JP5589898B2 - DRIVE CONTROL DEVICE, SHEET CONVEYING DEVICE, AND IMAGE FORMING DEVICE - Google Patents

Description

  The present invention relates to a drive control device that controls an object to be driven by a motor, a sheet conveyance device that performs sheet conveyance control, and an image forming apparatus that forms an image on a sheet.

  Conventionally, there has been known an image forming apparatus that forms an image on a sheet by intermittently conveying the sheet by a predetermined amount. In this type of image forming apparatus, a sheet is conveyed by a predetermined amount by rotation control of a roller using a motor.

  Also, as a motor control device, in order to prevent the drive target from exceeding the specified rotation speed, a threshold is set to a rotation speed smaller than the specified rotation speed, and the motor is operated on the condition that the rotation speed of the drive object has reached the threshold value. There is known one that cuts off the drive current supplied to (see, for example, Patent Document 1). In this motor control device, after the drive current is cut off, the drive current is re-supplied to the motor so that the rotation can be maintained at the specified rotation speed after the drive target is rotated to the specified rotation speed by inertia.

JP 2007-037236 A

  By the way, in an image forming apparatus such as an ink jet printer that forms an image on a sheet by intermittently conveying the sheet by a predetermined amount, the quality of the image formed on the sheet deteriorates unless the sheet is conveyed accurately by the predetermined amount. . For this reason, in the field of image forming apparatuses, a technique capable of accurately stopping the sheet at the target stop position is required. Even if the sheet can be stopped accurately, if the time required until the sheet is stopped is long, it adversely affects the throughput of the entire image forming process. For this reason, in the field of image forming apparatuses, a technology capable of realizing sheet conveyance at high speed is required. Furthermore, such a technique is widely requested not only in the field of image forming apparatuses but also in the field of motor control.

However, it is difficult to accurately stop the drive target at the target stop position and to stop the drive target at high speed, and there is room for improvement in the prior art.
In particular, in an image forming apparatus, when a sheet is intermittently conveyed, a load in the direction opposite to the conveyance direction is often applied to the sheet. For example, the load in the direction opposite to the conveyance direction is applied to the sheet through the contact point between the upstream roller and the sheet because the roller on the upstream side of the conveyance roller used for intermittent conveyance of the sheet is not driven by a motor. Work.

  When the drive target is displaced to the target stop position through a drive mechanism that applies a load in the direction opposite to the traveling direction of the drive target, an event that the drive target exceeds the target stop position due to load fluctuations Etc. are likely to occur, making it difficult to achieve both stop accuracy and high speed.

  The present invention has been made in view of these problems, and is a technology that can suitably execute control for displacing a drive target and stopping it at a target stop position in an environment where a load in a direction in which the drive target moves backward is applied. The purpose is to provide.

  A first invention made to achieve the above object is applied to a drive control device for controlling the motor of a drive mechanism that realizes displacement of the drive target by applying power generated from the motor to the drive target. It is. In particular, the present invention is a drive that controls a motor of a drive mechanism that is configured to apply a load that causes the drive target to move backward in a direction opposite to the direction of travel toward the target stop position of the drive target that is displaced by motor control of the drive control device. Applies to control devices.

  The drive control device of the present invention includes a position detection unit, an operation amount calculation unit, and a motor driver, and controls the motor included in the drive mechanism by these units, and advances the drive target toward the target stop position. Displace in the direction. The position detection means detects the position of the drive target. The operation amount calculation means calculates an operation amount for the motor for stopping the drive target at the target stop position based on the position of the drive target detected by the position detection means and the target stop position. The motor driver drives the motor by supplying the motor with electric power corresponding to the operation amount calculated by the operation amount calculating means.

  Furthermore, the drive control device of the present invention includes a prohibiting unit and a restart control unit. The prohibiting unit prohibits power supply to the motor by the motor driver when detecting that the driving target is overrun from the target stop position to the downstream side in the traveling direction based on the position of the driving target detected by the position detecting unit. Then, when the predetermined condition is satisfied, the restart control means causes the motor driver to restart the power supply to the motor prohibited by the prohibiting means (claim 1).

  According to this drive control device, when an overrun occurs, power supply to the motor driver is prohibited, and the drive target is moved backward using the load. Then, the power supply to the motor is resumed at an appropriate time. By such a procedure, the drive target is stopped at the target stop position. Therefore, according to the present invention, preferable motor control can be performed in an environment in which a load is applied in the direction opposite to the traveling direction, and the drive target is suitably stopped (with high accuracy and high speed) at the target stop position. Can do.

  For example, applying the conventional technology that cuts off the drive current to the motor on the condition that the rotation speed of the drive target has reached a threshold value smaller than the specified rotation speed, the drive current is cut off when approaching the target stop position. When the method of displacing the drive target by inertia is used, overrun can be suppressed, but the drive target does not reach the target stop position, and the drive target cannot be stopped at the target stop position. In such a case, if the motor is redriven to place the drive target at the target stop position, an overrun may occur next, and the drive target is set to the target stop position with high accuracy and high speed. It is difficult to stop. Further, when overrun occurs, if it is attempted to stop the drive target at the target stop position only by feedback control, it takes time to eliminate the overrun.

  On the other hand, according to the present invention, the overrun is corrected by utilizing the backward movement of the object to be driven by the load. Therefore, the overrun can be eliminated faster than the overrun is corrected only by feedback control. Therefore, according to the present invention, the drive target can be stopped at the target stop position more appropriately (with high accuracy and at high speed) than in the past. In the present invention, the power supply to the motor is once inhibited and then resumed because the motor drive that balances the load is required to maintain the drive target at the target stop position.

  By the way, the restart control means determines that when the overrun drive object moves backward to the target stop position based on the position of the drive object detected by the position detection means, the motor driver is supplied with electric power to the motor. The supply can be resumed (claim 2). According to such control, the drive target can be appropriately stopped at the target stop position while receiving a load in the direction opposite to the traveling direction.

