JP2018001445A - Printing device and abnormality determining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately perform determination of whether rubbing between a medium and a head occurs.SOLUTION: The printing device, which is configured to perform printing by discharging liquid from a head to a medium while moving a carriage mounted with the head capable of discharging liquid in a main scanning direction, comprises: a motor which moves the carriage in the main scanning direction; and a control portion which outputs driving signals for driving the motor to the motor, on the basis of feedback control. The control portion determines a first threshold value on the basis of an average value of the driving signals outputted during a first movement of the carriage accompanied by discharge of liquid by the head; and determines that abnormality occurs when the average value of the driving signals outputted during a second movement of the carriage accompanied by the discharge of the liquid by the head following the first movement exceeds the first threshold value.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a printing apparatus and an abnormality determination method.

  2. Description of the Related Art A so-called serial type ink jet printer is known that performs printing while moving a carriage on which a head capable of ejecting ink is mounted in a main scanning direction orthogonal to a conveyance direction of a sheet placed on a platen. In such a printer, the distance between the platen and the head (platen gap) is set so that the paper and the head are not rubbed (paper rub), but the paper warps and the discharged ink is absorbed. The paper may be rubbed due to deformation of the paper such as so-called cock ring. Paper rubbing can cause further paper deformation and paper jam.

  For the purpose of preventing troubles caused by paper rubbing, a current sensor for detecting a current value applied to a motor that moves the carriage in the main scanning direction and a current sensor while the carriage is being accelerated are used. Threshold setting means for setting a threshold based on the peak value of the detected current value, and when an image is formed, the discharge head and the paper are rubbed when the current value detected by the current sensor exceeds the threshold. There is known an image forming apparatus that includes a ruin determination unit that determines that occurrence of the image is generated (see Patent Document 1).

JP 2010-184443 A

Regarding the configuration for determining the presence or absence of paper rubbing, further cost reduction and improvement in determination accuracy are required.
The present invention has been made in view of such a problem, and provides a printing apparatus and an abnormality determination method that contribute to determining the occurrence of rubbing between a medium and a head.

  One aspect of the present invention is a printing apparatus that performs printing by ejecting liquid from the head to a medium while moving a carriage on which a head capable of ejecting liquid is mounted in a main scanning direction. And a control unit that outputs a drive signal for driving the motor based on feedback control to the motor, and the control unit discharges liquid by the head. A first threshold value is determined based on an average value of the drive signals output during the first movement of the carriage, and the carriage is accompanied by ejection of liquid by the head after the first movement. When the average value of the drive signals output during the second movement exceeds the first threshold value, it is determined as abnormal.

  According to this configuration, the controller is abnormal, that is, during the second movement, depending on whether or not the average value of the drive signal output to the motor during the second movement of the carriage exceeds the first threshold value. In addition, it is possible to appropriately determine whether or not the rubbing between the medium and the head has occurred. The drive signal is naturally output under feedback control in order to drive the motor. Therefore, a sensor or the like is not necessary for determining the first threshold value, and the cost required for the configuration for determining the abnormality can be reduced.

One aspect of the present invention is that the first movement is the carriage movement for the first time in printing for one page of the medium, and the control unit performs the first movement for each page of the medium. The threshold value of 1 may be updated.
According to this configuration, while printing on a plurality of media is executed, the optimal first threshold value corresponding to the current situation such as an increase in the value of the drive signal due to the influence of heat generated by the motor is set. The determination can be made.

One aspect of the present invention is that the control unit outputs the drive signal that is output during the movement of a constant speed section that controls the driving of the motor so that the speed of the carriage in the first movement is constant. The first threshold value is determined based on the average value of the second movement, and the constant speed section of the second movement at the timing when the movement of the constant speed section of the second movement ends. It may be determined whether or not the average value of the drive signal output during the movement exceeds the first threshold value.
According to this configuration, whether or not an abnormality (the rubbing) has occurred in the movement of the constant speed section in the second movement can be determined every time the movement of the constant speed section ends.

In one aspect of the present invention, the control unit determines a second threshold value that is higher than the first threshold value, and the movement of the constant speed section of the second movement is completed. Until then, it may be determined whether or not the drive signal exceeds the second threshold value, and when the drive signal exceeds the second threshold value, it may be determined as abnormal.
According to this configuration, even when the driving signal temporarily becomes high enough to exceed the second threshold during the movement in the constant speed section in the second movement, it is determined that there is an abnormality. Can do.

According to one aspect of the present invention, the control unit may determine that an abnormality occurs even when a deviation between a predetermined target speed of the carriage and a speed of the carriage exceeds a predetermined allowable range. Good.
According to this configuration, it can be determined with higher accuracy whether or not an abnormality (the rubbing) has occurred.

One of the aspects of the present invention is that the control unit allows the speed of the carriage to be constant in the allowable range corresponding to the acceleration section in which the control unit controls the driving of the motor to accelerate the carriage. Further, it may be wider than the allowable range corresponding to a constant speed section following the acceleration section for controlling the driving of the motor.
According to this configuration, it is possible to accurately determine whether the deviation is abnormally large (the rubbing has occurred) for each carriage movement section (acceleration section, constant speed section).

