JP7722008B2 - Conveying device and image recording device - Google Patents

Description

The present invention relates to a conveying device and an image recording device.

Patent Document 1 describes an inkjet printer as an example of an image recording device. In the printer, when recording an image on a single sheet, after a cueing process is performed, image recording and intermittent conveying are alternately and repeatedly performed. In the cueing process, a feed roller sends each sheet onto the conveying path, and a conveying roller, using power from a motor, conveys the sheet to a recording start position directly below the recording head. In image recording, the recording head ejects ink toward the stopped sheet while being conveyed in the main scanning direction by a carriage over the stopped sheet. After image recording is completed, the conveying roller conveys the sheet a predetermined amount in the conveying direction through intermittent conveying. This process of image recording and intermittent conveying is repeated until image recording on one sheet is completed (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2001-251878

In intermittent conveyance, a motor (e.g., a DC motor) rotates and stops under the control of a controller. Motor drive control includes acceleration control, constant speed control, and deceleration control. For stop control, PID control using the PWM method may be used. In PID control, the controller calculates the position deviation between the stop position and the current position of the sheet, and calculates proportional, integral, and derivative elements based on that position deviation. The controller determines the duty ratio of the PWM signal according to these elements so that it follows a predetermined speed table.

However, from the start to the end of deceleration control, the current position of the sheet is gradually aligned with the stopping position using PID control (i.e., feedback control), which increases the time required from the start to the stop of sheet transport.

The present invention was made in consideration of the above circumstances, and its purpose is to provide technology that can shorten the time required from the start to the stop of sheet transport.

(1) A conveying device of the present invention includes a motor, a driver that applies a drive current to the motor to rotate it, a conveying mechanism that conveys an object in a conveying direction by forward rotation of the motor, and a controller. The controller outputs a first control signal to the driver in response to the timing to convey the object, causing the drive current to flow in a first direction within the motor and for the motor to rotate forward at a constant speed. In response to determining that the object has reached a first position upstream of a stop position of the object in the conveying direction, the controller sequentially outputs a second control signal to the driver in response to determining that the object has reached a first position upstream of a stop position of the object in the conveying direction, causing the driver to interrupt an electrical path from the driver to the motor, and a third control signal to cause the drive current to flow in a second direction opposite to the first direction and without exceeding the maximum current value of the driver. In response to determining that the object has reached a second position closer to the stop position than the first position in the conveying direction, the controller outputs a fourth control signal to the driver in response to determining that the object has reached a second position in the conveying direction, closer to the stop position than the first position, causing the motor to reduce its rotation speed based on the deviation between the current position of the object and the stop position. The controller stops outputting the fourth control signal to the driver in response to determining that the object has reached the stop position.

According to the above process, a third control signal is given to the driver while the object is traveling from the first position to the second position, causing the object's transport speed to suddenly decelerate from a constant speed. As a result, the transport time required for the object to reach the stop position is shortened.

(2) The conveying device transmits power generated by the motor to the conveying mechanism and includes a plurality of gears that mesh with each other, and a memory that stores first information indicating the amount of backlash in the plurality of gears. In response to the output of the fourth control signal being stopped, the controller stores second information in the memory indicating whether the motor is rotating in the forward direction. At the timing of conveying the next object, in response to determining that the second information stored in the memory indicates that the motor is not rotating in the forward direction, the controller determines the stop position of the next object based on the stop position and the first information in the memory, and outputs the first control signal through the fourth control signal in sequence. In response to determining that the next object has reached the determined stop position, the controller stops outputting the fourth control signal.

According to the above process, if the motor is not rotating forward when the output of the fourth control signal stops, when the motor is rotated forward to transport the next object in the transport direction, backlash will cause a period of time during which the next object cannot be transported. However, according to the above process, the stopping position of the next object can be corrected based on the amount of backlash, so the next object will stop in the correct stopping position.

(3) The image recording device of the present invention includes a first motor, a driver that applies a drive current to the first motor to rotate the first motor, a transport mechanism that transports a sheet in a transport direction by forward rotation of the first motor, a second motor, a carriage that moves in a direction intersecting the transport direction by rotation of the second motor, a recording head mounted on the carriage and ejecting ink, and a controller. The controller outputs a first control signal to the driver in response to the timing for transporting the sheet, for causing the drive current to flow in a first direction within the first motor and for the first motor to rotate forward at a constant speed. The controller outputs a second control signal to the driver in sequence in response to determining that the sheet has reached a first position upstream of the stop position of the sheet in the transport direction, for interrupting an electrical path from the driver to the first motor, and a third control signal for causing the drive current to flow in a second direction opposite to the first direction and not exceeding the maximum current value of the driver. When the controller determines that the sheet has reached a second position in the transport direction that is closer to the stop position than the first position, it outputs a fourth control signal to the driver to reduce the number of rotations of the first motor based on the deviation between the current position of the sheet and the stop position. When the controller determines that the sheet has reached the stop position, it stops outputting the fourth control signal to the driver. When the controller determines that the sheet has reached the stop position, it causes the driver to rotate the second motor so that the print head moves together with the carriage in the intersecting direction at a position facing the sheet at the stop position, and causes the print head to eject ink toward the sheet at the stop position.

According to the above process, a third control signal is given to the driver while the sheet is moving from the first position to the second position, causing the object's transport speed to suddenly decelerate from a constant speed. As a result, the transport time required for the sheet to reach the stop position is shortened.

(4) The image recording device further includes a timer and a memory. The controller acquires third information indicating the time from the start of conveyance of the sheet to the stop of conveyance from the timer and stores it in the memory, and starts rotating the second motor at a timing based on the third information stored in the memory.

According to the above process, the load on the first motor fluctuates over time, resulting in an increase in the sheet transport time. According to the above process, the print head begins to move at a timing based on the third information, so even if the load on the first motor fluctuates, misalignment of the image printed on the sheet can be suppressed.

(5) The image forming device further includes an input interface. The controller outputs the first control signal through the fourth control signal in response to receiving an operation through the input interface. While the first control signal through the fourth control signal are being output, the controller acquires the third information from the timer and stores it in the memory.

