JP4342906B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  As various image forming apparatuses such as printers, facsimiles, copying apparatuses, plotters, printer / fax / copier multifunction machines, etc., a recording head constituted by a droplet discharge head is mounted on a carriage, and the carriage is used as a recording medium (paper). (Also referred to as a recording medium, etc.) in the direction perpendicular to the conveying direction of the recording medium, and the recording medium is intermittently conveyed according to the recording width, and the conveyance and recording are repeated alternately. A serial type that forms an image on a recording medium (recording, printing, printing, and printing are also used synonymously), a recording medium that includes a recording head having a line width, and that feeds the recording medium while sub-scanning. There is a line type for forming an image.

  In such an image forming apparatus, in order to continuously record an image on a recording medium by droplets ejected from a recording head that outputs an image having a certain width, intermittent conveyance of the recording medium is performed. (Sub-scanning) is performed. At this time, the feeding accuracy of the recording medium and the positioning accuracy of the recording medium affect the image quality. Therefore, in order to record a high-speed, high-quality image, the recording medium must be transported at high speed and with high accuracy.

Therefore, in general, a DC servo motor is used as a driving motor for the sub-scanning mechanism in order to absorb load fluctuations due to variations in assembly between apparatuses, inertia of the paper feed mechanism (sub-scanning mechanism), frictional force, rigidity (spring property), and the like. Is driven by PID control.
JP 2000-37919 A

And as described in Patent Document 2, such a servo motor drive control device is closer to the optimum by detecting the speed of the servo motor without fixing the control parameters in the PID control loop. 2. Description of the Related Art A so-called learning servo type servo motor control device that calculates and resets control parameters is known. This device has a means for detecting the load to be controlled outside the servo loop, and prepares several sets of control parameters for initial calculation that are calculated in advance corresponding to the amount of load expected. Thus, the initial control parameter most suitable for the detected load is selected, and the learning is started after setting it.
Japanese Patent Laid-Open No. 5-284768

In addition, as described in Patent Document 3, in order to perform appropriate speed control at the time of deceleration with respect to a change with time such as a temperature change of a drive motor or a load, a servo loop gain is determined according to a speed diagram of the scanner. Switching means, means for detecting the temperature of the motor, means for changing the servo loop gain at the time of motor deceleration according to the scanner stop position at the time of scanner return, and change according to the motor temperature and the scanner stop position. There is also known a servo motor speed control device provided with means for storing the servo loop gain when the motor is decelerated.
JP-A-7-322019

  However, in the learning servo motor control device disclosed in Patent Document 2 described above, a load such as the number of heads and the presence or absence of an ink cartridge is detected, and a control parameter is selected according to the detected load. Since the actual load fluctuation detection accuracy is poor and only a predetermined control parameter is selected, it is difficult to stop at the target position with high accuracy.

  In the servo motor control device disclosed in Patent Document 3 described above, even if the stop position control of the scanner can be performed, it cannot be applied to other devices, and particularly in the image forming apparatus. When high-precision positioning accuracy such as feed control of the recording medium is required, it cannot be handled.

  The present invention has been made in view of the above problems, and provides a motor drive control device capable of obtaining high-speed and high-precision positioning accuracy, and an image forming apparatus capable of forming a high-quality image at high speed by including this device. The purpose is to do.

In order to solve the above-described problems, a motor drive control device according to the present invention includes:
Storage means for storing the speed profile of the drive target;
A unit that feeds back a deviation between a target speed obtained from the speed profile and a current speed of the driving target, and calculates a PID control amount for a DC servo motor that moves the driving target ;
In the motor drive control device that performs acceleration control, constant speed control, and deceleration control on the DC servo motor based on the speed profile ,
The speed profile includes a profile that sets a target speed of a constant speed lower than the target speed of the constant speed control for a predetermined period when shifting from the constant speed control to the deceleration control,
Holding means for holding the PID control amount for a predetermined number of times when the DC servo motor is controlled at a constant speed;
Comparing means for comparing an average value of the PID control amount held in the holding means with a predetermined value ;
Means for calculating the PID control amount, the can and the process proceeds to the deceleration control from the constant speed control, the so constant speed control control corresponding to the target speed such as low speed than a target speed of is made, the comparison means depending on the comparison result, if before Kitaira average value is equal to or greater than the predetermined value, the integral gain reduces, before Kitaira average value is the predetermined value when computing the PID control quantity If less than, was configured to increase the integral gain at the time of calculating the pre-Symbol PID control amount.