The control unit may stop printing when determining that the abnormality has occurred, and notify the outside that an abnormality has occurred. Further, the control unit may stop printing when it is determined that the abnormality is present, and increase a height from the medium to the head.
According to these configurations, it is possible to prevent the trouble caused by the rubbing from expanding and notify the user or prevent the rubbing from occurring in subsequent printing.

The technical idea of the present invention is also realized by a device other than a printing device. For example, a method including a process executed by a printing apparatus can be regarded as an invention. In other words, this is an abnormality determination method executed by the printing apparatus, and is output based on feedback control during the first movement of the carriage accompanying the ejection of liquid by the head to the motor that moves the carriage in the main scanning direction. A threshold value determining step for determining a first threshold value based on an average value of drive signals for driving the motor, and the liquid ejection by the head after the first movement. A determination step of determining an abnormality when an average value of the drive signals output to the motor based on the feedback control exceeds the first threshold value during the second movement of the carriage. Can be regarded as an invention.
In addition, a program that causes a computer to execute such a method and a computer-readable storage medium that stores the program are also established as inventions.

FIG. 2 is a block diagram illustrating a main configuration of the printing apparatus. The figure which shows the partial structure containing a carriage. 6 is a flowchart showing print control processing. The flowchart which shows a 1st measurement process. The flowchart which shows an abnormality presence determination process. The graph which shows the aspect of a change of the speed and duty ratio of a carriage. The flowchart which added the 2nd abnormality presence determination process to FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Each figure is only an example for explaining this embodiment.

1. Schematic description of device configuration:
FIG. 1 is a block diagram illustrating the main configuration of a printing apparatus 10 according to the present embodiment. The printing apparatus 10 performs printing by discharging liquid from the print head 13 to a medium while moving a carriage 12 mounted with a head (print head 13) capable of discharging liquid (ink or liquid other than ink) in the main scanning direction. Execute. The printing apparatus 10 is also an execution subject of the abnormality determination method. The printing apparatus 10 is grasped as a product such as a printer, a multifunction machine including a plurality of functions such as a printer, a scanner, and a facsimile. The printing apparatus may be called a printing apparatus, a recording apparatus, a liquid ejection (ejection) apparatus, or the like. A part of the printing apparatus 10 may be referred to as a printing apparatus.

  In FIG. 1, the printing apparatus 10 is illustrated as a configuration including a control unit 11, a carriage 12, a print head 13, a conveyance unit 14, a carriage (CR) motor 15, a display unit 16, and the like. The control unit 11 includes, for example, an IC having a CPU (see reference numeral 20 in FIG. 2), a ROM, a RAM, and other storage media. In the control unit 11, the CPU 20 controls the behavior of each component of the printing apparatus 10 by executing arithmetic processing according to programs and data stored in the ROM or the like using the RAM or the like as a work area.

  FIG. 2 schematically shows a partial configuration including the carriage 12. The carriage 12 is equipped with a print head 13 and is movable along a predetermined main scanning direction D <b> 1 under the control of the control unit 11. The carriage 12 receives power from the CR motor 15 and moves along the main scanning direction D1. The print head 13 has a plurality of holes (nozzles) for discharging a liquid such as ink. The print head 13 may be called a print head, a recording head, a liquid discharge (ejection) head, or the like.

  The transport unit 14 transports the medium under the control of the control unit 11. Hereinafter, the description will be continued assuming that the medium conveyed by the conveyance unit 14 is a sheet (for example, the sheet 50 illustrated in FIG. 2), but materials other than the sheet are also used as a medium that receives liquid discharge. The transport unit 14 includes a roller that rotates to transport the paper 50 along a predetermined transport direction, a motor that generates power that rotates the roller, and the like. As an example, the transport unit 14 includes a paper feed (PF) motor 25 and a transport roller 26 that is rotated by the PF motor 25 and transports the paper 50 in the transport direction. Further, the transport unit 14 may include an automatic document feeder (ADF) that continuously transports the paper 50 from a document tray or a cassette (not shown). The transport direction intersects (orthogonally) the main scanning direction D1.

  The print head 13 receives ink supplied from, for example, a cartridge (not shown) that holds ink, and discharges the supplied ink from each nozzle under the control of the control unit 11. For example, the print head 13 ejects ink from each nozzle based on print data (raster data) representing an image to be printed. Printing is realized by the ink ejected from each nozzle landing on the paper 50 transported by the transport unit 14.

  As illustrated in FIG. 2, the printing apparatus 10 includes a motor control unit 21 that is a circuit for driving and controlling the CR motor 15. At least a part of the functions of the motor control unit 21 can be called a motor driver or the like. Further, the printing apparatus 10 includes a linear encoder 22 fixed to the carriage 12, a code plate 23 having slits formed at predetermined intervals along the main scanning direction D1, and a platen 24 that supports the paper 50 to be conveyed. And a pulley 30 attached to the rotating shaft of the CR motor 15 and a timing belt 31 driven by the pulley 30.

