JP2007302468A - Printing device, conveying device and printing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing device capable of adequately controlling the conveyance of a medium by winding. <P>SOLUTION: The printing device 10 to use a medium roll 20 comprises a delivery roller 102 for rotatably holding the medium roll 20, a printing unit 112 for printing a medium 30 delivered from the medium roll 20, a winding roller 108 for winding the medium 30 printed by the printing unit 112, a motor 122 for rotating the winding roller 108 in the winding direction of the medium 30, a conveyance amount detection unit 114 for detecting the conveyance amount of the medium 30 to be successively delivered from the medium roll 20, a roller diameter calculation unit 116 for calculating the winding roller diameter as the diameter of the roll-shaped medium 30 wound by the winding roller 108 based on the conveyance amount detected by the conveyance amount detection unit 114, and an output control unit 118 for controlling the output of the motor 122 based on the winding roller diameter calculated by the roller diameter calculation unit 116. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a printing apparatus, a conveying apparatus, and a printing method.

  In a printing apparatus that prints on a medium such as roll paper or film, a roller with a motor dedicated to feeding is often used to convey the medium. In this configuration, the medium is conveyed by a roller, and printing is performed at a designated position. Thereafter, the medium is fed out again for the next printing.

  When a roller with a motor dedicated to feeding is used, since the outer diameter of the roller is constant, it is easy to control the tension applied to the medium during conveyance and the conveyance speed. However, in this configuration, slip is likely to occur between the medium and the roller, and the medium may be rubbed or the conveyance accuracy may be affected. Moreover, if a roller or a motor is added to prevent slipping, the price of the apparatus will increase.

  Therefore, the inventor of the present application has studied to drive a take-up roller for taking up the medium after printing and to carry the medium by taking up. However, particularly when a thin medium such as a film is transported, for example, if the medium is simply fed out and wound up, the medium is likely to wrinkle and it is difficult to obtain an accurate printing result. For example, when the rotational torque of the winding is too large or when the rotational torque fluctuates, there are cases where the winding roll is wound up or vertical wrinkles are generated due to excessive tension. Further, when the medium is transported by winding, the outer diameter of the winding roller changes as the amount of winding of the medium increases. Therefore, it becomes difficult to keep the tension applied to the medium, the conveyance speed, and the like constant. Even when the tension, the conveyance speed, and the like are not constant, the medium is likely to be wrinkled.

  Conventionally, in a printer using an ink ribbon, a configuration is known in which the traveling speed of the ink ribbon is directly detected and the traveling speed of the ink ribbon is adjusted (Patent Document 1). However, when the medium to be printed is transported, the generation of wrinkles or the like tends to be a big problem compared to the case of transporting the ink ribbon. For example, when the transport speed is controlled by directly detecting the transport speed of the medium, the transport speed is adjusted by changing the rotation torque of winding. In this case, the rotational torque continues to fluctuate around a value corresponding to the target speed. Therefore, in this case, there is a possibility that the tension or the conveyance speed applied to the medium fluctuates and causes wrinkles. Therefore, the ink ribbon transport method cannot be directly applied to the medium transport of the printing apparatus.

  Conventionally, a belt-like body winding device that measures the roll diameter of the belt-like body wound around the winding means and controls the angular velocity of the winding means is known (Patent Document 2). In this apparatus, the roll diameter is measured using a detection needle or the like that is supported by a spring and is movable in the radial direction of the roll. However, when the roll diameter is measured in this way, the price of the apparatus increases due to an increase in the number of parts.

