JP2018144903A - Recording device and conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording device which can highly accurately detect information about a sheet which is conveyed without installing an additional sensor or the like.SOLUTION: A recording device comprises: recording means; a conveyance roller 1; a pinch roller 2 which faces the conveyance roller 1; a motor 3 for giving a driving force to the conveyance roller 1; detection means 5 for detecting at least one of the rotation speed or the rotation position of the conveyance roller 1; and generation means 7 for generating a drive command for driving the motor 3 on the basis of a detection value of the detection means 5. It detects sheet information on the basis of a detection value of the rotation speed within a prescribed time period during which an end part of a sheet passes a nip part between the conveyance roller 1 and the pinch roller 2. The generation means 7 switchably executes a first control mode for generating a drive command in which effects of the detection value of the detection means 5 is relatively large and a second control mode for generating a drive command in which effects of the detection value is relatively small. The second control mode is executed during the prescribed time period during which the sheet information is detected.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a recording apparatus and a conveying apparatus.

2. Description of the Related Art Conventionally, in a recording apparatus such as an ink jet printer or a copying machine, a transport apparatus that transports a sheet-like recording medium while being sandwiched between rollers is often used. In recent years, such a recording apparatus has a high demand for high image quality, and the conveyance apparatus is also required to convey a recording medium with high conveyance accuracy. In order to transport the recording medium with high accuracy, there is a limit only by improving the processing accuracy of the mechanical parts, and the transport method is changed based on information on the transported recording medium, such as thickness, width, skew state, etc. It is effective. However, providing various sensors for detecting such information in the transport apparatus complicates the apparatus and causes an increase in cost. Therefore, a method for detecting such information without providing a new sensor or the like is desired.
Patent Document 1 describes a method for obtaining the thickness of a sheet-like member from the detection result of the rotational angular velocity of the roller at the timing when the sheet-like member enters the roller pair or is discharged. When the sheet-like member enters or exits the roller pair, a load torque fluctuation occurs in the roller. In the above method, the sheet-like member is detected from the change in the rotational angular velocity of the roller caused by the load torque fluctuation. Can be obtained.

JP 2009-203011 A

However, the method described in Patent Document 1 has the following problems. In other words, since the drive motor that drives the roller is controlled to rotate the roller at a predetermined speed, it operates so as to suppress the speed fluctuation of the roller due to the load torque fluctuation, and as a result, it is desired to detect. Roller speed fluctuation is suppressed. Actually, the speed fluctuation is not completely suppressed with respect to the sudden load torque fluctuation, but the speed fluctuation amount still decreases, so that the S / N ratio is lowered and the detection accuracy is deteriorated. Become.
Accordingly, an object of the present invention is to provide a recording apparatus and a conveying apparatus that can detect information relating to a conveyed sheet with high accuracy without providing a new sensor or the like.

In order to achieve the above-described object, the recording apparatus of the present invention includes a recording unit that records an image on a sheet, a conveying roller that conveys the sheet, a pinch roller that faces the conveying roller and sandwiches the sheet together with the conveying roller, A motor for applying a driving force to the conveying roller; a detecting means for detecting at least one of the rotational speed and rotational position of the conveying roller; and a generating means for generating a driving command for driving the motor based on a detection value by the detecting means. The sheet skew state information, the thickness information, the width based on the rotational speed detected by the detection means during a predetermined period when the end of the sheet passes through the nip portion between the conveyance roller and the pinch roller The recording device detects sheet information including at least one of information and conveyance position information, and the generation unit generates a drive command that is relatively influenced by the detected value. The first control mode is switched to the second control mode that generates a drive command that is relatively less influenced by the detection value, and the second control mode is executed during a predetermined period in which the sheet information is detected. It is executed.
The conveying device of the present invention includes a conveying roller that conveys a sheet, a pinch roller that faces the conveying roller and sandwiches the sheet together with the conveying roller, a motor that applies driving force to the conveying roller, and the rotation speed and rotation of the conveying roller. A detecting unit that detects at least one of the positions, and a generating unit that generates a drive command for driving the motor based on a value detected by the detecting unit. The sheet includes the nip portion between the conveying roller and the pinch roller. Detecting sheet information including at least one of sheet skew state information, thickness information, width information, and conveyance position information based on the rotation speed detected by the detection means during a predetermined period during which the end of the sheet passes. In the transport apparatus, the generation unit generates a drive command that has a relatively large influence by the detection value, and the influence by the detection value is relatively small. By switching the second control mode for generating the dynamic instruction run, the second control mode is characterized in that the sheet information is performed in a predetermined period is detected.

  According to the present invention, it is possible to provide a recording apparatus and a conveying apparatus that can detect information on a conveyed sheet with high accuracy without providing a new sensor or the like.

It is a perspective view which shows the internal structure of an inkjet printer. It is a perspective view which shows the structure of a conveyance part. It is a conceptual diagram which shows the biting conveyance force required when a recording medium is bitten. It is a graph which shows the load torque fluctuation | variation and rotation speed fluctuation | variation of a main conveyance roller. It is a block diagram which shows the structure of the drive control part of a conveyance motor. It is a block diagram which shows the structure of the drive command production | generation part of 1st Embodiment. It is a flowchart which shows the motor drive control method of 1st Embodiment. It is a graph which shows the rotational speed fluctuation | variation at the time of the drive control of 1st Embodiment. It is a graph which shows the relationship between a skew state, load torque, and rotational speed. It is a graph which shows the relationship between the thickness of a recording medium, load torque, and rotational speed. It is a block diagram which shows the structure of the drive command production | generation part of 2nd Embodiment. It is a flowchart which shows the motor drive control method of 2nd Embodiment. It is a graph which shows the rotational speed fluctuation | variation at the time of the drive control of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present specification, the case of applying the present invention to an ink jet printer will be described as an example. Note that members, numerical values, materials, and the like used in the following description are merely examples for the purpose of helping understanding, and are not intended to limit the present invention.