  Further, it is preferable that the operation amount calculation is continuously executed even during a period in which power supply to the motor is prohibited by the prohibiting unit. When the motor driver resumes power supply to the motor in accordance with the instruction from the restart control means, the motor driver supplies power corresponding to the latest operation amount at that time to resume driving the motor. (Claim 3). According to such restart control, the motor drive can be restarted with an appropriate operation amount corresponding to the deviation between the actual position of the drive target and the target stop position, and control for stopping the drive target at the target stop position is performed. It can be suitably executed.

  In such a case, the power supply prohibiting operation by the prohibiting means and the power supply restarting operation by the restart control means can be realized by switching the enable signal input to the motor driver separately from the operation amount. (Claim 4). As the motor driver, when the enable signal is an on signal, power corresponding to the operation amount is supplied to the motor. When the enable signal is an off signal, for example, all of the switching elements constituting the H bridge in the motor driver are supplied. An apparatus that stops power supply to a motor by an operation such as turning it off is known.

  The drive mechanism is configured such that when the motor rotates forward, the drive target is displaced in the traveling direction toward the target stop position, and when the motor rotates negatively, the drive target is displaced in the direction opposite to the traveling direction. Can be adopted.

  As the motor driver, a motor driver that drives the motor by switching the rotation direction of the motor between positive and negative according to the magnitude of the operation amount calculated by the operation amount calculating means from the reference value can be adopted. For example, when the operation amount calculated by the operation amount calculating means is positive, the motor is rotated forward, and when the operation amount calculated by the operation amount calculating means is negative, the motor is rotated negatively. Can do.

  Further, the restart control means detects that the overrun drive target has moved back to the target stop position, or when the operation amount is switched in a direction in which the rotation direction of the motor is switched from positive to negative (for example, based on the zero value). When the positive / negative of the operation amount is switched), it can be configured that the motor driver resumes the power supply to the motor, assuming that the predetermined condition is satisfied (claim 5). According to this configuration, the drive target can be stopped more quickly at the target stop position.

  In addition, a second invention made to achieve the above object is directed to a sheet conveying mechanism as the driving mechanism and a motor provided in the sheet conveying mechanism, thereby directing the sheet to the target stop position in the sheet conveying mechanism. And a drive control device that transports the drive control device, the drive control device having a configuration similar to that of the first invention. The sheet transport mechanism includes, for example, a motor and a roller that is rotationally driven by the motor, and transports a sheet that contacts the roller by the rotation of the roller.

According to the sheet conveying apparatus having such a configuration, it is possible to suitably execute control for stopping the sheet at the target stop position for the reason described above.
As a sheet transport mechanism, a sheet transport mechanism including a first roller and a second roller located upstream of the first roller in the sheet traveling direction is known. When the sheet conveying device is configured to convey the sheet by driving the first roller of such a sheet conveying mechanism with a motor, the sheet end does not pass through the second roller with respect to the sheet. A load in the direction opposite to the traveling direction is likely to work. Therefore, when the drive control device of the present invention is applied to the drive control device that controls the motor that drives the first roller, the influence of the load can be suppressed and the sheet can be suitably stopped at the target stop position. 7).

  The sheet conveying mechanism includes a U-shaped sheet conveying path that regulates the movement of the sheet between the first roller and the second roller, and the sheet is curved through the U-shaped sheet conveying path. In the sheet conveying apparatus conveyed toward the target stop position, a load in the direction opposite to the traveling direction is likely to be applied to the sheet due to the curvature. Therefore, when the above-described drive control device (first invention) is used for such a sheet conveying device, the above-described effect is further exhibited (claim 8).

  A third invention made to achieve the above object is an image forming apparatus, comprising an image forming means, a sheet conveying mechanism, a supplying means, and a drive control means. The sheet conveying mechanism is disposed on the upstream side of the first conveying mechanism in the sheet conveying direction with respect to the first conveying mechanism that conveys the sheet toward the image forming point by the image forming unit, and supplies the sheet to the first conveying mechanism. A second transport mechanism. The image forming unit forms a line image in the main scanning direction on the sheet that has been transported and stopped by the first transport mechanism.

  On the other hand, the supply unit drives the second transport mechanism to supply the sheet to the first transport mechanism. The drive control unit controls the motor included in the first conveyance mechanism to cause the first conveyance mechanism to convey the sheet in the sheet conveyance direction from the sheet supply point to which the sheet is supplied toward the image forming point. In the sheet transport mechanism of the image forming apparatus, the second transport mechanism is supplying the sheet to the first transport mechanism at a speed slower than the speed of the first transport mechanism, or the second transport mechanism is connected to the first transport mechanism. In a state where the sheet feeding operation is completed and stopped, the first transport mechanism is controlled by the drive control unit to transport the sheet to the image forming point.

  The drive control unit in the image forming apparatus of the present invention includes a position detection unit, a position update unit, an operation amount calculation unit, a motor driver, a prohibition unit, and a restart control unit. The position detecting means detects the position of the sheet. The position updating unit sets the target stop position of the sheet to be updated downstream in the sheet conveying direction every time a line image is formed by the image forming unit.

  The operation amount calculation means calculates an operation amount for the motor for stopping the sheet at the target stop position based on the position of the sheet detected by the position detection means and the target stop position set by the position update means. Then, the motor driver drives the motor by supplying electric power corresponding to the operation amount calculated by the operation amount calculating means to the motor. In this manner, the sheet is intermittently conveyed in the image forming apparatus of the present invention.

  The prohibiting unit prohibits the motor driver from supplying power to the motor when detecting that the sheet has overrun from the target stop position to the downstream side in the sheet conveying direction based on the position of the sheet detected by the position detecting unit. . The resumption control means causes the motor driver to resume power supply to the motor prohibited by the inhibition means when the overrun sheet moves back to the target stop position based on the position of the sheet detected by the position detection means. .

  According to the image forming apparatus having such a configuration, back tension is applied to the sheet during intermittent conveyance of the sheet. Even in such a state, the sheet can be stopped at the target stop position at high speed and with high accuracy. In this state, an image can be formed on the sheet. Therefore, according to the image forming apparatus of the present invention, the sheet can be intermittently conveyed at a predetermined amount accurately and at high speed, and a good image can be formed on the sheet.