The above process allows the third information to be stored in memory while ink is not being ejected from the recording head.

(6) While the first control signal, second control signal, or fourth control signal is being output in response to the timing for conveying the sheet, the controller acquires the third information from the timer and stores it in the memory.

With the above process, the third information is automatically stored in memory, so the user does not need to operate the image recording device to store the third information in memory.

This invention reduces the time required from the start to the stop of sheet transport.

1A is a perspective view that schematically shows the appearance of an MFP 500, and FIG. 1B is a vertical cross-sectional view that schematically shows the configuration of a printer unit 100. FIG. 1A is a plan view showing the CR transport mechanism 18 and the like, and FIG. 1B is a plan view showing the power transmission mechanism 21 and the like. FIG. 5 is a block diagram of an MFP 500. 3A and 3B are schematic diagrams showing the configuration of a driver 22 and illustrating the operation of a PF motor 211. 3 is a main flowchart of the printer unit 100. 6 is a flowchart showing a detailed processing procedure of the intermittent conveyance of FIG. 5 . 10 is a graph showing changes over time in the conveying distance Dc (position) of a sheet in the embodiment and the reference example. 10 is a flowchart of intermittent conveyance in a first modified example. 9 is a flowchart showing a detailed processing procedure of the intermittent conveyance (reverse rotation) of FIG. 8 . 10 is a main flowchart of the printer unit 100 in a second modified example. 11 is a flowchart showing a detailed processing procedure of the first half of the intermittent conveyance shown in FIG. 10 . 11 is a flowchart showing a detailed processing procedure of the second half of the intermittent transport shown in FIG. 10 .

The following describes in detail an MFP 500 (an example of an image recording device) according to an embodiment of the present invention. The embodiment is merely an example of the present invention, and can be modified as appropriate without departing from the spirit and scope of the present invention.

[Definition of terms]
In the following description, the direction of an arrow is expressed as the progression from the starting point to the end point, and the movement on the line connecting the starting point and end point of the arrow is expressed as the direction.

The up-down direction 7 is defined based on the state in which the MFP 500 is installed and ready for use (the state shown in Figure 1(A)). The front-to-back direction 8 is defined with the surface of the MFP 500 where the opening 510 is provided as the front surface 520. The left-to-right direction 9 is defined when the MFP 500 is viewed from the front. The up-to-down direction 7, the front-to-back direction 8, and the left-to-right direction 9 are perpendicular to one another.

[MFP 500, printer unit 100]
In FIG. 1A, the MFP 500 has a generally rectangular parallelepiped shape and has a printer unit 100 at the bottom. The printer unit 100 records an image on a sheet S (see FIG. 1B) using an inkjet method. The sheet S is paper, an overhead projector sheet, or the like. The printer unit 100 is an example of a conveying device or an image recording device. The sheet S is an example of an object. In addition to the printing function provided by the printer unit 100, the MFP 500 also has a facsimile function, a scanning function, and the like.

As shown in FIG. 1(A), the printer unit 100 has an operation panel 11 on the front surface 520. As shown in FIG. 1(B), the printer unit 100 has an internal space 530 that includes a supply tray 12, an output tray 13, a feed unit 14, a transport path 15, a transport unit 16, a rotary encoder SE1, a platen 17, a CR transport mechanism 18 (see also FIG. 2(A)), a recording head 19, and an output unit 20. The internal space 530 is partitioned by the housing of the MFP 500. The printer unit 100 also has a power transmission mechanism 21 (see FIG. 2(B)), a driver 22, and a controller 23 (see FIG. 3) in the internal space 530.

In FIG. 1(A), the operation panel 11 is an example of an input interface and includes a touch panel and physical buttons. When a user operates the touch panel or physical buttons, an operation signal is output to the controller 23.

[Supply tray 12, discharge tray 13]
The supply tray 12 and the discharge tray 13 are attached to the internal space 530 and exposed forward from the opening 510. The supply tray 12 has a thin box-like shape with a top and bottom, and supports a plurality of sheets S in a stacked state. The discharge tray 13 is located above the supply tray 12, and supports the sheets S on which images have been recorded.

[Feeding section 14]
1B, the feeding unit 14 includes a feeding roller 141 and a feeding arm 142. The feeding roller 141 is supported at the tip of the feeding arm 142 so as to contact the sheet S in the feeding tray 12, and is rotatable about an axis extending to the left and right. The feeding roller 141 is rotated by power from a PF motor 211 (see FIG. 2B, etc.), and sends the topmost sheet S in the feeding tray 12 to the conveying path 15.

[Transport path 15]
The transport path 15 is a so-called U-turn path, and has a curved portion 151 and a straight portion 152. The curved portion 151 extends upward and forward from the rear end of the supply tray 12. The straight portion 152 extends linearly forward from the downstream end of the curved portion 151 and reaches the rear end of the discharge tray 13. The upper and lower ends of the straight portion 152 are defined by the lower surface 19A of the recording head 19 and the upper end 17A of the platen 17.

The sheet S is transported in the transport path 15 in the transport direction 5. The transport direction 5 is indicated by the dashed arrow in Figure 1(B). The sheet S is supported by the platen 17, particularly in the straight section 152, and is transported in the transport direction 5 (i.e., forward) by the transport force applied from the transport section 16 and the discharge section 20.

[Conveying section 16, discharging section 20]
The conveying section 16 is located at the downstream end of the curved section 151 and includes a drive roller 161 and a pinch roller 162. The pinch roller 162 contacts the drive roller 161 from below. The discharge section 20 is located in front of the conveying section 16 in the straight section 152 and slightly behind the rear end of the discharge tray 13. The discharge section 20 includes a drive roller 201 and a spur 202. The spur 202 contacts the drive roller 201 from above. The drive rollers 161 and 201 are rotated by the power of a PF motor 211 (see FIG. 2B ). The pinch roller 162 and the spur 202 rotate following the rotation of the drive rollers 161 and 201. The sheet S is conveyed in the conveying direction 5 (i.e., forward) in the straight section 152 by the forward rotation of the drive rollers 161 and 201. The conveying section 16 and the discharge section 20 are an example of a conveying mechanism.

