Printer and method for controlling the same

Abstract

To provide a printer capable of detecting skewing of a medium at a proper timing and a method for controlling the same.SOLUTION: This printer comprises: a printing unit that executes printing on a medium; a conveyance unit that supports and conveys the medium; a rear end detection unit that detects the rear end of the medium in the conveying direction of the conveyance unit; a skewing detection unit that detects skewing of the medium during conveyance by the conveyance; and a control unit. The conveyance unit supports and conveys the medium upstream and downstream of the printing unit in the conveying direction. The control unit starts detection of skewing by the skewing detection unit in response to reception of detection of the rear end by the rear end detection unit.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a printing apparatus and a method for controlling the printing apparatus.

Background Art

[0002] Conventionally, a technique for detecting an inclination when transporting a medium such as paper has been known. For example, Patent Document 1 discloses a configuration in which an image forming apparatus detects the inclination of a sheet being transported based on the timing at which the leading edge of the sheet reaches the reading position of a sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an apparatus for printing on a medium, an inclination of the medium during printing causes an unnatural inclination in the printed finish. For this reason, in addition to the leading edge of the medium, it is desirable to detect the inclination of the medium during printing, but there has been a problem that constantly performing the process of monitoring the inclination of the medium places a large load.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a printing apparatus including a printing unit that prints on a medium, a transport unit that supports and transports the medium, a rear end detection unit that detects the rear end of the medium in the transport direction of the transport unit, a skew detection unit that detects skew of the medium during transport by the transport unit, and a control unit, wherein the transport unit supports and transports the medium upstream and downstream of the printing unit in the transport direction, and the control unit starts detection of skew by the skew detection unit in response to receiving detection of the rear end by the rear end detection unit.

[0006] One aspect of the present disclosure is a control method for a printing apparatus including a printing unit that prints on a medium and a conveyance unit that supports and conveys the medium upstream and downstream of the printing unit in the conveyance direction of the medium, the control method including: performing a trailing edge detection operation for detecting a trailing edge of the medium in the conveyance direction of the conveyance unit, and a skew detection operation for detecting skew of the medium during conveyance by the conveyance unit; and starting the skew detection operation to detect skew of the medium in response to receiving detection of the trailing edge by the trailing edge detection operation.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0008] [1. Configuration of the Printing Apparatus] FIG. 1 is a perspective view of a printing apparatus 1 according to an embodiment. FIG. 2 is a cross-sectional view of the printing apparatus 1. The configuration of the printing apparatus 1 will be described based on these figures.

[0009] In FIGS. 1, 2, and FIGS. 4 to 6 described below, an X-axis, a Y-axis, and a Z-axis are shown. The X-axis, Y-axis, and Z-axis are orthogonal to each other. The Z-axis is an axis extending in the vertical direction, and can also be said to be an axis extending in the plumb direction. The X-axis and Y-axis are parallel to the horizontal plane. In the following description, the direction along the X-axis is defined as the left-right direction, and the direction along the Y-axis is defined as the front-back direction. Specifically, the positive direction along the Z-axis is the upward direction, the positive direction along the X-axis is the leftward direction, and the positive direction along the Y-axis is the forward direction.

[0010] As will be described later, the printing apparatus 1 is an inkjet printer that includes a print head 42 that discharges ink, and forms a printed image P on the surface of a medium M with the ink discharged from the print head 42. The printed image P includes characters, symbols, patterns, images, and other printing objects. The number of colors of the ink discharged from the print head 42 is not limited. The printing apparatus 1 may be a device that performs monochrome printing or a device that performs color printing. The medium M is a sheet-shaped printing medium, for example, paper, non-woven fabric, cloth, or a sheet made of synthetic resin. The medium M may be a long continuous sheet or a cut sheet cut to a predetermined size. In the present embodiment, an example in which paper cut to a standard size is used as the medium M will be described.

[0011] As shown in FIG. 1, the printing apparatus 1 has a box-shaped main body 11, and each part is accommodated in the main body 11. A paper feed port 13 is opened at the rear end of the main body 11, and a paper discharge port 14 is opened at the front surface of the main body 11. The printing apparatus 1 performs printing on the medium M supplied from the paper feed port 13 to the main body 11, and discharges the printed medium M from the paper discharge port 14.

[0012] At the rear of the main body 11, a paper feed tray 20 for guiding the medium M toward the paper feed port 13 is installed. A plurality of media M can be placed on the paper feed tray 20, and the media M placed on the paper feed tray 20 is taken into the main body 11 one by one by a paper feed roller unit 51 described later. The paper feed tray 20 includes a paper feed tray main body 21 connected to the main body 11 and an extended paper feed tray 22 slidably attached to the paper feed tray main body 21. By pulling out the extended paper feed tray 22 from the paper feed tray main body 21, a medium M of a larger size can be placed on the paper feed tray 20. Also, when the printing device 1 is not in use, the extended paper feed tray 22 can be slid downward and stored.

[0013] At the front of the main body 11, a paper discharge tray 30 for receiving the medium M discharged from the paper discharge port 14 is arranged. The paper discharge tray 30 includes a first paper discharge tray 31 connected to the main body 11, and a second paper discharge tray 32 and a third paper discharge tray 33 slidably attached to the lower part of the first paper discharge tray 31. When the printing device 1 performs printing on the medium M, the second paper discharge tray 32 and the third paper discharge tray 33 are pulled forward. In a state where the second paper discharge tray 32 and the third paper discharge tray 33 are pulled out, the paper discharge tray 30 has a size capable of supporting the medium M from below. In a state where the printing device 1 is not performing printing, the paper discharge tray 30 can be made into a compact shape by sliding the second paper discharge tray 32 and the third paper discharge tray 33 backward.

