JP2006334834A - Recorder and method of controlling conveyance of recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recorder capable of performing high speed, high quality recording by controlling a conveyance roller so as to convey a recording medium with high accuracy in a high speed without generating reverse rotation or vibration of the conveyance roller, and a method for controlling the conveyance of a recording medium. <P>SOLUTION: When a conveyance motor is controlled to be driven by feeding back a detected position signal and a detected velocity signal respectively indicative of a position and a velocity of the conveyance roller, an instruction value for controlling the driving is generated and the instruction values generated at a prescribed interval are output in order to control the driving. It is judged that the conveyance roller is in a region requiring the precise controlling of the conveyance roller based on the position signal. By comparing the position signal with the instruction value, it is judged whether or not the position of the conveyance roller is in the overrunning with respect to the instruction value based on the compared result. The instruction value is updated at an interval smaller than the prescribed interval according to the above judgment results. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording apparatus and a recording medium conveyance control method, and more particularly to, for example, an inkjet recording apparatus, a conveyance roller for conveying a recording medium used by the apparatus, and a drive control method thereof.

  With the remarkable development of electronics technology, the processing power of computers has made great progress. In particular, in order to perform color image processing, a large amount of data must be processed in a short time. Conventionally, there has been difficulty in terms of processing speed, but in recent years the improvement in computer capabilities has made such color image processing very common.

  Along with this, the range of use of recording apparatuses for outputting color images is rapidly expanding. Instead of conventional photographic printing, a color image is increasingly output using a recording apparatus typified by an ink jet printer. The range of use of inkjet printers is expanding from small business cards to large poster sizes larger than B0. In addition, with the widespread use of recording apparatuses, demands for image quality improvement and throughput improvement for the apparatuses are increasing.

  In a general serial type recording apparatus, recording is performed while transporting the recording medium and scanning the recording head. Therefore, higher accuracy and higher speed are required for transporting the recording medium.

  In response to such a request, the recording apparatus detects a conveyance amount of the recording medium with an encoder, and conveys the recording medium according to a difference between a separately defined target conveyance amount and a detected conveyance amount. Is adopted.

  Generally, the recording medium is urged by a conveying roller, and the recording medium is conveyed by driving the conveying roller. Therefore, the load accompanying this energization acts on the servo mechanism. In other words, the static friction and dynamic friction of the drive system act as loads, which is a difficult condition for the servo mechanism to overcome technically. That is, it is a well-known fact that when a small conveyance amount is controlled in the convergence range of positioning, the presence of a friction load impairs the convergence of positioning.

  As a conventional technique, there is one that attempts to ensure convergence by switching the control law in accordance with the driving state of the transport roller (see, for example, Patent Document 1). That is, linear PID control is performed when the transport roller is driven at a speed having a certain size, and nonlinear control such as sliding mode control is performed in the convergence region where a small transport amount is controlled.

Further, when the control law is switched, if the operation amount given to the actuator is extremely discontinuous, vibration may be induced. Some conventional techniques attempt to switch the control law so as to maintain the continuity of the manipulated variable (see, for example, Patent Document 2). In general, in a servo mechanism, an operation amount is obtained by compensating for a deviation between a command value and a control amount. The command value is calculated backward from the operation amount so that the operation amount is continuous before and after the switching of the control law.
JP 2002-120425 A (5th page, FIG. 1) Special Registration No. 3294492 (5th page, Fig. 1)

  However, the problem with the servo mechanism of the transport roller in the prior art is that although switching of the control law enables control of a minute transport amount in the convergence range, it causes reverse rotation of the transport roller and unnecessary vibration. That is. This problem will be described below with reference to the drawings.

  FIG. 10 is a block diagram showing a control configuration around the conveyance roller for conveying a recording medium in a conventional recording apparatus.

  As shown in FIG. 10, the transport roller 100 is driven by a transport motor 90 that is an actuator. The driving amount of the conveying roller 100 is detected in the form of a position signal and a speed signal by a sensor such as an encoder (not shown).

  Now, the command value generation unit 101 generates a command value for conveying roller driving. The command value takes the form of a position command value, a speed command value, and an acceleration command value corresponding to the physical dimension of driving. The driving amount of the transport roller and the command value to the transport roller are guided to the compensation unit 120, and an appropriate control law is calculated so that the deviation between them is zero.