[Rotary encoder SE1]
In FIG. 1B , in the rotary encoder SE1, the disk 163 is coaxially fixed to the rotating shaft 161A and has A-phase and B-phase optical patterns. The A-phase and B-phase optical patterns have light-transmitting and light-blocking portions that alternate in the circumferential direction of the rotating shaft 161A at different radial locations. The circumferential positions of the optical patterns are shifted from each other by a phase difference of 90°. In the rotary encoder SE1, the optical sensors 164 for each phase are fixed to the housing of the MFP 500 and have an LED (Light Emitting Device) and a PD (Photo Detector). Each LED emits light toward the in-phase optical pattern. Each PD faces the LED across the in-phase optical pattern and outputs pulse signals AS1 and BS1, respectively, with a phase difference of 90°. The number of pulses in the pulse signals AS1 and BS1 is also referred to as the encoder quantity.

[Power transmission mechanism 21]
2(B), the power transmission mechanism 21 includes a PF motor 211, pulleys 212, 213, 217, and 218, endless belts 214 and 219, and gears 215 and 216 (an example of multiple gears). The PF motor 211 is a DC motor or the like, and is an example of a motor or a first motor. The PF motor 211 is located to the left of the straight portion 152 and behind the drive roller 161 in the internal space 530. The PF motor 211 rotates under the control of the controller 23 (see FIG. 3) and generates power in an output shaft extending left and right. The pulley 212 is attached to the output shaft of the PF motor 211, and the pulley 213 is attached to the rotation shaft 161A in front of the pulley 212. An endless belt 214 is wound around the pulleys 212 and 213. Gear 215 is coaxially fixed to rotation shaft 161A at a position between pulley 213 and straight portion 152. Gear 216 is attached to a frame (not shown) provided in internal space 530, meshes with gear 215 from below, and rotates around an axis extending left and right. Pulley 217 is coaxially fixed to gear 216, and pulley 218 is fixed to rotation shaft 201A of drive roller 201 forward of pulley 217. An endless belt 219 is wound around pulleys 217 and 218.

[Driver 22]
3 and 4, the driver 22 is an integrated circuit including an H-bridge circuit. In Fig. 4, the driver 22 has two input terminals Tin, two output terminals Tout, and four switches SW1 to SW4.

In Figure 4, a voltage Vcc is applied across input terminals Tin. A PF motor 211 is connected across output terminals Tout. Each switch SW1 to SW4 is a semiconductor power transistor such as a MOSFET. Control signals CS1 to CS4 are provided to switches SW1 to SW4 by ASIC 235 (see Figure 3). The control signals CS1 to CS4 are pulse-width modulated signals (hereinafter also referred to as "PWM signals") and include four combinations. The first set includes control signals CS1a, CS2a, CS3a, and CS4a (see Figure 4(A), an example of a first control signal). The second set includes control signals CS1b to CS4b (see Figure 4(B), an example of a second control signal). The third set includes control signals CS1c to CS4c (see Figure 4(C)). The fourth group consists of control signals CS1d to CS4d (see Figure 4(D), an example of the third control signal). The third group will be mentioned later in the "Other Modifications" section.

The duty ratios of the control signals CS1a and CS4a are non-zero, and the duty ratios of the control signals CS2a and CS3a are zero. The first set turns on switches SW1 and SW4 and turns off switches SW2 and SW3, as shown in Figure 4(A). Control signals CS1a to CS4a form an electrical path L1 between input terminal Tin, passing through switch SW1, PF motor 211, and switch SW4 in the direction of arrow AR1 (an example of the first direction). Control signals CS1a to CS4a cause PF motor 211 to rotate forward.

The duty ratio of the control signals CS1b to CS4b is zero. When the PF motor 211 is rotating forward (see (A) in the same figure), if the second group turns off switches SW1 to SW4 as shown in (B) in Figure 4, the electrical path L1 is interrupted. Furthermore, the current flowing through the PF motor 211 is regenerated to the input terminal Tin via the parasitic diodes of switches SW2 and SW3, and the PF motor 211 gradually decelerates while rotating forward by inertia, eventually coming to a stop (inertia stop).

The duty ratios of the control signals CS1c and CS3c are zero, while the duty ratios of the control signals CS2c and CS4c are not zero. When the PF motor 211 is rotating forward (see (A) in the same figure), the third group turns off switches SW1 and SW3 and turns on switches SW2 and SW4, as shown in (C) in Figure 4, thereby interrupting the electrical path L1. Furthermore, the induced voltage in the PF motor 211 causes current to flow through the closed loop L2, consuming the rotational energy of the PF motor 211. As a result, the PF motor 211 is subjected to a deceleration force and eventually stops (short brake).

The duty ratios of the control signals CS1d and CS4d are zero, while the duty ratios of the control signals CS2d and CS3d are not zero. When the PF motor 211 is rotating forward (see (A) in the same figure), switches SW1 and SW4 are turned off and switches SW2 and SW3 are turned on, interrupting the electrical path L1. Current in the PF motor 211 is regenerated to the input terminal Tin via switches SW2 and SW3. As a result, electrical path L3 is formed between the input terminal Tin, passing through switch SW2, the PF motor 211, and switch SW3, with current flowing in the direction of arrow AR2. Arrow AR2 is an example of a second direction, and indicates the opposite direction to arrow AR1. The PF motor 211 receives a deceleration force due to the rotational energy generated by the regenerative current and stops (reverse braking). The deceleration force produced by reverse braking is stronger than the deceleration force produced by short braking.

Semiconductor devices such as driver ICs have absolute maximum ratings. In Japan, the definition of absolute maximum ratings is based on the Japanese Industrial Standards (JIS) "JIS C 7032 General Rules for Transistors." The absolute maximum rating of the driver 22 includes the maximum current that can be passed through the driver 22. Note that the maximum current value of the driver 22 is different from the maximum current value that flows through the PF motor 211.