Here, the said speed profile, once the target speed is set period to 0 can configured Ru Tei when migrating to the deceleration control from the constant speed control.

  An image forming apparatus according to the present invention includes a motor drive control device according to the present invention for driving and controlling a DC servo motor of a sub-scanning mechanism for feeding a recording medium.

According to the motor drive control device of the present invention, the PID control amount for a predetermined number of times is held during constant speed control, and the average value of the held PID control amounts is compared with a predetermined value. Then, when shifting from the constant speed control to the deceleration control, the average value is set according to the comparison result of the comparison means so that the control corresponding to the constant speed target speed lower than the target speed of the constant speed control is performed. If the value is greater than a predetermined value, the integral gain when calculating the PID control amount is decreased, and if the average value is smaller than the predetermined value, the integral gain when calculating the PID control amount is increased. Since the configuration is adopted, it is possible to perform the deceleration control according to the fluctuation of the driving load during the constant speed control, and a high-accuracy stop position can be obtained even when driving at high speed.

  In the image forming apparatus according to the present invention, the DC servo motor of the sub-scanning mechanism that feeds the recording medium is driven and controlled by the motor drive control apparatus according to the present invention. The accuracy is improved, and a high-quality image can be formed at high speed.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is an explanatory side view for explaining the overall configuration of the image forming apparatus according to the present invention, FIG. 2 is an explanatory plan view of the main part of the apparatus, and FIG.
In this image forming apparatus, a carriage 3 is slidably held in a main scanning direction by a guide rod 1 and a guide rail 2 which are guide members horizontally mounted on left and right side plates (not shown), and a timing belt 5 is held by a main scanning motor 4. 2 is moved and scanned in the direction indicated by the arrow (main scanning direction) in FIG.

  The carriage 3 includes, for example, four recording heads 7 each including a droplet discharge head that discharges yellow (Y), cyan (C), magenta (M), and black (Bk) ink droplets. The ejection ports are arranged in a direction crossing the main scanning direction, and are mounted with the ink droplet ejection direction facing downward.

  The droplet discharge head constituting the recording head 7 includes a piezoelectric actuator such as a piezoelectric element, a thermal actuator that uses film boiling of the recording liquid using an electrothermal transducer such as a heating resistor, and a metal phase change due to a temperature change. A shape memory alloy actuator to be used, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink (liquid) can be used. Note that the recording head can also be configured by one or a plurality of liquid droplet ejection heads provided with a plurality of nozzle rows that eject different colors.

  The carriage 3 is equipped with sub-tanks 8 for each color for supplying ink of each color to the recording head 7. Ink is supplied to the sub tank 8 from a main tank (ink cartridge) (not shown) via an ink supply tube 9. In addition to the recording head 7 that discharges ink droplets, a recording head that discharges a fixing treatment liquid (fixing ink) that reacts with the recording liquid (ink) to improve the fixing property of the ink can be provided.

  On the other hand, as a paper feeding unit for feeding paper 12 stacked on a paper stacking unit (pressure plate) 11 such as a paper feeding cassette 10, a half-moon roller (for separating and feeding the paper 12 one by one from the paper stacking unit 11) A separation pad 14 made of a material having a large friction coefficient is provided facing the sheet feeding roller 13 and the sheet feeding roller 13, and the separation pad 14 is urged toward the sheet feeding roller 13 side.

  As a transport unit for transporting the paper 12 fed from the paper feed unit on the lower side of the recording head 7, a transport belt 21 for transporting the paper 12 by electrostatic adsorption and a paper feed unit A counter roller 22 for transporting the paper 12 fed through the guide 15 while sandwiching it between the transport belt 21 and the paper 12 fed substantially vertically upward are changed by about 90 ° and copied onto the transport belt 21. A conveying guide 23 for adjusting the pressure and a tip pressing roller 25 urged toward the conveying belt 21 by a pressing member 24. In addition, a charging roller 26 as a charging unit for charging the surface of the transport belt 21 is provided.