[0014] On the upper surface of the main body 11, a cover 12 is attached so as to be openable and closable. By opening the cover 12, access to a carriage 41 and a print head 42 described later becomes possible. On the front surface of the main body 11, an operation panel 15 and an LCD (Liquid Crystal Display) display unit 18 are provided. The operation panel 15 has an operation section 16 and an indicator 17. The operation section 16 has operating elements such as buttons and switches for the user to operate the printing apparatus 1. The indicator 17 displays the operating state of the printing apparatus 1. The indicator 17 has an LED (Light Emitting Diode) and other light emitters. The LCD display unit 18 displays information regarding the operating state of the printing apparatus 1 and other information by means of a liquid crystal display panel. The configurations of the operation panel 15 and the LCD display unit 18 are examples. For example, instead of the LCD display unit 18, the printing apparatus 1 may be provided with a touch panel having a touch sensor on its surface and capable of receiving input operations. In this case, some or all of the operating elements of the operation panel 15 may be omitted.

[0015] FIG. 2 shows a cross section in the Y-Z plane of the printing apparatus 1. As shown in FIG. 2, inside the main body 11, a carriage 41, a print head 42, a platen 43, a paper feed roller unit 51, a paper transport roller unit 54, and a paper discharge roller unit 57 are arranged. In FIG. 2, the transport path MW of the medium M is indicated by a virtual line, and the transport direction of the medium M is indicated by the symbol F.

[0016] The carriage 41 mounts the print head 42 and reciprocates along the X-axis direction together with the print head 42. While moving in the X-axis direction, the print head 42 discharges ink toward the surface of the medium M. The platen 43 is installed opposite to the range in which the print head 42 moves, with the transport path MW therebetween. The upper surface of the platen 43 is flat, and the platen 43 stably supports the medium M during printing by the print head 42. The carriage 41 and the print head 42 constitute a printing unit. The printing unit may include the platen 43.

[0017] The paper feed roller unit 51, the paper transport roller unit 54, and the paper discharge roller unit 57 convey the medium M. The paper feed roller unit 51 is disposed at a position close to the paper feed port 13. The paper feed roller unit 51 includes a feed roller 52 and a driven roller 53 disposed opposite to the feed roller 52. The feed roller 52 is driven by a transport motor 65 described later, sandwiches the medium M placed on the paper feed tray 20 between the driven roller 53, and feeds out one sheet of the medium M toward the print head 42.

[0018] The paper transport roller unit 54 and the paper discharge roller unit 57 constitute the transport unit 50. The transport unit 50 may include the paper feed roller unit 51.

[0019] The paper transport roller unit 54 is located upstream of the print head 42 in the transport direction F. The paper transport roller unit 54 includes a drive roller 55 and a driven roller 56 disposed opposite to the drive roller 55 with the transport path MW therebetween. In this embodiment, as an example, the drive roller 55 is located below the transport path MW, and the driven roller 56 is located above the transport path MW. The paper transport roller unit 54 nips the medium M by the drive roller 55 and the driven roller 56, and conveys the medium M toward the print head 42.

[0020] The paper discharge roller unit 57 is located downstream of the print head 42 in the transport direction F. The paper discharge roller unit 57 includes a drive roller 58 and a driven roller 59 disposed opposite to the drive roller 58 with the transport path MW therebetween. In this embodiment, as an example, the drive roller 58 is located below the transport path MW, and the driven roller 59 is located above the transport path MW. The paper discharge roller unit 57 nips the medium M printed by the print head 42 by the drive roller 58 and the driven roller 59, and conveys the medium M toward the paper discharge port 14. The medium M conveyed by the driven roller 56 exits the paper discharge port 14 and is accumulated on the paper discharge tray 30.

[0021] In the conveyance path MW, a rear-end sensor 45 is arranged downstream of the paper feed roller unit 54. The rear-end sensor 45 detects the presence or absence of the medium M at a detection position corresponding to the installation position of the rear-end sensor 45.

[0022] The carriage 41 is equipped with a paper width sensor 47. The paper width sensor 47 moves together with the carriage 41 and detects the presence or absence of the medium M within the range where the carriage 41 reciprocates in the X-axis direction.

[0023] The rear-end sensor 45 and the paper width sensor 47 are, for example, any one of a light transmission type sensor, a light reflection type sensor, an ultrasonic sensor, or other types of sensors.

[0024] A control device 100 for controlling the printing device 1 is installed in the main body 11. There is no limitation on the position of the control device 100. For example, the control device 100 is arranged at a position close to the operation panel 15 or the LCD display unit 18. The control device 100 is an example of a control unit.

[0025] [2. Configuration of the control system of the printing device] FIG. 3 is a block diagram showing the configuration of the control system of the printing device 1. Connected to the control device 100 are a display unit 61, an operation unit 16, a conveyance motor 65, a carriage drive motor 67, a print head 42, a rear-end sensor 45, a paper width sensor 47, and an interface 102.

[0026] The control device 100 is a computer including a processor 110 and a storage unit 120. The processor 110 is composed of, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), and may be composed of a plurality of processors.