[Platen 17]
1B, the platen 17 is located between the conveying section 16 and the discharge section 20 in the straight section 152. The platen 17 supports the sheet S conveyed in the straight section 152 from below with its upper end 17A. The upper end 17A is the protruding end of a plurality of ribs protruding upward from the platen 17.

[CR transport mechanism 18]
2A, the CR transport mechanism 18 includes two bases 181 and 182, a carriage 183, two pulleys 184 and 185, an endless belt 186, and a CR motor 187 (an example of a second motor). The CR transport mechanism 18 further includes a linear encoder SE2.

The bases 181, 182 are positioned along the front and rear edges of the platen 17 and have guide grooves 181A, 182A. Each guide groove 181A, 182A extends parallel to the left-right direction 9 and occupies a wider area than the area between the left and right ends P11, P12 of the straight portion 152.

The carriage 183 is suspended between the guide grooves 181A and 182A above the platen 17, crossing the platen 17 from front to back. The carriage 183 is fixed to an endless belt 186, and is capable of sliding in the left-right direction 9 along the guide grooves 181A and 182A by power transmitted via the endless belt 186.

Each pulley 184, 185 is located on the upper surface of the base 181 between the guide groove 181A and the platen 17. The pulleys 184, 185 are located outside both ends P11, P12, respectively, and are rotatable around an axis parallel to the vertical direction 7. An endless belt 186 is wound around the pulleys 184, 185.

The CR motor 187 is a DC motor or the like, and is located below the right end of the base 181. Under the control of the controller 23 (see Figure 3), it generates power to rotate the pulley 185. As the pulley 185 rotates, the endless belt 186 moves left and right between the pulleys 184 and 185. As a result, the carriage 183 moves in a main scanning direction 6 (an example of a cross direction) perpendicular to the conveying direction 5, crossing the straight portion 152 from left to right. The main scanning direction 6 is parallel to the left-right direction 9. Hereinafter, the path that the carriage 183 travels from one end of the straight portion 152 to the other, either left or right, is also referred to as one pass.

In linear encoder SE2, strip 188 extends along endless belt 186 on base 181 over a wider area than the distance between ends P11 and P12, and has A-phase and B-phase optical patterns. Each phase's optical pattern has light-transmitting and light-blocking portions that are arranged alternately left and right in different portions in the vertical direction 7. Each optical pattern is shifted left and right by a phase difference of 90°. In linear encoder SE2, optical sensors 189 for each phase are fixed to carriage 183 and have an LED and a PD. Each LED emits light toward the optical pattern of the same phase. Each PD faces the LED across the optical pattern of the same phase, and outputs pulse signals AS2 and BS2 with a phase difference of 90°.

[Recording head 19]
In FIG. 1B, the recording head 19 is fixed to the carriage 183 and has a substantially rectangular parallelepiped shape. A lower surface 19A of the recording head 19 faces the upper end 17A of the platen 17 across a linear portion 152. A plurality of nozzle holes 19B are arranged in the front-rear and left-right directions on the lower surface 19A. The recording head 19 ejects ink stored therein from the nozzle holes 19B as it moves left and right together with the carriage 183 for one pass based on image data sent from the controller 23 (see FIG. 3) via the FFC 241 (see FIG. 2A). Ink is supplied to the recording head 19 through ink tubes 19C (see FIG. 2A) in accordance with this ink consumption.

[Controller 23]
3, the controller 23 has, as its main components in this embodiment, a CPU 231, a ROM 232, a RAM 233, an EEPROM 234, and an ASIC 235. These main components are connected to each other via an internal bus 237 so that they can communicate with each other. The ROM 232 stores a control program for the MFP 500, etc. The CPU 231 executes the control program using the RAM 233 and the EEPROM 234. In FIG. 3, the stop orientation D21 and the timer 236 will be described in detail in a modified example below.

The ASIC 235 has a register group 2351, an orientation determination unit 2352, a position determination unit 2353, and a speed determination unit 2354.

Register group 2351 stores various parameters required for intermittent conveyance. The various parameters include information indicating unit distance Df, distances D11 and D12, and stop direction D21. Unit distance Df is also called the line feed width, and is the distance that sheet S is conveyed in conveyance direction 5 after one pass of image recording. Distance D11 is a distance shorter than unit distance Df. Distance D12 is a distance longer than distance D11 and shorter than unit distance Df.

Pulse signals AS1 and BS1 are input to the direction determination unit 2352, position determination unit 2353, and speed determination unit 2354, respectively. The direction determination unit 2352 determines the rotation direction of the rotating shaft 161A by logically determining whether a rising edge or a falling edge is detected in the pulse signal AS1 when the level of the pulse signal BS1 is zero. In this embodiment, a rising edge indicates a forward rotation direction. The position determination unit 2353 counts the encoder amount (i.e., the encoder) relative to the initial position of the rotating shaft 161A during each intermittent conveyance using an up/down counter that is initialized with each intermittent conveyance. The count value of the encoder amount correlates with the amount of rotation relative to the initial position of the rotating shaft 161A. The speed determination unit 2354 counts the number of clocks per cycle of the pulse signals AS1 and BS1. The count value of the number of clocks correlates with the rotation speed of the rotating shaft 161A.

[Operation of Printer Unit 100]
The following is a detailed description of the operation of the printer unit 100. In the following, "output control signals CS1 to CS4 to switches SW1 to SW4" may be abbreviated to "output control signals CS1 to CS4."

An information processing device (not shown) is connected to the MFP 500 so that data can be transmitted therethrough. Image data transmitted from the information processing device is stored in the RAM 233. The image data is, for example, bitmap data, and represents an image to be recorded on, for example, one sheet S. When image data is stored in the RAM 233, the CPU 231 and ASIC 235 begin executing the main processing shown in FIG. 5.

