JP2005144846A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in the case where a DC servomotor having a sintered bearing is used as a driving source, as a load of the bearing is increased when a tension of a belt is increased, it is impossible to raise a controlling property by increasing the tension of the belt and the friction coefficient of the bearing is large so that the durability is insufficient. <P>SOLUTION: A carriage 23 is slidably mounted on a guide rod 21 and can be moved by a DC servomotor 102 via a timing belt 107 suspended between a driving pulley 104 and a follower pulley 106. The DC servomotor 102 is constituted of an inner rotor type DC motor having ball bearings 112, 113 holding a motor shaft 103. As the driving pulley 104 is directly attached to the motor shaft 103, the friction load can be reduced and the tension of the belt can be increased, thereby improving the control performance and the durability. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus.

  As various image forming apparatuses such as printers, facsimiles, copying apparatuses, plotters, etc., a recording head constituted by a droplet discharge head is mounted on a carriage, and this carriage is orthogonal to the conveyance direction of a recording medium (paper, etc.). There is a serial type in which an image is formed (recorded) on a recording medium by serially scanning the recording medium in a moving direction, intermittently conveying the recording medium according to a recording width, and alternately repeating conveyance and recording.

As a main scanning motor for main-scanning the carriage of such an image forming apparatus or a sub-scanning motor for driving a conveying means for conveying a recording medium, one using a DC servo motor is known. .
JP 2000-37919 A

  For example, a carriage main scanning mechanism for main-scanning a carriage is arranged by attaching a driving pulley to a motor shaft of a DC servo motor on one side of the main scanning region and arranging a driven pulley on the other side. A timing belt is bridged between the pulley and the driven pulley, a part of the carriage body is fixed to the timing belt, and an encoder for detecting the movement of the carriage is provided, and the DC servo motor is controlled in a closed loop by the detection output of the encoder. The carriage is moved and scanned via the timing belt while moving.

  As a DC servo motor constituting such a carriage main scanning mechanism, a motor using a sintered bearing is generally used as a bearing for holding a motor shaft.

  When the driven body is driven via the timing belt as described above, a tension is applied to the timing belt between the driving pulley and the driven pulley to prevent the belt from being loosened or bent during driving. I must. By appropriately applying this belt tension, the controllability (control accuracy) with respect to the position and speed of the driven body is improved.

  However, when a DC servo motor using a sintered bearing as a motor shaft bearing is used as a drive source as in the prior art, if the belt tension is increased in order to improve controllability, the sintered bearing has a large friction coefficient. As the belt tension increases, the load on the bearing increases, the power consumption of the DC servo motor increases, and if the PV value (P: surface pressure, V: rotational speed) at the bearing becomes too large, the durability will be increased. Will be significantly reduced. Therefore, when the belt tension is lowered, the control accuracy of the position and speed of the driven body is lowered as described above.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus with improved controllability and improved durability.

  The image forming apparatus according to the present invention is configured such that a driven body is driven by a DC servo motor via a timing belt, and the DC servo motor is an inner rotor type DC motor having a ball bearing that holds a motor shaft. .

  Here, it is preferable that the driven body is a carriage on which a droplet discharge head is mounted, and a linear encoder for detecting the movement of the carriage is provided.

  Further, it is preferable that a vibration absorbing means for absorbing the vibration of the carriage is provided between the guide rod for guiding the carriage and the carriage body. In this case, the vibration absorbing means is preferably an elastic member. Furthermore, the vibration absorbing means is preferably a damper. The vibration absorbing means is preferably an elastic member and a damper.

  Furthermore, of the two bearings that hold the motor shaft of the DC servo motor, the bearing on the side where the drive pulley that bridges the timing belt is mounted is a ball bearing, and the other bearings are sintered bearings. .

  Moreover, it is preferable that the flywheel is provided in the motor shaft of DC servo motor.

  Furthermore, it is preferable that the bearing of the driven pulley that bridges the timing belt is a ball bearing.

  According to the image forming apparatus of the present invention, since the DC servo motor includes the ball bearing that holds the motor shaft, the belt tension can be increased, the controllability is improved, and the friction associated with the increase in the belt tension. The increase in load can be suppressed and durability is improved.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. An example of an image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram illustrating the overall configuration of the image forming apparatus, and FIG. 2 is a plan view illustrating an image forming unit and a conveyance unit of the apparatus.