  The sheet conveying mechanism includes a U-shaped sheet conveying path between the first conveying mechanism and the second conveying mechanism, and the sheet is curved through the U-shaped sheet conveying path toward the target stop position. When the present invention is applied to an image forming apparatus conveyed in this manner, the above-described effect is further exhibited (claim 10).

  In particular, the second transport mechanism includes a roller for supplying the sheet to the first transport mechanism, and a pressing mechanism that presses the roller against the sheet, and the roller is rotated while the roller is pressed against the sheet. In the image forming apparatus configured to convey the sheet, a strong load is applied to the sheet due to the pressing by the second conveying mechanism. However, when the configuration of the above-described drive control device is adopted for such an image forming apparatus. The effect that the sheet can be conveyed accurately and at high speed to the target stop position is further conspicuous (claim 11).

1 is a block diagram illustrating a configuration of an image forming apparatus 1. FIG. 2 is a cross-sectional view illustrating a mechanical configuration of the image forming apparatus 1. FIG. 3 is a flowchart illustrating processing executed by a main control unit 90. FIG. 4 is a block diagram illustrating configurations of a sheet conveyance control unit 70 and a motor driver DR2. 6 is a flowchart illustrating processing executed by an on / off control unit 709. It is the figure which showed the mode of ON / OFF of an enable signal. It is the graph which showed the change of the position and the operation amount when the enable signal is kept on (a) and when the enable signal is turned on / off (b).

Embodiments of the present invention will be described below with reference to the drawings.
The image forming apparatus 1 according to the present embodiment is an ink jet printer, and as illustrated in FIG. ASF motor M1 that is a direct current motor that imparts power, a motor driver DR1 that drives the ASF motor M1, an LF motor M2 that is a direct current motor that imparts power to the paper transport mechanism 20, and a motor driver DR2 that drives the LF motor M2 A CR motor M3 that is a DC motor that applies power to the printing mechanism 30, a motor driver DR3 that drives the CR motor M3, and a head drive circuit DR4 that drives the recording head 31.

  The paper feed mechanism 10 separates the paper P stored in the paper feed tray 101 one by one and supplies it to the paper transport mechanism 20, and a plurality of paper P are stacked as shown in FIG. A paper feed tray 103, a paper feed roller 103 that rotates by receiving the power of the ASF motor M1, an arm 104 that holds the paper feed roller 103 in a rotatable state, and an encoder signal that is generated as the paper feed roller 103 rotates. A rotary encoder 105 (see FIG. 1) for output.

  The arm 104 has an end opposite to the end provided with the paper feed roller 103 fixed so as to be rotatable in the image forming apparatus 1, and holds the paper feed roller 103 in a pendulum shape. . The arm 104 presses the paper feed roller 103 against the surface of the paper P stored in the paper feed tray 101 by using an urging force by gravity or a spring.

  That is, in the paper feed mechanism 10, the paper feed roller 103 is rotated by receiving power from the ASF motor M 1 while being pressed against the paper P, and the top of the paper feed tray 101 is rotated by the rotation of the paper feed roller 103. Sheet P is separated and sent to a sheet conveying path connected to the sheet conveying mechanism 20. The paper transport path between the paper transport mechanism 20 and the paper feed mechanism 10 is composed of a U-turn path 111 that is a U-shaped transport path, and the paper P delivered from the paper feed tray 101 is a U-turn path 111. The paper is transported between the transport roller 201 and the pinch roller 202 included in the paper transport mechanism 20 in a state where the movement is restricted and curved.

  As described above, the paper transport mechanism 20 includes the transport roller 201 and the pinch roller 202 disposed so as to face the transport roller 201, and outputs an encoder signal as the transport roller 201 rotates (see FIG. 1). ), A paper discharge roller 211, and a pinch roller 212 disposed to face the paper discharge roller 211.

  The rotary encoder 205 includes a rotating plate (not shown) mounted on the rotating shaft of the conveying roller 201, reads a slit formed in the rotating plate, and outputs an encoder signal corresponding to the reading result. It is configured as a rotary encoder. The rotary encoder 205 outputs an A phase signal and a B phase signal, which are pulse signals having phases different from each other by π / 2 as encoder signals.

  Further, the paper discharge roller 211 is provided downstream of the paper conveyance path with respect to the conveyance roller 201. The transport roller 201 and the paper discharge roller 211 receive power from the LF motor M2 through, for example, a power transmission mechanism 220 (see FIG. 1) that connects the rollers 201 and 211 with belts, and rotate so as to interlock with each other. Specifically, they rotate by the same amount in the circumferential direction. The conveyance roller 201 and the paper discharge roller 211 cooperate with each other to convey the paper P supplied from the paper supply mechanism 10 to a paper discharge tray (not shown) downstream of the paper discharge roller 211.

  The pinch roller 202 rotates so as to follow the rotational movement of the transport roller 201 with the paper P being sandwiched between the pinch roller 202 and the pinch roller 212. In a state where P is sandwiched, the paper discharge roller 211 rotates to follow the rotational movement. The paper P is thus sandwiched between the transport roller 201 and the pinch roller 202, and further, in a state of being sandwiched between the paper discharge roller 211 and the pinch roller 212, the transport roller 201 and the paper discharge roller 211. Is conveyed downstream of the paper conveyance path.

  Further, a platen 240 is provided between the transport roller 201 and the paper discharge roller 211 to support the paper P transported from the transport roller 201 from below and to guide it to the paper discharge roller 211. An image is formed on the platen 240 by the ink droplets ejected from the recording head 31 constituting the printing mechanism 30 on the sheet P conveyed from the conveying roller 201 to the discharge roller 211 side.

  As shown in FIGS. 1 and 2, the printing mechanism 30 receives power from a recording head 31 that ejects ink droplets from a nozzle surface facing the platen 240, a carriage 33 on which the recording head 31 is mounted, and a CR motor M3. A carriage transport mechanism (not shown) that transports the carriage 33 in the main scanning direction (the normal direction of the paper in FIG. 2), and a linear encoder that outputs an encoder signal as the carriage 33 moves in the main scanning direction. 35 etc.