(First embodiment)
First, with reference to FIG. 1, an outline of the configuration and operation of an ink jet printer to which a transport apparatus according to a first embodiment of the present invention is applied will be described. FIG. 1 is a perspective view showing the internal structure of the ink jet printer according to the present embodiment.

  An ink jet printer (recording apparatus) 10 includes a recording unit that records an image on a recording medium, a feeding unit that feeds the recording medium, a transport unit that transports the recording medium, and a control unit that controls the operation of each unit. Have. Hereinafter, the configuration and operation of each unit will be described.

(Recording part)
The recording unit records an image on a recording medium by a recording head (not shown) mounted on the carriage 11. The recording head is positioned above the platen 15 that supports the recording medium from below, and ejects ink onto the recording medium that is transported to a predetermined position by a transport unit described later to record an image corresponding to the image data. The carriage 11 is driven by a carriage motor 12 via a timing belt 13 and can move in the movement direction X on the guide rail 14. The recording head discharges ink onto the recording medium while the carriage 11 moves in the movement direction X, whereby image recording is performed along the width direction of the recording medium.

(Feeding department)
The feeding unit is provided upstream of the recording unit in the conveyance direction of the recording medium, and separates the stacked recording media one by one and conveys them to the conveyance unit. The feed roller 17 is rotationally driven by a feed motor 18 via a drive transmission gear (not shown). The feed motor 18 is rotationally detected and controlled by a code wheel and an encoder sensor (both not shown). As the feeding roller 17 rotates, the recording medium loaded on the pressure plate 16 is sent to the nip portion between the feeding roller 17 and the separation roller, and only the uppermost recording medium separated by the nip portion is conveyed. Is done. The separated and transported recording medium is transported by a paper feed (PF) roller that is rotationally driven by a feed motor 18 and a PF pinch roller (both not shown) opposed thereto, and sent to a transport unit. The PF roller is configured to perform a registration operation for correcting the skew of the recording medium in cooperation with the conveyance unit before the recording operation, in addition to the conveyance of the recording medium to the conveyance unit.

(Transport section)
The conveyance unit is provided downstream of the feeding unit in the conveyance direction of the recording medium, and conveys the recording medium fed from the feeding unit with high accuracy. The conveyance of the recording medium by the conveyance unit is mainly performed by a main conveyance roller 1 and a discharge roller (not shown) that are rotationally driven by a conveyance motor (not shown). The conveyance motor is a DC motor, and the recording medium is conveyed by a predetermined amount while detecting the rotation of the main conveyance roller 1 by a code wheel and an encoder sensor (both not shown) provided coaxially with the main conveyance roller 1. Drive control is performed. After the conveyance of the recording medium by the conveyance unit and the image recording by the recording unit described above are repeatedly performed, the recording medium is discharged to the outside of the printer 10 by the discharge roller, and a series of image recording operations is completed.

  Here, with reference to FIG. 2, the configuration of the transport unit and the details of the recording medium transport operation centered on the transport unit will be described. FIG. 2 is a perspective view showing the structure of the transport unit of the present embodiment.

The transport unit includes a main transport roller 1, a plurality of pinch rollers 2, a transport motor 3, a code wheel 4, and an encoder sensor 5. As shown in FIG. 2, main mechanism components of the transport unit are attached to the main side plate 20, the right side plate 21, and the left side plate 22.
The main conveyance roller 1 conveys a sheet-like recording medium. The main transport roller 1 has a configuration in which ceramic fine particles are coated on the surface of a metal shaft, and is supported by a right side plate 21 and a left side plate 22 at both ends of the metal shaft. On the upstream side of the main conveyance roller 1 in the conveyance direction Y of the recording medium, the PF roller 23 that conveys the recording medium to the conveyance unit and the PF roller 23 that is urged by the spring are rotated. And a PF pinch roller 24 that rotates in response to the rotation. A path from the PF roller 23 to the main conveyance roller 1 is provided with a pinch roller holder 25 that guides the recording medium and a PF guide (not shown) that faces the recording medium, and these form a conveyance path for the recording medium. doing. Further, in this path, there are provided a rotary lever 26 for detecting the passage of the leading end and the trailing end of the recording medium, and a paper edge sensor 27 for detecting the rotation of the lever 26.

The plurality of pinch rollers 2 are arranged to face the main transport roller 1, sandwich the recording medium together with the main transport roller 1, and are supported by the pinch roller holder 25. The pinch roller 2 is driven so that the pinch roller holder 25 is driven by the rotation of the main transport roller 1 when the pinch roller holder 25 receives a moment from the pinch roller spring 28 and is urged against the main transport roller 1. 1 is press-contacted.
The conveyance motor 3 gives a driving force to the main conveyance roller 1, and is connected to a pulley gear 31 provided on the axis of the main conveyance roller 1 via a conveyance motor pulley 29 and a timing belt 30. The main conveyance roller 1 is rotationally driven by transmitting a driving force from the conveyance motor 3 through these.

  As described above, the code wheel 4 is directly connected on the same axis of the main transport roller 1, and the encoder sensor 5 is provided on the left side plate 22 so as to face the code wheel 4. The code wheel 4 has slits formed at a pitch of 150 to 360 lpi (line / inch). The encoder sensor 5 detects this slit and outputs a pulse signal corresponding to the rotation of the main transport roller 1. Thus, the encoder sensor 5 functions as detection means for detecting the rotation speed and rotation position (rotation angle) of the main transport roller 1.

  A discharge roller 34 including a metal shaft and a rubber roller inserted through the metal shaft is provided downstream of the main transport roller 1 in the recording medium transport direction Y. The discharge roller 34 is rotationally driven by the driving force from the gear portion of the pulley gear 31 being transmitted to the discharge roller gear 33 via the idler gear 32. A plurality of spurs 35 attached to a spur holder (not shown) are provided at a position facing the discharge roller 34. These spurs 35 are pressed against the discharge roller 34 by a spur spring 36 formed of a bar-shaped coil spring.