  Here, the conveyance belt 21 is an endless belt, is stretched between the conveyance roller 27 and the tension roller 28, and the conveyance roller 27 rotates from the sub-scanning motor 31 via the timing belt 32 and the timing roller 33. By doing so, it is configured to circulate in the belt conveyance direction (sub-scanning direction) of FIG. A guide member 29 is disposed on the back side of the conveying belt 21 corresponding to the image forming area by the recording head 7.

  Further, as shown in FIG. 2, a slit disk 34 is attached to the shaft of the transport roller 27, and a sensor 35 for detecting the slit of the slit disk 34 is provided. An encoder 36 is configured.

  The charging roller 26 is disposed so as to contact the surface layer of the conveyor belt 21 and rotate following the rotation of the conveyor belt 21, and applies 2.5N to both ends of the shaft as a pressing force.

  Further, as shown in FIGS. 1 and 3, an encoder scale 42 having slits is provided on the front side of the carriage 3, and a transmission type photosensor that detects the slits of the encoder scale 42 is provided on the front side of the carriage 3. An encoder 44 for detecting the position of the carriage 3 in the main scanning direction is configured.

  Further, as a paper discharge unit for discharging the paper 12 recorded by the recording head 7, a separation unit for separating the paper 12 from the conveyance belt 21, a paper discharge roller 52 and a paper discharge roller 53, and paper discharge And a paper discharge tray 54 for stocking the paper 12 to be stored.

  A double-sided paper feeding unit 61 is detachably mounted on the back. The double-sided paper feeding unit 61 takes in the paper 12 returned by the reverse rotation of the transport belt 21, reverses it, and feeds it again between the counter roller 22 and the transport belt 21.

  In the image forming apparatus configured as described above, the sheets 12 are separated and fed one by one from the sheet feeding unit, and the sheet 12 fed substantially vertically upward is guided by the guide 15, and includes the transport belt 21 and the counter roller 22. The leading end is guided by the conveying guide 23 and pressed against the conveying belt 21 by the leading end pressing roller 25, and the conveying direction is changed by approximately 90 °.

  At this time, a positive output and a negative output are alternately repeated from the high voltage power source to the charging roller 26 by a control circuit (not shown), that is, an alternating voltage is applied, and a charging voltage pattern in which the conveying belt 21 is alternating, that is, In the sub-scanning direction, which is the circumferential direction, plus and minus are alternately charged in a band shape with a predetermined width. When the sheet 12 is fed onto the conveyance belt 21 charged alternately with plus and minus, the sheet 12 is attracted to the conveyance belt 21 by electrostatic force, and the sheet 12 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 21. Is done.

  Therefore, by driving the recording head 7 according to the image signal while moving the carriage 3, ink droplets are ejected onto the stopped paper 12 to record one line, and after the paper 12 is conveyed by a predetermined amount, Record the next line. Upon receiving a recording end signal or a signal that the trailing edge of the paper 12 has reached the recording area, the recording operation is finished and the paper 12 is discharged onto the paper discharge tray 54.

  In the case of double-sided printing, when recording on the front surface (surface to be printed first) is completed, the recording belt 12 is fed into the double-sided paper feeding unit 61 by rotating the conveyor belt 21 in the reverse direction. The paper 12 is reversed (with the back surface being the printing surface), fed again between the counter roller 22 and the conveyor belt 21, controlled in timing, and conveyed onto the conveyor bell 21 as described above. Then, after recording on the back surface, the paper is discharged onto the paper discharge tray 54.

Next, an outline of the control unit of the image forming apparatus will be described with reference to the block diagram of FIG.
The control unit 80 includes a CPU 81 that controls the entire apparatus, a ROM 82 that stores programs executed by the CPU 81 and other fixed data, a RAM 83 that temporarily stores image data, and the power supply of the apparatus. A rewritable NVRAM 84 for holding data and an ASIC 85 for processing image signals for performing various signal processing and rearrangement on image data and other input / output signals for controlling the entire apparatus are provided.