[0027] The storage unit 120 has a volatile memory and a non-volatile storage unit. The volatile memory is, for example, a RAM (Random Access Memory). The non-volatile storage unit is composed of a ROM (Read Only Memory), a hard disk, a flash memory, etc.

[0028] The storage unit 120 stores programs executed by the processor 110 and data processed by the processor 110. For example, the storage unit 120 stores a control program 121 and setting data 122. The processor 110 controls each part of the printing apparatus 1 by executing the control program 121. Also, when controlling the printing apparatus 1, the processor 110 uses various setting values included in the setting data 122.

[0029] An interface (I / F) 102 is connected to the control device 100. The interface 102 is a communication device that performs wired communication using a cable or wireless communication using a wireless communication line. The interface 102 communicates with the host computer 2 to receive print data. The print data includes data of images and characters to be printed by the printing apparatus 1 on the medium M, commands for instructing the printing apparatus 1 to execute printing, and other data.

[0030] The display unit 61 includes an indicator 17 and an LCD display unit 18. The display unit 61 turns on, turns off, or blinks the indicator 17 according to the control of the control device 100. Also, the display unit 61 displays characters and images on the LCD display unit 18 according to the control of the control device 100.

[0031] The operation unit 16 detects an operation on an operator by the user and outputs operation data corresponding to the detected operation to the control device 100. The conveyance motor 65 drives the pay-out roller 52 and the drive rollers 55 and 58. The conveyance motor 65 rotates in the forward or reverse direction according to the control of the control device 100. The conveyance motor 65 may be configured to include a rotation amount detection device that detects the rotation amount of the conveyance motor 65 and outputs the detection value of the rotation amount detection device to the control device 100. The rotation amount detection measure is, for example, a rotary encoder.

[0032] The carriage drive motor 67 is connected to the carriage 41 via a transmission belt (not shown) or the like. The carriage drive motor 67 rotates in the forward or reverse direction according to the control of the control device 100 and moves the carriage 41 in the X-axis direction. The conveyance motor 65 and the carriage drive motor 67 are composed of a stepping motor or a servo motor.

[0033] The printing device 1 includes a position detection device that detects the position of the carriage 41 in the X-axis direction. The position detection device is, for example, a linear encoder or a rotary encoder that detects the rotation amount of the carriage drive motor 67. The control device 100 identifies the position of the carriage 41 in the X-axis direction by the function of this position detection device.

[0034] The print head 42 discharges ink according to the control of the control device 100. The rear end sensor 45 and the paper width sensor 47 perform detection of the medium M according to the control of the control device 100 and output the detection value to the control device 100.

[0035] The processor 110 includes a print control unit 111, a rear end detection unit 112, and a skew detection unit 113. These functional units are configured by the processor 110 executing the control program 121.

[0036] The printing control unit 111 acquires printing data from the host computer 2 via the interface 102. The printing control unit 111 causes the printing on the medium M to be executed based on the printing data. Specifically, the printing control unit 111 conveys the medium M by operating the conveyance motor 65, and moves the carriage 41 in the X-axis direction by operating the carriage drive motor 67. The printing control unit 111 controls the print head 42 to eject ink corresponding to the position of the print head 42.

[0037] The rear end detection unit 112 detects the rear end of the medium M. The rear end of the medium M refers to the end on the upstream side in the conveyance direction F among the ends of the medium M in the conveyance direction F. The rear end detection unit 112 detects the rear end of the medium M by at least one of a method using the rear end sensor 45 and a method using the conveyance amount by the conveyance motor 65. In the present embodiment, the rear end detection unit 112 detects that the rear end of the medium M has moved downstream of the nip position of the feeding roller 52.

[0038] When using the rear end sensor 45, the rear end detection unit 112 monitors the change in the detection value of the rear end sensor 45. The rear end detection unit 112 detects that the rear end of the medium M has passed the position of the rear end sensor 45 when, during the conveyance of the medium M, the detection value of the rear end sensor 45 changes from a detection value indicating the presence of the medium M to a detection value indicating the absence of the medium M. In the conveyance direction F, the rear end sensor 45 is located downstream of the nip position of the feeding roller 52 and upstream of the nip position of the paper discharge roller unit 57. Further, the rear end sensor 45 is located upstream of the print head 42. Therefore, when the rear end of the medium M passes the position of the rear end sensor 45, it can be said that the rear end of the medium M has moved downstream of the nip position of the feeding roller 52.

[0039] When using the conveyance amount of the conveyance motor 65, the rear-end detection unit 112 specifies the position of the rear end of the medium M based on the conveyance amount after the conveyance of the medium M is started by the paper feed roller unit 51 and the size of the medium M in the conveyance direction F. In this case, the rear-end detection unit 112 specifies the timing when the position of the rear end of the medium M reaches a position downstream of the nip position of the feeding roller 52.

[0040] The skew detection unit 113 detects the skew of the medium M, that is, the skew. The skew of the medium M refers to a state in which the direction of the medium M being conveyed by the conveyance unit 50 is inclined with respect to the conveyance direction F, that is, the Y axis, and may include the conveyance of the medium M in that state. The skew detection unit 113 detects the occurrence of skew based on, for example, the width of the medium M detected by the paper width sensor 47. Hereinafter, the skew of the medium M conveyed by the printing apparatus 1 will be described.

[0041] [3. Conveyance state of the medium] FIGS. 4, 5, and 6 are explanatory diagrams showing examples of the conveyance state of the medium M in the printing apparatus 1, and are plan views of main parts including the carriage 41, the print head 42, the paper feed roller unit 54, and the paper discharge roller unit 57 of the printing apparatus 1. In these figures, the rear end of the medium M is indicated by the symbol ME.