In such a configuration, when performing the recording operation, first, the recording medium is conveyed from the feeding unit to the conveying unit, and the leading end of the recording medium is a nip portion between the main conveying roller 1 and the pinch roller 2. Is conveyed to a position that passes a predetermined amount. At this time, the feed motor 18 and the transport motor 3 are controlled so that the PF roller 23 and the main transport roller 1 operate in synchronization. The position control of the recording medium is performed by controlling the rotational position of the main transport roller 1 assuming that the recording medium is ideally transported with the rotation of the PF roller 23 and the main transport roller 1. The position of the recording medium is not directly detected.
When the leading edge of the recording medium is conveyed to a position where it passes through the nip portion by a predetermined amount, a registration operation for correcting the skew of the recording medium is performed. In the registration operation, the main conveyance roller 1 is rotated in the reverse direction with the PF roller 23 stopped, the leading edge of the recording medium is escaped from the nip portion, and the skew is corrected by following the nip portion. Alternatively, the recording medium is temporarily fed back to the upstream side of the nip, and then the PF roller 23 is rotated forward, and the leading end of the recording medium is pressed against the nip while the main conveyance roller 1 is reversed or stopped. You can also
After completion of the registration operation, the recording medium is conveyed to the recording unit, and the above-described image recording is repeatedly performed. When all the images have been recorded, the recording medium is discharged to the outside of the printer 10 by the discharge roller 34, and the recording operation is completed.

Here, referring to FIG. 3 and FIG. 4, when the leading edge of the recording medium passes through a nip portion (hereinafter also referred to as “roller nip portion”) between the main conveyance roller 1 and the pinch roller 2, the main conveyance roller. A phenomenon in which the rotation speed of 1 is changed will be described.
FIG. 3 is a conceptual diagram showing the biting and conveying force required when the leading edge of the recording medium P is bitten by the roller nip portion. As shown in FIG. 3, when the leading end of the recording medium P is caught in the roller nip portion, the pinch roller pressure generated by the pinch roller spring 28 acts on the recording medium P as a paper pressure contact force via the pinch roller 2. To do. In order for the recording medium P to be bitten into the roller nip portion, the main conveying roller 1 that is in contact with the recording medium P generates a pressure reaction force and a biting and conveying force that are balanced with the above-mentioned sheet pressure contact force. There is a need. Here, the biting and conveying force is a force in the rotation direction of the main conveying roller 1 and is a force added to the torque for rotating the main conveying roller 1. That is, when the leading end of the recording medium P is bitten into the roller nip portion, the load torque varies by the biting and conveying force.

FIG. 4A shows how the load torque fluctuates. Load torque shown, and the pinch roller pressure, the pinch roller 2, the main transport roller 1 is obtained by theoretically calculated from the geometric positional relationship of the recording medium P, t ₀ is the starting time biting. FIG. 4B shows how the main conveyance roller 1 changes in rotational speed when the load torque changes as shown in FIG. Here, the rotational speed fluctuation when the drive control of the conveyance motor 3 to be described later is not switched is shown.
As shown in FIG. 4B, at the time t ₀ when the biting into the roller nip portion is started, the rotational speed is instantaneously decreased due to a sudden increase in the load torque. Thereafter, as will be described later, the transport motor 3 is controlled to follow the position command. Therefore, when the rotational speed decreases and the deviation from the position command increases, the drive command increases and the speed fluctuation is suppressed. The FIG. 4B shows a simulation result for easy understanding of the explanation of the phenomenon, but it has been confirmed by the present inventors that the same situation occurs in an actual ink jet printer. . The same applies to the graphs showing the rotational speed fluctuations shown in the following description.

  As described above, when the leading edge of the recording medium is caught in the roller nip portion, load torque fluctuations due to the pinch roller pressure are generated, and accordingly, rotational speed fluctuations are generated. Since the rotational speed fluctuation accompanying the load torque fluctuation varies depending on the skew state and thickness of the recording medium, it is possible to detect various information about the recording medium by detecting the rotational speed fluctuation. Although details of these detections will be described later, in this embodiment, the rotational speed of the main transport roller 1 when the recording medium is fed and transported and is caught in the nip portion between the main transport roller 1 and the pinch roller 2. Based on the above, various information about the recording medium is detected.

(Control part)
Hereinafter, with reference to FIG. 5 and FIG. 6, the configuration of the control unit, particularly, the configuration related to the drive control of the conveyance motor 3 which is a major feature of the present invention will be described. FIG. 6 is a block diagram illustrating a configuration of the drive control unit of the transport motor 3, and FIG. 7 is a block diagram illustrating a configuration of the drive command generation unit 7.

As shown in FIG. 5, the drive control unit of the carry motor 3 includes a motor driver 6 that supplies power to the carry motor 3 and a drive command generator that is a generation unit that generates a drive command for driving the carry motor 3. 7. The drive command generated by the drive command generation unit 7 is given to the motor driver 6, and accordingly, electric power is supplied from the motor driver 6 to the transport motor 3.
The motor driver 6 includes a PWM signal generator 42 and an inverter 43. The PWM signal generation unit 42 generates a PWM signal that is a pulse signal that is pulse-width modulated in accordance with a drive command that is a voltage command value input from the drive command generation unit 7. The inverter 43 is an H bridge circuit composed of four switching elements. The switching element is turned ON / OFF according to the PWM signal input from the PWM signal generation unit 42, whereby a drive current is supplied to the transport motor 3 and the transport motor 3 rotates.
As described above, the rotation of the main conveyance roller 1 that is rotationally driven with the rotation of the conveyance motor 3 is detected by the code wheel 4 and the encoder sensor 5. Based on the pulse signal output from the encoder sensor 5, the rotation speed calculation unit 44 and the rotation position calculation unit 45 perform arithmetic processing, respectively, to calculate the detection position and the detection rotation speed.