  This image forming apparatus has an image forming part (means) 2 for forming an image, a sub-scanning conveying part (means) 3, etc. in the inside (enclosure) of the apparatus main body 1. A recording medium (hereinafter referred to as “paper”, but not limited to paper) 5 is fed one by one from the provided paper feeding unit (means) 4, and the paper 5 is imaged by the sub-scanning conveyance unit 3. The image forming unit 2 ejects liquid droplets onto the paper 5 while forming (recording) it while conveying it at a position facing the forming unit 2, and then forms it on the upper surface of the apparatus main body 1 through the paper discharge conveying unit 6. The paper 5 is discharged onto the discharged paper discharge tray 7.

  The image forming apparatus also has an image reading unit (scanner) for reading an image above the discharge tray 7 above the apparatus main body 1 as an input system for image data (print data) formed by the image forming unit 2. Part) 11. The image reading unit 11 includes a scanning optical system 15 including an illumination light source 13 and a mirror 14 and a scanning optical system 18 including mirrors 16 and 17. The scanned document image is read as an image signal by the image reading element 20 disposed behind the lens 19, and the read image signal is digitized and subjected to image processing, and the image-processed print data is printed. be able to. A pressure plate 10 is provided on the contact glass 12 for pressing the document.

  Further, this image forming apparatus uses an information processing apparatus such as an external personal computer, an image reading apparatus such as an image scanner, and an imaging apparatus such as a digital camera as an input system for image data (print data) formed by the image forming unit 2. For example, print data including image data from the host side can be received via a cable or a network, and the received print data can be processed and printed.

  Here, as shown in FIG. 2, the image forming unit 2 of the image forming apparatus is guided by a guide rod 21 and can move in a main scanning direction (a direction orthogonal to the paper transport direction), which will be described later. A recording head 24 for discharging droplets of a plurality of different colors is mounted thereon, the carriage 23 is moved in the main scanning direction by a carriage scanning mechanism to be described later, and the paper 5 is moved in the paper conveying direction ( A shuttle type is used in which droplets are ejected from the recording head 24 while feeding in the sub-scanning direction) to form an image.

  The recording head 24 includes four liquid droplet ejection heads that eject black (Bk) ink, cyan (C) ink, magenta (M) ink, and yellow (Y) ink, respectively, and a sub tank 25 mounted on the carriage 23. Are supplied with ink of each color. Ink is replenished and supplied to each sub tank 25 from an ink cartridge 26 (FIG. 1) of each color which is a main tank detachably mounted in the apparatus main body 1 through a tube (not shown). In addition to the recording head 24 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.

  The recording head 24 uses a piezoelectric element as a pressure generating means (actuator means) for pressurizing the ink in the ink flow path (pressure generation chamber) to deform the vibration plate that forms the wall surface of the ink flow path. A so-called piezo type that discharges ink droplets by changing the volume in the flow channel, or discharges ink droplets with a pressure generated by heating the ink in the ink flow channel using a heating resistor to generate bubbles. The so-called thermal type, the diaphragm that forms the wall surface of the ink flow path and the electrode are placed opposite to each other, and the diaphragm is deformed by the electrostatic force generated between the vibration plate and the electrode, thereby the ink flow path inner volume It is possible to use an electrostatic type or the like that discharges ink droplets by changing the above.

  Although a plurality of recording heads are provided here, a configuration in which one or a plurality of recording heads having a plurality of nozzle rows that eject ink droplets of different colors may be provided.

  In addition, a maintenance / recovery mechanism (hereinafter referred to as “subsystem”) 27 including a head cleaning device for maintaining and recovering the state of the nozzles of the recording head 24 is provided in a non-printing area on one side in the scanning direction of the carriage 23. It is arranged. The subsystem 27 includes cap members 28a, 28b, 28c, and 28d for capping the nozzle surface of the recording head 24, a wiper blade 29 for wiping the nozzle surface, and the like.

  The sub-scanning conveyance unit 3 is a drive roller between a conveyance roller 32 and a driven roller 33 for conveying the paper 5 fed from below to the image forming unit 2 while changing the conveyance direction by approximately 90 degrees. An endless conveyance belt 31 laid over the surface, a charging roller 34 to which a high voltage is applied from a high voltage power source (not shown) for charging the surface of the conveyance belt 31, and the conveyance belt 31 are opposed to the image forming unit 2. The guide member 35 that guides in the area, the pressing roller (pressure roller) 36 that presses the sheet 5 against the conveying belt 31 at a position facing the conveying roller 32, and the sheet 5 on which the image is formed by the image forming unit 2 are discharged. A transport roller 37 for feeding to the transport unit 6 is provided.