  The recording head 31 is mounted on a carriage 33 that moves in the main scanning direction, and moves in the main scanning direction on the platen 240. During this movement, the recording head 31 receives a drive signal from the head drive circuit DR4 and ejects ink droplets corresponding to the drive signal from the nozzle surface.

  The control unit 50 also includes a paper feed control unit 60 that performs paper feed control, a paper transport control unit 70 that performs transport control of the paper P supplied from the paper feed tray 101 to the paper transport mechanism 20 by the paper feed control, A print control unit 80 that controls conveyance of the carriage 33 and discharge control of ink droplets by the recording head 31, a main control unit 90 that performs overall control thereof, and an interface 95 that can communicate with an external personal computer (PC) 3. Is provided.

  The paper feed controller 60 detects the rotational position of the paper feed roller 103 based on the encoder signal input from the rotary encoder 105, and based on the detection result, the drive current / voltage supplied from the motor driver DR1 to the ASF motor M1. Paper feed control is performed by adjusting. By this paper feed control, the paper P is supplied from the paper feed tray 101 to the paper transport mechanism 20 one by one. Specifically, the paper P is supplied to the paper transport mechanism 20 in a curved state through the U-turn path 111.

  On the other hand, the paper transport control unit 70 detects the rotational position of the transport roller 201 based on the encoder signal input from the rotary encoder 205, and controls the LF motor M2 based on this rotational position (detected position). P transport control is performed. As a result, the paper P is conveyed in the sub-scanning direction perpendicular to the main scanning direction.

  Further, the print control unit 80 controls the CR motor M3 through the motor driver DR3 to convey the recording head 31 at a constant speed in one direction in the main scanning direction, and by controlling the recording head 31 during the conveyance, The recording head 31 is caused to eject ink droplets corresponding to image data to be printed input from the PC 3 through the interface 95, and a line image of a predetermined width (hereinafter also referred to as “line image for one pass”) on the paper P. .). Specifically, the print control unit 80 detects the carriage 33 and thus the conveyance speed of the recording head 31 based on the encoder signal input from the linear encoder 35, and conveys the recording head 31 at a constant speed.

  In addition, the main control unit 90 controls the paper feed control unit 60, the paper transport control unit 70, and the print control unit 80 so as to supply the paper P to the paper transport mechanism 20 one sheet at a time. Are intermittently conveyed through the sheet conveying mechanism 20 and when the sheet P is stopped, a line image for one pass is formed on the sheet P through the print control unit 80. With this operation, the main control unit 90 sequentially sends the paper P to the image formation point on the platen 240 and forms a series of images corresponding to the image data to be printed input from the PC 3 through the interface 95 on the paper P. To do.

  Here, processing executed by the main control unit 90 will be described with reference to FIG. The main control unit 90 executes main control processing shown in FIG. 3 every time image data for one sheet is input from the PC 3 through the interface 95.

  When the main control process is started, the main control unit 90 first executes a paper feed process. In the paper feed process, the paper feed control unit 60 is activated to cause the paper feed control unit 60 to execute rotation control of the ASF motor M1. As a result, the paper P is transported to the paper feed mechanism 10 (paper feed roller 103) up to the transport start point of the paper P by the paper transport mechanism 20 (contact point between the transport roller 201 and the pinch roller 202) (S100).

  When this process is finished, the main control unit 90 executes an image forming process (S200). In the image forming process, first, a cueing process of the paper P is performed through the paper transport control unit 70 (S210). Specifically, the target stop position is specified while starting the paper transport control unit 70, and the paper transport control unit 70 is controlled to transport the paper P to the specified target stop position (in other words, the rotation control of the LF motor M2). ) Is executed (S210). As a result, the paper P is conveyed to the target stop position by a method peculiar to the present embodiment, and is held in a stopped state at that point. That is, the sheet P is held in a stopped state after being cued.

  After the cueing process is completed, the main control unit 90 executes an image forming process for one pass (S220). Specifically, the print control unit 80 is activated, and the print control unit 80 executes the conveyance control of the carriage 33 so that the recording head 31 is conveyed at a constant speed for one way in the main scanning direction. Further, during conveyance of the recording head 31, the print control unit 80 is caused to execute drive control (ink droplet ejection control) of the recording head 31 through the head drive circuit DR4 (S220). With this process, a line image for one pass is formed on the paper P.

  Thereafter, the main control unit 90 determines whether or not the image formation for one sheet has been completed (S230), and determines that the image formation has not been completed (No in S230), executes the conveyance process for one pass. (S240). Specifically, the main control unit 90 sets the target stop position to the downstream side in the transport direction of the paper P by the distance corresponding to the width of the line image in the sub-scanning direction from the current position (from the transport roller 201 to the discharge roller 211). The updated target stop position is designated in the paper conveyance control unit 70, and the paper conveyance control unit 70 performs paper conveyance control (rotation control of the LF motor M2) up to the designated target stop position. Let As a result, the paper P is conveyed to the target stop position by a method peculiar to the present embodiment, and is held in a stopped state at that point. That is, the sheet P is sent downstream by one pass in the conveyance direction, and then held in a stopped state at that point. Here, it is possible to determine whether or not the paper P has stopped depending on whether or not it has stopped at a target stop position for a predetermined time.

  When the paper conveyance control unit 70 performs the paper conveyance control, the rotation control of the paper feed roller 103 by the paper feed control unit 60 may not be executed. That is, the sheet feeding operation by the motor driving of the sheet feeding roller 103 is completed when the leading edge of the sheet P reaches the contact portion between the conveying roller 201 and the pinch roller 202 which is a sheet supply point to the sheet conveying mechanism 20. Alternatively, when the paper is transported by the paper transport mechanism 20, the paper feed roller 103 may be set in a freely rotating state without being driven by a motor.