  The carriage 12 is connected to the CR motor 15 via a pulley 30 by a timing belt 31, and is guided by a guide member (not shown) to move along the main scanning direction D1. As is known, various information such as the moving direction and speed of the carriage 12 and the position and moving distance of the carriage 12 in the main scanning direction D1 can be acquired and calculated based on the pulse signal output from the encoder 22. The motor control unit 21 feeds back the drive of the CR motor 15 so that the carriage 12 moves at the target speed based on a predetermined target speed command of the carriage 12 sent from the CPU 20 and an output from the encoder 22. Control. The feedback control is so-called PID control or PI control.

  The motor control unit 21 corresponds to an example of a control unit that outputs a drive signal for driving the CR motor 15 to the CR motor 15 based on feedback control. Further, the motor control unit 21 may be regarded as a part of the control unit 11, and the control unit 11 may be interpreted as an example of a control unit that outputs the drive signal to the CR motor 15. Therefore, the processing executed by the motor control unit 21 described below may be interpreted as processing by the control unit 11.

  The display unit 16 is a part for displaying various information related to the printing apparatus 10 and is configured by, for example, a liquid crystal display (LCD). The display unit 16 also functions as a touch panel, for example. Although not specifically described, the printing apparatus 10 may have a known configuration or means (for example, input means) included in a printer or a multifunction peripheral.

2. First embodiment:
FIG. 3 is a flowchart showing print control processing according to the first embodiment. The flowchart is a process for realizing printing on one sheet of paper 50. Accordingly, when printing on a plurality of sheets 50 is continuously performed, the flowchart is repeatedly executed for the number of printed sheets.

  In step S <b> 100, the control unit 11 causes the transport unit 14 to execute the first paper feed. The first paper feed is a process of transporting the paper 50 to a predetermined position for receiving printing in the first pass. The first paper feed is also called cueing. The transport unit 14 drives the PF motor 25 and rotates the transport roller 26 to execute the first paper feed. A pass is a movement of the carriage 12 accompanied by liquid ejection by the print head 13. The first paper feed of the paper 50 by the transport unit 14 is a predetermined time for the transport unit 14 to receive printing by the first pass along the transport direction from the predetermined transport source (document tray, cassette, etc., not shown). It can be said that it is a part of the process of sending to a position.

  In step S110, the control unit 11 causes the first pass (first pass) to be executed. That is, the control unit 11 causes the motor control unit 21 to drive the CR motor 15 (movement of the carriage 12) and causes the print head 13 to perform liquid ejection based on the print data. As a result, printing in the first pass is performed on the paper 50 that is stationary on the platen 24 after the first paper feed. The first pass for the paper 50 corresponds to the first movement of the carriage 12. In step S110, the first measurement process is performed in parallel. The first measurement process will be described later with reference to FIG.

  In step S <b> 120, the control unit 11 causes the transport unit 14 to execute the next paper feed (second and subsequent paper feeds). The transport unit 14 drives the PF motor 25 and rotates the transport roller 26 to further feed the paper 50 along the transport direction by the distance of the instructed paper feed.

  In step S130, the control unit 11 causes the next pass (second and subsequent passes) to be executed. The control unit 11 causes the motor control unit 21 to drive the CR motor 15 (movement of the carriage 12) and causes the print head 13 to perform liquid ejection based on the print data. Thus, printing is performed on the paper 50 that is stationary on the platen 24 after the second and subsequent paper feeds. The second and subsequent passes for the paper 50 correspond to the second movement of the carriage 12 after the first movement. For each step S130, the abnormality presence / absence determination process is performed in parallel. The abnormality presence / absence determination process will be described later with reference to FIG.

  In step S140, the control unit 11 determines whether or not the path executed in the latest step S130 is the last path. That is, it is determined whether or not printing on the currently printing page (paper 50) is finished. If the path executed in the latest step S130 is the last path, the process proceeds to step S150, and if the path executed in the latest step S130 is not the last path, the processes in and after step S120 are repeated.

  In step S150, the control unit 11 causes the transport unit 14 to discharge (discharge) the paper 50. For example, the transport unit 14 rotates a paper discharge roller (not shown) by the PF motor 25 to further transport the paper 50 that has been printed, and discharge the paper 50 from a predetermined discharge port of the printing apparatus 10. Thus, the printing process on one sheet 50 is completed.

FIG. 4 is a flowchart showing the first measurement process executed along with the first pass.
In step S200, the motor control unit 21 determines whether or not the carriage 12 is moving in the constant speed section. If it is determined that the carriage 12 is moving in the constant speed section, the process proceeds to step S210. The constant speed section is a section in which the driving of the CR motor 15 is controlled so that the speed of the carriage 12 is maintained at a certain constant speed (constant speed). As is known, the movement of the carriage 12 along the main scanning direction D1 (the movement of the carriage 12 corresponding to one pass) accelerates from a stopped state and reaches a certain constant speed and then reaches the constant speed. It is controlled to move and then decelerate and stop. The motor control unit 21 performs such speed control of the carriage 12 (drive control of the CR motor 15) according to a predetermined speed curve (which may be referred to as a speed table, a speed profile, or the like). A section in which the carriage 12 accelerates according to the speed curve is referred to as an acceleration section, and a section in which the carriage 12 decelerates according to the speed curve is referred to as a deceleration section.