  The power amplifier 110 supplies power to the carry motor 90 according to the output signal of the compensation unit 120. As can be seen from the configuration shown in FIG. 10, a feedback loop of such a signal is configured in this control system. Furthermore, in order to obtain a desired transport amount, the control law in the compensation unit 120 is switched according to the driving state. Normally, the control law is switched depending on whether or not the driving state is in the convergence range of positioning. This is because the load characteristic varies greatly depending on whether or not it is within the convergence range.

  FIG. 11 is a diagram illustrating load characteristics of the conveyance roller.

  In FIG. 11, the horizontal axis indicates the speed of the conveying roller, and the vertical axis indicates the magnitude of the load. The load characteristics are classified into static friction when the conveying roller is stationary, dynamic friction when it is driven, and viscous resistance that increases in proportion to the speed of driving. In the case of a convergence range for controlling a minute conveyance amount, a jumping characteristic of a load is observed due to the presence of friction. This means that there is a zero-cross dead band when viewed from the compensation unit 120. On the other hand, when the recording medium is transported at a speed having a certain size, an increase in load proportional to the speed appears due to viscous resistance. In this case, the load characteristic can be controlled by so-called linear PID control if the offset of the load due to dynamic friction is canceled.

  For this reason, it is normal for the control system of the transport roller to switch the control law depending on whether or not the driving state is within the positioning convergence range.

  Returning to FIG. 10, the description will be continued. The control law calculated by the compensation unit 120 is switched by the convergence range determination unit 102. The convergence area determination unit 102 determines whether or not the driving state is in the positioning convergence area in accordance with the position signal of the transport roller 100. As a conventional means conventionally used, when the driving state is not the convergence range of positioning, the control law calculated by the compensation unit 120 is PID control, and when the driving state is the convergence region of positioning, the friction load In addition to the offset cancellation, a proportional gain increase of PID control is performed. In order to position and hold the transport roller, it is necessary to impart so-called servo rigidity to the transport roller by increasing the proportional gain. In the convergence range, the friction load plays a role of energy consumption and damping, so that the proportional gain can be increased without impairing the stability of the control system as compared with the case where the friction load is not.

  The problem here is that if the control law described above is not smoothly switched, reverse rotation and vibration of the conveying roller 100 are induced.

  As described so far, the control law in the compensation unit 120 is largely switched depending on whether or not the driving state is within the positioning convergence range. Therefore, a transient disturbance in servo performance is induced at the time of switching. In particular, the problem is remarkable when the position deviation is large.

  In order to increase positioning measurement accuracy and maintain positioning, servo rigidity is imparted to the conveying roller 100 by increasing the proportional gain of PID control as much as possible in the convergence range of the driving state. Therefore, if the position deviation is large immediately before the switching of the control law, the position deviation correction operation is performed abruptly after the switching, so that vibration is induced. In addition, when the transport roller 100 has gone too far with respect to the position command value, the follow-up action to the position command value after switching causes the transport roller 100 to undergo a transient reverse rotation.

  For the purpose of the recording apparatus for conveying the recording medium at high speed and with high accuracy, the reverse rotation of the conveying roller is an operation that is completely unnecessary.

  In the prior art, a technique for maintaining the continuity of the operation amount before and after the switching of the control law is disclosed, but no consideration has been given to preventing the phenomenon of vibration or reverse rotation of the transport roller.

  The present invention has been made in view of the above problems, and controls the conveying roller so as to convey the recording medium at high speed and with high accuracy without inducing reverse rotation and vibration of the conveying roller. It is an object of the present invention to provide a recording apparatus that performs recording and a recording medium conveyance control method.

  In order to achieve the above object, the recording apparatus of the present invention has the following configuration.

  That is, a recording apparatus that performs recording by conveying a recording medium via a conveyance roller by a driving force from a conveyance motor, the detection unit detecting the position and speed of the conveyance roller, and the detection unit detecting A drive control means for driving and controlling the carry motor by feeding back a position signal and a speed signal representing the position and speed of the carry roller, and a command value for driving the carry motor to the drive control means. Command value generating means for generating the command value, command value output means for outputting the command value generated by the command value generating means at a predetermined time interval to the drive control means, and the transport roller based on the position signal. First position determining means for determining whether or not fine control is entered, the position signal is compared with the command value, and the command value is determined based on the comparison result. The command value generation means is configured to output the command at a time interval smaller than the predetermined time interval in accordance with a second determination device that determines whether the position of the transport roller is excessive or not, and a determination result by the first and second determination devices. And control means for controlling to update the value.

