Printing device and method for controlling printing device

Abstract

To provide a printer that improves printing quality.SOLUTION: A printer includes: a printing part for printing on recording paper; a conveyance part which has a roller rotating in a first direction about a shaft to convey the recording paper, and a motor for rotating the shaft; a detection part for detecting rotation in the first direction of the shaft, and rotation in a second direction being an opposite direction to the first direction; and a control part for controlling the conveyance part on the basis of rotation of the shaft detected by the detection part. In the printer, after rotating the shaft in the first direction using the motor of the conveyance part and then stopping the shaft, the control part rotates the shaft in the first direction using the motor before printing with the printing part, on the basis of rotation of the shaft in the second direction detected by the detection part.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] 2. Description of the Related Art As disclosed in Patent Document 1, a printing device is known in the art that is configured such that a head is separated from a platen by a link in order to suppress deformation of the platen, which is a roller, during periods of non-use. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-127552 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the printing device described in Patent Document 1 does not take into consideration deformation of the platen during use, which may result in poor print results. [Means for solving the problem]

[0005] The printing device includes a printing unit that prints on recording paper, a transport unit having a roller that rotates in a first direction around an axis and transports the recording paper, and a motor that rotates the axis, a detection unit that detects rotation of the axis in the first direction and rotation in a second direction opposite to the first direction, and a control unit that controls the transport unit based on the rotation of the axis detected by the detection unit, and after the motor of the transport unit rotates the axis in the first direction and stops it, based on the rotation of the axis in the second direction detected by the detection unit, the control unit rotates the axis in the first direction using the motor before printing by the printing unit.

[0006] A control method for a printing device including a printing unit that prints on recording paper, a transport unit having a roller that rotates in a first direction around an axis and transports the recording paper, and a motor that rotates the axis, and a detection unit that detects rotation in the first direction about the axis and rotation in a second direction opposite to the first direction, wherein after the motor of the transport unit rotates the axis in the first direction and stops, based on the rotation of the shaft in the second direction detected by the detection unit, the motor rotates the shaft in the first direction before printing by the printing unit. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing the configuration of a printing apparatus. [Diagram 2] FIG. 2 is a cross-sectional view showing a main part of the printing apparatus. [Diagram 3] 4 is a time chart showing control by a control unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 1. Embodiment 1-1. Configuration of Printer 1 1 and 2 is, for example, a line thermal printer. As shown in FIG. 1, the printing device 1 includes a control unit 10, a storage unit 20, a printing unit 30, a transport unit 40, and a detection unit 50.

[0009] The control unit 10 includes a CPU. The CPU is also called a processor. The control unit 10 reads and executes programs such as firmware stored in the storage unit 20, and controls each part of the printing device 1.

[0010] The printing unit 30 includes a head 31 as shown in FIG. 2. The head 31 is, for example, a line thermal head. The printing unit 30 also includes a pressing mechanism that presses the head 31 against a roller 43. The recording paper P is thermal paper, and while being brought into contact with the head 31 by the pressing mechanism, the recording paper P develops color due to heat generated by the head 31 and is printed. The control unit 10 controls the head 31 to perform printing based on print data received from an external device. The recording paper P printed by the head 31 is cut by a cutter and discharged from a paper discharge port.

[0011] 2, the conveying unit 40 is configured such that a motor 41 rotates under the control of the control unit 10, the rotation is transmitted to a shaft 44 while being decelerated via a gear 42, and a roller 43 rotates around the shaft 44 to convey the recording paper P. The roller 43 is formed into a cylindrical shape from a material such as rubber or other flexible resin, and is fixed to the shaft 44. The roller 43 is located opposite the head 31 with the recording paper P interposed therebetween, and is also called a platen.

[0012] The motor 41 is, for example, a DC motor. The control unit 10 detects the speed of the motor 41 by inputting a detection signal from a detection unit 50 (described later) and performs PWM (Pulse Width Modulation) control on the motor 41 so as to rotate at a predetermined speed.

[0013] The recording paper P is stored in the printing device 1 as roll paper 90 wound in a roll. Roller 43 and the opposing head 31 pinch the recording paper P together with the pressure of the pressing mechanism, and a transport force F is generated by the rotation of roller 43, which pulls out and transports the recording paper P from the roll paper 90. The direction in which roller 43 rotates when transporting the recording paper P is the first direction, which is the clockwise direction CW. The control unit 10 controls the printing unit 30 to print while the conveying unit 40 conveys the recording paper P in the CW direction.