  However, in a case where the length in the conveyance direction of the sheet P is larger than the length of the conveyance path of the sheet from the contact point between the sheet feed roller 103 and the sheet P to the contact point between the conveyance roller 201 and the sheet P, the sheet feed control unit 60, the rotation control of the paper feed roller 103 may be executed. That is, the paper feed control unit 60 may execute rotation control of the paper feed roller 103 in conjunction with the paper transport control by the paper transport control unit 70. At this time, it is preferable to cause the paper feed control unit 60 to perform rotation control of the paper feed roller 103 so that back tension is applied to the paper P.

  For example, depending on the paper feed roller 103, rotation control of the paper feed roller 103 is executed by the paper feed controller 60 so that the paper P is transported at a transport speed slower than the transport speed of the paper P in the paper transport mechanism 20. It is made to do. Specifically, a roller rotation amount smaller than the update amount of the target stop position specified for the paper transport control unit 70 (difference before and after the update of the target stop position) is specified to the paper feed control unit 60, and the paper feed control is performed. By causing the unit 60 to perform rotation control of the paper feed roller 103 corresponding to the roller rotation amount in synchronization with the paper transport control unit 70, the paper feed control unit 60 performs transport at a lower speed than the paper transport control unit 70. Control can be executed.

When the process in S240 ends, the main control unit 90 returns to S220 and executes the image forming process for one pass described above. Thus, a line image for one pass is formed on the paper P.
In this way, the main control unit 90 intermittently conveys the paper P and repeatedly executes a process (S220 to S240) for forming a line image for one pass on the paper P, thereby forming an image for one paper. If it is determined that the process has been completed (Yes in S230), the process proceeds to S300 to execute a paper discharge process. That is, the main control unit 90 executes a process of rotating the transport roller 201 and the paper discharge roller 211 through the paper transport control unit 70 until the paper P is discharged. Thereafter, the main control process shown in FIG.

  Next, a detailed configuration of the sheet conveyance control unit 70 used for intermittent conveyance of the sheet P will be described with reference to FIG. FIG. 4A is a block diagram illustrating a detailed configuration of the paper conveyance control unit 70.

  The sheet conveyance control unit 70 according to the present exemplary embodiment includes an encoder signal processing unit 701, an operation amount calculation unit 703, a target position command output unit 705, and a signal output unit 707. The encoder signal processing unit 701 detects the rotation position (in other words, the rotation amount) of the transport roller 201 based on the encoder signals (A phase signal and B phase signal) input from the rotary encoder 205. The rotation amount of the conveyance roller 201 corresponds to the conveyance amount of the paper P. That is, the encoder signal processing unit 701 indirectly detects the transport position of the paper P by detecting the rotational position of the transport roller 201. Hereinafter, the position detected by the encoder signal processing unit 701 is expressed as “detection position”.

  Specifically, the encoder signal processing unit 701 detects the rotation direction of the conveyance roller 201 based on the phase difference between the A-phase signal and the B-phase signal, and when the rotation is normal (in other words, the sheet P is downstream in the conveyance direction). In the case of forward movement), every time the rising edge of the A-phase signal is detected, the detection position is counted up, and in the case of negative rotation (in other words, when the paper P moves backward), The detection position can be counted down every time the rising edge of the A phase signal is detected.

  On the other hand, the operation amount calculation unit 703 calculates the operation amount for the LF motor M2 in the direction of reducing the deviation based on the deviation between the position detected by the encoder signal processing unit 701 and the target position output from the target position command output unit 705. The calculated operation amount is input to the signal output unit 707.

  When the target stop position is designated by the main control unit 90, the target position command output unit 705 generates a target position locus from the current position to the target stop position, and the sheet P up to the target stop position is generated according to the target position locus. The target position at each time in the transport process is input to the operation amount calculation unit 703. An example of the target position trajectory is shown within the dotted line in FIG. The target position trajectory is set to a position trajectory that allows the drive target to be smoothly displaced to the target stop position using a sine function or the like.

  The operation amount calculation unit 703 calculates the operation amount with respect to the LF motor M2 in the direction of reducing the deviation based on the deviation between the target position generated and output in this way and the detection position. An operation amount for the LF motor M2 to be stopped at the stop position is calculated, and the calculated operation amount is input to the signal output unit 707. The operation amount calculation unit 703 feedback-controls the rotation position of the transport roller 201 and, consequently, the transport position of the paper P, by using such a method, and stops the paper P at the target stop position.

  Although an example in which the LF motor M2 is controlled by position control has been described here, the operation amount calculation unit 703 may be configured to control the LF motor M2 by position control and speed control. For example, the operation amount calculation unit 703 performs a speed control in the initial stage of conveyance, and performs a position control instead of the speed control in the second half of the conveyance, so that the sheet P is stopped at the target stop position at a high speed. it can. In this case, for example, the encoder signal processing unit 701 measures the rising edge interval (time interval) of the A-phase signal and obtains the reciprocal thereof, thereby detecting the rotational speed of the transport roller 201 and calculating the detected speed. Used for speed control. In addition, a known controller such as a proportional (P) controller, an integral (I) controller, a proportional-integral (PI) controller, or a proportional-integral-derivative (PID) controller is used for the operation amount calculation unit 703. it can.

  The signal output unit 707 includes a drive signal generation unit 708 and an on / off control unit 709. The drive signal generator 708 generates a drive signal for driving the LF motor M2 with electric power (drive current) corresponding to the operation amount calculated by the operation amount calculator 703, and inputs the drive signal to the motor driver DR2. It is. Specifically, a PWM signal for driving the LF motor M2 with a drive current corresponding to the operation amount is generated as the drive signal and is input to the motor driver DR2. On the other hand, the on / off control unit 709 generates an enable signal for permitting / prohibiting the power supply of the LF motor M2, and inputs this to the motor driver DR2.

  FIG. 4B is a circuit diagram showing a basic configuration of an H bridge provided in the motor driver DR2. When the enable signal input from the on / off control unit 709 is an on signal, the motor driver DR2 of the present embodiment turns on / off the switching elements SW1 to SW4 of the H bridge according to the driving signal (PWM signal). As a result, the drive current corresponding to the operation amount calculated by the operation amount calculation unit 703 is supplied to the LF motor M2. Specifically, by turning on the switching elements SW1 and SW4 and turning off the switching elements SW2 and SW3, the LF motor M2 is rotated forward, the switching elements SW2 and SW3 are turned on, and the switching elements SW1 and SW4 are turned off. As a result, the LF motor M2 is rotated negatively.