  Here, the control unit controls the command value generation unit to update the command value when the first determination unit determines that the transport roller has entered an area requiring fine control. Further, it is preferable that the command value generating means controls the command value to be updated until the position of the transport roller represented by the position signal becomes substantially equal to the position represented by the command value.

  Here, the detection means includes a rotary slit provided at an end of the transport roller, a rotary encoder that reads the slit of the rotary slit, and an output signal from the rotary encoder, based on the position signal and the speed. It is desirable to include signal generation means for generating a signal.

  The command value generated by the command value generating means preferably includes a position command value, a speed command value, and an acceleration command value for the transport motor.

  Furthermore, it is preferable that the drive control means switches a control law for driving the carry motor according to whether or not the carry roller has entered an area requiring fine control.

  The recording head may be an ink jet recording head that performs recording by discharging ink, and the ink jet recording head uses electric energy to generate thermal energy to be applied to the ink in order to discharge ink using thermal energy. More preferably, a converter is provided.

  According to another invention, there is provided a recording medium conveyance control method for a recording apparatus that performs recording by conveying a recording medium via a conveyance roller by a driving force from a conveyance motor, wherein the position and speed of the conveyance roller are set. A detection step for detecting, a drive control step for driving and controlling the conveyance motor by feeding back a position signal and a velocity signal respectively representing the position and velocity of the conveyance roller detected in the detection step, and driving of the conveyance motor A command value generating step for generating a command value for control, a command value output step for outputting the command value generated in the command value generating step at predetermined time intervals for the drive control, and the position signal Based on the comparison result, the first determination step for determining whether or not the transport roller has entered an area that requires fine control is compared with the position signal and the command value. According to the determination result in the second determination step for determining whether or not the position of the conveying roller is excessive with respect to the command value, and the determination result in the first and second determination steps, the interval is finer than the predetermined time interval. And a control step of controlling the command value generation step to update the command value.

  Therefore, according to the present invention, the conveying roller can be positioned with high speed and high accuracy, and there is an effect that the recording medium can be conveyed with high speed and high accuracy.

  For example, if the transport roller is too far from the position command value, the updated appropriate command value is input at the same timing as the switching of the control rule, so the control region of the transport roller enters the convergence range. Even if the switching of the control law occurs, it does not induce reverse rotation or vibration of the transport roller, and the transport roller can be controlled promptly without being influenced by a transient failure at the time of switching the control law. .

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings.

  In this specification, “recording” (sometimes referred to as “printing”) is not only for forming significant information such as characters and figures, but also for human beings visually perceived regardless of significance. Regardless of whether or not it has been manifested, it also represents a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or the medium is processed.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used for forming a pattern or the like, processing a recording medium, or processing an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port or a liquid channel communicating with the ejection port and an element that generates energy used for ink ejection.

<Description of Inkjet Recording Apparatus (FIG. 1)>
FIG. 1 is an external perspective view showing an outline of the configuration of an ink jet recording apparatus which is a typical embodiment of the present invention.

  As shown in FIG. 1, an ink jet recording apparatus (hereinafter referred to as a recording apparatus) transmits a driving force generated by a carriage motor M1 to a carriage 2 on which a recording head 3 that performs recording by discharging ink according to an ink jet system is mounted. 4, the carriage 2 is reciprocated in the direction of arrow A, and for example, a recording medium P such as recording paper is fed through a paper feeding mechanism 5 and conveyed to a recording position. Recording is performed by ejecting ink onto the recording medium P.

  Further, in order to maintain the state of the recording head 3 satisfactorily, the carriage 2 is moved to the position of the recovery device 10 and the ejection recovery process of the recording head 3 is performed intermittently.

  In addition to mounting the recording head 3 on the carriage 2 of the recording apparatus 1, an ink cartridge 6 for storing ink to be supplied to the recording head 3 is mounted. The ink cartridge 6 is detachable from the carriage 2.

  The recording apparatus shown in FIG. 1 is capable of color recording. For this reason, the carriage 2 contains four inks containing magenta (M), cyan (C), yellow (Y), and black (K) inks, respectively. A cartridge is installed. These four ink cartridges are detachable independently.