  The control unit 80 also includes an I / F 86 for transmitting and receiving data and signals to and from the host side, a head drive control unit 87 and a head driver 88 for driving and controlling the recording head 7, and the main scanning motor 4. The main scanning motor driving unit 90 for driving the sub-scanning motor 31, the sub-scanning motor driving unit 91 for driving the sub-scanning motor 31, the detection pulses from the encoders 36 and 44, and the detection from the temperature sensor 95 that detects the environmental temperature. An I / O 92 for inputting signals and detection signals from other various sensors is provided. The control unit 80 is connected to an operation panel 93 for inputting and displaying information necessary for the apparatus.

  The control unit 80 receives print data and the like from the host side such as an information processing apparatus such as a personal computer, an image reading apparatus such as an image scanner, and an imaging apparatus such as a digital camera via the cable or the network via the I / F 86.

  The CPU 81 reads and analyzes the print data in the reception buffer included in the I / F 86, performs necessary image processing, data rearrangement processing, and the like in the ASIC 85, and transfers the image data to the head drive control unit 87. To do. The dot pattern data for image output may be generated by storing font data in the ROM 82, for example, or the image data is developed into bitmap data by a host-side printer driver and transferred to this apparatus. You may do it.

  When the head drive control unit 87 receives image data (dot pattern data) corresponding to one row of the recording head 7, the dot pattern data for one row is serialized to the head driver 88 in synchronization with the clock signal. Data is sent out, and a latch signal is sent to the head driver 88 at a predetermined timing.

  The head drive control unit 87 includes a ROM (which can be configured by the ROM 82) storing pattern data of a drive waveform (drive signal), and a D / A converter for D / A conversion of drive waveform data read from the ROM. A waveform generation circuit including an A converter and a drive waveform generation circuit including an amplifier and the like are included.

  In addition, the head driver 88 is a shift register that inputs a clock signal from the head drive control unit 87 and serial data that is image data, and a latch circuit that latches the register value of the shift register using a latch signal from the head drive control unit 87. A level conversion circuit (level shifter) that changes the output value of the latch circuit, an analog switch array (switch means) that is controlled to be turned on / off by the level shifter, and the like, and controls on / off of the analog switch array. As a result, a required drive waveform included in the drive waveform is selectively applied to the actuator means of the recording head 7 to drive the head.

  The main scanning motor driving unit 90 calculates a control value based on a target value given from the CPU 81 side and a speed detection value obtained by sampling a detection pulse from the encoder 44, and passes the main scanning motor via an internal motor driver. 4 is driven.

  Similarly, the sub-scanning motor drive unit 91 calculates a control value based on a target value given from the CPU 81 side and a speed detection value obtained by sampling a detection pulse from the encoder 36, and passes through an internal motor driver. The sub-scanning motor 31 is driven.

A motor drive control device according to the present invention relating to drive control of the sub-scanning motor in this image forming apparatus will be described with reference to the functional block diagram of FIG.
A speed profile (acceleration table target speed) of the sub-scanning motor 31 is stored in the speed profile storage unit 101, and a target speed is given to the sub-scanning motor driving unit 91 by the CPU 81. The speed profile storage unit 101 is configured by a ROM 82. The speed profile stored in the speed profile storage unit 101 includes an acceleration area, a constant speed area, and a deceleration area as shown in FIG.

  The speed detection unit 102 counts the detection pulses output from the encoder 36 and detects the feed speed of the transport belt 21 corresponding to the rotational speed of the transport roller 27, thereby detecting the current detection speed (speed detection). Value) and a relative movement amount of the conveyance belt 21 corresponding to the rotation amount of the conveyance roller 27 is detected and converted into a detection position. The sampling unit 103 samples the speed detection value output from the speed detection unit 102 at a predetermined sampling cycle and supplies the sampled value to the sub-scanning motor driving unit 91. The speed detection unit 102 and the sampling unit 103 are configured by the encoder 36, the CPU 81 of the control unit 80, and the like.