  For example, the motor control unit 21 determines whether or not the speed of the carriage 12 grasped based on the output from the encoder 22 has reached the constant speed. It can be determined that the vehicle is moving in the high speed section (“Yes” in step S200).

  Alternatively, the motor control unit 21 may determine whether or not the carriage 12 is moving in a constant speed section based on the passage of time after the carriage 12 starts moving. According to the speed curve, it can be said that the length of time (acceleration period) required for the carriage 12 to start acceleration from a stopped state and reach a constant speed is determined in advance. Therefore, when the time elapsed since the carriage 12 started moving exceeds the acceleration period, it can be determined that the carriage 12 has entered the constant speed section (“Yes” in step S200).

  Alternatively, the motor control unit 21 may determine whether or not the carriage 12 is moving in the constant speed section based on the moving distance of the carriage 12 after the carriage 12 starts moving. According to the speed curve, it can be said that the distance (acceleration section length) by which the carriage 12 moves from the stop state until acceleration reaches a constant speed is determined in advance. Therefore, when the movement distance of the carriage 12 after the carriage 12 starts moving exceeds the acceleration section length, it can be determined that the carriage 12 has entered the constant speed section (“Yes” in step S200). .

  In step S <b> 210, the motor control unit 21 starts measuring the drive signal output to the CR motor 15. The drive signal is a pulse signal that has been subjected to pulse width modulation (PWM) under the above-described feedback control. The motor control unit 21 measures the duty ratio of the pulse signal (the ratio of ON (High) in one cycle of the pulse) for each cycle of the pulse signal.

  After starting the measurement in step S210, the motor control unit 21 determines whether or not the movement of the carriage 12 in the constant speed section has ended (step S220). And when it determines with the movement of a constant speed area having been complete | finished (in step S220 "Yes"), the said measurement is complete | finished (step S230).

  As is known, the control unit 11 sets the range in which the carriage 12 moves for each pass (the movement start position and the movement stop position of the carriage 12 in one pass) by setting the print data or the preset value. It is determined on the basis of various printing conditions (the size of the paper 50, the print enlargement / reduction ratio, the margin (edge) width setting, etc.), the connection between passes, and the like. The motor control unit 21 controls the speed of the carriage 12 according to the speed curve so that the carriage 12 has a speed 0 at the end point of the movement range of the carriage 12 (the movement stop position of the carriage 12). Accordingly, when the end point of the movement range of the carriage 12 for each pass is determined, the start point of the deceleration section (= end point of the constant speed section) is also determined automatically. In other words, according to the speed curve, it can be said that the distance (deceleration section length) that the carriage 12 moves before the carriage 12 starts decelerating from the constant speed and becomes zero speed is determined in advance. The position before the end of the movement range of the carriage 12 by the length of the deceleration section is the start point of the deceleration section in the path (= end point of the constant speed section).

  In step S220, for example, the motor control unit 21 determines whether the position of the carriage 12 grasped based on the output from the encoder 22 has reached the start point of the deceleration section (= end point of the constant speed section) in the currently executed path. Determine whether or not. When the position of the carriage 12 reaches the start point of the deceleration section (= end point of the constant speed section), it can be determined that the movement of the constant speed section of the carriage 12 has ended.

  In step S240, the motor control unit 21 calculates the threshold value TH1 based on the result of the measurement executed during steps S210 to S230 (≈during the movement of the carriage 12 in the constant speed section). Specifically, an average value of the duty ratio measured by the measurement is calculated, and a value obtained by multiplying the average value by a predetermined coefficient (where the coefficient is greater than 1.0) is set as a threshold value TH1. . The motor control unit 21 updates the threshold value TH1 stored so far with the latest calculated threshold value TH1. The threshold value TH1 corresponds to an example of a first threshold value that is determined based on an average value of drive signals output during the first movement of the carriage 12 accompanied by liquid ejection by the print head 13. Step S240 corresponds to a threshold value determining step for determining the first threshold value.

  Thus, the first measurement process ends. In step S240, the motor control unit 21 may calculate a second threshold value (threshold value TH2) in addition to the threshold value TH1. The threshold value TH2 is higher than the threshold value TH1. The motor control unit 21 calculates the threshold value TH2 by, for example, multiplying the threshold value TH1 by some predetermined coefficient or adding a predetermined offset amount. The threshold value TH2 is information used in a second embodiment to be described later. The motor control unit 21 updates the previously stored threshold value TH2 with the calculated latest threshold value TH2.

FIG. 5 is a flowchart showing an abnormality presence / absence determination process executed with each pass after the second time.
Steps S300 to S330 are the same processes as steps S200 to S230 in FIG.
In step S340, the motor control unit 21 calculates an average value of the results of the measurement executed during steps S310 to S330 (≈during the movement of the carriage 12 in the constant speed section). That is, the motor control unit 21 calculates the average value of the duty ratio measured by the measurement between steps S310 to S330. For convenience, the average value calculated in step S340 is expressed as Duty_ave. Steps S300 to S340 may be referred to as a second measurement process. The average value Duty_ave corresponds to an example of an average value of drive signals output during the second movement of the carriage 12 accompanied by the liquid ejection by the print head 13 after the first movement.

