a return instruction detection circuit that detects the print instruction and other inputs indicating use of the printer. The power supply circuit is set to the “energy saving mode” in which power supply to the electric circuit that consumes power even during standby is stopped (27-28-32-36-37).

  However, when the color printing instruction is received in the “operation mode” and “input reading” (27), the printer controller 33 performs color printing in cooperation with the process controller 38 and restarts the timer Td1 (28 to 31). When a monochrome printing instruction arrives, monochrome printing is performed and the timer Td1 is restarted (32 to 35).

  When a print instruction arrives during the above-described “energy saving mode” setting, the return input detection circuit turns on the power supply line that activates the printer controller 33 of the power supply circuit. As a result, the printer controller 33 starts its operation and sets the power supply circuit to the “operation mode” (38, 39).

  When the operation mode is switched, the process controller 38 instructs the fixing heater driver to start fixing temperature control (40), and instructs the motor driver for the first electric motor 21 to drive the first electric motor 21 ( 41), “Measurement of start-up time RMt1 of first electric motor 21” (42). This content is the same as “Measurement of start-up time RMt1 of first electric motor 21” (6). Next, the process controller 38 determines whether or not the measured value t from the current start of the first electric motor 21 has reached the start time RRt1 of the register RRt1, and waits until it reaches RRt1 if not ( 43) When RRt1 is reached, "update RRt1" (44) is executed. This content is the same as “Update RRt1” (20) described above.

  Next, according to the contents of the print instruction (45), if it is a color print instruction, the motor driver for the second electric motor 22 is instructed to drive the second electric motor 22 (46). "Measurement of start-up time RMt2 of electric motor 22" (47) is executed. This content is the same as “Measurement of start-up time RMt2 of second electric motor 22” (19). Next, the process controller 38 determines whether or not the measured value t from the current start of the second electric motor 22 has reached the start time RRt2 of the register RRt2, and waits until it reaches RRt2 if not reached ( 48) When RRt1 is reached, "Update RRt2" (49) is executed, and color printing is executed (49-29 to 31). The content of “RRt2 update” (49) is the same as “RRt2 update” (25). If the print instruction is a monochrome print instruction, monochrome printing is performed without driving the second electric motor 22 (45-33 to 35).

  In the first embodiment described above, the time t is started when the first electric motor 21 is started, and the lock signal is switched from on to off when the rotational speed of the motor reaches the set value Vt1. Thereafter, the time value t until the peak value Ap1 of the motor current becomes equal to or less than the set value Apt1 is regarded as the activation time RMt1 of the first electric motor 21, and the past activation of the first electric motor 21 is matched with the past. The average value RRt1 of the j startup times RMt1 is determined as the startup delay time of the second electric motor 22 with respect to the startup start time of the first electric motor 21. When the startup time RMt1 measured this time is longer than the average value (startup delay time of the next drive motor) RRt1 so far, after the startup time RMt1 measured this time has elapsed, the second electric motor that is the next drive motor. Start of the motor 22 is started.

-Modification 1 of the first embodiment-
In Modification 1, “Measurement of start time RMt1 of first electric motor 21” (6), (42) of the first embodiment is replaced with “Measurement of start time RMt1 of first electric motor 21” shown in FIG. "(6a)" and "Measurement of start time RMt2 of second electric motor 22" (19), (47) is also "Measurement of start time RMt1 of first electric motor 21" (6a) shown in FIG. It is the same as the contents of. In the first modification, when the lock signal is switched from OFF to ON, the input / output interface 37 is provided with a sample hold circuit instead of a peak hold circuit in order to monitor the average value instead of the peak value of the motor current. The motor current detection circuit of the motor driver in block 39 is connected. The hardware and other functions of the first modification are the same as those in the first embodiment.