[0042] As shown in FIGS. 4, 5, and 6, in the conveyance path MW of the medium M, the paper feed roller unit 54, the rear-end sensor 45, the carriage 41, and the paper discharge roller unit 57 are arranged in order from the upstream in the conveyance direction F. In these figures, the detection position D1 where the rear-end sensor 45 detects the presence or absence of the medium M and the detection position D2 where the paper width sensor 47 detects the end of the medium M are indicated by virtual lines.

[0043] The drive roller 58 includes a plurality of rollers 58a, 58b, 58c, 58d arranged in the X-axis direction, that is, the width direction of the medium M. This configuration is an example, and there is no limit to the number of rollers included in the drive roller 58. The rollers 58a, 58b, 58c, 58d are attached to, for example, one shaft and rotate simultaneously by the power of the conveyance motor 65.

[0044] In the state shown in FIG. 4, since the rear end ME of the medium M is upstream of the paper feed roller unit 54, the medium M is nipped and conveyed by both the paper feed roller unit 54 and the paper discharge roller unit 57. This state is called the first conveyance state.

[0045] In the state shown in FIG. 5, the rear end ME of the medium M is downstream of the paper feed roller unit 54. For this reason, the rear part of the medium M is not nipped by the paper feed roller unit 54. That is, the medium M is only nipped by the paper discharge roller unit 57, is not supported and conveyed by the paper feed roller unit 54, and is in a state of being supported and conveyed by the paper discharge roller unit 57. This state is called the second conveyance state.

[0046] The inventors of the present invention have found that skew of the medium M is more likely to occur in the second conveyance state than in the first conveyance state. The factors of skew include (1) the printing apparatus 1 being installed in an unstable location, and (2) the second paper discharge tray 32 and the third paper discharge tray 33 of the paper discharge tray 30 not being fully pulled out. Further, (3) poor conveyance by the conveyance unit 50 and (4) defective parts of the printing apparatus 1 are also cited as factors.

[0047] Factor (1) causes a reaction force that reciprocates the carriage 41 in the X-axis direction to act on the main body 11, generating shaking of the printing apparatus 1. As a result, a force in a direction intersecting the conveyance direction F acts on the medium M and each part of the conveyance unit 50, causing the medium M to advance in a direction intersecting the conveyance direction F. In the first conveyance state, since the medium M is supported by both the paper feed roller unit 54 and the paper discharge roller unit 57, it is less likely to be affected by factor (1), and in the second conveyance state, it is more likely to be affected by factor (1).

[0048] Factor (2) causes the leading edge of the medium M in the conveyance direction F to collide with the second paper discharge tray 32 or the third paper discharge tray 33. Due to the collision of the leading edge of the medium M, a force that pushes the medium M in a direction different from the conveyance direction F acts on the medium M inside the main body 11. Also, due to factor (2), a force that pulls the medium M in a direction intersecting the conveyance direction F acts on the medium M due to the sagging or bending of the portion of the medium M that protrudes from the leading edge of the first paper discharge tray 31. In the first conveyance state, since the medium M is supported by both the paper feed roller unit 54 and the paper discharge roller unit 57, even if any of the above forces is applied to the medium M, skew does not easily occur. On the other hand, in the second conveyance state, the paper discharge roller unit 57 cannot resist the force applied to the medium M, and skew is likely to occur.

[0049] Therefore, the printing apparatus 1 detecting skew in the second conveyance state is useful in that it can promptly respond to the occurrence of skew. Also, for the printing apparatus 1 to detect skew in the first conveyance state, it is necessary to perform the processes related to skew detection in a state where skew is unlikely to occur, which increases the load on the control device 100 and thus is not efficient.

[0050] Therefore, the printing apparatus 1 of the present embodiment starts monitoring whether skew of the medium M has occurred, that is, detecting skew, after detecting that the medium M has entered the second conveyance state. Thereby, skew can be detected efficiently and countermeasures can be taken against skew. Naturally, in a state before detecting that the medium M has entered the second conveyance state, that is, in the first conveyance state, skew detection is not executed.

[0051] Measures for dealing with the occurrence of skew of the medium M include notifying the user and correcting the print data according to the skew state.

[0052] FIG. 6 is an example of a state in which skew of the medium M has occurred, and an example in which the medium M is inclined in the direction indicated by the arrow SC with respect to the conveyance direction F. When the printing apparatus 1 detects the skew of the medium M, it notifies the detection of the skew by the LCD display unit 18 or the indicator 17. For example, the control device 100 lights or blinks the indicator 17 in a pattern indicating the occurrence of skew. Further, the control device 100 may perform notification including guidance regarding the cause of the skew. For example, the control device 100 causes the LCD display unit 18 to display a message requesting confirmation as to whether the paper discharge tray 30 is fully pulled out.

[0053] Also, for example, the control device 100 transmits data notifying the occurrence of skew to the host computer 2, and causes a display (not shown) provided in the host computer 2 to display a message or the like notifying the occurrence of skew. At this time, the host computer 2 may cause the display to display a message requesting confirmation as to whether the paper discharge tray 30 is fully pulled out. That is, the control device 100 may cause the host computer 2 to perform notification including guidance regarding the cause of the skew.