  Now, the carriage 2 and the recording head 3 can achieve and maintain a required electrical connection by properly contacting the joint surfaces of both members. The recording head 3 applies energy according to a recording signal to selectively eject ink from a plurality of ejection ports for recording. In particular, the recording head 3 of this embodiment employs an ink jet system that ejects ink using thermal energy, and includes an electrothermal transducer to generate thermal energy, which is applied to the electrothermal transducer. Electric energy is converted into thermal energy, and ink is ejected from the ejection port by utilizing pressure changes caused by bubble growth and contraction caused by film boiling caused by applying the thermal energy to the ink. The electrothermal transducer is provided corresponding to each of the ejection ports, and ink is ejected from the corresponding ejection port by applying a pulse voltage to the corresponding electrothermal transducer in accordance with the recording signal.

  As shown in FIG. 1, the carriage 2 is connected to a part of the driving belt 7 of the transmission mechanism 4 that transmits the driving force of the carriage motor M <b> 1, and slides in the direction of arrow A along the guide shaft 13. It is guided and supported freely. Accordingly, the carriage 2 reciprocates along the guide shaft 13 by forward and reverse rotations of the carriage motor M1. A scale 8 is provided for indicating the absolute position of the carriage 2 along the direction of movement of the carriage 2 (the direction of arrow A). In this embodiment, the scale 8 uses a transparent PET film printed with black bars (slits) at a necessary pitch, one of which is fixed to the chassis 9 and the other is a leaf spring (not shown). It is supported. The carriage 2 is provided with an encoder (not shown) for reading the slits of the scale 8.

  Further, the recording apparatus is provided with a platen (not shown) facing the discharge port surface where the discharge port (not shown) of the recording head 3 is formed, and the recording head 3 is driven by the driving force of the carriage motor M1. Simultaneously with the reciprocating movement of the mounted carriage 2, recording is performed over the entire width of the recording medium P conveyed on the platen by giving a recording signal to the recording head 3 and discharging ink.

  Further, in FIG. 1, 14 is a conveyance roller driven by a conveyance motor M2 to convey the recording medium P, 15 is a pinch roller that abuts the recording medium P against the conveyance roller 14 by a spring (not shown), and 16 is a pinch. A pinch roller holder 17 that rotatably supports the roller 15 is a conveyance roller gear fixed to one end of the conveyance roller 14. Then, the conveyance roller 14 is driven by the rotation of the conveyance motor M2 transmitted to the conveyance roller gear 17 via an intermediate gear (not shown).

  The position and speed of the transport roller 14 are detected by a rotary encoder (not shown), and the position and speed of the transport roller are feedback-controlled based on the detection signal.

  Further, reference numeral 20 denotes a discharge roller for discharging the recording medium P on which an image is formed by the recording head 3 to the outside of the recording apparatus, and is driven by transmitting the rotation of the transport motor M2. . The discharge roller 20 abuts on a spur roller (not shown) that presses the recording medium P by a spring (not shown). Reference numeral 22 denotes a spur holder that rotatably supports the spur roller.

  Further, as shown in FIG. 1, the recording apparatus includes a desired position (for example, a home position) outside the range of reciprocating motion (outside the recording area) for the recording operation of the carriage 2 on which the recording head 3 is mounted. A recovery device 10 for recovering the ejection failure of the recording head 3 is disposed at a position corresponding to (1).

  The recovery device 10 includes a capping mechanism 11 for capping the ejection port surface of the recording head 3 and a wiping mechanism 12 for cleaning the ejection port surface of the recording head 3, and interlocks with the capping of the ejection port surface by the capping mechanism 11. Ink recovery such as forcibly discharging ink from the discharge port by suction means (suction pump or the like) in the recovery device, thereby removing ink or bubbles having increased viscosity in the ink flow path of the recording head 3 Process.

  Further, when the recording head 3 is not in operation or the like, the ejection port surface of the recording head 3 is capped by the capping mechanism 11 to protect the recording head 3 and to prevent ink evaporation and drying. On the other hand, the wiping mechanism 12 is disposed in the vicinity of the capping mechanism 11 and wipes ink droplets adhering to the ejection port surface of the recording head 3.

  The capping mechanism 11 and the wiping mechanism 12 can keep the ink ejection state of the recording head 3 normal.

  FIG. 2 is a diagram showing a detailed configuration of the recording medium transport mechanism.