  In “Measurement of start-up time RMt1 of first electric motor 21” (6a) shown in FIG. 7, process controller 38 starts time t (measurement of elapsed time t) (7), and LOCK (lock) signal is displayed. Wait for it to turn on (8). When the lock signal is switched on, the data reading count n is set to 1 (9a). Next, the sample hold circuit in the input / output interface 37 connected to the motor current detection circuit in the motor driver for driving and energizing the first electric motor 21 in the block 39 is temporarily turned on, The motor current detection signal (level) is held (10a), and the signal (level) Am is A / D converted and read (11a). Then, the read current data Am is written to the address n of the current data memory RAm determined in one area of the RAM (12a). This motor current reading is repeated Nt times (13a, 14a-10a to 13a). Next, an average value of Nt read data in the current data memory RAm is calculated and written to the register Am1 (15a). If the average value Am1 is not equal to or less than the threshold value (set value) Amt1 that is slightly higher than the motor current at the time of steady constant speed rotation, the motor current is read Nt times and the average value of the read data is calculated (16a-9a). 13a). When the average value Am1 becomes equal to or less than the threshold value Amt1, the time count t at that time is written in the register RMt1 (16a-16).

  In the first modification described above, the time t is started when the first electric motor 21 is started, and after the lock signal is switched from on to off when the motor rotation speed reaches the set value Vt1. The measured value t until the average value Am1 of the motor current becomes equal to or less than the set value Amt1 is regarded as the starting time RMt1 of the first electric motor 21.

-Modification 2 of the first embodiment-
In the second modification, “measurement of the start time RMt1 of the first electric motor 21” (6) and (42) in the first embodiment described above is shown in FIG. "(6b)" and "Measurement of start time RMt2 of second electric motor 22" (19), (47) is also "Measurement of start time RMt1 of first electric motor 21" (6b) shown in FIG. It is the same as the contents of. In Modification 2, when the lock signal is switched from OFF to ON, the input / output interface 37 is provided with a sample hold circuit instead of a peak hold circuit in order to monitor the standard deviation instead of the peak value of the motor current. The motor current detection circuit of the motor driver in block 39 is connected. The hardware and other functions of the second modification are the same as those in the first embodiment.

  In “Measurement of start time RMt1 of first electric motor 21” (6b) shown in FIG. 8, process controller 38 starts time t (measurement of elapsed time t) (7), and LOCK (lock) signal is displayed. Wait for it to turn on (8). When the lock signal is switched on, the data reading count n is set to 1 (9a). Next, the sample hold circuit in the input / output interface 37 connected to the motor current detection circuit in the motor driver for driving and energizing the first electric motor 21 in the block 39 is temporarily turned on, The motor current detection signal (level) is held (10a), and the signal (level) Am is A / D converted and read (11a). Then, the read current data Am is written to the address n of the current data memory RAm determined in one area of the RAM (12a). This motor current reading is repeated Nt times (13a, 14a-10a to 13a). Next, the standard deviation As of Nt read data in the current data memory RAm is calculated and written in the register As1 (15b). If the standard deviation As1 is not less than the threshold value (set value) Ast1 that is slightly higher than the standard deviation of the motor current during steady constant speed rotation, the motor current is read Nt times and the average value of the read data is calculated (16b). -9a to 13a). When the average value Am1 is less than or equal to the threshold value Amt1, the time count t at that time is written in the register RMt1 (16b-16).

  In the second modification described above, the time t is started when the first electric motor 21 is started, and after the lock signal is switched from on to off when the motor rotation speed reaches the set value Vt1. The time value t until the motor current standard deviation As1 becomes equal to or less than the set value Ast1 is regarded as the starting time RMt1 of the first electric motor 21.

-Modification 3 of the first embodiment-
In Modification 3, “RRt1 update” (20), (44) of the first embodiment is changed to “RRt1 update” (20a) shown in FIG. 9, and “RRt2 update” (25). , (49) are also changed in the same manner as the contents of “Update RRt1” (20a) shown in FIG. The hardware and other functions of the third modification are the same as those in the first embodiment.