The drive command generation unit 7 includes a position command generation unit 40 that generates a position command that is a target position (target value of the rotational position), and a voltage command generation unit 41 that generates a drive command to be input to the motor driver 6. ing. The position command generator 40 calculates and outputs the rotational position at which the main transport roller 1 should be at that time as a position command. Further, the position command generation unit 40 outputs a control switching signal for switching the operation mode of the voltage command generation unit 41 based on the calculated position command. The voltage command generation unit 41 generates a drive command that is a voltage command value based on the position command input from the position command generation unit 40 and the control switching signal, and outputs the drive command to the motor driver 6.
The control switching signal output from the position command generation unit 40 is also input to the rotation speed holding unit 50. The rotation speed holding unit 50 stores a detected rotation speed during a period in which a second control mode to be described later is selected by a control switching signal.

  Here, with reference to FIG. 6, the detail of the drive command production | generation part 7 is demonstrated. As shown in FIG. 6, the drive command generation unit 7 is configured to generate two types of drive commands and switch them by the output selection unit 49 and output them. One is a control system that generates a drive command that is relatively influenced by the detected position and the detected rotational speed (detected value), specifically, based on the deviation between the detected position and the detected rotational speed and each target value. This is a feedback control system that generates a drive command. Hereinafter, a mode in which the feedback (FB) control system is selected and a drive command is generated is referred to as a first control mode. The other is a control system that generates a drive command that is relatively less influenced by the detected value, specifically, a feedforward control system that generates a drive command without feeding back the detected position and detected rotational speed. Hereinafter, a mode in which this feedforward (FF) control system is selected to generate a drive command is referred to as a second control mode. These control modes are, as will be described later, the second control mode during the period in which various information about the recording medium is detected, that is, the predetermined period before and after the recording medium is bitten into the roller nip portion. In the period, the first control mode is selected.

In the first control mode, a difference between the position command output from the position command generation unit 40 and the detected position is calculated, and a proportional (P) control calculation is executed by the position control calculation unit 46 to rotate the rotational speed. A command (target value of rotation speed) is generated. Further, a difference between the rotation speed command and the detected rotation speed is calculated, and a proportional integration (PI) control calculation is executed by the speed control calculation unit 47 to generate a drive command.
In the second control mode, the FF command generator 48 refers to the drive command generated by the FB control system described above, and switches to the second control mode in accordance with the control switching signal from the position command generator 40. The drive command generated by the FB control system immediately before is held and output.

Next, with reference to the flowchart shown in FIG. 7, the drive control method of the conveyance motor 3 of this embodiment is demonstrated.
When drive control of the conveyance motor 3 is started, first, the first control mode is selected (step S1). When the drive command update timing comes (step S2), it is determined whether or not the new position command calculated by the position command generation unit 40 is a position where detection of various information on the recording medium is started (step S3). The detection start position and end position are the start and end points of a predetermined section before and after the nip portion between the main transport roller 1 and the pinch roller 2. It is determined in advance in consideration of variations in the transport operation. The drive command is updated every 1 ms, for example, and the timing is managed by a timer interrupt or the like.

If it is determined in step S3 that the current position is the detection start position, switching from the first control mode to the second control mode is performed. Specifically, first, the FF command generation unit 48 holds and outputs the drive command generated immediately before in the first control mode (step S4). Then, the output control unit 49 selects the second control mode and switches the drive command (step S5), and the rotation speed holding unit 50 starts storing the rotation speed (step S6). Next, the position command is updated to a new value (step S11). Thereafter, as described above, the drive command generation unit 7 generates and outputs a new drive command in accordance with the selected mode (step S12). When the drive command is output, the motor driver 6 supplies power corresponding to the drive command to the transport motor 3, and the transport motor 3 is rotationally driven.
After the drive command is generated and output in step S12, it is determined whether or not the updated position command is a predetermined stop position. Here, since it has not yet reached the stop position, it is determined that the stop position is not reached, and the process returns to step S2 and waits until the next drive command update timing. Then, Steps S2 to S3 are executed again, but since it is determined that the detection start position is set in the previous Step S3, it is determined that the detection start position is not set in Step S3.

If it is determined in step S3 that it is not the detection start position, it is then determined whether or not the new position command is the detection end position (step S7). If it is determined that the detection end position is not reached, the second control mode is continued. After steps S11 to S13 are executed, the process returns to step S2 and waits until the next drive command update timing. Then, steps S2 to S3, S7, and S11 to 13 are repeatedly performed until the position command reaches the detection end position, and the second control mode is continued.
Thereafter, when it is determined in step S7 that the detection end position is reached, switching from the second control mode to the first control mode is performed. First, the position command generation unit 40 corrects a new position command based on the displacement amount of the rotational position generated during the drive control period in the second control mode (step S8). Specifically, the difference between the movement position when the conveyance motor 3 is assumed to rotate at a constant speed and the actual movement position is calculated, and the difference is added to the position command. This is a process for suppressing sudden speed fluctuations when switching from the second control mode to the first control mode. Then, the storage of the rotation speed in the rotation speed holding unit 50 is terminated (step S9), the second control mode is selected by the output selection unit 49, and the drive command is switched (step S10).

And after step S11-13 is performed, step S2-S3, S7, S11-13 are repeatedly performed until the updated position command turns into a stop position, and 1st control mode is continued. Then, when it is determined in step S13 that it is the stop position, a stop process such as turning off the output of the motor driver 6 is executed after the detection position matches the stop position (step S14), and the conveyance is performed. The drive control of the motor 3 ends.
In addition, after the drive control of the conveyance motor 3 is started and the first control mode is selected in step S1, the steps S2 to S3, S7, and S11 are performed until a new position command reaches the detection start position. ˜13 are repeatedly performed, and the first control mode is continued.

As described above, in the present embodiment, the conveyance motor 3 is driven and controlled in the second control mode during the period in which various information of the recording medium is detected before and after the recording medium is caught in the roller nip portion. During this period, the conveyance motor 3 is driven and controlled in the first control mode.
Note that the configuration / operation of the control system described above is merely an example, and the present invention is not limited to this. In the example described above, the first control mode is a mode that feeds back the position and the rotational speed, but may be a mode that feeds back only the position and the rotational speed. Further, the control calculation units 46 and 47 are not limited to the P control or the PI control, but may be executed by adding a differential (D) control calculation or other control calculations. May be. In addition, regarding the determination of the drive command in the FF command generation unit 48 at the time of switching to the second control mode, the previous drive command generated in the first control mode is held, but in a predetermined period before the switch You may make it use the average value of.