  In step S350, the motor control unit 21 determines whether or not the average value Duty_ave calculated in step S340 exceeds the latest threshold value TH1. If average value Duty_ave> threshold value TH1, the process proceeds to step S360, and if average value Duty_ave ≦ threshold value TH1, the flowchart (abnormality presence / absence determination process) ends.

  In step S360, the control unit 11 determines that an abnormality has occurred in printing (the currently executed pass) (makes an abnormality determination). As the abnormality mentioned here, the rubbing (paper rubbing) between the paper 50 and the print head 13 is mainly assumed. When the control unit 11 makes an abnormality determination, the control unit 11 ends the flowchart of FIG. 3 while executing the abnormality handling process. Steps S350 and S360 correspond to a determination process. The control unit 11 stops printing as the abnormality handling process. That is, the control unit 11 stops driving the print head 13, the CR motor 15, and the transport unit 14. The determination in step S350 is executed at a timing immediately after the end of the movement of the carriage 12 in the constant speed section of the currently executed pass (the second and subsequent passes with respect to the paper 50). When S360) is issued, printing stops in the middle of the currently executed pass (for example, the beginning of the deceleration zone).

  Thus, by stopping printing according to the abnormality determination, it is possible to prevent trouble (further deformation of the paper 50 and paper jam) due to paper rubbing. The control unit 11 may further notify the outside that an abnormality has occurred as an abnormality handling process. For example, the control unit 11 causes the display unit 16 to display a message for notifying that there is a possibility that paper rubbing has occurred and that printing has been stopped. Alternatively, the control unit 11 may output such a message by voice from a speaker (not shown). By recognizing such a message, the user can take appropriate measures such as taking out the paper 50 that has stopped being transported by the transport unit 14 from the printing apparatus 10.

  FIG. 6 exemplifies changes in the speed of the carriage 12 and the duty ratio measured as described above, corresponding to one pass (any pass after the second pass). In FIG. 6, the horizontal axis represents time (msec), and the vertical axis represents the speed of the carriage 12 and the duty ratio (Duty (%)). In FIG. 6, a change in the target speed Vref of the carriage 12 is indicated by a one-dot chain line. The target speed Vref is a speed determined by the speed table described above. In FIG. 6, a change in the actual speed Vcr of the carriage 12 (the speed of the carriage 12 grasped based on the output from the encoder 22) is shown by a solid line. In FIG. 6, the change in the duty ratio (Duty (%)) is indicated by a two-dot chain line.

  Further, in FIG. 6, the carriage 12 movement period (acceleration period R1) corresponding to the acceleration section, the carriage 12 movement period (constant speed period R2) corresponding to the constant speed section, and the carriage 12 movement period corresponding to the deceleration section. (Deceleration period R3) is shown. FIG. 6 illustrates the above-described threshold value TH1 and threshold value TH2.

  The duty ratio (Duty (%)) tends to increase as the load on the CR motor 15 increases. Therefore, when the paper rubbing has occurred, the duty ratio (Duty (%)) becomes higher overall as compared with the case where the paper rubbing has not occurred. In view of such circumstances, in the present embodiment, abnormality determination processing (FIG. 5) is also executed in each pass after the second time, and abnormality determination is made if average value Duty_ave> threshold value TH1. I am doing so.

  As described above, according to the present embodiment, the control units (11, 21) average the drive signals output to the CR motor 15 during the first movement (first pass) of the carriage 12 accompanied by the liquid ejection by the print head 13. The threshold value TH1 is determined based on the value, and the average of the drive signals output during the second movement (second and subsequent passes) of the carriage 12 accompanied by the liquid ejection by the print head 13 after the first movement. When the value Duty_ave exceeds the threshold value TH1, it is determined that there is an abnormality. According to this configuration, the control unit (11, 21) can appropriately determine whether an abnormality, that is, paper rubbing has occurred during the second movement of the carriage 12. The drive signal (pulse signal) is naturally output under feedback control in order to drive the CR motor 15. Therefore, the printing apparatus 10 does not require a current sensor or the like to determine the threshold value TH1, and can reduce the cost required for the configuration for determining the abnormality.

  The CR motor 15 generates heat as printing on the paper 50 is repeated. The drive amount (the duty ratio) of the CR motor 15 required for the same load differs between when the CR motor 15 is heated and when it is not, and when the CR motor 15 generates heat, A large amount of drive is required. Therefore, it is preferable that the reference (threshold value TH1) for determining whether or not the sheet rubbing has occurred is determined based on the state of the CR motor 15 at that time. According to the present embodiment, the control unit (11, 21) executes the first measurement process (FIG. 4) along with the first pass in printing for one sheet 50 (one page). Thus, the threshold value TH1 is updated for each page of the paper 50. According to such a configuration, while printing on a plurality of sheets of paper 50 is continuously performed, an increase in the value of the drive signal (increase in the duty ratio) due to the influence of heat generated by the CR motor 15 is present. The determination in step S350 (FIG. 5) can be performed using the optimum threshold value TH1 according to the situation.