  The transport belt 31 of the sub-scan transport unit 3 rotates in the belt transport direction (sub-scan direction) in FIG. 2 by rotating the transport roller 32 from the sub-scan motor 131 via the timing belt 121 and the timing roller 133. It is configured to do.

  The paper feed unit 4 can be inserted into and removed from the apparatus main body 1, and a paper feed cassette 41 for stacking and storing a large number of papers 5 and a paper feed for separating and feeding the papers 5 in the paper feed cassette 41 one by one. A paper roller 42 and a friction pad 43, and a paper feed conveyance roller 44 that conveys the fed paper 5 to the sub-scanning conveyance unit 3 are provided.

  The paper feed roller 42 is rotated by a paper feed motor (drive source) 141 formed of an HB type stepping motor via a paper feed clutch (not shown), and the paper feed transport roller 44 is also rotationally driven by the paper feed motor 141. By using a stepping motor as the paper feed motor, synchronization control with the sub-scanning motor 131 is facilitated, and loop formation control is facilitated.

  The paper discharge conveyance unit 6 includes a pair of paper discharge conveyance rollers 61 and 62 for conveying the paper 5 on which image formation has been performed, a pair of paper discharge conveyance rollers 63 and a pair of paper discharge rollers for sending the paper 5 to the paper discharge tray 7. 64.

  Next, the carriage main scanning mechanism will be described with reference to FIGS. 3 is a front explanatory view of the carriage main scanning mechanism, FIG. 4 is a side explanatory view of FIG. 3, and FIG.

  As shown in FIG. 5, the carriage 23 is slidably mounted on the guide rod 21 via bearings 121 and 121. The carriage main scanning mechanism 101 for main scanning the carriage 23 is arranged with a driving pulley 104 attached to the motor shaft 103 of the DC servo motor 102 on one side of the main scanning region, and a bearing 105 on the other side. A driven pulley 106 is arranged, a timing belt 107 is bridged between the driving pulley 104 and the driven pulley 106, and a part of the carriage 23 is fixed to the timing belt 107.

  Here, the DC servo motor 102 is constituted by an inner rotor type DC motor having ball bearings 112 and 113 for holding the motor shaft 103, and a drive pulley 104 is directly attached to the motor shaft 103.

  A linear scale 109 is arranged along the guide rod 21, and an encoder sensor 108 for detecting the linear scale 109 is attached to the carriage 23. The linear scale 109 and the encoder sensor 108 detect the movement of the carriage 23. An encoder 110 is configured. A rotary encoder provided with a slit disk on the motor shaft 103 can be used as the encoder, but the accuracy is lower than that of a linear encoder.

  As will be described later, the carriage 23 is moved and scanned along the guide rod 21 via the timing belt 107 while the DC servo motor 104 is driven and controlled in a closed loop based on the output of the encoder 110 (output of the encoder sensor 108). To do.

Further, as shown in FIG. 5, vibration absorbing means 120 for absorbing the vibration of the carriage 23 is provided between the main body 23 a of the carriage 23 and the guide rod 21.
As the vibration absorbing means 120, one using only the elastic member 120a as shown in FIG. 6 (a), one using only the damper member 120b as shown in FIG. 6 (b), and FIG. 6 (c). As shown in the figure, the elastic member 120a and the damper member 120b are both used in parallel.

  By pressing the carriage 23 in one direction by the vibration absorbing means 120, the carriage 23 sliding along the guide rod 21 is prevented from vibrating.

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 200 includes a CPU 201 that controls the entire apparatus, a ROM 202 that stores programs executed by the CPU 201 and other fixed data, a RAM 203 that temporarily stores image data, and the power supply of the apparatus. A non-volatile memory (NVRAM) 204 for holding data, image processing for performing various signal processing and rearrangement on image data, and other ASIC 205 for processing input / output signals for controlling the entire apparatus, and host An I / F 206 for transmitting and receiving data and signals to and from the side, and a scanner control unit 207 for performing image reading by the image reading unit 11 and data processing of the read image.