In the cueing process of S501, the ASIC 235 controls the rotation of the feed roller 141 and drive roller 161 to transport the sheet S (see Figure 1B) in the supply tray 12 to the cueing position in the straight section 152. The cueing position is directly below the front-row nozzle holes 19B on the upper end 17A of the platen 17. More specifically, in the cueing process, the ASIC 235 first outputs control signals CS1 to CS4 to rotate the feed roller 141 forward and stop or reverse the drive roller 161. This causes the sheet S to be sent from the supply tray 12 to the curved section 151 of the conveying path 15. An actuator is located near the downstream end of the curved section 151, and a photointerrupter is located outside the curved section 151. The position of the actuator changes depending on whether the sheet S is in contact with it or not. The optical path of the photointerrupter is blocked or opened depending on the position of the actuator. The photointerrupter outputs a signal whose level differs depending on whether the optical path is blocked or open. Based on this output signal, the ASIC 235 determines that the sheet S has reached the transport section 16 and switches the control signals CS1 to CS4 to rotate the drive roller 161 forward. A reflective optical sensor is attached to the carriage 183 directly above the index position. Based on the output signal from this optical sensor, the ASIC 235 determines that the sheet S has reached the index position and stops outputting the control signals CS1 to CS4. This completes the indexing process, and the beginning of the image recording area on the sheet S is aligned with the index position.

In S502, the ASIC 235 performs preparations for image recording, such as flushing. During flushing, the ASIC 235 drives the CR motor 187 to move the carriage 183 in the main scanning direction 6 onto the ink receiver, and then ejects ink from the recording head 19 into the ink receiver. During this movement, when the carriage 183 reaches the origin in the main scanning direction 6, the ASIC 235 begins acquiring pulse signals AS2 and BS2 from the linear encoder SE2. The ASIC 235 identifies the direction of movement and current position of the carriage 183 using configurations similar to those of the orientation identification unit 2352 and position identification unit 2353.

In S503, the ASIC 235 starts driving the CR motor 187, and causes the CR transport mechanism 18 to move the carriage 183 in the main scanning direction 6 toward the sheet S.

In S504, as the movement speed of the carriage 183 becomes constant, the ASIC 235 ejects ink from the nozzle holes 19B based on image data for one pass toward the sheet S that is stopped directly below the recording head 19. This causes an image for one pass to be recorded in the image recording area of the sheet S.

In S505, the ASIC 235 terminates driving of the CR motor 187 upon completion of one pass of image recording, and stops the carriage 183.

In S506, the ASIC 235 determines whether images for all passes have been printed. If the ASIC 235 determines Yes, it determines that image printing on one sheet S has been completed and executes S507. On the other hand, if the ASIC 235 determines No, it determines that it is time to intermittently transport the sheet S and executes S508.

In the discharge process of S507, the ASIC 235 outputs control signals CS1 to CS4 to discharge the sheet S onto the discharge tray 13 (see Figure 1). The discharge process causes the drive rollers 161 and 201 to continuously rotate forward. As a result, the sheet S is transported in the conveying direction 5 along the straight section 152 and discharged onto the discharge tray 13.

In S508, the ASIC 235 controls intermittent transport and outputs various control signals CS1 to CS4. Based on the control signals CS1 to CS4, the driver 22 supplies a drive current to the PF motor 211 to control the rotation of the PF motor 211. The drive rollers 161 and 201 use the power generated by the PF motor 211 to transport the sheet S to the next stop position, which is a unit distance Df away in the transport direction 5 from the current stop position (hereinafter also referred to as the "sheet initial position").

[Detailed procedure for intermittent transport]
In S601 of FIG. 6, the ASIC 235 outputs control signals CS1a to CS4a (i.e., a first set) (see FIG. 4A). The duty ratios of the control signals CS1a and CS4a are adjusted so that a drive current of value Ia that does not exceed the maximum current value flows through the driver 22 during steady rotation of the PF motor 211. The closer the value Ia is to the maximum current value of the driver 22, the better. During the output time period of the first set, current flows through the driver 22 in the direction indicated by arrow AR1, causing the PF motor 211 to rotate forward. Furthermore, due to the above duty ratios, during the output time period of the first set, the rotation speed of the PF motor 211 increases from zero and then becomes a high, constant speed. As a result, as shown by the solid curve in FIG. 7, the sheet S is transported at a high, constant speed in the transport direction 5 within a range from the sheet initial position to a distance D11.

At S601, the ASIC 235 further initializes the up/down counter of the position identification unit 2353 in response to the start of the first set of output, and the orientation identification unit 2352, position identification unit 2353, and speed identification unit 2354 each begin to capture pulse signals AS1 and BS1. The orientation identification unit 2352 performs the aforementioned logical operation, and the position identification unit 2353 and speed identification unit 2354 each begin to count the encoder amount and clock count as described above.

In S602, the ASIC 235 determines the current conveyance distance Dc relative to the sheet initial position based on the encoder count value, etc. In S603, the ASIC 235 determines whether the conveyance distance Dc is equal to or greater than the distance D11 (see Figure 3). In other words, the ASIC 235 determines whether the current position of the sheet S has reached a first position that is the distance D11 away from the sheet initial position. If the ASIC 235 determines No in S603, it determines that it is not yet time to switch the control signals CS1 to CS4, and executes S604. On the other hand, if the ASIC 235 determines Yes in S603, it determines that it is time to switch the control signals CS1 to CS4, and executes S605.

In S604, the ASIC 235 continues to output control signals CS1a to CS4a, and then executes S602.

In S605, the ASIC 235 outputs control signals CS1b to CS4b (i.e., the second set) (see FIG. 4B). This interrupts the electrical path L1 (see FIG. 4A), and as shown by the solid curve in FIG. 7, the sheet S gradually decelerates after reaching the distance D11.

In S606, the ASIC 235 determines whether the rotation speed Vr, which correlates with the clock count, is equal to or less than the speed reference value Vref. In S607, the PF motor 211 is braked by the reverse brake. If the PF motor 211 does not decelerate to the speed reference value Vref or less, a large drive current exceeding the maximum current value may instantaneously flow to the driver 22 due to the back electromotive force acting on the coil (not shown) of the PF motor 211. To prevent this, S605 and S606 are executed. If the ASIC 235 determines No in S606, it determines that the PF motor 211 has not decelerated sufficiently and executes S605. On the other hand, if the ASIC 235 determines Yes in S606, it executes S607.