  Furthermore, according to the present embodiment, the control unit (11, 21) is in a constant speed section for driving and controlling the CR motor 15 so that the speed of the carriage 12 in the first movement (first pass) is constant. Based on the average value of the drive signals output during the movement, the threshold value TH1 is determined (see FIG. 4), and the movement in the constant speed section of the second movement (each pass after the second time) is completed. At the timing, it is determined whether or not the average value Duty_ave of the drive signal output during the movement in the constant speed section of the second movement exceeds the threshold value TH1 (see FIG. 5). According to this configuration, it is possible to determine whether or not an abnormality (paper rubbing) has occurred during the movement of the constant speed section in the second movement every time the movement of the constant speed section ends.

  In order to avoid the occurrence of paper rubbing as much as possible, a certain distance (platen gap) is secured between the platen 24 and the print head 13. In such a situation, the paper rubbing often occurs when the paper 50 that has received the liquid is swollen and curled (curved) by the liquid. Therefore, as printing on a single sheet 50 proceeds, the sheet 50 curls and approaches the print head 13. In other words, the paper 50 is hardly rubbed with the print head 13 before the paper 50 is subjected to the liquid ejection or at a timing just after the liquid ejection. Therefore, according to the configuration in which the first measurement process is executed along with the first pass for the paper 50 as in the present embodiment, the first measurement process can be executed in a situation where there is no paper rubbing. Therefore, it is possible to reasonably obtain a reference (threshold value TH1) for determining whether or not paper rubbing has occurred.

  The present invention is not limited to the above-described embodiments, and for example, embodiments and modifications as described below can be further employed.

3. Second embodiment:
As described above, the control unit (11, 21) determines the threshold value TH1 and the threshold value TH2 higher than the threshold value TH1 (step S240 in FIG. 4). Then, the controller (11, 21) performs the second abnormality presence / absence determination process in addition to the above-described abnormality presence / absence determination process (FIG. 5) in the second and subsequent passes (step S130 in FIG. 3). May be executed.

  FIG. 7 is a flowchart in which a second abnormality presence / absence determination process is added to FIG. In FIG. 7, the flow indicated by the two-dot chain line is the second abnormality presence / absence determination process. Also in FIG. 7, the flow of the abnormality presence / absence determination process is as described with reference to FIG. According to the second abnormality presence / absence determination process, the control unit (11, 21) executes step S315, for example, after the start of measurement (step S310), and in step S315, the drive signal exceeds the threshold value TH2. (Determine whether the measured duty ratio> threshold value TH2?). Such determination in step S315 is repeatedly performed until the movement of the constant speed section in the current path is completed (until “Yes” is determined in step S320). Further, when it is determined as “Yes” in step S320, the second abnormality presence determination process ends. When it is determined in step S315 that the duty ratio> threshold value TH2 is satisfied, the control unit (11, 21) makes an abnormality determination (step S360).

  According to the second embodiment, not only the abnormality presence / absence determination process (FIG. 5) described in the first embodiment but also the second abnormality presence / absence determination process is executed. As a result, when the drive signal temporarily becomes high enough to exceed the threshold value TH2 during the movement of the constant speed section in the second movement (second and subsequent passes) of the carriage 12, an abnormality is immediately detected. Judgment can be made. As a result, it is possible to more quickly prevent an increase in trouble due to paper rubbing.

  The printing apparatus 10 is subjected to a vibration test before being shipped from the factory to the market. The vibration test is a test for determining whether or not the printing apparatus 10 can continue printing with a certain level of image quality even when a predetermined vibration is externally applied to the printing apparatus 10. During the vibration test, the speed Vcr of the carriage 12 is disturbed due to the applied vibration even in the constant speed section. Therefore, the duty ratio (Duty ( %)) Is not stable. In such a situation, if the printing apparatus 10 adopts the control that the abnormality determination is made immediately if the duty ratio measured in the constant speed section> the threshold value TH1 is satisfied, the printing apparatus 10 is almost In such a case, the vibration test cannot be passed, and there is a problem that the product cannot be shipped. On the other hand, if any abnormality occurs in the movement of the carriage 12, it can be said that it is desirable to stop the printing as quickly as possible to prevent the damage from spreading. In view of these situations, in the present embodiment, as described above, during the movement of the carriage 12 in the constant speed section, when the duty ratio to be measured exceeds the threshold value TH2 higher than the threshold value TH1, it is immediately performed. After the movement of the carriage 12 in the constant speed section is finished, the abnormality determination is made when the average value Duty_ave exceeds the threshold value TH1. By adopting such a configuration, the problem that the printing apparatus 10 cannot pass the vibration test is solved, and when a relatively large abnormality occurs, the abnormality determination is made immediately.