[0014] The detection unit 50 is a so-called rotary encoder that detects the rotational position of the shaft 44. The detection unit 50 is an optical encoder that includes a disk 52, which is a scale with slits at predetermined intervals, and a transmission type photosensor 51 that detects the slits of the disk 52, as shown in FIG.

[0015] The photosensor 51 is composed of a light-emitting element and a light-receiving element. The light-emitting element and the light-receiving element are arranged to sandwich a disk 52. The disk 52 is attached so as to rotate around the shaft 44. When the shaft 44 rotates due to the motor 41, the disk 52 also rotates, and when the position of the slit provided in the disk 52 is on the optical path of the light-emitting element, the light passes through the slit and reaches the light-receiving element, which detects the light. At this time, the light-receiving element generates a specified current, which can be extracted as a high-level voltage detection signal. On the other hand, when the position of the slit is not on the optical path of the light-emitting element, the light is blocked by the disk 52, and the light-receiving element does not detect the light. At this time, the light-receiving element does not generate a specified current, so it can be extracted as a low-level voltage detection signal.

[0016] 1-2. Control by the control unit As shown in FIG. 3, when the voltage of the detection signal output by the detection unit 50 is at a high level, this is when the photosensor 51 of the detection unit 50 has detected the position of a slit provided in the disc 52, and when the voltage of the detection signal is at a low level, this is when the photosensor 51 has detected the position of a part of the disc 52 that is not the slit. The disk 52 has two sets of slits that are out of phase with each other, and are configured to be detected by the photosensor 51. Therefore, as shown in FIG. 3, the detection unit 50 outputs A-phase and B-phase detection signals that are out of phase with each other by 90 degrees, i.e., 1 / 4 period, and input them to the control unit 10. The control unit 10 can determine whether the rotation direction of the shaft 44 is the CW direction or the CCW direction, which is the counterclockwise direction opposite to the CW direction, from the order of phase shifts of the A phase and the B phase. The CCW direction is the second direction.

[0017] 3, the control performed by the control unit 10 on the transport unit 40 and the printing unit 30 based on the detection signal input from the detection unit 50 will be described. Fig. 3 shows the detection signal output from the detection unit 50 in chronological order from t0 to t5, which indicates the time.

[0018] First, the time t0 will be described. The control unit 10 controls the transport unit 40, the motor 41 rotates the shaft 44 in the CW direction, and the detection unit 50 detects the rotation of the shaft 44 and outputs a detection signal. The detection signal of the detection unit 50 is output as a pulse with a predetermined period. A pulse in one period of the detection signal of the detection unit 50 is defined as 1 pulse. This pulse indicates that the shaft 44 is rotating, and the number of pulses indicates the amount of rotation of the shaft 44. The control unit 10 rotates the roller 43 in the CW direction via the shaft 44 of the transport unit 40 to transport the recording paper P. At this time, the control unit 10 may control the printing unit 30 to perform printing while transporting the recording paper P.

[0019] At time t1, the control unit 10 controls the conveying unit 40 to stop the rotation of the motor 41. When the rotation of the motor 41 is stopped, the rotation of the shaft 44 also stops, so that the detection signal of the detection unit 50 does not output a pulse. At this time, the recording paper P is not conveyed.

[0020] However, at time t2, even though control unit 10 has stopped the rotation of motor 41, the detection signal of detection unit 50 outputs a pulse indicating that shaft 44 is rotating in the direction opposite to the direction in which recording paper P is transported. Based on the detection signal of detection unit 50, control unit 10 determines that shaft 44 has rotated in the CCW direction an amount of rotation equivalent to two pulses of the detection signal between time t2 and time t3. The control unit 10 can determine that the rotation direction of the shaft 44 is the CCW direction because the order of phase shifts of the A and B phases of the detection signal from the detection unit 50 is reversed from when the shaft 44 is rotating in the CW direction.

[0021] The phenomenon in which the shaft 44 rotates in the CCW direction even though the motor 41 is stopped will be described. As described above, the roller 43 of the transport unit 40 is pressed against the head 31 by the pressure of the pressing mechanism of the printing unit 30. The roller 43 is made of a flexible material such as rubber or other resin.

[0022] At time t0, roller 43 of transport unit 40 is pressed against head 31 by the pressure of the pressing mechanism of printing unit 30, while rotating in the CW direction with the rotation of shaft 44, transporting recording paper P sandwiched between it and head 31. At this time, due to the flexibility of roller 43, a twisting deflection occurs in roller 43 relative to shaft 44 in the CW direction, which is the direction of transport force F, and roller 43 is deformed.