  As shown in FIG. 2, the recording medium P is conveyed by driving of the conveyance roller 14 and the pinch roller 15. A pulley 30 is provided at the end of the conveying roller 14. The timing belt 31 is suspended from the pulley 30 and the motor pulley 32 without being loosened. A conveyance motor M <b> 2 that is an actuator is connected to the motor pulley 32. The driving force generated by the conveyance motor M2 is transmitted to the conveyance roller 14 via the motor pulley 32, the timing belt 31, and the pulley 30. The pinch roller 15 is rotated by being urged by the conveying roller 14. A rotary scale 33 is provided at the end of the transport roller 14.

  In this embodiment, a rotary encoder (not shown) and a rotary scale 33 detect the rotation amount of the transport roller 14 as a position signal and a speed signal.

<Control Configuration of Inkjet Recording Apparatus (FIG. 3)>
FIG. 3 is a block diagram showing a control configuration of the recording apparatus shown in FIG.

  As shown in FIG. 3, the controller 600 includes an MPU 601, a program corresponding to a control sequence to be described later, a required table, a ROM 602 storing other fixed data, a control of the carriage motor M1, a control of the transport motor M2, and a recording. A special purpose integrated circuit (ASIC) 603 that generates a control signal for controlling the head 3, and a RAM 604, an MPU 601, an ASIC 603, and a RAM 604, which are provided with image data development areas and program execution areas, are connected to each other. A system bus 605 for transferring data, and an A / D converter 606 for inputting analog signals from the sensor group described below, A / D converting them, and supplying digital signals to the MPU 601 and the like.

  In FIG. 3, reference numeral 610 denotes a computer (or a reader for image reading, a digital camera, or the like) serving as a supply source of image data, and is collectively referred to as a host device. Image data, commands, status signals, and the like are transmitted and received between the host apparatus 610 and the recording apparatus 1 via an interface (I / F) 611.

  Further, reference numeral 620 denotes a switch group, which instructs activation of a power switch 621, a print switch 622 for instructing printing start, and a process (recovery process) for maintaining the ink ejection performance of the recording head 3 in a good state. For example, a recovery switch 623 for receiving a command input from the operator. Reference numeral 630 denotes a position sensor 631 such as a photocoupler for detecting the home position h, a temperature sensor 632 provided at an appropriate location of the recording apparatus for detecting the environmental temperature, and the like. It is a sensor group.

  Further, 640 is a carriage motor driver that drives a carriage motor M1 for reciprocating scanning of the carriage 2 in the direction of arrow A, and 642 is a transport motor driver that drives a transport motor M2 for transporting the recording medium P.

  The ASIC 603 transfers drive data (DATA) of the printing element (ejection heater) to the printing head while directly accessing the storage area of the RAM 602 during printing scanning by the printing head 3.

  A position / speed detection mechanism 641 generates a position signal and a speed signal from the encoder signal from the rotary encoder 33a that reads the rotary scale 33 provided at the end of the conveying roller 14, and these are transferred to the MPU 601 of the controller 600. .

  FIG. 4 is a diagram showing a typical drive profile of the transport roller.

  In FIG. 4, the horizontal axis represents time, and the vertical axis represents the position command value for the conveying roller 14. The control area is divided in order of time into an acceleration area where driving of the transport roller 14 is started, a constant speed area, a deceleration area, and a convergence area where minute positioning is performed. The control mechanism of the transport roller 14 provided in the recording apparatus operates so that appropriate driving is performed in each of these predetermined control areas.

  FIG. 5 is a functional block diagram showing a feedback control configuration of the conveyance roller.

  5 is a functional block diagram, and each of the components 41 to 47 shown in FIG. 5 may be realized by a program executed by the MPU 601, may be realized by an ASIC 603, or other hardware. It may be realized by wear.

  Now, the command value generation unit 41 performs a time-series command value generation calculation. As described in the prior art, the command value has dimensions of acceleration, velocity, and position, and is in a relationship of differentiation and integration, respectively, and maintains physical consistency. When the predetermined time increment is Δt, the number of pulses of the trigger signal (TRIG) given to the command value generation unit 41 is n, and the calculation function is f, the calculation performed by the command value generation unit 41 is as shown in Equation 1. It seems.

f (Δt × n) (1)
Each time the trigger signal is given, the command value generator 41 updates the calculation. Note that Δt coincides with the sampling period of the speed signal and the position signal. Although a shorter value of Δt is desirable, it is limited to the performance of the recording apparatus and is usually about 1 ms.