In S607, the ASIC 235 outputs control signals CS1d to CS4d (i.e., an example of the fourth set of third control signals) (see FIG. 4D). The duty ratios of the control signals CS2d and CS3d are set so that a drive current of value Ib that does not exceed the maximum current value flows through the driver 22. The closer the value Ib is to the maximum current value of the driver 22, the better, and it may be the same as or different from value Ia. During the output period of the fourth set, current flows through the driver 22 in the direction indicated by arrow AR2. Furthermore, due to the above duty ratios, during the output period of the fourth set, the PF motor 211 is rapidly decelerated from the speed reference value Vref by reverse braking. Accordingly, the sheet S rapidly decelerates in the straight portion 152 after the rotational speed Vr falls below the speed reference value Vref, as shown by the solid curve in FIG. 7.

In S608, the ASIC 235 determines the conveying distance Dc using the same method as in S602, and in S609 determines whether the conveying distance Dc is equal to or greater than the distance D12 (see Figure 3). In other words, the ASIC 235 determines whether the current position of the sheet S has reached a second position that is the distance D12 away from the initial position of the sheet. If the ASIC 235 determines No in S609, it determines that it is not yet time to switch the control signals CS1 to CS4, and executes S607. On the other hand, if the ASIC 235 determines Yes in S609, it determines that it is time to switch the control signals CS1 to CS4, and executes S610.

In S610, the ASIC 235 determines the conveying distance Dc using the same method as in S602, and in S611 determines whether the conveying distance Dc matches the unit distance Df (see Figure 3). If the ASIC 235 determines No in S610, it determines that it is not yet time to stop the sheet S and executes S613. On the other hand, if the ASIC 235 determines Yes in S610, it stops outputting the control signals CS1 to CS4 (S612), exits the processing in Figure 6, and executes S503 in Figure 5.

In S613, the ASIC 235 calculates the position deviation ΔP by subtracting the conveying distance Dc from the unit distance Df.

In S614, the ASIC 235 determines the control amount for the PF motor 211 using PID control (proportional-integral-derivative control) based on the position deviation ΔP obtained in S614. In this PID control, the gains of the integral and derivative terms are set so that the conveying distance Dc quickly approaches the unit distance Df without excessively overshooting the unit distance Df. The ASIC 235 generates and outputs control signals CS1e to CS4e with duty ratios corresponding to the determined control amount. The control signals CS1e to CS4e are a fifth set of control signals CS1 to CS4 and are an example of a fourth control signal. After executing S615, the ASIC 235 executes S610.

PID control allows the PF motor 211 to be stopped stably, and after the sheet S reaches distance D12, it stops stably and accurately at the next stop position, which is a unit distance Df away from the sheet's initial position, as shown by the solid curve in Figure 7.

[Effects of the embodiment]
In FIG. 7, a curve showing the change in conveyance distance Dc over time T in a reference example, which differs from the intermittent conveyance in the embodiment, is shown by a dashed line. In the reference example, as shown by the dashed line in FIG. 7, deceleration of the PF motor begins at a distance D41, which is closer to the sheet's initial position than distance D11. From the start to the end of deceleration control, PID control gradually aligns the sheet with the next stop position. Therefore, it takes time T2 for the sheet to stop at the stop position. However, in the embodiment, due to the intermittent conveyance in FIG. 6, the ASIC 235 outputs a first set of control signals CS1 to CS4 (see FIG. 4A) (see S601 and S604 in FIG. 6). The ASIC 235 outputs a fourth set (see FIG. 4D) within the range from distance D11 to distance D12 (see S607). Because there is a risk that the sheet S may overshoot the next stop position due to the reverse braking, the ASIC 235 outputs a fifth set of control signals CS1 to CS4 based on PID control (see S614). According to the intermittent control in FIG. 6, the sheet S is allowed to overshoot, and the time required for the sheet S to stop at the next stop position due to the sudden braking caused by the reverse braking of the PF motor 211 is only T1, which is shorter than the time T2.

The ASIC 235 outputs the second set before outputting the fourth set (see S605). This prevents a large drive current exceeding the maximum current value of the driver 22 from flowing through the driver 22.

[Modification]
The following describes modified examples of the printer unit 100 of the embodiment. In the modified examples, differences from the embodiment will be described, and explanations of commonalities between the modified examples and the embodiment will be omitted or simplified.

[First Modification]
The first modified example differs from the embodiment in the following respects. First, the rotary encoder SE1 is provided on the output shaft of the PF motor 211 (see FIG. 2B) instead of the rotary shaft 161A (see FIG. 1B). Second, information (an example of first information) indicating the amount of backlash of the gears 215 and 216 (see FIG. 2B) is stored in advance in the EEPROM 234 (an example of memory). Third, information (an example of second information) indicating a stop orientation D21 is stored in the register group 2351. The stop orientation D21 is information indicating whether the PF motor 211 was rotating forward or backward when the sheet S reached the next stop position. Fourth, the controller 23 controls the intermittent conveyance shown in FIGS. 8 and 9 instead of the intermittent conveyance shown in FIG. 6.

In S801 of FIG. 8, the ASIC 235 of the controller 23 determines whether the information indicating the stop orientation D21 indicates forward rotation. If the ASIC 235 determines Yes, it executes S802, and if the ASIC 235 determines No, it executes S803.

In S802, intermittent transport (forward rotation) is the same as the intermittent transport in Figure 6.

In S803, intermittent conveyance (during reverse rotation) differs from the intermittent conveyance in Figure 6 in that S603, S609, and S611 are replaced by S901, S902, and S903, as shown in Figure 9.

In S901, the ASIC 235 determines whether the conveying distance Dc is equal to or greater than the correction distance D31. The correction distance D31 is the sum of the distance D11 (see Figure 3) and the amount of backlash. If the ASIC 235 determines No in S901, it executes S604, and if the ASIC 235 determines Yes in S901, it executes S605.