[0023] When the rotation of the motor 41 stops at time t1, the conveying force F is no longer generated. At this time, due to the flexibility of the roller 43, a force acts on the shaft 44 and the head 31 to return the torsional deflection, which is the deformation, to its original state. The shaft 44 is connected to the motor 41 via a gear 42. The head 31 is pressed against the roller 43 by the pressing force of the pressing mechanism of the printing unit 30. A detent torque that acts to maintain the position of the rotor within the motor 41 is smaller than the pressing force of the pressing mechanism of the printing unit 30. In particular, when the motor 41 is a DC motor, the detent torque is smaller than that of other motors such as step motors. Therefore, a force that tries to return roller 43 to its original state acts to reversely rotate shaft 44. As a result, shaft 44 rotates in the CCW direction, which is the direction of the reaction force of the CW torsional deflection force that has been generated in roller 43 during the period from time t2 to time t3. The time from time t1 when motor 41 stops rotating to time t2 when shaft 44 starts rotating in the reverse direction is approximately 100 msec. The phenomenon in which shaft 44 rotates in the reverse direction due to the flexibility of roller 43 even though motor 41 has stopped rotating occurs in a very short time after roller 43 has been used to transport recording paper P.

[0024] As shown in Fig. 3, in this example, during the period from time t2 to time t3, the detection signal indicates that shaft 44 rotates in the CCW direction by an amount of rotation of two pulses. The amount of rotation of two pulses also indicates the amount of deformation of the torsional deflection of roller 43. The amount of deformation of roller 43 is affected by the load and transport speed during transport. Therefore, if the diameter of rolled paper 90 is larger and the inertia during transport is greater, or if the transport speed is faster, the amount of deformation of roller 43 increases, and shaft 44 may rotate in the reverse direction by more than two pulses.

[0025] Here, a case will be described where the control unit 10 starts printing at time t4 in FIG. When the control unit 10 receives print data from an external device, it attempts to start printing with the printing unit 30 while the conveying unit 40 conveys the recording paper P in the CW direction. At this time, when the control unit 10 starts to rotate the motor 41 of the conveying unit 40, the rotation is transmitted to the shaft 44. However, due to the flexibility of the roller 43, when the shaft 44 starts to rotate, the roller 43 is twisted and deformed in the CW direction, which is the direction of the conveying force F, relative to the shaft 44. In this case, the period during which the roller 43 is twisted and deformed corresponds to the amount of rotation of two pulses of the detection signal, as described above. When the detection signal reaches the third pulse or later, the roller 43 finally starts to rotate.

[0026] In this way, the rotation of motor 41 rotates shaft 44 in the CW direction by an amount equivalent to two pulses of the detection signal. However, in roller 43, the torque, which is the rotational force generated at this time, is used to deform roller 43 by torsional bending, and roller 43 itself does not rotate. Therefore, during the first two pulses of the detection signal, roller 43 does not rotate in the CW direction, so no transport force F is generated and recording paper P is not transported. The control unit 10 starts conveying the recording paper P in the CW direction by the conveyance unit 40, and at the same time starts printing the print data by the printing unit 30. Therefore, even during the two pulses of the detection signal, the control unit 10 continues printing on the recording paper P by the printing unit 30. However, because the recording paper P is not conveyed in the CW direction, the print result may become clogged or crushed, resulting in degradation. When the detection signal reaches the third pulse or later, the roller 43 finally starts to rotate in the CW direction in conjunction with the rotation of the shaft 44, and a conveying force F is generated to convey the recording paper P. At this point, the print result becomes normal for the first time.

[0027] Therefore, in this embodiment, in order to improve the printing results at the start of printing, as shown in FIG. 3, during the period from time t4 to time t5, before the printing unit 30 starts printing, the control unit 10 causes the motor 41 of the conveying unit 40 to rotate the shaft 44 in the CW direction by an amount equivalent to 2 pulses of the detection signal. Specifically, when the control unit 10 receives print data from an external device and is about to start printing, before the printing unit 30 starts printing, at time t4, the motor 41 starts rotating the shaft 44 in the CW direction, and by time t5, the shaft 44 has rotated an amount equivalent to two pulses of the detection signal, and then at time t5, the printing unit 30 starts printing.