  In “Update RRt1” (20a) shown in FIG. 9, the process controller 38 determines that the start time RMt1 (data in the register RMt1) and the register RRt1 obtained in “Measurement of the start time RMt1 of the first electric motor 21” (6). The data in the register RRt1 is rewritten to the weighted average value of the data RRt1 (20a). k is a weighting factor. When k = 1, the start time RMt1 (data of the register RMt1) obtained in “Measurement of the start time RMt1 of the first electric motor 21” (6) is updated and written to the register RRt1. Become. When k = 2, the data of the register RRt1 is set to the average value of the start time RMt1 (data of the register RMt1) obtained in “Measurement of the start time RMt1 of the first electric motor 21” (6) and the data RRt1 of the register RRt1. Will be rewritten. In order to simplify the calculation, k = 1, k = 2, k = 4 or 8. It can be a power of 2 exceeding 8. When the k value is increased, the weight of the startup time RMt1 to be included in the latest with respect to the weighted average value is reduced, but the smoothing effect of the measurement value is increased.

  In the first embodiment, a simple smooth value of the startup time measurement value RMt1 when the first electric motor 21 is started up most recently j times is determined as the startup delay timing value RRt1 of the hour drive motor by “update RRt1” (20). On the other hand, in the third modification described above, the time series weighted smooth value of the startup time measurement value RMt1 at each startup of the first electric motor 21 is time-driven by “update of RRt1” (20a). It is determined as a motor start delay timing value RRt1.

-Modification 4 of the first embodiment-
In the fourth modification example, “RRt1 update” (20) and (44) in the first embodiment is changed to “RRt1 update” (20b) shown in FIG. 10, and “RRt2 update” (25). , (49) are also changed in the same manner as the contents of “Update RRt1” (20b) shown in FIG. The hardware and other functions of the modified example 4 are the same as those of the first embodiment described above.

  In “Update RRt1” (20b) shown in FIG. 10, the process controller 38 performs an address shift to rewrite data at addresses 2 to j in the RMt1 memory to addresses 1 to (j−1), and then vacant address j The start time RMt1 (data of register RMt1) obtained in “Measurement of start time RMt1 of first electric motor 21” (6) is written (21, 22), and the maximum value among the data of addresses 1 to j is set. Search and overwrite it in the register RRt1 (23a).

  In the fourth modification, the maximum value in the group of start time measurement values RMt1 at the time of the latest j start of the first electric motor 21 is set to the start delay timing of the next drive motor by the “update of RRt1” (20b). The value is set to RRt1. Since this becomes the start delay timing value RRt1 of the next drive motor, it is extremely reliable to prevent duplication that the next drive motor is started within the start time RMt1 of the first electric motor 21.

-Modification of the first embodiment-
In the modified example 5, “RRt1 update” (20), (44) of the first embodiment is changed to “RRt1 update” (20c) shown in FIG. 11, and “RRt2 update” (25). , (49) are also changed in the same manner as the contents of “Update RRt1” (20c) shown in FIG. The hardware and other functions of the modified example 5 are the same as those of the first embodiment described above.

  In “Update RRt1” (20c) shown in FIG. 11, the process controller 38 determines that the start time RMt1 (data in the register RMt1) obtained in “Measurement of the start time RMt1 of the first electric motor 21” (6) is the register If it is longer than the data RRt1 of RRt1, the data in the register RRt1 is updated to the activation time RMt1 (21c, 22c).

  In the fifth modification, the maximum value of the startup time measurement value RMt1 at the time of startup of the first electric motor 21 so far is determined as the startup delay timing value RRt1 of the next drive motor by “update RRt1” (20c). . Since this is the start delay timing value RRt1 of the next drive motor, the start time RMt1 of the first electric motor 21 when the next drive motor uses the first electric motor exhibiting the degradation characteristic that the start time gradually increases in time series. It is possible to permanently prevent duplication of being activated within the system.

  In the second embodiment, as shown in FIG. 12, a third electric motor 23 is added, and the first electric motor 21 drives the intermediate transfer belt 3 and the black image forming unit 21. The paper roller 13 is driven by a third electric motor 23. The first, second and third electric motors are brushless motors. Other mechanisms are the same as in the first embodiment.

  13 and 14 show an outline of printer control executed by the printer controller 33 using the process controller 38. FIG. First, referring to FIG. 13, when an unillustrated main power switch is turned on and an operating voltage is supplied to the printer PTR, the controller 33 resets itself and then sets each part of the printer to an initial state (1, 2). Then, the power supply circuit is set to the “operation mode” in which the operation voltage necessary for the image forming operation is applied to each unit (3), and the fixing heater driver is instructed to start fixing temperature control (4).