  As described above, the rotation amount of the transport roller 14 is detected as a position signal and a speed signal. The convergence area determination unit 42 determines whether or not the control area is in the convergence area based on the detected position signal. The overshoot determination unit 43 determines whether or not the transport roller 14 has exceeded the position command value from the position command value and the position signal.

  Each time the command value is updated by the calculation of the command value generation unit 41, the overshoot determination unit 43 performs a determination, and when it is determined that there is an overshoot, a pulse signal indicating that is output. The outputs of the convergence area determination unit 42 and the overshoot determination unit 43 are input to the AND gate 45. The sampling period signal is a pulse signal that defines the timing at which this feedback control mechanism inputs / outputs signals to / from other parts of the recording apparatus. The output of the AND gate 45 and the sampling period signal are input to the OR circuit 46. That is, the trigger signal given to the command value generation unit 41 is a logical sum of the above-described determination result and the sampling period signal.

  When the control area is the convergence area shown in FIG. 4 and the conveying roller 14 has exceeded the position command value, the OR circuit 46 is in accordance with the output signal from the AND gate 45 regardless of the sampling period signal. Is output a trigger signal (TRIG), and the position command value, speed command value, and acceleration command value are updated by the calculation of the command value generation unit 41. The updated position command value is fed back to the overshoot determination unit 43, and if there is still an overshoot even when compared with the input position signal, the calculation is updated again. In this way, the calculation by the command value generation unit 41 is repeated and updated until the position signal of the transport roller 14 and the position command value are substantially equal.

  Now, the acceleration command value, the speed command value, and the position command value from the command value generation unit 41 are stored in the corresponding buffers 40a to 40c, respectively. The buffers 40a to 40c output these command values at the timing when the sampling period signal pulse is input.

  Therefore, according to the above configuration, calculation of the command value generator 41 is performed by the determination of the overshoot determination unit 43, and even when each command value is updated, the input command to the transport motor M2 that is an actuator is updated. Is the timing of the sampling period signal.

  FIG. 6 is a block diagram showing a control configuration around the conveying roller for conveying the recording medium according to this embodiment. As can be seen by comparing FIG. 10 and FIG. 6, the control of the transport roller in this embodiment is similar to the servo mechanism of the transport roller found in the prior art. Therefore, detailed description here is omitted. Moreover, the same reference numerals are given to the components described so far. In FIG. 6, 642b is the same as the power amplifier 110 shown in FIG.

  The acceleration command value, the speed command value, and the position command value generated as described above are input to the compensation unit 642a similar to the prior art as shown in FIG. The control law calculated by the compensation unit 642a is switched by the convergence range determination unit. As described above, the convergence area determination unit 42 determines whether or not the control area is a convergence area. Here, when it is determined that it is not the convergence range, the control law calculated by the compensation unit 642a is PID control, and when it is determined that it is the convergence range, the offset cancellation of the friction load and the PID control are performed. Proportional gain up is performed. In order to position and hold the transport roller 14 and improve positioning accuracy, servo rigidity is imparted to the transport roller 14 by increasing the proportional gain.

  FIG. 7 is a diagram showing a time-series plot of the trigger signal given to the command value generation unit.

  As can be seen from FIG. 7, the sampling period signal is generated at a constant time interval Δt. At the timing of time t = t2, the control region enters the convergence region, and the control law and command value of the compensation unit 642a are switched. At this time, it is determined that the transport roller 14 has exceeded the position command value, and a trigger signal based on the determination of the overshoot determination unit 43 is generated several times between time t2 and time t3.

  FIG. 8 is a diagram illustrating the response of the transport roller using the position command value and the position signal in the convergence range.

  In FIG. 8, (a) shows the response characteristic according to the prior art, and (b) shows the response characteristic according to this embodiment. According to FIG. 8A, it can be seen that the reverse rotation of the transport roller occurs at the switching timing of the control law. This is a phenomenon that occurs because the control law is switched in a state in which the transport roller is excessive with respect to the position command value. On the other hand, according to FIG. 8B, since the position command value is updated so as to coincide with the position signal at the timing of switching the control law, the transport roller is quickly positioned and stable. . The reverse rotation phenomenon of the conveyance roller which has occurred in the prior art does not appear.

  From these comparisons, the superiority of the conveyance roller control according to this embodiment is clear.

  The conveyance control processing of this embodiment described above is summarized in the flowchart shown in FIG.

  FIG. 9 is a flowchart showing the conveyance control process.