  The sub-scanning motor drive unit 91 includes a comparison calculation unit 111, a PID control calculation unit 112, a motor driver 113, and a deceleration compensation unit 114. Here, the comparison calculation unit 111 compares the target speed corresponding to the target position given from the speed profile 101 with the detection speed (current speed) outputted from the speed detection unit 102 and given by the sampling unit 103, Is calculated and given to the PID control calculation unit 112.

  The PID control calculation unit 112 performs PID (proportional, integral, differentiation) control on the deviation from the comparison calculation unit 111 to calculate a control value for the sub-scanning motor 31 that is a DC servo motor. Here, assuming that the sub-scanning motor 31 is driven by PWM (Pulse Width Modulation) control, the PID control calculation unit 112 performs PID control on the deviation to obtain the PWM duty ratio. By supplying the duty ratio to the motor driver 113 and driving the motor 31 by PWM control, the conveyor belt 21 is driven to a target position at a target speed.

  The deceleration compensation unit 114 increases or decreases the driving load of the sub-scanning mechanism with a predetermined set value based on the control amount output from the PID control calculation unit 112 when the sub-scanning motor 31 is controlled at a constant speed. And give this result to the PID control calculation unit 112. The PID control unit 112 determines the control amount by correcting the integral (I) component based on the determination result from the deceleration compensation unit 114 when shifting from the constant speed control to the deceleration control of the sub-scanning motor 31.

  For example, as shown in FIG. 7, the deceleration compensation unit 114 is a control amount (PWM control value) output from the PID control calculation unit 112 when the sub-scanning motor 31 is controlled at a constant speed (for example, 200 mm / sec). PWM history acquisition / holding unit 121 that captures and holds a predetermined number of times (for example, 10 times) at a predetermined time interval, and average value calculation unit 122 that calculates an average value of the results held in PWM history acquisition / holding unit 121 And a comparison unit that compares the average value calculated by the average value calculation unit 122 with a setting value corresponding to a driving load assumed in advance and determines a magnitude relationship with respect to the setting value of the driving load (becomes a transport load). 123. The PID control calculation unit 112 constitutes means for setting the PID control amount by resetting the integral component according to the determination result of the comparison unit 123.

  That is, here, the PWM history capturing / holding unit 121 constitutes a holding unit, the average value calculation unit 122 and the comparison unit 123 compare, and the PID control calculation unit 112 resets the integral component.

The operation of the servo motor drive control apparatus configured as described above will be described with reference to FIG.
First, the control unit 80 reads out the speed profile stored in the speed profile storage unit 101 corresponding to the target position and the target speed when starting paper feeding, and gives it to the comparison calculation unit 111 of the sub-scanning motor driving unit 91. (Target position, target speed setting). An initial control amount is output from the sub-scanning motor driving unit 91 and driving of the sub-scanning motor 31 is started.

  As a result, the speed detection unit 102 outputs information corresponding to the current position and current speed of the conveyor belt 21, is sampled by the sampling unit 103, and is supplied to the comparison calculation unit 111 of the sub-scanning motor driving unit 91. As described above, the PWM control value (control amount) is output from the PID control calculation unit 112 in accordance with the speed deviation, and the sub-scanning motor 31 sets the acceleration region, constant speed region, and deceleration region of the set speed profile. Driven at speed.

  Here, when the sub-scanning motor 31 is controlled in the constant speed region (when constant speed control is performed), the PWM control value output from the PID control calculation unit 112 is the PWM history acquisition of the deceleration compensation unit 114. It is held a predetermined number of times by the holding holder 121 Then, the average value of the PWM control value for a predetermined number of times is calculated by the average value calculation unit 122 and compared with the set value by the comparison unit 123, and the actual drive load is larger or smaller than the preset drive load. Is determined, and the determination result is given to the PID control calculation unit 112.

  Therefore, the PID control calculation unit 11 resets the integral component based on the determination result given from the deceleration compensation unit 114 when shifting from the constant speed region to the deceleration region (shifting to deceleration control), and performs PID control. The amount (PWM control value) is calculated and output. As described above, the sub-scanning motor 31 is decelerated by the PWM control value corresponding to the driving load, and when the driving to the target position is completed, the sub-scanning motor 31 stops.