FIG. 8 shows how the rotational speed of the main conveyance roller 1 fluctuates when the drive control (switching of control mode) of the present embodiment described above is performed and when it is not performed. The solid line in FIG. 8 indicates the case where the drive control of this embodiment is performed, and the broken line indicates the case where the FB control corresponding to the first control mode is always performed without switching the control mode. Show. As is clear from a comparison between the solid line and the broken line, when the drive control of this embodiment is performed, a larger fluctuation in the rotational speed occurs. This is because when the FB control is performed, the rotational speed fluctuation is suppressed by the FB control. After the recording medium is completely caught in the roller nip portion, the load torque is almost the same as before the biting, so even if the drive command is held constant as in this embodiment, it is almost the same as before the biting. Return to the same rotation speed.
As described above, by performing the drive control of the present embodiment, the fluctuation amplitude of the rotational speed that is the detection target is increased, and a high S / N ratio is obtained, thereby enabling highly accurate detection.

  Next, a method for detecting various information (sheet information) relating to the conveyed recording medium based on the rotation speed stored in the rotation speed holding unit 50 as described above will be described.

(Detection of skew status information of recording media)
The detection of the skew state information of the recording medium is performed in a state where the thickness information and width information of the recording medium are known in advance. As thickness information and width information, information preset in a printer driver or the like may be used, or information detected by a method described later may be used.

FIG. 9 shows the state of load torque fluctuation and rotational speed fluctuation before and after being caught in the roller nip portion when a recording medium having the same thickness and width is not skewed and skewed by 1%. Show. FIG. 9A shows the state of load torque fluctuation, and FIG. 9B shows the state of rotational speed fluctuation. In both cases of FIG. 9A and FIG. 9B, the solid line in the figure indicates a case where the diagonal line is not skewed, and the dotted line indicates a case where the dotted line is diagonally skewed.
As can be seen from FIG. 9A, when the recording medium is skewed (see the dotted line in the figure), the peak value is smaller than in the case where the recording medium is not skewed (see the solid line in the figure). The load torque fluctuation has occurred for a long period of time. This is because the above-described biting and conveying force is generated with a time shift in the width direction of the recording medium. When such a load torque fluctuation occurs, a rotational speed fluctuation occurs as shown in FIG. 9B. With respect to the rotational speed before being caught in the nip portion, the rotational speed is decreased by a maximum Δω1 when the skew is not performed and by a maximum Δω2 when the skew is performed. Since it is known that there is a correlation between the fluctuation amount of the rotational speed and the skew amount of the recording medium, the skew amount can be estimated from the fluctuation amount of the rotational speed.
Specifically, the above-described correlation is stored in advance as a lookup table for each thickness and width of the recording medium. Then, the difference between the rotation speed at the start of detection, that is, immediately after switching to the second control mode, and the minimum value of the rotation speed during the detection period is calculated, and the lookup table is referred to according to the calculated difference. The skew amount of the recording medium can be obtained. Alternatively, the skew amount can be obtained using a calculation formula approximating the above-described correlation.

  In the ink jet printer, the skew state information of the recording medium thus detected can be used as follows. For example, when the detected skew amount is compared with a preset skew amount determination threshold value and the detected skew amount is equal to or less than the determination threshold value, the skew amount is determined before starting the recording operation in the recording unit. Execution of the registration operation for correcting the line can be omitted. By doing so, the time required for image recording can be shortened. Further, the registration operation method and parameters may be changed according to the detected skew amount. Further, the detected skew amount is compared with a preset skew abnormality determination threshold value, and if the detected skew amount is equal to or larger than the determination threshold value, the recording operation is stopped and an error is notified. May be. In that case, it is preferable to display a message or the like prompting confirmation of the alignment state of the stacked recording media. Alternatively, the distortion of the recorded image with respect to the recording medium can be corrected by rotating the image data in accordance with the detected skew amount.

(Detection of recording medium thickness information)
The thickness information of the recording medium is detected in a state where the width information of the recording medium is known in advance. As the width information, information preset in the printer driver or the like may be used.

FIG. 10A and FIG. 10B show the state of load torque fluctuation and rotational speed fluctuation before and after being bitten by the roller nip portion of recording media having the same width and different thicknesses. FIG. 10 (a) shows the state of load torque fluctuation, and FIG. 10 (b) shows the state of rotational speed fluctuation. In both cases of FIG. 10A and FIG. 10B, the solid line in the figure indicates the case where the thickness of the recording medium is 300 μm, and the broken line indicates the case where the thickness of the recording medium is 100 μm. Note that the solid line and the broken line in FIG. 10B indicate the case where the recording medium is not skewed, but the dotted line is 1% of the recording medium having the same thickness and width as those indicated by the solid line. The fluctuation of the rotational speed in the case of skew is shown.
As can be seen from FIG. 10 (a), when the thickness is small (see the broken line in the figure), the peak value is smaller than when the thickness is large (see the solid line in the figure), and the load is reduced over time. Torque fluctuation has occurred. This is because the biting and conveying force described above is small and the time until the bite is completely bitten is short. When such a load torque fluctuation occurs, a rotational speed fluctuation occurs as shown in FIG. 10B. By reducing the load torque fluctuation, the fluctuation amount of the rotational speed is also reduced. However, as described above, the amount of fluctuation in the rotational speed is reduced even when the recording medium is skewed, so it is difficult to determine which is due to the amount of fluctuation in the rotational speed alone. That is, as indicated by the broken line and the dotted line in FIG. 10B, it is difficult to detect the thickness of the recording medium only by the magnitude of the rotational speed variation.