  First, in step S10, when the command value generation unit 41 issues a position, speed, and acceleration command value, the specified values are set in the buffers 40a to 40c in step S20. In step S30, when the designated value is output to the compensation unit 642a of the carry motor driver 642 based on the next sampling cycle signal, the carry motor driver 642 drives the carry motor M2 based on the command value.

  In step S40, the rotation of the transport roller 14 is monitored by the rotary encoder 33a, and a position signal and a speed signal are output from the position / speed detection mechanism 641 and fed back to the convergence area determination unit 42 and the overshoot determination unit 43. In step S50, the convergence area determination unit 42 checks whether the control area is a convergence area. If it is determined that the control area is in the convergence area, the process proceeds to step S60. If it is determined that the control area is not in the convergence area, the process proceeds to step S110.

  In step S60, the overshoot determination unit 43 compares the position command value with the position signal, and checks whether the transport roller 14 has excessively exceeded the position command value. If it is determined that there has been an overshoot, a trigger signal (TRIG) is issued, the process proceeds to step S70, the command value generation unit 41 updates the command value, and then the process returns to step S60. On the other hand, if it is determined that the transport roller 14 is appropriate with no excess over the position command value, the process proceeds to step S80, and the update command value is set in the buffers 40a to 40c.

  Next, in step S90, the process waits for the input of the next sampling synchronization signal, and when there is an input signal, the update command value set in the buffers 40a to 40c is output to the compensation unit 642a. Further, in step S100, the conveyance motor driver 642 performs offset cancellation of the friction load and proportional gain increase of PID control, and drives and controls the conveyance motor M2 with the update command value.

  If it is determined that it is not within the convergence range, the process proceeds to step S110, and the conveyance motor M2 is driven and controlled based on the command value (position, speed, acceleration), the detected position signal, and the detected speed signal by PID control. To do.

  Finally, in step S120, it is confirmed whether or not there is a conveyance roller stop command. If there is a stop command, the process proceeds to step S130, and the conveyance motor M2 is stopped. Returning to step S40, the position speed detection by the rotary encoder 33a is continued.

  Therefore, according to the embodiment described above, when the control area of the transport motor is in the convergence area, the position command value and the position signal are compared at an interval shorter than the signal period of the sampling period signal to drive the transport roller. It is possible to compare whether there is an overshoot, update the value based on the comparison result so as to obtain an appropriate position command value, and drive and control the transport motor based on the updated command value. Thereby, for example, even when the control region of the transport motor enters the convergence region and the control law is switched, the position command value is updated so as to coincide with the position signal, so that the transport roller is quickly It is positioned and stable, and it is possible to prevent the reverse rotation of the transport roller as occurs in the prior art.

  In the embodiment described above, the case where the control region is in the convergence region has been described as an example, but the present invention is not limited thereto. The present invention can be suitably implemented even when the control region is in the acceleration region, constant velocity region, or deceleration region.

  In the embodiment described above, the physical consistency of the position, speed, and acceleration in the command value is preserved. In general, a servo mechanism for positioning purposes uses a speed command value and an acceleration command value in addition to a position command value in order to improve responsiveness. In this embodiment, since the speed command value and the acceleration command value are switched together with the position command value, there is an advantage that vibration due to physical mismatch does not occur.

  Furthermore, in the above embodiments, the liquid droplets ejected from the recording head have been described as ink, and the liquid stored in the ink tank has been described as ink. However, the storage is limited to ink. It is not a thing. For example, a treatment liquid discharged to the recording medium may be accommodated in the ink tank in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

  The above embodiment includes means (for example, an electrothermal converter or a laser beam) that generates thermal energy as energy used to perform ink ejection, particularly in the ink jet recording system, and the ink is generated by the thermal energy. By using a system that causes a change in the state of recording, it is possible to achieve higher recording density and higher definition.

  In the above embodiments, the serial scan type ink jet recording apparatus has been described as an example. However, the present invention is not limited to this, and the present invention is also effective for recording apparatuses employing other recording methods, for example, a thermal transfer recording method. Applicable to.

  In addition, even the serial scan type as in the above-described embodiments is mounted on the recording head fixed to the apparatus main body or the apparatus main body so that the electrical connection with the apparatus main body and the ink from the apparatus main body The present invention is also effective when an exchangeable cartridge type recording head that can be supplied is used.

  In addition, the ink jet recording apparatus according to the present invention may be used as an image output apparatus for information processing equipment such as a computer, a copying apparatus combined with a reader, or a facsimile apparatus having a transmission / reception function. It may be one taken.