  In the drive signal generation unit 708, when the operation amount is positive, a PWM signal that causes the LF motor M2 to rotate in the forward direction is input as the drive signal, so that the transport roller 201 is rotated in the forward direction and the paper P is loaded. It is transported downstream in the transport direction. On the other hand, when the operation amount is negative, a PWM signal for negatively rotating the LF motor M2 is input as the driving signal, so that the transport roller 201 is negatively rotated and transported in the direction in which the paper P moves backward. To be.

  In addition, when the enable signal that is input is an off signal, the motor driver DR2 sets all of the H-bridge switching elements SW1 to SW4 to be off and does not depend on the driving signal, thereby supplying power to the LF motor M2. The supply is prohibited.

  The on / off control unit 709 permits / inhibits power supply to the LF motor M2 by switching on / off of the enable signal processed in this way in the motor driver DR2.

  As the motor driver DR2, the above-described motor driver that sets all of the H-bridge switching elements SW1 to SW4 to OFF when the enable signal is an OFF signal can be employed. May be a motor driver that brakes the LF motor M2 by turning off the switching elements SW1 and SW2 and turning on the switching elements SW3 and SW4.

  Next, the operation of the on / off control unit 709 unique to the present embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing on / off control processing executed by the on / off control unit 709. When the paper conveyance control unit 70 is activated and the target stop position is designated, the on / off control unit 709 repeatedly executes the processing shown in FIG. 5 at predetermined intervals thereafter.

  When the processing shown in FIG. 5 is started, the on / off control unit 709 determines whether or not the position detected by the encoder signal processing unit 701 is larger than the target stop position (S310). Thereby, it is determined whether or not the sheet P has overrun to the downstream side in the transport direction from the target stop position.

  If it is determined that the detection position is equal to or less than the target stop position (No in S310), the enable signal is set to an on signal (S320). Accordingly, the operation amount calculated by the operation amount calculation unit 703 is reflected in the drive current of the LF motor M2 under the situation where the paper P is not overrun. Thereafter, the on / off control unit 709 once ends the process shown in FIG. 5 and repeatedly executes the same process from S310.

  On the other hand, if it is determined that the detection position is larger than the target stop position (Yes in S310), the on / off control unit 709 considers that the paper P is overrun downstream from the target stop position in the transport direction. The processing after S330 is executed. Specifically, in S330, it is determined whether or not the operation amount calculated by the operation amount calculation unit 703 is positive. If the manipulated variable is positive (Yes in S330), the enable signal is set to an off signal (S340). In this manner, in a situation where the operation amount is positive and a forward force is applied to the paper P, the power supply to the LF motor M2 by the motor driver DR2 is prohibited.

  In this embodiment, at the time of intermittent conveyance, the rear end of the paper P is curved by the U-turn path 111, and due to this curvature, a force that moves backward in the conveyance direction acts on the paper P. Further, when the end point of the paper P does not pass through the end point of the paper feed roller 103, a force that moves backward in the transport direction acts on the paper P at the contact point with the paper feed roller 103, and the transport roller 201 is negative. Load in the rotation direction. Therefore, the operation amount calculation unit 703 calculates a positive value as the operation amount even when the paper P is in the target stop position, and the forward force that balances the load acts on the paper P through the transport roller 201. It operates to maintain the paper P at the target stop position.

  Therefore, in this embodiment, even when the paper P overruns the target stop position, the operation amount remains positive for a while. In this embodiment, in this state, the enable signal is set to the off signal, and the power supply to the LF motor M2 by the motor driver DR2 is prohibited, so that the sheet P can be moved backward to the target stop position and the load can be reduced. Use and promote. When the on / off control unit 709 switches the enable signal to the off signal in this manner, the on / off control unit 709 once ends the process illustrated in FIG. 5 and executes the same process again from S310.

  FIG. 6 is a graph showing the relation between the on / off state of the enable signal, the drive current supplied to the LF motor M2, and the target stop position and the detection position, with the horizontal axis as time. FIG. 6 shows an example in which the amount of operation increases because the position of the drive target until reaching the target stop position is lower than the target position, and overrun occurs due to this. Under such circumstances, in this embodiment, when the detection position exceeds the target stop position, the enable signal is switched off and the supply of the drive current to the LF motor M2 is prohibited.

  On the other hand, even when the paper P is overrun to the downstream side in the transport direction from the target stop position, the operation amount is negative, and the force for moving the paper P backward in the direction opposite to the transport direction is LF motor M2. In such a situation, a negative determination is made in S330, and the enable signal is set to the ON signal (S350). Thereby, the power supply to the LF motor M2 by the motor driver DR2 is resumed. Thereafter, the on / off control unit 709 once ends the process shown in FIG. 5 and executes the same process again from S310. In this way, in this embodiment, the enable signal is switched on / off so as to quickly eliminate the overrun.

  Even if the operation amount does not become negative, as a result of switching the enable signal to the off signal, the sheet P moves backward, and when the detected position coincides with the target stop position, the on / off control unit 709 proceeds to S310. A negative determination is made, and the enable signal is reset to the ON signal (S320). Thereby, the power supply to the LF motor M2 by the motor driver DR2 is resumed. In this embodiment, such an operation is repeatedly executed.

  In the example shown in FIG. 6, after the overrun occurs and the enable signal is switched to the off signal (S340), the enable signal is reset to the on signal when the detection position matches the target stop position (No in S310). It is set (S320), and power supply to the LF motor M2 is resumed. Further, due to the occurrence of an overrun due to the restart of the power supply, the enable signal is switched again to the off signal, and the power supply to the LF motor M2 is prohibited (S340). Then, when the detected position again coincides with the target stop position, the power supply to the LF motor M2 is resumed (S320).