  Next, referring to the fixing temperature, it is determined whether it is a set value that is slightly lower than the target temperature (60). If it is more than the set value, the fixing roller is heated and the startup time is short. The start of the third electric motor 23 (development unit 17) is started (65), and the drive of the first electric motor 21 (transfer belt 3, black image forming unit 4k) is started after RRt3 has elapsed from the start of the start (68). ), The driving of the second electric motor 22 (image forming units 4m, 4c, 4y) is started after the RRt1 has elapsed from the start of the start (72), and the timer Td1 is started after the RRt2 has elapsed from the start of the start ( 26), the process proceeds to “input reading” (27).

  However, if the fixing temperature is less than the set value, the starting load of the fixing device 17 is large, and it takes a relatively long time to heat up the fixing temperature to the target temperature. When the RRt1 elapses from the start of activation (2), the second electric motor 22 is activated (18), and when RRt2 elapses from the start of activation, the third electric motor 23 is activated (61). After elapse of RRt3 from the start of activation, the timer Td1 is started (26), and the process proceeds to "input reading" (27).

  When any of the first to third electric motors 21 to 23 is activated, “measurement of activation time” (69), (73), (66) / (6), (19), (62) is executed. Each content is the same as that of the above-mentioned step 6 (FIG. 4), 6a (FIG. 7) or 6b (FIG. 8). Further, the “update of RRt” (74), (76), (70) / (20), (25), (64) executed based on the measurement values RMt1, RMt2, RMt3 of “activation time measurement”. The contents are the same as those in the aforementioned step 20 (FIG. 4), 20a (FIG. 9), 20b (FIG. 10) or 20c (FIG. 11).

  Refer to FIG. While waiting for a print instruction in “input reading” (27), when there is no print instruction and the timer Td1 times out, the printer controller 33 detects a return instruction detection circuit that detects the print instruction and other inputs indicating use of the printer. The power supply circuit is set to the “energy saving mode” in which power supply to the electric circuit that consumes power even during standby is stopped (27-28-32-36-37).

  However, when the color printing instruction is received in the “operation mode” and “input reading” (27), the printer controller 33 performs color printing in cooperation with the process controller 38 and restarts the timer Td1 (28 to 31). When a monochrome printing instruction arrives, monochrome printing is performed and the timer Td1 is restarted (32 to 35).

  When a print instruction arrives during the above-described “energy saving mode” setting, the return input detection circuit turns on the power supply line that activates the printer controller 33 of the power supply circuit. As a result, the printer controller 33 starts its operation and sets the power supply circuit to the “operation mode” (38, 39). When the mode is switched to the “operation mode”, the process controller 38 instructs the fixing heater driver to start fixing temperature control (40). Depending on whether the print instruction is a color print instruction or a monochrome print instruction (45), the process controller 38 is a monochrome print instruction. First, the process controller 38 starts driving the first electric motor 21 (transfer belt 3, black image forming unit 4k) (41), and after the RRt1 has elapsed from the start of the start, the third electric motor 23 (developer 17). ) Is started (77), and after RRt3 has elapsed from the start of the start, the process proceeds to monochrome printing (81-33 to 35). The second electric motor 22 is not driven.

  However, if it is a color printing instruction, first the first electric motor 21 is started (82), and when the RRt1 has elapsed from the start of the start, the second electric motor 22 is started (46), and the RRt2 from the start of the start. Then, the third electric motor 23 is started (87). After elapse of RRt3 from the start of the start, the process proceeds to color printing (89-29 to 31).

  When any of the first to third electric motors 21 to 23 is started, “measurement of start time” (42), (83), (47), (78), and (87) is executed. Each content is the same as that of the above-mentioned step 6 (FIG. 4), 6a (FIG. 7) or 6b (FIG. 8). The contents of “RRt update” (79), (85), (49), (81), (89) executed based on the measurement values RMt1, RMt2, RMt3 of “activation time measurement” are described above. Step 20 (FIG. 4), 20a (FIG. 9), 20b (FIG. 10) or 20c (FIG. 11).