In S902, the ASIC 235 determines whether the conveying distance Dc is equal to or greater than the correction distance D32. The correction distance D32 is the sum of the distance D12 (see Figure 3) and the amount of backlash. If the ASIC 235 determines No in S902, it executes S607, and if the ASIC 235 determines Yes in S902, it executes S610.

In S903, the ASIC 235 determines whether the conveying distance Dc is equal to or greater than the correction unit distance Df1. The correction unit distance Df1 is the sum of the unit distance Df (see Figure 3) and the amount of backlash. The ASIC 235 executes S613 if it determines No in S903, and executes S612 if it determines Yes in S903.

In FIG. 8, S804 is executed after S802 or S803 is executed. In S804, the ASIC 235 updates the information on the stop orientation D21 (an example of second information) in the register group 2351 with the rotation orientation identified by the orientation identification unit 2352 immediately after executing S612 in FIGS. 6 and 9.

In the first variant, if the PF motor 211 was rotating in reverse when the output of the control signals CS1 to CS4 was stopped during the previous intermittent transport, rotating the PF motor 211 forward during the current intermittent transport will prevent the sheet S from being transported by the amount of backlash. However, because the rotary encoder SE1 is attached to the output shaft of the PF motor 211, pulse signals AS1 and BS1 are output even when the sheet S is not transported due to the amount of backlash. Therefore, when the transport distance Dc of the sheet S is determined based on the amount of rotation detected by the position identification unit 2353, the transport distance Dc contains an error. Due to this technical background, in S901, S902, and S903 of Figure 9, the transport distance Dc is compared with the correction distance D31, correction distance D32, and correction unit distance Df1, thereby canceling out the error contained in the transport distance Dc.

[Second Modification]
The second modified example differs from the embodiment in the following respects. First, the controller 23 further includes a timer 236 (see FIG. 3). The timer 236 is a timer IC mounted on a circuit board together with the CPU 231, but may also be incorporated within the CPU 231. Second, information (an example of third information) indicating the required time Tm (see FIG. 12) measured by the timer 236 in at least one recent intermittent transport is stored in the EEPROM. The required time Tm is the time required for the sheet S to be transported from the sheet initial position to the next stop position in the corresponding intermittent transport. Since the load torque of the PF motor 211 increases with age, the required time Tm becomes longer with age. Third, the controller 23 executes the processes shown in FIGS. 10 to 12 instead of the processes shown in FIGS. 5 and 6.

Compared to Figure 5, Figure 10 differs in that it further includes S1001 to S1005 instead of S506 and S507. Compared to Figure 6, Figures 11 and 12 differ in that they further include S1101 to S1106.

In Figure 10, after S505, the ASIC 235 determines that it is time to perform intermittent transport of sheet S, and executes intermittent transport in S1001.

In FIG. 11, after S601, in S1101, the ASIC 235 outputs a command to the timer 236 to initialize the clock value and start clocking. In response to this command, the timer 236 initializes the clock value to zero and starts accumulating the clock value.

In this modified example, in order to shorten the time from the start of feeding of sheet S to the end of discharge, an overlay process is executed in which the movement of carriage 183 begins when sheet S reaches a position slightly upstream of the next stop position through intermittent transport. For the overlay process, in S1102 after S608, ASIC 235 acquires information on required time Tm from EEPROM 234. Required time Tm is also the estimated time it takes for sheet S to reach the next stop position from the sheet initial position through this intermittent transport. By subtracting a predetermined small time ΔT from required time Tm, ASIC 235 obtains the time Tcr at which carriage 183 movement begins, based on the start of intermittent transport (hereinafter also referred to as "CR movement time").

In S1103, the ASIC 235 obtains the current clock value Tp from the timer 236 and determines whether the clock value Tp is equal to or greater than the CR movement time Tcr. In S1104, the ASIC 235 determines whether the carriage 183 is stopped. If the ASIC 235 determines Yes in both S1103 and S1104, it executes S1105. On the other hand, if the ASIC 235 determines No in either S1103 or S1104, it skips S1105 and executes S609.

In S1105, the ASIC 235 drives the CR motor 187, causing the CR transport mechanism 18 to move the carriage 183 above the sheet S in the main scanning direction 6.

In FIG. 12, after S612, in S1106, the ASIC 235 acquires information on the current time value Tp from the timer 236 and updates the information on the required time Tm stored in the EEPROM with the acquired information.

In FIG. 10, after S1001, in S1002, the ASIC 235 records one pass' worth of image in the image recording area of the sheet S, as in S504. In S1003, the ASIC 235 stops the carriage 183 at the end position, as in S505. In S1004, the ASIC 235 determines whether all passes' worth of image have been recorded, as in S506, and if the determination is Yes, executes the same discharge process as in S507 (S1005), and if the determination is No, it determines that it is time to intermittently transport the sheet S and executes S1101.

According to this modified example, the CR movement time Tcr can be changed according to the load torque of the PF motor 211, and the drive start timing of the CR motor 187 can be appropriately overlapped before the PF motor 211 stops.

In intermittent transport, the ASIC 235 automatically starts measuring the required time Tm without user operation and automatically stores the required time Tm information in the EEPROM. This eliminates the need for the user to operate the printer unit 100 to store the required time Tm information in the EEPROM.

[Third Modification]
The third modified example differs from the second modified example in the following respects. First, a GUI button for starting the measurement process is displayed on the touch panel of the operation panel 11, and the operation panel 11 transmits an operation signal GS instructing the start of the measurement process to the controller 23 in response to operation of the GUI button. Second, the ASIC 235 executes the measurement process in response to receiving the operation signal GS from the operation panel 11. In the measurement process, a cueing process, intermittent conveyance, and discharge process are executed for one sheet S. The cueing process and discharge process are the same as S501 and S1005 in FIG. 10. Furthermore, in the intermittent conveyance, each set of control signals CS1 to CS4 in FIGS. 11 and 12 is output in sequence based on the distance D11, the distance D12, and the unit distance Df. During this process, the ASIC 235 acquires from the timer 236 the time value Tp required for the sheet S to be transported from the sheet initial position to the next stop position, and updates the information on the required time Tm stored in the EEPROM with the acquired time value Tp.