  In this embodiment, by repeating such operations, the drive current of the LF motor M2 is finally adjusted to a drive current that balances the force acting on the drive target (paper P) by the LF motor M2 with the load. The paper P is stopped at the target stop position. The drive current when the enable signal is switched from the off signal to the on signal and the power supply to the LF motor M2 is resumed is determined by the operation amount at that time, but in this embodiment, the operation amount is Regardless of whether the enable signal is on or off, the operation amount calculation unit 703 continuously calculates the enable signal. Therefore, according to the present embodiment, the LF motor M2 can be driven with a drive current corresponding to the latest operation amount when the enable signal is switched. As a result, according to this embodiment, the overrun can be quickly resolved and the paper P can be suitably stopped at the target stop position. Note that the processing shown in FIG. 5 can be stopped when it is determined that the paper P has stopped at the target stop position and the image forming processing for one pass (S220) is started. However, the processing shown in FIG. 5 is performed at the target stop position for the next one-pass conveyance process so that the holding current for holding at the stop position can be supplied to the LF motor M2 during the image forming process for one pass. It may be continued until designation is made.

  FIG. 7 shows changes in the detection position when the enable signal is always turned on, and changes in the detection position when the enable signal is turned on / off as described above. FIG. 7A shows a change in the detection position when the enable signal is always turned on, and FIG. 7B shows a change in the detection position when the enable signal is turned on / off. Is. Specifically, FIGS. 7A and 7B show the change in the detection position in each case in the upper stage, the change in the operation amount (drive current) in the middle stage, and the change in the enable signal in the lower stage. It is shown.

  As can be understood by comparing FIGS. 7A and 7B, according to this embodiment, the sheet P can be quickly stopped at the target stop position as compared with the case where the enable signal is not turned on / off. . That is, according to the image forming apparatus 1 of the present embodiment, in an environment in which a load is applied in the direction opposite to the conveyance direction of the drive target (paper P), the load is used to move from the target stop position of the drive target. The overrun can be quickly eliminated, and as a result, a high-quality image can be formed on the paper P at a high speed.

  Although the configuration of the image forming apparatus 1 has been described above, the correspondence between terms is as follows. The LF motor M2 corresponds to an example of a motor to be controlled by the drive control device. The paper transport mechanism 20 corresponds to an example of a first transport mechanism, the paper feed mechanism 10 corresponds to an example of a second transport mechanism, and the transport roller 201 corresponds to an example of a first roller. The roller 103 corresponds to an example of a second roller. The arm 104 corresponds to an example of a pressing mechanism provided in the second transport mechanism.

  The encoder signal processing unit 701 corresponds to an example of a position detection unit, the operation amount calculation unit 703 and the target position command output unit 705 correspond to an example of an operation amount calculation unit, and the on / off control unit 709 includes: This corresponds to an example of prohibiting means and restart control means.

  In addition, the recording head 31 and the like correspond to an example of an image forming unit, the paper feed control unit 60 corresponds to an example of a supply unit, and the paper conveyance control unit 70 and the motor driver DR2 include a drive control device and a drive control. Corresponding to an example of the means, the main control unit 90 corresponds to an example of the position updating means.

  Further, the present invention is not limited to the above-described embodiments, and can take various forms. For example, the example in which the present invention is used for sheet conveyance of the image forming apparatus has been described above, but the present invention can be applied to a general technique for stopping other driving objects at a target stop position. In the above embodiment, the power supply to the LF motor M2 is prohibited by the enable signal from the on / off control unit 709. However, the operation amount calculated by the operation amount calculation unit 703 is forcibly set to zero. By doing so, power supply may be prohibited. In the above embodiment, the operation amount calculation by the operation amount calculation unit 703 is continued while the power supply to the LF motor M2 is prohibited, but the operation amount at the moment when the power supply is prohibited is stored. In addition, while the power supply is prohibited, the operation amount calculation may be interrupted. When the supply of power is resumed, the drive signal generation unit 708 may generate a drive signal based on the stored operation amount.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Paper feed mechanism, 20 ... Paper conveyance mechanism, 30 ... Printing mechanism, 31 ... Recording head, 33 ... Carriage, 50 ... Control part, 60 ... Paper feed control part, 70 ... Paper conveyance control part , 80 ... Print control unit, 90 ... Main control unit, 101 ... Paper feed tray, 103 ... Paper feed roller, 104 ... Arm, 105, 205 ... Rotary encoder, 111 ... U-turn path, 201 ... Conveyance roller, 211 ... Paper discharge Roller, 220 ... Power transmission mechanism, 701 ... Encoder signal processing unit, 703 ... Operation amount calculation unit, 705 ... Target position command output unit, 707 ... Signal output unit, 708 ... Driving signal generation unit, 709 ... On / off control Part, DR1, DR2, DR3 ... motor driver, DR4 ... head drive circuit, M1 ... ASF motor, M2 ... LF motor, M3 ... CR motor, P ... paper, SW1-SW4 Switching element

Claims (12)