  Therefore, in order to detect the thickness of the recording medium, an integral value of the rotational speed in at least a part of the detection period is used. FIG. 10C shows the result of sequentially adding and accumulating the difference (absolute value) between the rotation speed at the start of detection and the rotation speed at each time. As shown in FIG. 10C, the integral value when the thickness is 300 μm (see the solid line and dotted line in the figure) is Δd1, and the integral value when the thickness is 100 μm (see the broken line in the figure) is Δd2. Is smaller, the integral value of the rotational speed fluctuation amount becomes smaller. Since it is known that there is a correlation between the integral value and the thickness of the recording medium, the thickness of the recording medium can be estimated from the integral value. That is, similarly to the detection of the skew state information described above, the thickness of the recording medium can be reduced by using a lookup table storing the above-mentioned correlation for each recording medium width or a calculation formula approximating the correlation. Can be sought.

  In the ink jet printer, the thickness information of the recording medium thus detected can be used as follows. For example, the method and parameters of the registration operation can be changed according to the detected thickness. By doing so, it is possible to perform the optimum skew correction corresponding to the thickness of the recording medium. Further, depending on the detected thickness, the conditions of the recording operation such as the amount of ink shot may be changed. Alternatively, if the detected thickness is compared with the thickness information set by the user, and if the two do not match, the recording operation is stopped and an error notification is issued, thereby suppressing unnecessary recording operations due to setting mistakes. can do.

(Detection of recording medium width information)
The width information of the recording medium is detected in a state where the thickness information of the recording medium is known in advance. The fluctuations in the rotation speed when the width of the recording medium is different behaves similar to the case where the thickness of the recording medium is different. Is difficult to determine. In other words, if the thickness information of the recording medium is known in advance, the width information of the recording medium can be determined by using the same method as the thickness information detection described above, that is, by using the integral value of the rotational speed fluctuation amount. Detection can be performed. Similar to the detection of the thickness information described above, by using a lookup table storing the correlation between the width of the recording medium and the integral value for each recording medium thickness or a calculation formula approximating the correlation, The width of the medium can be determined. Examples of methods for utilizing the detected width information include changing the registration operation method and parameters according to the width, and notifying an error when the detected width of the recording medium is smaller than the width of the image to be recorded. A method is mentioned.

(Detection of recording medium transport position information)
The detection of the conveyance position information of the recording medium is performed by detecting the timing at which the peak of the rotational speed fluctuation occurs.
As described above, the position control of the recording medium is performed by controlling the rotational position of the roller on the assumption that the recording medium is ideally conveyed along with the rotation of the main conveying roller 1. The position of the medium is not detected directly. However, in practice, there may be a deviation between the rotation position of the main transport roller 1 and the position of the recording medium due to variations in mechanical parts. Therefore, by using the rotational speed fluctuation when the recording medium is caught in the roller nip portion, the timing at which the leading end of the recording medium actually reaches the roller nip portion is detected, and the accurate position of the conveyed recording medium is obtained. Can do. Specifically, first rotation speed to detect the rotational position p ₁ of the main conveying roller 1 at the timing to be minimized during the detection period. Here, when the recording medium in accordance with the rotation of the main conveying roller 1 is conveyed ideally, the rotational position of the main conveying roller 1 when the leading end of the recording medium is bitten roller nip portion between p _0. p ₀ is a value that can be calculated in advance. The difference between p ₀ and p ₁ corresponds to the aforementioned shift. Therefore, by adding this difference to the detected rotational position of the main transport roller 1, the generated deviation is corrected, and the rotational position of the main transport roller 1 and the position of the recording medium correspond exactly. By using the corrected rotation position of the main transport roller 1, the position control of the recording medium can be performed more accurately.

  So far, the method for detecting various information about the recording medium has been described. However, prior to the above-described detection of various information, the following pre-processing may be performed. For example, in order to remove high-frequency noise, a process such as applying a low-pass filter to the detected rotation speed may be performed. Alternatively, when it is known that the rotational speed fluctuation periodically occurs due to the torque ripple of the conveyance motor 3 or the meshing effect of the timing belt 30, a process of removing the periodic fluctuation by a notch filter is performed. May be. By performing such pre-processing, further improvement in detection accuracy of various information related to the transported recording medium can be expected.

  As described above, according to the present embodiment, the conveyance motor 3 can be driven so that the effect of suppressing the fluctuation in the rotational speed by the FB control does not appear when the leading edge of the recording medium passes through the roller nip portion. That is, when the leading edge of the recording medium passes through the roller nip portion, the effect of suppressing the fluctuation of the rotation speed of the conveyance motor 3 is not exhibited. Can be increased. As a result, it becomes possible to detect various information related to the transported recording medium with high accuracy.

(Second Embodiment)
A transport apparatus according to a second embodiment of the present invention will be described. This embodiment differs from the first embodiment only in the configuration and drive control method of the drive control unit of the conveyance motor 3, and the other configurations and operations are the same as those in the first embodiment. Therefore, here, the description will focus on the differences from the first embodiment of the drive control unit of the transport motor 3, and the other description will be omitted.

With reference to FIG. 11, the detail of the drive command production | generation part 7 of this embodiment is demonstrated. FIG. 11 is a block diagram showing the configuration of the drive command generation unit 7.
In the present embodiment, as in the first embodiment, the second control mode is executed when the recording medium is caught in the nip portion between the main conveyance roller 1 and the pinch roller 2, and otherwise the first control mode is executed. 1 control mode is executed. However, in the present embodiment, the first and second control modes are FB control that generates a drive command in accordance with the deviation between the detected position and the detected rotational speed and the respective target values. In addition, as shown in FIG. 11, the drive command generation unit 7 is configured to generate two types of drive commands by changing the gain in the control calculation by the position control calculation unit 56 and the speed control calculation unit 57. Has been. That is, in the present embodiment, the influence of the detection position and the detection rotation speed on the drive command is different between the first control mode and the second control mode.