[0028] During the period from time t4 to time t5 before the printing unit 30 starts printing on the recording paper P, the control unit 10 rotates the motor 41 in the CW direction by an amount of rotation equivalent to two pulses of the detection signal. During this time, the torsional deformation of the roller 43 ends. After time t5, the roller 43 rotates normally, a conveying force F is generated, and the recording paper P is conveyed normally in the CW direction. The control unit 10 starts printing by the printing unit 30 at time t5 when the recording paper P starts to be normally transported in the CW direction, so that the print result is prevented from being clogged or crushed, and the print result can be improved.

[0029] 1-3. Head resolution and detection signal The detection unit 50 is set to have a detection signal resolution of 1440 pulses / inch, for example. In other words, the detection unit 50 is set to output one pulse of a detection signal every time the recording paper P is transported by the transport unit 40 a length of 1 / 1440 inch. Meanwhile, the resolution of the head 31 is, for example, 180 dpi (dots per inch), or 1 dot / 180 inch. When the recording paper P is transported by the transport unit 40 a length of 1 / 180 inch, which is the same as the resolution of the head 31, the detection unit 50 outputs eight pulses of a detection signal. Therefore, the control unit 10 controls the head 31 at a timing such that one dot is driven during a period in which the detection signal input from the detection unit 50 is 8 pulses, and prints one dot on the recording paper P.

[0030] As described above, the control unit 10 controls the motor 41 to rotate the shaft 44 in the CW direction by an amount of rotation equivalent to 2 pulses of the detection signal before starting printing by the printing unit 30. Since the resolution of the detection signal of the detection unit 50 is 1440 pulses / inch and the resolution of the head 31 is 1 / 180 inch, the amount of rotation equivalent to 2 pulses of the detection signal corresponds to 1 / 4 of the resolution of the head 31, which is 1 / 180 inch.

[0031] In this way, the amount of rotation of 2 pulses of the detection signal, which is the amount by which shaft 44 is rotated in the CW direction by motor 41 before printing by printing unit 30 is started, is the amount of rotation based on 1 / 180 inch of the resolution of head 31. Here, the amount of rotation by which shaft 44 is rotated in the CW direction before printing is a value obtained by dividing the resolution of head 31 by an integer. This amount of rotation may be an integer multiple of the resolution of head 31. Also, each may be an approximate value.

[0032] The disk 52 has two sets of slits that are out of phase with each other, and are configured to be detected by the photosensor 51. Therefore, as shown in FIG. 3, the detection unit 50 outputs A-phase and B-phase detection signals that are out of phase with each other by 90 degrees, i.e., 1 / 4 period, and input them to the control unit 10. The control unit 10 can adjust the A-phase and B-phase detection signals to suit the resolution of various heads 31 by dividing, multiplying, combining, etc. In this way, before printing by the printing unit 30 begins, the amount of rotation of the detection signal, which is the amount by which the motor 41 rotates the shaft 44 in the CW direction, can be based on the resolution of the detection signal of the detection unit 50, and can be based on the resolution of the head 31.

[0033] According to the embodiment described above, the following effects can be obtained. A printing device 1 according to one embodiment includes a printing unit 30 that prints on recording paper P, a transport unit 40 having a roller 43 that rotates in a first direction, which is CW, around an axis 44 and transports the recording paper P, and a motor 41 that rotates the axis 44, a detection unit 50 that detects the rotation of the axis 44 in the first direction and the rotation in a second direction, which is the CCW direction opposite to the first direction, and a control unit 10 that controls the transport unit 40 based on the rotation of the axis 44 detected by the detection unit 50. The control unit 10 rotates the axis 44 in the first direction using the motor 41 of the transport unit 40 and stops it, and then, based on the rotation of the axis 44 in the second direction detected by the detection unit 50, rotates the axis 44 in the first direction using the motor 41 before printing by the printing unit 30.

[0034] The roller 43 that transports the recording paper P is flexible. Therefore, when the shaft 44 of the roller 43 is rotated in a first direction, which is the transport direction of the recording paper P, the roller 43 is deformed. When the shaft 44 is stopped after transporting the recording paper P, the roller 43 tries to return to its original shape, and a force acts in a second direction opposite to the first direction. As a result, the shaft 44 rotates in the second direction. Then, when the shaft 44 of the roller 43 is rotated in the first direction again, the roller 43 is only required to deform by the amount of rotation of the shaft 44 in the second direction, and is unable to transport the recording paper P. During this time, even if the printing unit 30 prints on the recording paper P, the recording paper P is not transported, so the printout may become clogged or crushed, resulting in a deterioration in print quality. Therefore, according to the above-described aspect, before printing by the printing unit 30, the control unit 10 rotates the shaft 44 in the first direction based on the rotation of the roller 43 in the second direction, allowing printing to be performed while the recording paper P is actually being transported, thereby improving print quality. In addition, since the roller 43 deforms when it starts to rotate and after it has rotated, the detection unit 50 detects the rotation of the shaft 44 instead of the roller 43 .