  As described above, when the mechanism drive is started in response to the print instruction (39 or less), the third electric motor 23 is activated last. This is because, when the mechanism driving is started upon receiving a printing instruction, it is more likely that printing can be started earlier than if the printing paper is started first, rather than conveying the printing paper to the registration roller 15. It is. For example, when the mechanism drive is started in response to a print instruction when the fixing temperature is close to the target temperature, in the case of monochrome printing, image formation can be started when the first electric motor 21 is started, and color printing is started. In this case, after the start of the first electric motor 21 is completed and the start of the second electric motor 22 is completed, image formation can be started and printing can be started early.

It is a longitudinal cross-sectional view of the mechanism part of printer PTR which is 1st Example of this invention. FIG. 2 is a block diagram showing an outline of a power system that drives an intermediate transfer belt 3 and image forming units 4k to 4y of the printer PTR shown in FIG. FIG. 2 is a block diagram showing an outline of an image processing system of the printer PTR shown in FIG. 1. 4 is a flowchart showing a part of print control executed by a printer controller 33 shown in FIG. FIG. 3 is a flowchart illustrating a remaining part of print control executed by a printer controller 33 shown in FIG. Changes in the motor current and rotational speed of the first electric motor 21 shown in FIG. 2 and the control signal (ON / OFF) given to the motor driver that rotationally drives the first electric motor and the lock signal generated by the motor driver. It is a time chart which shows. It is a flowchart which shows a part of printing control of the 1st modification of 1st Example. It is a flowchart which shows a part of printing control of the 2nd modification of 1st Example. It is a flowchart which shows a part of printing control of the 3rd modification of 1st Example. It is a flowchart which shows a part of printing control of the 4th modification of 1st Example. It is a flowchart which shows a part of printing control of the 5th modification of 1st Example. It is a block diagram which shows the outline | summary of the motive power system which drives the intermediate transfer belt 3 and the image formation units 4k-4y of printer PTR of 2nd Example of this invention. 10 is a flowchart illustrating a part of print control executed by a printer controller 33 according to a second embodiment using a process controller 38; 10 is a flowchart illustrating a remaining part of print control executed by a printer controller 33 according to a second embodiment using a process controller 38;

Explanation of symbols

1: Driving roller 2: Tension roller 3: Transfer belt 4 (4k-4y): Image forming unit 5: Photoconductor drum 6: Charge roller 7: Developer 8: Primary transfer roller 9: Cleaner 10: Laser scanner 11 : Secondary transfer roller 12: paper feed tray 13: paper feed roller 14: paper feed path 15: registration roller 16: delivery path 17: fixing device 18: paper discharge path 19: paper discharge tray

Claims (17)