4). Third embodiment:
The control unit (11, 21) also determines that an abnormality has occurred even when the deviation between the predetermined target speed of the carriage 12 and the speed of the carriage 12 exceeds a predetermined allowable range (makes an abnormality determination). , An abnormality handling process may be performed). The deviation is a difference between the target speed Vref and the speed Vcr with reference to FIG. When an abnormality such as paper rubbing occurs, the deviation tends to increase due to a change in the load of the CR motor 15. The allowable range is stored in a ROM or the like included in the control unit 11 and is defined by an upper limit value for a deviation on the higher speed side than the target speed Vref and a lower limit value for a deviation on the lower speed side than the target speed Vref. .

  During the movement of the carriage 12, the control unit (11, 21) causes the speed Vcr to deviate from the range (allowable range) of the lower limit value to the upper limit value based on the target speed Vref, that is, the deviation exceeds the allowable range. Even in this case, an abnormality determination is made in the same manner as in step S360 (FIGS. 5 and 7), and an abnormality handling process is performed. Such a determination as to whether or not the deviation exceeds the allowable range is performed regardless of whether the first pass or the second and subsequent passes. By adopting the third embodiment on the premise of the first embodiment or the second embodiment, the printing apparatus 10 can determine whether or not an abnormality (paper rubbing) has occurred during the movement of the carriage 12. Can be determined.

  The allowable range need not be constant over the movement range of the carriage 12. That is, the allowable range is set to a value suitable for each of the acceleration section, constant speed section, and deceleration section of the carriage 12. As an example, the allowable range corresponding to the acceleration section may be wider than the allowable range corresponding to the constant speed section. In the acceleration section, since the speed of the carriage 12 is controlled to increase to a predetermined constant speed in a short time, the instantaneous speed Vcr is likely to be disturbed with respect to the target speed Vref. In view of such a situation, by setting the allowable range corresponding to the acceleration section wider than the allowable range corresponding to the constant speed section, an erroneous determination (abnormality such as paper rubbing has occurred in the acceleration section). It is possible to avoid making an abnormality determination).

5. Variations:
The controller 11 may stop the printing and further increase the height from the paper 50 to the print head 13 as the abnormality handling process. In this case, the control unit 11 controls the drive mechanism (not shown) for adjusting the position of the carriage 12 in the height direction (vertical direction), so that the position of the carriage 12 in the height direction is set higher than the current position. Change to a higher position. Thereby, the platen gap is widened, and as a result, the height from the paper 50 to the print head 13 is widened. By increasing the height from the paper 50 to the print head 13, it is possible to prevent paper rubbing from occurring in subsequent printing. Note that the timing of changing the position of the carriage 12 to a position higher than the current position may be immediately after the abnormality determination is made, or after making the abnormality determination, a new print is performed according to a user instruction. It may be just before the printing apparatus 10 starts.

  In step S240 (FIG. 4), the average value of the duty ratio calculated to determine the threshold value TH1 is not only the duty ratio obtained by the measurement during the movement of the carriage 12 in the constant speed section, but also the fixed ratio. It may be an average value calculated including the duty ratio obtained by (at least a part of) the measurement in the acceleration section immediately before the speed section. Similarly, the average value Duty_ave of the duty ratio calculated in step S340 (FIGS. 5 and 7) is not only the duty ratio obtained by the measurement during the movement of the carriage 12 in the constant speed section, but also immediately before the constant speed section. It may be an average value calculated including the duty ratio obtained by (at least a part of) the measurement in the acceleration section. In addition, the average value described so far may be a value obtained by multiplying the average value by some correction coefficient instead of the average value itself.

  The carriage 12 reciprocates along the main scanning direction D1. Here, the movement of the carriage 12 from one end side to the other end side in the main scanning direction D1 is referred to as forward movement, and the movement of the carriage 12 from the other end side to the one end side in the main scanning direction D1 is referred to as backward movement. To do. Therefore, the determination using the threshold value TH1 and the threshold value TH2 described above and the determination using the allowable range may be executed for each of the forward movement and the backward movement.

  That is, the above-mentioned first pass (step S110, FIG. 2) actually indicates each of the first forward movement and the first backward movement for one sheet 50. Therefore, the first measurement process (FIG. 4) is also executed with each of the first forward movement and the first backward movement, and the threshold value TH1, TH1 is obtained by the first measurement process executed with the first forward movement. TH2 (threshold values TH1 and TH2 for the forward path) is obtained, and threshold values TH1 and TH2 (threshold values TH1 and TH2 for the return path) are obtained by the first measurement process executed in association with the first return path movement. It is done. In this case, paper feeding is executed once between the first forward movement and the first backward movement, and the “second paper feeding” in step S120 is actually the first forward movement and the first backward movement. It is paper feeding after. The second and subsequent passes in step S130 indicate the second and subsequent forward movements for the single sheet 50 and the second and subsequent backward movements, respectively. Accordingly, the abnormality presence / absence judgment processing (FIG. 5 or FIG. 7) executed with each pass after the second time is performed in accordance with the abnormality presence / absence judgment processing executed with the second or subsequent outward movement. It can be divided into the abnormality presence / absence determination processing that is executed along with the movement. In this case, as a matter of course, the abnormality presence / absence determination process executed with the second and subsequent outward movements performs determination using the forward thresholds TH1 and TH2, and the abnormality executed with the second and subsequent backward movements. In the presence / absence determination processing, determination using the return path thresholds TH1 and TH2 is performed.