1 is an external perspective view showing an outline of a configuration of an ink jet recording apparatus that is a typical embodiment of the present invention. FIG. 3 is a diagram illustrating a detailed configuration of a recording medium conveyance mechanism. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. It is a figure which shows the typical drive profile of a conveyance roller. It is a functional block diagram showing a feedback control configuration of a conveyance roller. FIG. 4 is a block diagram illustrating a control configuration around a conveyance roller that conveys a recording medium. It is a figure which shows the time series plot of the trigger signal given to a command value production | generation part. It is a figure which shows the response of the conveyance roller using the position command value and position signal in a convergence area. It is a flowchart which shows a conveyance control process. FIG. 10 is a block diagram illustrating a control configuration around a conveyance roller that conveys a recording medium in a conventional recording apparatus. It is a figure which shows the load characteristic of a conveyance roller.

Explanation of symbols

2 Carriage 8 Scale 14 Transport roller 15 Pinch roller 30 Pulley 31 Timing belt 32 Motor pulley 33 Rotary scale 33a Rotary encoders 40a to 40c Buffer 41 Command value generation unit 42 Convergence area determination unit 43 Overshoot determination unit 45 AND gate 46 OR circuit 601 MPU
640 Carriage motor driver 641 Position speed detection mechanism 642 Carriage motor driver 642a Compensator 642b Power amplifier
M1 Carriage motor M2 Conveyance motor P Recording medium

Claims (9)

A recording apparatus that performs recording by conveying a recording medium via a conveyance roller by a driving force from a conveyance motor,
Detecting means for detecting the position and speed of the conveying roller;
Drive control means for driving and controlling the transport motor by feeding back a position signal and a speed signal respectively representing the position and speed of the transport roller detected by the detection means;
Command value generating means for generating a command value for driving the transport motor to the drive control means;
Command value output means for outputting the command value generated by the command value generation means at a predetermined time interval to the drive control means;
First determination means for determining whether or not the transport roller has entered an area requiring fine control based on the position signal;
A second determination unit that compares the position signal with the command value and determines whether the position of the transport roller is excessive with respect to the command value based on the comparison result;
And a control unit configured to control the command value generation unit to update the command value at intervals smaller than the predetermined time interval according to the determination results by the first and second determination units. .   The control unit controls the command value generation unit to update the command value when the first determination unit determines that the transport roller has entered an area requiring fine control. The recording apparatus according to claim 1.   The control means further controls the command value generating means to update the command value until the position of the transport roller represented by the position signal becomes substantially equal to the position represented by the command value. The recording apparatus according to claim 2. The detection means includes
A rotary slit provided at an end of the conveying roller;
A rotary encoder that reads the slit of the rotary slit;
4. The recording apparatus according to claim 1, further comprising a signal generation unit configured to generate the position signal and the velocity signal based on an output signal from the rotary encoder.   5. The recording according to claim 1, wherein the command value generated by the command value generating unit includes a position command value, a speed command value, and an acceleration command value for the conveyance motor. apparatus.   6. The drive control unit according to claim 1, wherein the driving control unit switches a control law for driving the transport motor according to whether or not the transport roller has entered an area requiring fine control. The recording device described in 1.   The recording apparatus according to claim 1, wherein the recording head is an ink jet recording head that performs recording by discharging ink. The recording apparatus according to claim 7, wherein the ink jet recording head includes an electrothermal transducer for generating thermal energy to be applied to the ink in order to eject the ink using thermal energy. . A recording medium conveyance control method for a recording apparatus that performs recording by conveying a recording medium via a conveyance roller by a driving force from a conveyance motor,
A detection step of detecting the position and speed of the transport roller;
A drive control step for driving and controlling the carry motor by feeding back a position signal and a velocity signal respectively representing the position and velocity of the carry roller detected in the detection step;
A command value generating step for generating a command value for driving control of the transport motor;
A command value output step of outputting the command value generated in the command value generation step at a predetermined time interval for the drive control;
Based on the position signal, a first determination step of determining whether or not the transport roller has entered an area requiring fine control;
A second determination step of comparing the position signal with the command value and determining whether the position of the transport roller is excessive with respect to the command value based on the comparison result;
And a control step for controlling the command value generation step to update the command value at intervals smaller than the predetermined time interval according to the determination results in the first and second determination steps. Transport control method.

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