[0054] When performing correction of print data according to the skew state, the control device 100 corrects the print data according to the inclination of the medium M. Specifically, the control device 100 prints a printed image P inclined at an angle corresponding to the inclination of the medium M with respect to the conveyance direction F. As a result, the skew of the medium M is not corrected, but since the printed image P printed on the medium M is inclined corresponding to the orientation of the medium M, a print result with a small relative inclination between the medium M and the printed image P can be obtained.

[0055] [4. Operation of Printing Apparatus] FIG. 7 is a flowchart showing the operation of the printing apparatus 1. The operations shown in FIG. 7 are executed by the control device 100. Specifically, steps S11 to S12, S17 to S18, and S21 are executed by the print control unit 111. Steps S13, S15 to S16, and S19 to S20 are executed by the skew detection unit 113, and step S14 is executed by the trailing edge detection unit 112.

[0056] The printing apparatus 1 acquires print data from the host computer 2 (step S11), and starts printing including conveyance of the medium M (step S12).

[0057] After starting printing, the printing apparatus 1 detects the paper width and the edge position of the medium M by the paper width sensor 47 (step S13). The printing apparatus 1 stores the paper width W detected in step S13 in the storage unit 120 as the paper width A, and stores the edge position EG detected in step S13 in the storage unit 120 as the edge position A.

[0058] The edge position of the medium M is the position of the edge of the medium M in the moving direction of the carriage 41, that is, the X-axis direction, and is the two edge positions EG shown in FIGS. 4 to 5. The paper width sensor 47 moves in the X-axis direction at the detection position D2 and detects the edge position EG. The paper width of the medium M is the size of the medium M in the moving direction of the carriage 41, and is the paper width W shown in FIGS. 4 to 6. The printing apparatus 1 may calculate the paper width W as the distance between the edge position EG and the edge position EG.

[0059] The printing apparatus 1 determines whether or not the rear end ME of the medium M has been detected (step S14). Step S14 is a process of determining whether or not the rear end ME has moved downstream from the detection position D1, and is a process of identifying whether the medium M is in the first conveyance state or the second conveyance state. When the rear end ME has not been detected at the detection position D1 (step S14: NO), the medium M is in the first conveyance state. In this case, the printing apparatus 1 returns to step S13.

[0060] When the rear end ME is detected at the detection position D1 (step S14: YES), the medium M has transitioned to the second conveyance state. In this case, the printing apparatus 1 detects the paper width and the edge position of the medium M by the paper width sensor 47 (step S15). The printing apparatus 1 stores the paper width W detected in step S15 in the storage unit 120 as the paper width B, and stores the edge position detected in step S13 in the storage unit 120 as the edge position B.

[0061] As shown in FIG. 6, the edge position EG´ detected by the paper width sensor 47 in a state where skew of the medium M has occurred is different from the edge position EG detected by the paper width sensor 47 in a state where no skew has occurred. Further, the paper width W detected by the paper width sensor 47 at the detection position D2 becomes a larger value when skew occurs than in a state where no skew has occurred.

[0062] The printing apparatus 1 determines whether the difference between the paper width A and the paper width B and the difference between the edge position A and the edge position B are equal to or greater than a threshold value (step S16). Specifically, the printing apparatus 1 determines whether any one or more of the conditions that the difference between the paper width A and the paper width B is equal to or greater than the threshold value for paper width determination and the difference between the edge position A and the edge position B is equal to or greater than the threshold value for edge position determination are satisfied, or whether neither condition is satisfied. Here, when any one or more of the difference between the paper width A and the paper width B and the difference between the edge position A and the edge position B are equal to or greater than the threshold value, the printing apparatus 1 determines that skew has occurred. Further, when neither the difference between the paper width A and the paper width B nor the difference between the edge position A and the edge position B is equal to or greater than the threshold value, the printing apparatus 1 determines that no skew has occurred. Performing such determination is also referred to as detection of skew. That is, the printing apparatus 1 starts detection of skew (step S16) triggered by detecting the trailing edge ME at the detection position D1 in step S14 (step S14: YES). Further, in a state where the trailing edge ME is not detected at the detection position D1 in step S14 (step S14: NO), detection of skew (step S16) is not started.

[0063] When the difference between the paper width A and the paper width B and the difference between the edge position A and the edge position B are not equal to or greater than the threshold value (step S16: NO), the printing apparatus 1 determines whether the medium M has reached the printing end position (step S17). When the medium M has reached the printing end position (step S17: YES), the printing apparatus 1 ends printing (step S18). Further, when the medium M has not reached the printing end position (step S17: NO), the printing apparatus 1 returns to step S15.

[0064] When either one or more of the difference between the paper width A and the paper width B and the difference between the end position A and the end position B is equal to or greater than the threshold value (step S16: YES), the printing apparatus 1 determines that skewing has occurred and executes an operation corresponding to the skewing. That is, the printing apparatus 1 notifies the occurrence of skewing (step S19). Further, the printing apparatus 1 calculates the inclination of the medium M with respect to the conveyance direction F based on the difference between the paper width A and the paper width B (step S20), and corrects the print data according to the calculated inclination (step S21). Thereafter, the printing apparatus 1 proceeds to step S17.

[0065] In step S20, the printing apparatus 1 may calculate the inclination of the medium M from the difference between the end position A and the end position B.

[0066] (Modification example) The above-described operation is an example of the operation when skewing of the medium M is detected. For example, in the operation of FIG. 7, the printing apparatus 1 may execute step S19 and steps S20 to S21 in the reverse order, or may execute them in parallel. Further, the printing apparatus 1 may omit step S19. Further, the printing apparatus 1 may omit steps S20 to S21.