When the first electric motor is started, timing is started, and the peak value within the set time of the motor current of the first electric motor is repeatedly detected until the peak value falls below the set value. Means for measuring the elapsed time until a drop in value is detected below a set value;
Means for setting a delay time from the start of the first electric motor to the start of the second electric motor corresponding to the elapsed time; and
Start control means for starting the first electric motor and starting the second electric motor after the delay time has elapsed since the start of the start;
A drive control device for a plurality of motors. When the first electric motor is started, time measurement is started, and the average value of the motor current of the first electric motor is repeatedly detected until the average value falls below the set value. Means for measuring the elapsed time until a decrease in the value below the set value is detected;
Means for setting a delay time from the start of the first electric motor to the start of the second electric motor corresponding to the elapsed time; and
Start control means for starting the first electric motor and starting the second electric motor after the delay time has elapsed since the start of the start;
A drive control device for a plurality of motors. When the first electric motor is started, time measurement is started, and the standard deviation value of the motor current of the first electric motor is repeatedly detected until the standard deviation value falls below the set value. Means for measuring the elapsed time until a decrease in the standard deviation value below the set value is detected;
Means for setting a delay time from the start of the first electric motor to the start of the second electric motor corresponding to the elapsed time; and
Start control means for starting the first electric motor and starting the second electric motor after the delay time has elapsed since the start of the start;
A drive control device for a plurality of motors.   The means for measuring the elapsed time starts the repetitive detection when the rotational speed of the first electric motor reaches a set value; drive control of a plurality of motors according to any one of claims 1 to 3; apparatus.   The means for measuring the elapsed time starts the repeated detection in response to the switching of a lock signal that switches from OFF to ON when the rotational speed of the first electric motor reaches a set value; A drive control apparatus for a plurality of motors according to 1.   The means for setting the delay time sets an average value of a plurality of adjacent elapsed times of the first electric motor as the delay time; drive control of a plurality of motors according to any one of claims 1 to 5; apparatus.   The means for setting the delay time calculates a weighted average value of the measured elapsed time and the delay time held in a nonvolatile manner, and updates the delay time held in the nonvolatile manner to the weighted average value; The drive control apparatus for a plurality of motors according to any one of the above.   The means for setting the delay time sets a maximum value of a plurality of adjacent elapsed times of the first electric motor as the delay time; drive control of a plurality of motors according to any one of claims 1 to 5; apparatus.   The means for setting the delay time updates the delay time held in a nonvolatile manner to the elapsed time when the measured elapsed time is longer than the delay time held in a nonvolatile manner; Drive control device for multiple motors.   The means for measuring the elapsed time further measures the elapsed time of the second electric motor in the same manner as the measurement of the elapsed time; the means for setting the delay time is further in the same manner as the setting of the delay time. The drive control device for a plurality of motors according to any one of claims 1 to 9, wherein a delay time from the start of motor start is set.   The means for measuring the elapsed time further measures the elapsed time of the third electric motor in the same manner as the measurement of the elapsed time; the means for setting the delay time is further in the same manner as the setting of the delay time. The delay time from the start of motor start is set; and the start control means starts the third electric motor after the delay time has elapsed from the start of start of the second electric motor; Drive control device. A plurality of image forming units that combine a rotating photosensitive member, a charging unit that charges the photosensitive member, a developing unit that visualizes an electrostatic latent image on the photosensitive member into a toner image, and a transfer unit are provided on the belt surface of the transfer belt. An image forming apparatus comprising: an exposure unit that is disposed along the exposure surface to expose the charged surface of the photoconductor to form the electrostatic latent image; and a fixing unit that fixes the sheet onto which the toner image has been transferred.
A first electric motor for driving the fixing device, the transfer belt, and at least one of the plurality of image forming units;
A second electric motor for driving the plurality of image forming units excluding the image forming unit driven by a first electric motor; and
A drive control device for a plurality of motors according to any one of claims 1 to 8;
An image forming apparatus comprising:   The image forming unit driven by the first electric motor is a black image forming unit, the image forming unit driven by the second electric motor is a magenta, cyan and yellow color image forming unit; When there is a monochrome printing instruction, only the first electric motor is driven, and when there is a color printing instruction, the first electric motor is driven, and the second electric motor is turned on after the delay time of the second electric motor has elapsed from the start of the start. The image forming apparatus according to claim 12, wherein the image forming apparatus is driven.   The image forming apparatus according to claim 12 or 13, wherein the first electric motor is a brushless motor. A black image forming unit that combines a rotating photosensitive member, a charging unit that charges the photosensitive member, a developing unit that develops an electrostatic latent image of the photosensitive member into a toner image, and a transfer unit, and magenta and cyan. And yellow color image forming units are arranged along the belt surface of the transfer belt, and expose the charging surface of the photosensitive member to form the electrostatic latent image, and fix the sheet onto which the toner image is transferred. An image forming apparatus having a fixing device for processing,
A first electric motor for driving the black image forming unit and the transfer belt;
A second electric motor for driving each color image forming unit;
A third electric motor for driving the fixing device; and a drive control device for a plurality of motors according to claim 11;
An image forming apparatus comprising:   The activation control means first activates the third electric motor in response to the color printing instruction, and after starting the activation, the first electric motor is started after the delay time from the start of the activation of the third electric motor. Is started, the second electric motor is started after the lapse of the delay time from the start of starting the first electric motor, and the first electric motor is started first in response to the monochrome printing instruction. The image forming apparatus according to claim 15, wherein the third electric motor is started after elapse of the delay time from the start of starting the first electric motor after starting the starting.   The image forming apparatus according to claim 12, wherein the first and second electric motors are brushless motors.

Images