According to the third modified example, the information on the required time Tm is updated during a time period unrelated to ink ejection from the recording head 19. This eliminates the need to measure the required time Tm during the intermittent transport of Figures 11 and 12, allowing the processing load on the CPU 231 and ASIC 235 to be distributed.

[Other Modifications]
In the embodiment and each modified example, the control signals CS1b to CS4b are output in S605. However, this is not limiting, and the control signals CS1c to CS4c (i.e., the third set, see FIG. 4C) may be output in S605.

In the embodiments, a printer unit 100 that records an image on a sheet S using a recording head 19 has been described as an example of an application to a conveying device. However, this is not limited to this, and the conveying device may also be used for conveying a sheet S, punching holes in the sheet S using a punching device, cutting the sheet S, etc. using a cutting device, etc.

In the embodiment, the conveying path 15 is a U-turn path. However, this is not limited to this, and the conveying path 15 may also be a so-called straight path or S path.

In the embodiment, the current conveyance distance Dc of the sheet S (see Figure 6, etc.) was calculated based on the pulse signals AS1 and BS1 output from the rotary encoder SE1. However, this is not limited to this, and the conveyance distance Dc can also be calculated without the pulse signals AS1 and BS1 output from the rotary encoder SE1. In particular, the ASIC 235 can calculate the conveyance distance Dc sensorlessly from the period and duty ratio of the control signal that rotates the PF motor 211.

In the second and third variants, in S1102, the ASIC 235 obtains information on a single required time Tm from the EEPROM 234 and subtracts a predetermined minute time ΔT from the required time Tm. However, this is not limited to this, and the EEPROM 234 may store information on multiple recent required times Tm. In this case, in S1102, the minute time ΔT may be subtracted from the average value of the multiple required times Tm.

500...MFP
100: Printer unit S: Sheet (object)
11...Operation panel (input interface)
16...Transport unit (transport mechanism)
18...CR transport mechanism 183...carriage 187...CR motor (second motor)
19: Recording head 20: Discharge section (transport mechanism)
21... Power transmission mechanism 211... PF motor (motor, first motor)
22: Driver 23: Controller 231: CPU
234...EEPROM (memory)
235...ASIC
236...Timer

Claims (6)

A motor;
a driver that applies a drive current to the motor to rotate the motor;
a conveying mechanism that conveys the object in a conveying direction by rotating the motor in the forward direction;
a controller;
The controller instructs the driver to:
outputting a first control signal for causing the drive current to flow in a first direction within the motor and for causing the motor to rotate forward at a constant speed in response to the timing for transporting the object;
outputting, in response to determining that the object has reached a first position upstream of a stop position of the object in the conveying direction, a second control signal for interrupting an electric path from the driver to the motor and a third control signal for causing the drive current to flow in a second direction opposite to the first direction and not exceeding a maximum current value of the driver;
a conveying device that, in response to determining that the object has reached a second position that is closer to the stop position than the first position in the conveying direction, outputs a fourth control signal to reduce the number of rotations of the motor based on the deviation between the current position of the object and the stop position, and, in response to determining that the object has reached the stop position, stops outputting the fourth control signal. a plurality of gears that transmit power generated by the motor to the conveying mechanism and mesh with each other;
a memory that stores first information indicating backlash amounts in the plurality of gears,
The above controller is
storing second information indicating whether the motor is rotating in the forward direction in the memory in response to the output of the fourth control signal being stopped;
determining a stop position for the next object based on the stop position and the first information in the memory in response to determining that the second information stored in the memory does not indicate forward rotation at a timing for transporting the next object;
outputting the first control signal to the fourth control signal in sequence;
2. The conveying device according to claim 1, wherein output of the fourth control signal is stopped in response to a determination that the next object has reached the determined stop position. a first motor;
a driver that applies a drive current to the first motor to rotate the first motor;
a conveying mechanism that conveys the sheet in a conveying direction by forward rotation of the first motor;
A second motor;
a carriage that moves in a direction intersecting the conveying direction by rotation of the second motor;
a recording head mounted on the carriage and configured to eject ink;
a controller;
The controller instructs the driver to:
outputting a first control signal for causing the driving current to flow in a first direction in the first motor and for causing the first motor to rotate forward at a constant speed in response to the timing for conveying the sheet;
outputting, in response to determining that the sheet has reached a first position upstream of the stop position of the sheet in the conveying direction, a second control signal for interrupting an electric path from the driver to the first motor and a third control signal for causing the drive current to flow in a second direction opposite to the first direction and not exceeding a maximum current value of the driver;
outputting a fourth control signal for reducing the number of rotations of the first motor based on a deviation between the current position of the sheet and the stop position in response to determining that the sheet has reached a second position that is closer to the stop position than the first position in the conveying direction;
Stopping output of the fourth control signal in response to determining that the sheet has reached the stop position;
an image recording device that rotates the second motor so that the recording head moves together with the carriage in the intersecting direction at a position facing the sheet at the stopped position, and ejects ink from the recording head toward the sheet at the stopped position. A timer and
a memory; and
The above controller is
third information indicating a time from the start of conveyance of the sheet to the stop of conveyance is acquired from the timer and stored in the memory;
4. The image recording apparatus according to claim 3, wherein the second motor starts to rotate at a timing based on the third information stored in the memory. further comprising an input interface;
The above controller is
outputting the first control signal to the fourth control signal in response to receiving an operation through the input interface;
5. The image recording device according to claim 4 , wherein after the output of said first control signal through said fourth control signal is stopped , said third information is obtained from said timer and stored in said memory. The image recording device described in claim 4, wherein the controller stops outputting the first control signal through the fourth control signal in response to the timing for transporting the sheet, and then acquires the third information from the timer and stores it in the memory.