[0067] Further, instead of or in addition to the operations of steps S20 to S21, the printing apparatus 1 may change the moving speed of the carriage 41.

[0068] Changing the moving speed of the carriage 41 is effective when the skew of the medium M is caused by the above-mentioned factor (1). In step S20, the printing apparatus 1 switches the rotation speed of the carriage drive motor 67, that is, the amount of rotation per unit time, to a lower speed. Thereby, the magnitude of the reaction force associated with the movement of the carriage 41 is reduced. Therefore, the vibration generated in the main body 11 due to the movement of the carriage 41 can be reduced, and the disturbance of the conveyance of the medium M can be reduced. This operation aims to eliminate or alleviate the factors causing the skew of the medium M. Therefore, after changing the moving speed of the carriage 41, it is preferable for the printing apparatus 1 to maintain the rotation speed of the carriage drive motor 67. For example, even after the printing of the medium M is completed in step S18, the setting of the rotation speed of the carriage drive motor 67 is maintained, and when printing the next medium M, the carriage drive motor 67 is operated at the rotation speed switched to the low speed. When an instruction to reset the setting of the rotation speed of the carriage drive motor 67 is input by the operation unit 16 or the host computer 2, the printing apparatus 1 returns the rotation speed of the carriage drive motor 67 to the initial value.

[0069] Also, for example, instead of the operations in steps S20 to S21, the printing apparatus 1 may execute skew correction by the paper discharge roller unit 57. In this case, the printing apparatus 1 is provided with a configuration for correcting the skew. Specifically, a configuration is possible in which the rotation speeds of some of the plurality of rollers 58a, 58b, 58c, 58d constituting the drive roller 58 are made different from the rotation speeds of the other rollers. The rotation speed refers to the amount of rotation per unit time and can be simply referred to as the amount of rotation. In this case, the control device 100 functions as a skew correction unit. The skew correction unit may include the rollers 58a, 58b, 58c, 58d of the drive roller 58.

[0070] In this configuration, the printing apparatus 1 can divide the rollers 58a, 58b, 58c, 58d into at least two roller groups and set the rotation speeds of the plurality of roller groups to be different from each other. The rotation speed of the drive roller 58 corresponds to the conveyance speed of the medium M and corresponds to the amount of conveyance of the medium M per unit time.

[0071] As an example, taking rollers 58a and 58b as the first rollers and rollers 58c and 58d as the second rollers, the printing apparatus 1 may be configured to rotate the first rollers and the second rollers at different speeds. In this configuration, the printing apparatus 1 can also rotate the first rollers and the second rollers at the same speed.

[0072] In the driving roller 58, various configurations can be used for the configuration to rotate the first roller and the second roller at different speeds. For example, a configuration can be adopted in which the first roller and the second roller are connected to the conveyance motor 65 via different drive gears, an actuator (not shown) for switching the drive gears is provided, and the actuator is driven under the control of the control device 100. Further, the printing apparatus 1 can adopt a configuration in which a plurality of conveyance motors 65 are provided and the first roller and the second roller are respectively connected to different conveyance motors 65.

[0073] The method of dividing the first roller and the second roller is arbitrary, but the first roller is composed of rollers among the plurality of rollers 58a, 58b, 58c, and 58d that are located on the +X side with respect to the second roller.

[0074] When performing skew correction, the control device 100 sets the rotation speeds of the first roller and the second roller of the driving roller 58 so as to compensate for the skew of the medium M. Specifically, the control device 100 relatively slows down the rotation speed of the first roller with respect to the rotation speed of the second roller so that the medium M tilts in the direction indicated by the arrow CO. Further, when a skew occurs in which the medium M tilts to the side opposite to the arrow CO, the rotation speed of the second roller is relatively slowed down with respect to the rotation speed of the first roller.

[0075] The rotation speed of the first roller and the rotation speed of the second roller are determined based on, for example, the inclination of the medium M obtained by the process of step S20.

[0076] [5. Other Embodiments] The above-described embodiment merely shows a specific example to which the present invention is applied. The present invention is not limited to the configuration of the above-described embodiment, and can be implemented in various aspects without departing from the gist of the invention.

[0077] In the above-described embodiment, the configuration in which the printing apparatus 1 conveys the medium M by the paper feed roller unit 54 located upstream of the carriage 41 and the paper discharge roller unit 57 located downstream of the carriage 41 has been described. This is an example, and the number and arrangement of the rollers of the conveyance unit 50 provided in the printing apparatus 1 can be arbitrarily changed. Also, the shape of the rollers constituting the conveyance unit 50 can be changed.

[0078] Further, in the above-described embodiment, the configuration for detecting skew during printing of the medium M which is a cut sheet has been illustrated. The printing apparatus 1 may be configured to perform printing on a continuous sheet such as a roll paper or a fan-fold paper. For example, when the printing apparatus 1 detects skew of the medium M during printing on a continuous sheet, it may stop printing and give a notification, and when detecting skew of the medium M during printing on a cut sheet, it may execute the operations of steps S19 to S21. In this case, the printing apparatus 1 may determine whether the medium M is a continuous sheet or a cut sheet based on the data transmitted from the host computer 2 to the printing apparatus 1 or the input by the operation of the operation panel 15.