  As described above, when shifting from the constant speed control to the deceleration control, by providing means for setting the control amount of the deceleration control based on the driving load at the constant speed control, the drive system at the constant speed control is provided. The amount of control during deceleration control can be set in accordance with a load fluctuation caused by a disturbance such as a friction torque, a fluctuation of the friction torque, a fluctuation of an inertial load, or a non-linear torque due to backlash. As a result, the steady load fluctuations of the drive target during deceleration control, individual differences (variations), and the load variation band due to changes over time can be widened, and stable deceleration can be performed. The feeding accuracy (stop position accuracy) of the recording medium can be obtained, and the image quality is improved.

Next, another example of the motor drive control device according to the present invention will be described with reference to FIG.
In this example, the speed profile stored in the speed profile storage unit 101 is a profile in which the target speed becomes “0” in a specific sampling period SPa. The specific sampling period SPa is a sampling period when shifting from constant speed control to deceleration control.

  Therefore, when shifting from the constant speed control to the deceleration control, the control amount (PWM control value) for rotating the sub-scanning motor 31 in the reverse direction is output from the PID control calculation unit 112 at the start of the deceleration control. It can decelerate with acceleration.

  That is, by setting a period for setting the target value to 0 at the start of deceleration control, a control amount in the direction opposite to the movement direction is output, and the maximum deceleration acceleration that can be driven can be obtained. Thereby, deceleration can be performed at high speed, and positioning stop can be performed at higher speed and with higher accuracy.

Next, still another example of the motor drive control device according to the present invention will be described with reference to FIG.
In this example, in the speed profile stored in the speed profile storage unit 101, as described above, the target speed is set to “0” at a specific sampling period SPa when shifting from constant speed control to deceleration control, A profile in which a constant velocity region (this is referred to as a “low constant velocity region”) that is lower than the velocity in the constant velocity region after the sampling period Pa is set.

  Therefore, when shifting from the constant speed control to the deceleration control, the control amount (PWM control value) for rotating the sub-scanning motor 31 in the reverse direction is output from the PID control calculation unit 112 at the start of the deceleration control. As the deceleration acceleration acts, the load fluctuation is large, and even when the drive is stopped, it is possible to quickly rise to the low constant velocity region, and the target speed is set to “0”. When the vibration 200 is generated in the actual speed change indicated by, the vibration can be attenuated at an early stage.

Therefore, the processing of this example will be described with reference to FIG.
First, the control unit 80 reads out the speed profile stored in the speed profile storage unit 101 corresponding to the target position and the target speed when starting paper feeding, and gives it to the comparison calculation unit 111 of the sub-scanning motor driving unit 91. (Target position, target speed setting). An initial control amount is output from the sub-scanning motor driving unit 91 and driving of the sub-scanning motor 31 is started.

  As a result, the speed detection unit 102 outputs information corresponding to the current position and current speed of the conveyor belt 21, is sampled by the sampling unit 103, and is supplied to the comparison calculation unit 111 of the sub-scanning motor driving unit 91. As described above, the PWM control value (control amount) is output from the PID control calculation unit 112 in accordance with the speed deviation, and the sub-scanning motor 31 sets the acceleration region, constant speed region, and deceleration region of the set speed profile. Driven at speed.

  Here, while determining the deceleration start position to the low constant speed conveyance (low constant speed area) until the target position is reached, if it is not the deceleration start position to the low constant speed conveyance (low constant speed area), When the scanning motor 31 is controlled in the constant speed region (when constant speed control is performed), the PWM control value output from the PID control calculation unit 112 is the PWM history capture holding unit 121 of the deceleration compensation unit 114. Is held a predetermined number of times. Then, the average value of the PWM control value for a predetermined number of times is calculated by the average value calculation unit 122 and compared with the set value by the comparison unit 123, and the actual drive load is larger or smaller than the preset drive load. The determination result is given to the PID control calculation unit 112, and the PID control calculation unit 112 resets the integral component based on the determination result.