  Considering that the carriage 12 reciprocates, in the third embodiment, the allowable range for the forward path for comparing with the deviation when the carriage 12 moves in the forward path is compared with the deviation when the carriage 12 moves in the backward path. Therefore, the allowable range for the return path is stored in advance in a ROM or the like included in the control unit 11. Then, the control unit (11, 21) performs determination using the allowable range for the forward path during the forward movement of the carriage 12, and determines using the allowable range for the backward path during the backward movement of the carriage 12. I do.

  If the CR motor 15 is subjected to PID control, the duty ratio to be measured depends on the sum of the proportional (P) control amount, the integral (I) control amount, and the differential (D) control amount. Value. The proportional (P) control amount is a value obtained by multiplying the proportional term (deviation) by a predetermined constant, and the integral (I) control amount is a value obtained by multiplying the integral term of the deviation by a predetermined constant, and the differential (D ) The control amount is a value obtained by multiplying the change amount of the deviation (differential term) by a predetermined constant. Further, the duty ratio to be measured may be a value corresponding to the sum of the proportional (P) control amount and the integral (I) control amount if the CR motor 15 is PI controlled. Of these control amounts, the integral (I) control amount has the greatest influence on the actual control amount (the duty ratio). Therefore, the threshold value T1 and the average value Duty_ave described so far may be obtained based on the average of the integral (I) control amount instead of obtaining the averaged duty ratio.

DESCRIPTION OF SYMBOLS 10 ... Printing apparatus, 11 ... Control part, 12 ... Carriage, 13 ... Print head, 14 ... Conveyance part, 15 ... CR motor, 16 ... Display part, 20 ... CPU, 21 ... Motor control part, 22 ... Linear encoder, 23 ... Code plate, 24 ... Platen, 25 ... PF motor, 26 ... Conveying roller, 30 ... Pulley, 31 ... Timing belt, D1 ... Main scanning direction, R1 ... Acceleration period, R2 ... Constant speed period, R3 ... Deceleration period, TH1... (First) threshold, TH2... (Second) threshold

Claims (9)

A printing apparatus that performs printing by discharging liquid from the head to a medium while moving a carriage mounted with a head capable of discharging liquid in the main scanning direction,
A motor for moving the carriage in the main scanning direction;
A control unit that outputs a drive signal for driving the motor based on feedback control to the motor, and
The control unit determines a first threshold value based on an average value of the drive signals output during the first movement of the carriage accompanied by liquid ejection by the head, and is later than the first movement. When the average value of the drive signal output during the second movement of the carriage accompanied by the liquid ejection by the head exceeds the first threshold value, it is determined as abnormal.
A printing apparatus characterized by that.   The first movement is the first movement of the carriage in printing for one page of the medium, and the control unit updates the first threshold value for each page of the medium. The printing apparatus according to claim 1.   The control unit is configured to control the first driving signal based on an average value of the driving signals output when moving in a constant speed section that controls driving of the motor so that the speed of the carriage is constant. 1 is determined, and at the timing when the movement of the constant speed section of the second movement ends, the drive signal output during the movement of the constant speed section of the second movement The printing apparatus according to claim 1, wherein it is determined whether an average value exceeds the first threshold value.   The control unit determines a second threshold value that is higher than the first threshold value, and the drive signal remains in the first state until the movement of the constant speed section of the second movement is completed. The printing apparatus according to claim 3, wherein it is determined whether or not a threshold value of 2 is exceeded, and an abnormality is determined when the drive signal exceeds the second threshold value.   2. The control unit according to claim 1, wherein the controller determines that an abnormality occurs even when a deviation between a predetermined target speed of the carriage and a speed of the carriage exceeds a predetermined allowable range. 5. The printing apparatus according to any one of 4.   The allowable range corresponding to an acceleration section in which the control unit controls the driving of the motor to accelerate the carriage is controlled by the control unit so that the speed of the carriage is constant. The printing apparatus according to claim 5, wherein the printing apparatus is wider than the allowable range corresponding to a constant speed section following the acceleration section.   The printing apparatus according to claim 1, wherein the control unit stops printing when it determines that the abnormality has occurred, and notifies the outside that an abnormality has occurred.   8. The printing apparatus according to claim 1, wherein when the controller determines that the abnormality is present, printing is stopped, and a height from the medium to the head is increased. 9. An abnormality determination method executed by a printing apparatus that performs printing by discharging liquid from the head to a medium while moving a carriage mounted with a head capable of discharging liquid in the main scanning direction,
Based on an average value of drive signals for driving the motor that is output based on feedback control during the first movement of the carriage accompanied by liquid ejection by the head to the motor that moves the carriage in the main scanning direction. A threshold value determining step for determining a first threshold value;
An average value of the drive signals output to the motor based on the feedback control during the second movement of the carriage accompanied by liquid ejection by the head after the first movement is the first threshold. And a determination step of determining an abnormality when the value is exceeded.

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