The drive command generation unit 7 is configured such that a proportional (P) control calculation is executed by the position control calculation unit 56 and a proportional integration (PI) control calculation is executed by the speed control calculation unit. In the first control mode, the P control gain in the position control calculation unit 56 is set to K _pp1, and the PI control gain in the speed control calculation unit 57 is set to K _pw1 and K _iw1 . In the second control mode, the P control gain in the position control calculation unit 56 is set to K _pp2, and the PI control gain in the speed control calculation unit 57 is set to K _pw2 and K _iw2 . The gains K _pp2 , K _pw2 , and K _iw2 used in the second control mode are smaller than the gains K _pp1 , K _pw1 , and K _iw1 used in the first control mode. Is the value of That is, the feedback gain is smaller in the second control mode than in the first control mode.

Next, with reference to the flowchart shown in FIG. 12, the recording medium conveyance operation by the conveyance unit of the present embodiment will be described. In addition, the same reference number is attached | subjected to the process similar to the conveyance operation of 1st Embodiment shown in FIG. 7, and the description is abbreviate | omitted.
In the present embodiment, it is determined that the detection start position is determined in step S3, and is held in the integrator 8 of the speed control calculation unit 57 when switching from the first control mode to the second control mode is performed. Is changed to a new value (step S24). The integrator 8 integrates the deviation between the detected rotation speed and the rotation speed command (target value of the rotation speed) generated by the position control calculation unit 56. The new value to be changed is calculated based on the drive command generated immediately before in the first control mode and the integral control gain K _iw2 used in the second control mode. Specifically, the new value to be changed is _{calculated so} that the product of this value and the gain K _iw2 is equal to the drive command generated immediately before in the first control mode. This process is a process for suppressing sudden speed fluctuations when switching from the first control mode to the second control mode. After the value held in the integrator 8 is changed in step S24, the second control mode is selected in step S5, and the control gains are gains _Kpp2 , _Kpw2 , K used in the second control mode. set to _iw2 .

Further, in the present embodiment, it is determined in step S7 that the detection end position is reached, and when switching from the second control mode to the first control mode is performed, the integrator 8 of the speed control calculation unit 57 is connected to the integrator 8. The held value is changed to a new value (step S28). The new value to be changed is calculated based on the drive command generated immediately before in the second control mode and the integral control gain K _iw1 used in the first control mode. Specifically, the new value to be changed is _{calculated so} that the product of this value and the gain K _iw1 is equal to the drive command generated immediately before in the second control mode. This process is a process for suppressing sudden speed fluctuations when switching from the second control mode to the first control mode. In step S28, the value held in the integrator 8 is changed, and in step S9, after storing the rotational speed in the rotational speed holding unit 50, each control gain is a gain K _pp1 used in the first control mode. , K _pw1 , K _iw1 .

As described above, also in this embodiment, the conveyance motor 3 is driven and controlled in the second control mode during the period in which various information of the recording medium is detected before and after the recording medium is caught in the roller nip portion. During this period, the transport motor 3 is driven and controlled in the first control mode.
Note that the configuration / operation of the control system described above is merely an example, and the present invention is not limited to this. Each of the control calculation units 56 and 57 may be configured to execute a differential (D) control calculation additionally or execute other control calculations. Further, in the second control mode, all the control gains are uniformly reduced as compared with the first control mode, but only a part of the gains may be reduced, or the amount of change for each gain may be reduced. It may be changed. In short, it is important to reduce the feedback gain as a whole so that a large speed fluctuation appears when the leading edge of the recording medium passes through the roller nip portion.

  FIG. 13 shows how the rotational speed of the main conveyance roller 1 fluctuates when the above-described drive control of the present embodiment (change in control gain associated with switching of the control mode) is performed and when it is not performed. The solid line in FIG. 13 indicates the case where the control of the present embodiment is performed, and the broken line indicates the case where the drive control is always performed in the first control mode having a large control gain without changing the control gain. Is shown. Moreover, the dotted line in FIG. 13 has shown the mode of the rotational speed fluctuation | variation when the drive control of 1st Embodiment is performed. As can be seen from FIG. 13, in the present embodiment indicated by the solid line, the amount of fluctuation in the rotational speed is slightly smaller than in the first embodiment indicated by the dotted line, but the control gain is always large (the broken line in the figure). Compared with the reference), a large rotational speed fluctuation occurs.

  As described above, in the present embodiment, the conveyance motor 3 can be driven so that the effect of suppressing the fluctuation in rotational speed by the FB control is reduced when the leading edge of the recording medium passes through the roller nip portion. That is, when the leading edge of the recording medium passes through the roller nip portion, the effect of suppressing fluctuations in the rotation speed of the conveyance motor 3 is reduced. The amplitude can be increased. As a result, it becomes possible to detect various information related to the transported recording medium with high accuracy. Further, in the second control mode of the present embodiment, since the FB control is performed while the gain is small, an emergency state in which the main conveyance roller 1 stops when an unexpectedly large load torque fluctuation occurs. Can be avoided. Alternatively, it is possible to expect an effect of stabilizing the rotational speed by suppressing the influence of the FB control on the long-cycle load torque fluctuation.

DESCRIPTION OF SYMBOLS 1 Main conveyance roller 2 Pinch roller 3 Conveyance motor 5 Encoder sensor 7 Drive command generation part

Claims (22)