A drive control device that displaces the drive target in the traveling direction toward the target stop position by controlling the motor included in the drive mechanism that realizes the displacement of the drive target by applying power generated from the motor to the drive target. There,
The drive mechanism is a drive mechanism having a configuration in which a load that causes the drive target to move backward in a direction opposite to the traveling direction works.
The drive control device includes:
Position detecting means for detecting the position of the drive target;
Based on the position of the drive target detected by the position detection means and the target stop position, an operation amount calculation means for calculating an operation amount for the motor for stopping the drive target at the target stop position;
A motor driver for driving the motor by supplying power to the motor corresponding to the operation amount calculated by the operation amount calculating means;
Based on the position of the drive target detected by the position detection means, when it is detected that the drive target has overrun from the target stop position to the downstream side in the traveling direction, the motor driver supplies power to the motor. Prohibiting means to prohibit,
When a predetermined condition is satisfied, resumption control means for causing the motor driver to resume power supply to the motor prohibited by the inhibition means;
A drive control device comprising: Based on the position of the driving target detected by the position detecting means, the restart control means determines that the predetermined condition is satisfied when the overrun driving target moves backward to the target stop position. The drive control device according to claim 1, wherein power supply to the motor is restarted. The operation amount calculation means continuously calculates the operation amount even during a period in which the power supply is prohibited,
When the motor driver resumes power supply to the motor in accordance with an instruction from the restart control means, the motor driver supplies power corresponding to the latest operation amount at that time to the motor to drive the motor. The drive control device according to claim 1, wherein the drive control device is resumed. The power supply prohibiting operation by the prohibiting unit and the power supply resuming operation by the restart control unit are realized by a switching operation of an enable signal input to the motor driver separately from the operation amount. The drive control apparatus according to claim 3. The motor driver is configured to rotationally drive the motor by switching the rotation direction of the motor to positive or negative according to the magnitude from the reference value of the operation amount calculated by the operation amount calculator.
In the drive mechanism, the drive object is displaced in the traveling direction by the forward rotation of the motor, and the drive object is displaced in the direction opposite to the traveling direction by the negative rotation of the motor,
The restart control means detects that the overrun drive object has moved backward to the target stop position based on the position of the drive object detected by the position detection means, or calculates by the operation amount calculation means. When it is detected that the operation amount is switched in a direction in which the rotation direction of the motor is switched from positive to negative based on the operated amount, the motor driver determines that the predetermined condition is satisfied and the power to the motor is transmitted to the motor driver. The drive control device according to any one of claims 1 to 4, wherein supply is resumed. A sheet conveyance mechanism that includes a motor and a roller that is rotationally driven by the motor, and conveys a sheet that contacts the roller by the rotation of the roller;
6. The sheet conveyance mechanism according to claim 1, wherein the sheet conveyance mechanism conveys the sheet toward the target stop position by controlling the motor included in the sheet conveyance mechanism as the driving mechanism. A drive control device,
A sheet conveying apparatus comprising: The sheet conveying mechanism includes a first roller as the roller and a second roller located on the upstream side in the traveling direction of the sheet with respect to the first roller,
The drive control device controls the motor that can rotationally drive the first roller, thereby causing the sheet conveyance mechanism to place the sheet supplied from the second roller to the first roller at the target stop position. The sheet conveying apparatus according to claim 6, wherein the sheet conveying apparatus is directed toward the sheet. The sheet conveying mechanism includes a U-shaped sheet conveying path that regulates the movement of the sheet between the first roller and the second roller,
The sheet conveying apparatus according to claim 7, wherein the sheet is conveyed toward the target stop position in a curved state through the U-shaped sheet conveying path. Image forming means for forming a line image in the main scanning direction with respect to the stopped sheet;
A first conveying mechanism that conveys the sheet toward an image forming point by the image forming unit; and a first conveying mechanism that is disposed upstream of the first conveying mechanism in the sheet conveying direction and supplies the sheet to the first conveying mechanism. A sheet conveying mechanism comprising two conveying mechanisms;
Supply means for driving the second transport mechanism to supply the sheet to the first transport mechanism;
Drive control for controlling the motor provided in the first transport mechanism to cause the first transport mechanism to transport the sheet in the sheet transport direction from the sheet supply point to which the sheet is supplied toward the image forming point. Means,
In the sheet transport mechanism, the second transport mechanism is supplying the sheet to the first transport mechanism at a speed slower than the speed of the first transport mechanism, or the second transport mechanism is the first transport mechanism. In the image forming apparatus, the first conveying mechanism is controlled by the drive control unit to convey the sheet to the image forming point in a state where the operation of supplying the sheet to the one conveying mechanism is completed and stopped. And
The drive control means includes
Position detecting means for detecting the position of the sheet;
Position updating means for setting the target stop position of the sheet to be updated downstream in the sheet conveying direction each time the line image is formed by the image forming means;
An operation amount for calculating an operation amount for the motor for stopping the sheet at the target stop position based on the position of the sheet detected by the position detection unit and the target stop position set by the position update unit. Computing means;
A motor driver for driving the motor by supplying power to the motor corresponding to the operation amount calculated by the operation amount calculating means;
Based on the position of the sheet detected by the position detection means, when it is detected that the sheet has overrun from the target stop position to the downstream side in the sheet conveying direction, the motor driver prohibits power supply to the motor. Prohibition means to do,
Based on the position of the sheet detected by the position detection means, when the overrun sheet retracts to the target stop position, the motor driver resumes power supply to the motor prohibited by the prohibition means. Restart control means for causing
An image forming apparatus comprising: The sheet conveying mechanism includes a U-shaped sheet conveying path that regulates the movement of the sheet between the first conveying mechanism and the second conveying mechanism,
The image forming apparatus according to claim 9, wherein the sheet is conveyed toward the target stop position in a curved state through the U-shaped sheet conveyance path. The second transport mechanism includes a roller for supplying the sheet to the first transport mechanism, a pressing mechanism for pressing the roller against the sheet,
The image forming apparatus according to claim 9, wherein the sheet is conveyed by rotating the roller while the roller is pressed against the sheet.   A drive control device that displaces the drive target in the traveling direction toward the target stop position by controlling the motor included in the drive mechanism that realizes the displacement of the drive target by applying power generated from the motor to the drive target. There,
  The drive mechanism is a drive mechanism having a configuration in which a load that causes the drive target to move backward in a direction opposite to the traveling direction works.
  The drive control device includes:
  Position detecting means for detecting the position of the drive target;
  Based on the position of the drive target detected by the position detection means and the target stop position, an operation amount calculation means for calculating an operation amount for the motor for stopping the drive target at the target stop position;
  A motor driver for driving the motor by supplying power to the motor corresponding to the operation amount calculated by the operation amount calculating means;
  Based on the position of the driving object detected by the position detecting means, when detecting that the driving object has overrun from the target stop position to the downstream side in the traveling direction, the motor driver based on the operation amount. A prohibition means for prohibiting power supply to the motor;
  When a predetermined condition is satisfied, resumption control means for causing the motor driver to resume power supply to the motor prohibited by the inhibition means;
  A drive control device comprising:

Images