[0079] The configurations shown in FIGS. 1 to 3 and the functional configuration shown in FIG. 4 are examples of the printing apparatus 1, and the application target of the present invention is not limited to the configurations shown in each figure. For example, the printing apparatus 1 may include a component not shown in FIG. 3. Also, when realizing the operation of the above-described printing apparatus 1 using the processor 110, the program to be executed by the processor can also be configured in the form of a non-temporary computer-readable recording medium or a transmission medium for transmitting the program. As the non-temporary computer-readable recording medium, a magnetic, optical recording medium or a semiconductor memory device can be used. The above-described recording medium may be an internal storage device provided in the server apparatus.

[0080] The step units of the operations shown in FIG. 7 are divided according to the main processing contents in order to facilitate the understanding of the operations of the printing apparatus 1, and are not limited by the method of dividing the processing units or the names. Depending on the processing contents, further division into more step units may be possible. One step unit may be further divided to include more processes. The order of the steps may be appropriately changed.

[0081] [6. Configuration Explained by Embodiment] The following configuration is explained by the above embodiment.

[0082] (Configuration 1) A printing unit that prints on a medium, a conveyance unit that supports and conveys the medium, a rear end detection unit that detects the rear end of the medium in the conveyance direction of the conveyance unit, a skew detection unit that detects skew of the medium during conveyance by the conveyance unit, and a control unit. The conveyance unit supports and conveys the medium upstream and downstream of the printing unit in the conveyance direction, and the control unit starts detection of skew by the skew detection unit in response to receiving detection of the rear end by the rear end detection unit. According to the printing apparatus of Configuration 1, a printing apparatus that supports and conveys a medium upstream and downstream of a printing unit starts detection of skew after detecting the rear end of the medium. For this reason, since the process related to detection of skew is performed after the state where skew is likely to occur, skew of the medium can be detected at an appropriate timing. Therefore, the processing load of the printing apparatus can be reduced, and skew can be detected efficiently.

[0083] (Configuration 2) The printing apparatus according to Configuration 1, further comprising a skew correction unit that corrects the conveyance state of the medium, wherein the control unit causes the skew correction unit to perform correction according to the detection result of skew by the skew detection unit. According to the printing apparatus of Configuration 2, when it is detected that skew of the medium has occurred, the conveyance state of the medium can be corrected. Therefore, it is possible to suppress a decrease in print quality in response to the occurrence of skew.

[0084] (Configuration 3) The printing apparatus according to Configuration 1 or Configuration 2, wherein when the skew detection unit detects skew of the medium, the control unit causes the printing unit to perform printing inclined in a direction to compensate for the skew of the medium. According to the printing apparatus of Configuration 3, when it is detected that skew of the medium has occurred, printing is performed so as to be inclined in a direction corresponding to the conveyance state of the medium. Therefore, it is possible to suppress a decrease in print quality in response to the occurrence of skew.

[0085] (Configuration 4) The conveyance unit includes a conveyance roller unit that nips the medium, the conveyance roller unit has a first roller and a second roller arranged in a direction intersecting the conveyance direction, and when the skew detection unit detects skew of the medium, the skew correction unit rotates the first roller and the second roller at different rotation amounts to correct the skew of the medium. The printing apparatus according to Configuration 2. According to the printing apparatus of Configuration 4, by varying the rotation amounts of a plurality of rollers that nip the medium, the medium can be intentionally inclined. Thereby, the orientation of the medium can be changed so that the inclination of the medium with respect to the conveyance direction becomes small, and the skew can be reduced or eliminated. Therefore, it is possible to suppress a decrease in print quality in response to the occurrence of skew.

[0086] (Configuration 5) The printing apparatus according to any one of Configurations 1 to 4, further comprising a paper discharge tray that is provided so as to be pullable out from the discharge port of the printing apparatus and on which the medium printed by the printing unit is placed, and when the skew detection unit detects skew of the medium, the control unit performs notification regarding the state of the paper discharge tray. According to the printing apparatus of Configuration 5, when skew of the medium occurs, by performing notification including information regarding the cause of the skew, it is possible to assist the user with respect to prevention of skew.

[0087] (Configuration 6) The printing unit includes a carriage that reciprocates in a direction intersecting the conveyance direction, and a print head mounted on the carriage. When the skew detection unit detects skew of the medium, the control unit reduces the moving speed of the carriage. The printing apparatus according to any one of Configurations 1 to 5. According to the printing apparatus of Configuration 6, when skew of the medium occurs, the cause of the skew can be eliminated or reduced.

[0088] (Configuration 7) The conveyance unit includes a paper feed roller unit and a paper discharge roller unit that nip the medium. The paper feed roller unit is located upstream of the printing unit in the conveyance direction, and the paper discharge roller unit is located downstream of the printing unit in the conveyance direction. The control unit identifies, by the rear end detection unit, a first conveyance state in which the medium is nipped by both the paper feed roller unit and the paper discharge roller unit, and a second conveyance state in which the medium is nipped by the paper discharge roller unit and not nipped by the paper feed roller unit. The printing apparatus according to any one of Configurations 1 to 6. According to the printing apparatus of Configuration 7, by identifying a first conveyance state in which skew of the medium is unlikely to occur and a second conveyance state in which skew is likely to occur, skew of the medium can be detected at an appropriate timing.

[0089] (Configuration 8) The rear end detection unit detects the rear end of the medium by a rear end sensor provided between the paper feed roller unit and the paper discharge roller unit. The printing apparatus according to Configuration 7. According to the printing apparatus of Configuration 8, by detecting the rear end of the medium by a sensor, the first conveyance state and the second conveyance state can be easily identified.