Recording means for recording an image on a sheet;
A conveying roller for conveying the sheet;
A pinch roller facing the transport roller and sandwiching the sheet together with the transport roller;
A motor for applying a driving force to the conveying roller;
Detecting means for detecting at least one of a rotational speed and a rotational position of the transport roller;
Generating means for generating a drive command for driving the motor based on a detection value by the detection means;
Based on the rotation speed detected by the detection means during a predetermined period in which the end of the sheet passes through the nip portion between the conveying roller and the pinch roller, the skew state information and thickness information of the sheet A recording apparatus for detecting sheet information including at least one of width information and conveyance position information,
The generation means generates a drive command that has a relatively large influence by the detection value, and a second control mode generates the drive instruction that has a relatively small influence by the detection value. Switch to run,
The recording apparatus according to claim 2, wherein the second control mode is executed during the predetermined period in which the sheet information is detected. The generation means includes means for generating a target value of at least one of the rotation speed and the rotation position of the transport roller,
The first control mode is feedback control that generates the drive command based on a deviation between the detected value and the target value;
The recording apparatus according to claim 1, wherein the second control mode is feedforward control that generates the drive command without feeding back the detected value.   The generating means, when switching from the first control mode to the second control mode, in the second control mode based on the drive command generated in the first control mode immediately before switching. The recording apparatus according to claim 2, wherein the drive command is determined.   When the generation unit switches from the second control mode to the first control mode, the generation unit determines the rotation position based on a displacement amount of the rotation position during the execution of the second control mode. The recording apparatus according to claim 2, wherein the target value is corrected. The generation means includes means for generating a target value of at least one of the rotation speed and the rotation position of the transport roller,
The first control mode and the second control mode are feedback control that generates the drive command based on a deviation between the detected value and the target value,
The recording apparatus according to claim 1, wherein the second control mode has a feedback gain smaller than that of the first control mode. The generating means includes an integrator that integrates a deviation between the rotational speed detected by the detecting means and the target value of the rotational speed,
The generator is held by the integrator based on the drive command generated in the first control mode immediately before switching when switching from the first control mode to the second control mode. The recording apparatus according to claim 5, wherein the value is changed. The generating means includes an integrator that integrates a deviation between the rotational speed detected by the detecting means and the target value of the rotational speed,
The generator is held in the integrator when switching from the second control mode to the first control mode based on the drive command generated in the second control mode immediately before switching. 7. The recording apparatus according to claim 5, wherein the value is changed.   The skew state information of the sheet is detected by detecting the width information of the sheet previously determined, the thickness information of the sheet previously determined, and the rotation speed detected by the detection means during the predetermined period. The recording apparatus according to claim 1, wherein the recording apparatus is performed on the basis of the magnitude of the fluctuation.   The detection of the sheet thickness information is performed based on the previously known sheet width information and the integral value of the rotational speed detected by the detection means during at least a part of the predetermined period. The recording apparatus according to claim 1, wherein the recording apparatus is a recording apparatus.   The detection of the sheet width information is performed based on the previously known sheet thickness information and the integral value of the rotational speed detected by the detection means during at least a part of the predetermined period. The recording apparatus according to claim 1, wherein the recording apparatus is a recording apparatus.   8. The detection of the sheet conveyance position information is performed based on a timing at which a peak of the rotation speed fluctuation detected by the detection unit occurs in the predetermined period. The recording apparatus according to claim 1. A transport roller for transporting the sheet;
A pinch roller facing the transport roller and sandwiching the sheet together with the transport roller;
A motor for applying a driving force to the conveying roller;
Detecting means for detecting at least one of a rotational speed and a rotational position of the transport roller;
Generating means for generating a drive command for driving the motor based on a detection value by the detection means;
Based on the rotation speed detected by the detection means during a predetermined period in which the end of the sheet passes through the nip portion between the conveying roller and the pinch roller, the skew state information and thickness information of the sheet A sheet conveying apparatus that detects sheet information including at least one of width information and conveyance position information,
The generation means generates a drive command that has a relatively large influence by the detection value, and a second control mode generates the drive instruction that has a relatively small influence by the detection value. Switch to run,
The transport apparatus according to claim 2, wherein the second control mode is executed in the predetermined period in which the sheet information is detected. The generation means includes means for generating a target value of at least one of the rotation speed and the rotation position of the transport roller,
The first control mode is feedback control that generates the drive command based on a deviation between the detected value and the target value;
The transport apparatus according to claim 12, wherein the second control mode is feedforward control that generates the drive command without feeding back the detected value.   The generating means, when switching from the first control mode to the second control mode, in the second control mode based on the drive command generated in the first control mode immediately before switching. The transport apparatus according to claim 13, wherein the drive command is determined.   When the generation unit switches from the second control mode to the first control mode, the generation unit determines the rotation position based on a displacement amount of the rotation position during the execution of the second control mode. The transport apparatus according to claim 13 or 14, wherein the target value is corrected. The generation means includes means for generating a target value of at least one of the rotation speed and the rotation position of the transport roller,
The first control mode and the second control mode are feedback control that generates the drive command based on a deviation between the detected value and the target value,
The transport apparatus according to claim 12, wherein the second control mode has a feedback gain smaller than that of the first control mode. The generating means includes an integrator that integrates a deviation between the rotational speed detected by the detecting means and the target value of the rotational speed,
The generator is held by the integrator based on the drive command generated in the first control mode immediately before switching when switching from the first control mode to the second control mode. The transport device according to claim 16, wherein the value is changed. The generating means includes an integrator that integrates a deviation between the rotational speed detected by the detecting means and the target value of the rotational speed,
The generator is held in the integrator when switching from the second control mode to the first control mode based on the drive command generated in the second control mode immediately before switching. The transport device according to claim 16 or 17, wherein a value is changed.   The skew state information of the sheet is detected by detecting the width information of the sheet previously determined, the thickness information of the sheet previously determined, and the rotation speed detected by the detection means during the predetermined period. The transfer device according to claim 12, wherein the transfer device is performed based on the magnitude of the fluctuation.   The detection of the sheet thickness information is performed based on the previously known sheet width information and the integral value of the rotational speed detected by the detection means during at least a part of the predetermined period. The conveying device according to any one of claims 12 to 18, wherein the conveying device is characterized in that:   The detection of the sheet width information is performed based on the previously known sheet thickness information and the integral value of the rotational speed detected by the detection means during at least a part of the predetermined period. The conveying device according to any one of claims 12 to 18, wherein the conveying device is characterized in that:   19. The detection of the sheet conveyance position information is performed based on a timing at which a peak of fluctuation in the rotation speed detected by the detection unit occurs in the predetermined period. The conveying apparatus of Claim 1.

Images