  The control unit 200 includes a head drive control unit 210 and a head driver 211 for driving and controlling the recording head 24, and a main scanning motor drive control unit 212 and a motor driver 213 for driving and controlling the main scanning motor 102. A sub-scanning motor drive control unit 214 and a motor driver 215 for driving and controlling the sub-scanning motor 131, an I / O 217 for inputting detection pulses from the encoders 136 and 110 and detection signals from various sensors, and the like. ing.

  A detection pulse from the encoder 110 is input to the main scanning motor drive control unit 212, and a detection pulse from the encoder 136 that detects the rotation of the sub scanning motor 131 is input to the sub scanning motor drive control unit 214. The control unit 200 is connected to an operation panel 218 for inputting and displaying information necessary for the apparatus.

  When the image reading unit 11 reads a document image, the control unit 200 processes the read image and stores it in a buffer in the scanner control unit 207. In addition, 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 are received by the I / F 206 via a cable or a network.

  Then, the CPU 201 reads and analyzes the print data in the reception buffer included in the scanner control unit 207 and the I / F 206, performs necessary image processing, data rearrangement processing, and the like in the ASIC 205, and the head drive control unit 210. Transfer image data to. The dot pattern data for image output may be generated by storing font data in the ROM 202, 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 210 receives image data (dot pattern data) corresponding to one row of the recording head 24, the dot pattern data for one row is serialized to the head driver 211 in synchronization with the clock signal. Data is sent out, and a latch signal is sent to the head driver 211 at a predetermined timing.

  The head drive control unit 210 includes a ROM (can also be configured by the ROM 202) storing pattern data of a drive waveform (drive signal), and a D / A converter that D / A converts the 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.

  The head driver 211 also receives a clock signal from the head drive control unit 210 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 210. 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. In this way, a required drive waveform included in the drive waveform is selectively applied to the actuator means of the recording head 24 to drive the head.

  The main scanning motor drive control unit 212 calculates a control amount based on a target value given from the CPU 201 side and a speed detection value obtained by sampling a detection pulse from the encoder 110, and via the motor driver 213, the main scanning motor. 102 is driven.

  Similarly, the sub-scanning motor drive control unit 214 calculates a control amount based on a target value given from the CPU 201 side and a speed detection value obtained by sampling a detection pulse from the encoder 136, and passes through the motor driver 215. The sub-scanning motor 131 is driven.

Here, drive control of the main scanning motor 102 by the main scanning motor drive control unit 212 will be described with reference to a functional block diagram shown in FIG.
The speed profile storage unit 251 stores the speed profile (set value acceleration table target speed) of the main scanning motor 102, and the CPU 201 gives the target speed to the main scanning motor drive control unit 212. The speed profile storage unit 251 is configured by the ROM 202.

  The speed detection unit 252 counts the detection pulses output from the encoder 110, converts it to a detection speed (speed detection value), and provides the speed detection value to the main scanning motor drive control unit 212 at a predetermined sampling period. The speed detection unit 252 includes the encoder 110 and the CPU 201 of the control unit 200.

  The main scanning motor drive control unit 212 includes a comparison calculation unit 261 and a PID control calculation unit 262, specifically, an LSI. Then, the comparison calculation unit 261 compares the target speed given from the speed profile 251 with the detected speed value given from the speed detection unit 252, calculates a deviation between them, and gives the PID control calculation unit 262. The PID control calculation unit 262 performs a general PID (any of proportionality, integration and differentiation, or a combination thereof) control on the deviation from the comparison calculation unit 261 to calculate a control value.

  Here, assuming that the main scanning motor 102 is driven by PWM control, the PID control calculation unit 262 performs PID control on the deviation to obtain the PWM duty ratio, and gives this PWM duty ratio to the motor driver 213. The carriage 102 is driven at a target speed by driving the motor 102 by PWM control.

In this way, in this image forming apparatus, the main scanning motor 102 is driven and controlled in a closed loop based on the output of the encoder 110, thereby performing main scanning (position, speed) control of the carriage 23.
At this time, the DC servo motor constituting the main scanning motor 102 is constituted by an inner rotor type DC motor provided with ball bearings 112 and 113 for holding the motor shaft 103 as described above. A carriage main scanning drive mechanism is configured in which a drive pulley 104 is directly attached to 103.