[0090] (Configuration 9) The rear end detection unit detects the rear end of the medium based on the conveyance amount of the conveyance unit and the size of the medium in the conveyance direction. The printing apparatus according to Configuration 7. According to the printing apparatus of Configuration 9, the first conveyance state and the second conveyance state can be easily identified with a simple configuration without using a sensor for detecting the rear end of the medium.

[0091] A control method for a printing apparatus including a printing unit that prints on a medium and a conveyance unit that supports and conveys the medium upstream and downstream of the printing unit in the conveyance direction of the medium, the control method including: a trailing edge detection operation for detecting a trailing edge of the medium in the conveyance direction of the conveyance unit; and a skew detection operation for detecting skew of the medium during conveyance by the conveyance unit, and starting the skew detection operation for detecting skew of the medium in response to receiving detection of the trailing edge by the trailing edge detection operation. According to the control method for the printing apparatus of Configuration 10, the same effects as those of the printing apparatus of Configuration 1 can be obtained.

Explanation of Reference Numerals

[0092] 1... printing apparatus, 2... host computer, 11... main body, 12... cover, 13... paper feed port, 14... paper discharge port, 15... operation panel, 16... operation unit, 17... indicator, 18... LCD display unit, 20... paper feed tray, 21... paper feed tray main body, 22... extended paper feed tray, 30... paper discharge tray, 31... first paper discharge tray, 32... second paper discharge tray, 33... third paper discharge tray, 41... carriage (printing unit), 42... print head (printing unit), 43... platen, 45... trailing edge sensor, 47... paper width sensor, 50... conveyance unit, 51... paper feed roller unit, 52... feed-out roller, 53... driven roller, 54... paper feed roller unit, 55... drive roller, 56... driven roller, 57... paper discharge roller unit, 58... drive roller, 58a, 58b, 58c, 58d... rollers, 59... driven roller, 65... conveyance motor, 67... carriage drive motor, 100... control device (control unit, skew correction unit), 102... interface, 110... processor, 111... print control unit, 112... trailing edge detection unit, 113... skew detection unit, 120... storage unit, 121... control program, 122... setting data, EG, EG´... end positions, F... conveyance direction, M... medium, ME... trailing edge, W... paper width.

Claims

1. a printing unit that prints on a medium; a conveyance unit that supports and conveys the medium; a rear end detection unit that detects the rear end of the medium in the conveyance direction of the conveyance unit; a skew detection unit that detects skew of the medium during conveyance by the conveyance unit; a control unit; and has, the conveyance unit supports and conveys the medium upstream and downstream of the printing unit in the conveyance direction, the control unit starts detection of skew by the skew detection unit in response to receiving detection of the rear end by the rear end detection unit, a printing apparatus.

2. having a skew correction unit that corrects the conveyance state of the medium, the control unit causes the skew correction unit to perform correction according to the detection result of skew by the skew detection unit, the printing apparatus according to claim 1.

3. the control unit causes the printing unit to perform printing inclined in a direction to compensate for skew of the medium when skew of the medium is detected by the skew detection unit, the printing apparatus according to claim 1.

4. the conveyance unit includes a conveyance roller unit that nips the medium, the conveyance roller unit has a first roller and a second roller arranged in a direction intersecting the conveyance direction, the skew correction unit corrects skew of the medium by rotating the first roller and the second roller at different amounts of rotation when skew of the medium is detected by the skew detection unit, the printing apparatus according to claim 2.

5. comprising a paper discharge tray provided so as to be pullable out from the discharge port of the printing apparatus and on which the medium printed by the printing unit is placed, the control unit gives a notification regarding the state of the paper discharge tray when skew of the medium is detected by the skew detection unit, the printing apparatus according to claim 1.

6. the printing unit includes a carriage that reciprocates in a direction intersecting the conveyance direction and a print head mounted on the carriage, the control unit reduces the moving speed of the carriage when skew of the medium is detected by the skew detection unit, the printing apparatus according to claim 1.

7. the conveyance unit includes a paper feed roller unit and a paper discharge roller unit that nip the medium, the paper feed roller unit is located upstream of the printing unit in the conveyance direction, and the paper discharge roller unit is located downstream of the printing unit in the conveyance direction, The control unit, by the rear end detection unit, discriminates a first conveyance state in which the medium is nipped by both the paper feed roller unit and the paper discharge roller unit, and a second conveyance state in which the medium is nipped by the paper discharge roller unit and not nipped by the paper feed roller unit. The printing apparatus according to any one of claims 1 to 6.

8. The rear end detection unit detects the rear end of the medium by a rear end sensor provided between the paper feed roller unit and the paper discharge roller unit. The printing apparatus according to claim 7.

9. The rear end detection unit detects the rear end of the medium based on the conveyance amount of the conveyance unit and the size of the medium in the conveyance direction. The printing apparatus according to claim 7.

10. A control method for a printing apparatus including a printing unit that prints on a medium and a conveyance unit that supports and conveys the medium upstream and downstream of the printing unit in the conveyance direction of the medium, performs a rear end detection operation for detecting the rear end of the medium in the conveyance direction of the conveyance unit, and a skew detection operation for detecting skew of the medium during conveyance by the conveyance unit, and starts the skew detection of the medium by executing the skew detection operation in response to receiving the detection of the rear end by the rear end detection operation. A control method for a printing apparatus.

Images