Then, when the Tsu name to the deceleration start position to a low constant velocity transport (low constant velocity region), since the target speed according to the speed profile shown in FIG. 10 is set at "0", the PID control amount corresponding thereto And, after that, outputs a PID control amount according to the speed profile in the low constant velocity region, and integrates based on the determination result given from the deceleration compensator 114 when shifting to the low constant velocity conveyance (low constant velocity region). The components are reset, and the PID control amount (PWM control value) is calculated and output.

  As described above, when shifting from the constant speed control to the deceleration control, there is provided a means for setting the control amount of the deceleration control based on the driving load at the constant speed control, and further, the control amount for the target speed 0 is set at the start of the deceleration control. It is possible to stop at a higher speed and with higher positional accuracy by setting and setting a control amount corresponding to a speed lower than that in the constant speed area by shifting to the low constant speed area of the deceleration control. Therefore, even if scanning is performed at high speed, it is possible to obtain the recording medium feeding accuracy (stop position accuracy) with high positional accuracy, and the image quality is improved.

  In the above embodiment, the DC servo motor drive control device according to the present invention is applied to the drive control of the sub-scanning motor of the image forming apparatus. However, the present invention is not limited to this.

1 is a schematic explanatory diagram of a mechanism unit of an image forming apparatus according to the present invention. It is principal part plane explanatory drawing of the mechanism part. It is principal part perspective explanatory drawing of the mechanism part. It is a schematic block explanatory drawing of the control part of the apparatus. It is a functional block explanatory drawing of the part which concerns on the motor drive control apparatus of the control part. It is explanatory drawing with which it uses for description of the speed profile of the motor drive control apparatus. It is a block diagram which shows an example of the deceleration compensation part of the drive control apparatus. It is a flowchart with which it uses for description of an example of the drive control by the motor drive control apparatus. It is explanatory drawing which shows the example of the speed profile with which it uses for description of the other example of the drive control by the motor drive control apparatus. It is explanatory drawing which shows the example of the speed profile with which it uses for description of the further another example of the drive control by the same motor drive control apparatus. It is a flowchart with which another example is demonstrated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Carriage 4 ... Main scanning motor 7 ... Recording head 21 ... Conveying belt 26 ... Charging roller 27 ... Conveying roller 31 ... Sub scanning motor 36 ... Encoder 91 ... Sub scanning motor drive part 101 ... Speed profile storage part 102 ... Speed detection part DESCRIPTION OF SYMBOLS 103 ... Sampling part 111 ... Comparison calculating part 112 ... PID control calculating part 113 ... Motor driver 114 ... Deceleration compensation part

Claims (3)

Storage means for storing the speed profile of the drive target;
A unit that feeds back a deviation between a target speed obtained from the speed profile and a current speed of the driving target, and calculates a PID control amount for a DC servo motor that moves the driving target ;
In the motor drive control device that performs acceleration control, constant speed control, and deceleration control on the DC servo motor based on the speed profile ,
The speed profile includes a profile that sets a target speed of a constant speed lower than the target speed of the constant speed control for a predetermined period when shifting from the constant speed control to the deceleration control,
Holding means for holding the PID control amount for a predetermined number of times when the DC servo motor is controlled at a constant speed;
Comparing means for comparing an average value of the PID control amount held in the holding means with a predetermined value ;
Means for calculating the PID control amount, the can and the process proceeds to the deceleration control from the constant speed control, the so constant speed control control corresponding to the target speed such as low speed than a target speed of is made, the comparison means depending on the comparison result, if before Kitaira average value is equal to or greater than the predetermined value, the integral gain reduces, before Kitaira average value is the predetermined value when computing the PID control quantity If smaller, the motor drive control apparatus characterized by increasing the integral gain at the time of calculating the pre-Symbol PID control amount. The motor drive control apparatus according to claim 1, wherein the speed profile, a motor drive, characterized in Tei Rukoto is once the target speed setting period to zero when moving to a deceleration control from the constant speed control Control device. Claims for driving and controlling the DC servo motor in an image forming apparatus having a sub-scanning mechanism including a DC servo motor for conveying a recording medium and forming an image by ejecting droplets onto the recording medium. An image forming apparatus comprising the motor drive control device according to Item 1 or 2 .

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