  In a mechanism in which a belt is directly driven by a drive pulley attached to a motor shaft such as the carriage main scanning mechanism and the carriage is moved and scanned, belt tension is an important factor for improving controllability. By using a ball bearing as the bearing of the servo motor (main scanning motor), the belt tension can be significantly increased as compared with the sintered bearing. That is, by providing the ball bearings, even if the belt tension is increased, the friction load on the motor is hardly increased, and as a result, the belt tension can be increased.

  By increasing the belt tension, the elastic coefficient of the timing belt approaches a constant value. The larger the elastic coefficient, the higher the resonance frequency, and the control gain at low frequency (the control gain is various for the system). The ratio between the output and the input when a frequency sine wave input is applied can be increased and the control gain can be increased, thereby improving the controllability.

  Further, by providing the ball bearing, it is possible to reduce a steady mechanical load and also to reduce a load fluctuation with time. In this way, by reducing the load, if the motor and the control unit have the same performance, there is a relative margin when performing closed loop control. Further, energy saving drive with less electric power can be achieved by reducing the load, and temperature rise of the DC servo motor can be suppressed.

  Further, by using a DC servo motor having a ball bearing, the vibration preventing means 120 can be interposed between the carriage 23 and the guide rod 21 as described above. In other words, in a conventional apparatus using a motor having a sintered bearing as a DC servo motor, if a vibration preventing member such as an elastic member is used, the mechanical load due to friction increases, so that it can withstand actual use. Although it was not possible, the mechanical load can be greatly reduced by using a DC servo motor equipped with a ball bearing as in the present invention. Therefore, even if the friction load is slightly increased by providing vibration preventing means. The overall mechanical load can be suppressed within an allowable range, and effective measures against carriage vibration can be taken.

  In the above-described embodiment, the bearings 112 and 113 that hold the motor shaft 103 rotatably as the DC servo motor constituting the main scanning motor 102 are described as examples of ball bearings. However, at least the driving pulley 104 is described. The bearing on the side to be mounted (bearing 112 in the above example) is a ball bearing, and the other bearing 113 is sufficiently effective as a sintered bearing. With such a configuration, the cost can be reduced. it can.

  In the above embodiment, the bearing on the driving pulley 104 side (the bearing of the DC servo motor) that bridges the timing belt 107 is described as a ball bearing. However, the bearing 105 on the driven pulley 106 side is also a ball bearing. By doing so, the friction load can be further reduced. Furthermore, by using a DC brushless servomotor as the DC servomotor, problems such as brush load and wear can be solved and durability can be improved.

Next, another example of the DC servo motor constituting the main scanning motor will be described with reference to FIG.
The main scanning motor 302 is constituted by an inner rotor type DC brushless motor provided with ball bearings 312 and 313 for holding a motor shaft 303, and a drive pulley 104 is directly attached to the motor shaft 303. Further, a flywheel 316 is attached to the end of the motor shaft 303 opposite to the side on which the drive pulley 104 is attached.

  Thus, by attaching the flywheel 316 to the motor shaft 303, it is possible to suppress changes in the carriage speed due to cogging torque, belt vibration, and carriage vibration. The size of the flywheel 316 preferably satisfies the relationship of the sum of the inertias of the motor shaft (rotor inertia + flywheel inertia) ≦ mechanical mechanism inertia inertia / 3 when considering closed-loop control. The carriage can be driven at a stable speed in this range.

  In other words, DC brush motors using sintered bearings as in the past have a large mechanical load, and rotor inertia is inherently large. It was. On the other hand, in the present invention that uses a motor that holds the motor shaft with a ball bearing, the mechanical load can be reduced as described above, and since the rotor inertia is small, the flywheel can be adjusted, Optimal position and speed control can be realized without deteriorating the start-up characteristics and the stop characteristics.

  In the above-described embodiment, an example in which the present invention is applied to a DC servo motor for scanning a carriage has been described. However, the present invention can also be applied to a DC servo motor for feeding paper. In the above embodiment, the copier / printer multi-function machine has been described. However, the present invention can be applied to a printer, copier / fax / printer multi-function machine, and the like, and also to an image forming apparatus using a liquid other than ink. Can be applied to.