[0035] In the printing device 1 according to one embodiment, the head 31 of the printing unit 30 is a line thermal head, the motor 41 is a DC motor, and the detection unit 50 includes an encoder that detects the rotation of the shaft 44 .

[0036] According to the above-mentioned embodiment, the head 31 of the printing unit 30 can be a line thermal head, and printing can be performed while the recording paper P is transported by the roller 43. The motor 41 can be a DC motor with a relatively small detent torque. Also, the detection unit 50 can be an encoder that detects the rotation of the shaft 44.

[0037] In the printing device 1 according to one embodiment, the amount by which the motor 41 rotates the shaft 44 in the first direction before printing by the printing unit 30 is based on the resolution of the line thermal head of the printing unit 30.

[0038] According to the above-described aspect, before printing by the printing unit 30 begins, the amount of rotation of the detection signal of the detection unit 50, which is the amount by which the motor 41 rotates the shaft 44 in the first direction, can be based on the resolution of the detection signal of the detection unit 50, and can be based on the resolution of the head 31, which is a line thermal head.

[0039] Although these embodiments have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and may be changed, substituted, deleted, etc. without departing from the gist of the present invention.

[0040] For example, in the printing device 1, the head 31 is described as a line thermal head, but the type of the head 31 is not important. For example, an inkjet head may be used. Moreover, although the motor 41 has been described as a DC motor, it may be a step motor or other type of motor. Further, the detector 50 has been described as an encoder, but it may be of another detection type, such as a tachogenerator. Furthermore, the recording paper P has been described as roll paper 90 wound in a roll, but it may also be cut sheets of paper such as A4 size. In addition, although the example has been described in which the disk 52 of the detection unit 50 is attached to the shaft 44, it may also be attached to the shaft of the gear 42 or the shaft of the motor 41, and it is sufficient for the detection unit 50 to be able to directly or indirectly detect the rotational position of the shaft 44. [Explanation of symbols]

[0041] 1...printing device, 10...control unit, 20...storage unit, 30...printing unit, 31...head, 40...conveying unit, 41...motor, 42...gear, 43...roller, 44...shaft, 50...detecting unit, P...recording paper.

Claims

1. A printing unit that prints on recording paper; a roller that rotates in a first direction around an axis and transports the recording paper; A conveying unit having a motor; Detecting rotation of the shaft in the first direction and in a second direction opposite to the first direction. A detection unit for detecting the A control unit that controls the conveying unit based on the rotation of the shaft detected by the detection unit. 、 The roller is flexible and conveys the recording paper by sandwiching it between the roller and the printing unit. Sometimes, torsional deflection occurs, The rotation in the second direction occurs based on the torsional deflection, The control unit is The motor of the conveying unit rotates the shaft in the first direction and stops the rotation. based on the rotation of the shaft in the second direction detected by the detection unit, before printing by the printing unit. and rotating the shaft in the first direction by the motor.

2. the printing unit is a line thermal head, the motor is a DC motor; The printing apparatus according to claim 1 , wherein the detection unit includes an encoder for detecting rotation of the shaft. Place.

3. Before printing by the printing unit, the shaft is rotated in the first direction by the motor. The amount is a value obtained by dividing the resolution of the line thermal head by an integer, or 3. The printing device according to claim 2, wherein the value is an integer multiple of the resolution of the thermal head.

4. A printing unit that prints on a recording paper and a roller that rotates in a first direction around an axis and transports the recording paper. a conveying unit having a roller and a motor for rotating the shaft; a detection unit that detects rotation in a first direction and a second direction opposite to the first direction, 、 The roller is flexible and conveys the recording paper by sandwiching it between the roller and the printing unit. At this time, a torsional deflection occurs, and the rotation in the second direction occurs based on the torsional deflection. A control method for a printing device comprising the steps of: The motor of the conveying unit rotates the shaft in the first direction and stops the rotation. based on the rotation of the shaft in the second direction detected by the detection unit, before printing by the printing unit. and rotating the shaft in the first direction by the motor.

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