1 is a schematic explanatory diagram illustrating an overall configuration of an image forming apparatus according to the present invention. FIG. 2 is an explanatory plan view of an image forming unit and a conveyance unit of the apparatus. It is front explanatory drawing of a carriage main scanning mechanism part. It is side surface explanatory drawing of FIG. It is principal part plane explanatory drawing of a carriage. It is explanatory drawing of the vibration prevention member of a carriage. 2 is a block diagram illustrating an overview of a control unit of the image forming apparatus. FIG. It is a block explanatory drawing which shows the outline | summary of the motor drive control part of the same apparatus. It is side surface explanatory drawing explaining the other example of the DC servomotor of the apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus main body 2 ... Image forming part 3 ... Sub-scanning conveyance part 4 ... Paper feed part 5 ... Recording medium (paper)
6... Paper discharge transport unit 7... Paper discharge tray 10 .. pressure plate 11... Image reading unit (scanner unit)
DESCRIPTION OF SYMBOLS 12 ... Contact glass 13 ... Illumination light source 14 ... Mirror 15 ... Scanning optical system 16 ... Mirror 17 ... Mirror 18 ... Scanning optical system 19 ... Lens 20 ... Image reading element 21 ... Guide rod 23 ... Carriage 24 ... Recording head 25 ... Sub tank 26 ... Ink cartridge 27 ... Maintenance and recovery mechanism (subsystem)
DESCRIPTION OF SYMBOLS 28 ... Cap member 29 ... Wiper blade 31 ... Conveyor belt 32 ... Conveyor roller 33 ... Driven roller 34 ... Charging roller 35 ... Guide member 36 ... Roller 37 ... Conveyor roller 41 ... Paper feed cassette 42 ... Paper feed roller 43 ... Friction pad 44 ... Paper feed roller 61 ... Discharge transport roller pair 62 ... Discharge transport roller pair 63 ... Discharge transport roller pair 64 ... Discharge transport roller pair 101 ... Carriage main scanning mechanism 102 ... DC servo motor 103 ... Motor shaft 104 ... Driving pulley 105 ... Bearing 106 ... Driving pulley 107 ... Timing belt 108 ... Encoder sensor 109 ... Linear scale 110 ... Linear encoder 112 ... Ball bearing 113 ... Ball bearing 120 ... Vibration absorbing means 121 ... Timing belt 131 ... Sub-scanning motor 133 ... Timing roller 141 Feed motor 200 ... control unit 201 ... CPU
202 ... ROM
203 ... RAM
204 ... NVRAM
205 ... ASIC
206: Host I / F
207 ... Scanner control unit 210 ... Head drive control unit 211 ... Head driver 212 ... Main scanning motor drive control unit 213 ... Motor driver 214 ... Sub-scanning motor drive control unit 215 ... Motor driver 217 ... I / O
218 ... Operation panel 251 ... Speed profile storage unit 252 ... Speed detection unit (encoder)
261 ... Comparison calculation unit 262 ... PID control calculation unit 302 ... Main scanning motor 303 ... Motor shaft 312 ... Ball bearing 313 ... Ball bearing 316 ... Flywheel

Claims (9)

  An image forming apparatus for driving a driven body with a DC servo motor via a timing belt, wherein the DC servo motor is an inner rotor type DC motor having a ball bearing for holding a motor shaft. .   The image forming apparatus according to claim 1, wherein the driven body is a carriage on which a droplet discharge head is mounted, and includes a linear encoder for detecting movement of the carriage. .   3. The image forming apparatus according to claim 2, wherein vibration absorbing means for absorbing vibrations of the carriage is provided between the guide rod for guiding the carriage and the carriage body.   4. The image forming apparatus according to claim 3, wherein the vibration absorbing means is an elastic member.   4. The image forming apparatus according to claim 3, wherein the vibration absorbing means is a damper.   4. The image forming apparatus according to claim 3, wherein the vibration absorbing means is an elastic member and a damper.   7. The image forming apparatus according to claim 1, wherein, of the two bearings holding the motor shaft of the DC servo motor, the bearing on the side on which the drive pulley that bridges the timing belt is mounted is a ball bearing. An image forming apparatus, wherein the other bearing is a sintered bearing.   8. The image forming apparatus according to claim 1, wherein a flywheel is provided on a motor shaft of the DC servo motor. 9. The image forming apparatus according to claim 1, wherein a bearing of the driven pulley that bridges the timing belt is a ball bearing. 10.

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