For this reason, conventionally, in a printing apparatus, it has been difficult to appropriately convey a medium by winding without causing wrinkles or the like. SUMMARY An advantage of some aspects of the invention is that it provides a printing apparatus, a conveyance apparatus, and a printing method that can solve the above-described problems.
JP 2003-154720 A Japanese Patent Laid-Open No. 10-147463

In order to solve the above problems, the present invention has the following configuration.
(Configuration 1) A printing apparatus using a medium roll in which the medium is wound in a roll shape, wherein the medium roll is rotatably held so that the medium is sequentially discharged from the medium roll in accordance with a pulling force of the medium. A roller, a printing unit that performs printing on the medium fed from the medium roll, a winding roller that winds up the medium printed by the printing unit, and a drive unit that rotates the winding roller in the direction of winding the medium; Conveys the conveyance amount detection unit that detects the conveyance amount of the medium that is sequentially fed from the medium roll according to the rotation of the take-up roller, and the diameter of the take-up roller that is the diameter of the roll-shaped medium wound around the take-up roller. A roller diameter calculation unit that calculates based on the conveyance amount detected by the amount detection unit, and an output control that controls the output of the drive unit based on the winding roller diameter calculated by the roller diameter calculation unit Provided with a door.

  If comprised in this way, conveyance of the medium by winding can be controlled appropriately. Therefore, even when a thin medium such as a film is used, it is possible to appropriately suppress the occurrence of winding or vertical wrinkles (hereinafter referred to as wrinkles) generated by winding. Thereby, an accurate printing result can be obtained.

  As the medium transport control, for example, a tension applied to the medium, a transport speed, a transport amount, or a combination of these can be considered. The roller diameter calculation unit calculates, for example, the diameter of the wound roll-shaped medium as the winding roller diameter. The roller diameter calculation unit may calculate a value that can be directly converted to a diameter such as a radius as the winding roller diameter. The printing apparatus is, for example, an ink jet printing apparatus. The printing unit is, for example, an inkjet head.

  (Configuration 2) The output control unit controls the drive unit so as to give the winding roller a rotational torque proportional to the winding roller diameter. In order to make the tension applied to the medium constant at the time of conveyance by winding, when the diameter of the winding roller is large, the required rotational torque becomes large. Further, when the diameter of the take-up roller is small, the required rotational torque is small. Therefore, with this configuration, the tension applied to the medium can be kept constant. This also makes it possible to appropriately suppress the occurrence of wrinkles on the medium.

  (Configuration 3) The output control unit controls the output of the driving unit so that the angular acceleration of rotation of the winding roller is proportional to the winding roller diameter, thereby making the rotational torque proportional to the winding roller diameter. The rotational torque (force moment) is the product of the moment of inertia and the angular acceleration. Therefore, if comprised in this way, a rotational torque can be controlled appropriately. This also makes it possible to keep the tension applied to the medium appropriately constant.

  (Configuration 4) A biasing unit that biases the feeding roller in a direction opposite to the direction in which the medium is fed is further provided, and the output control unit has a medium conveyance speed based on the medium conveyance amount detected by the conveyance amount detection unit. The urging force of the urging unit is further controlled so as to be constant. If comprised in this way, in addition to the tension concerning a medium, the conveyance speed of a medium can be controlled appropriately. Further, the conveyance amount can be controlled based on the conveyance speed.

  Here, in order to control the tension, the conveyance amount, and the like, it may be possible to provide a tension control unit and a conveyance control unit, respectively. In this case, however, the system is large and expensive. On the other hand, in the case of the configuration 4, the feeding roller and the winding roller can be appropriately controlled based on the calculated winding roller diameter without using a large-scale system. Therefore, if the configuration 4 is used, the tension, the conveyance amount, and the like can be appropriately controlled with a simple configuration using calculation.

  In Configuration 4, the rotational torque applied to the take-up roller by the drive unit is controlled to a magnitude proportional to the take-up roller diameter. Therefore, unlike the case where, for example, the speed is directly measured and controlled by feedback control or the like, excessive rotational torque is not applied. Therefore, with the configuration 4, it is possible to keep the conveyance speed constant while suppressing the generation of wrinkles.

  (Configuration 5) The output control unit controls the drive unit so as to rotate the winding roller at an angular velocity inversely proportional to the winding roller diameter. In order to convey the medium by a certain amount of conveyance, when the diameter of the take-up roller is large, the necessary rotation amount becomes large. Moreover, when the diameter of the winding roller is small, the required amount of rotation is large. Therefore, if the configuration 5 is adopted, the conveyance speed of the medium can be kept constant. This also makes it possible to appropriately suppress the occurrence of wrinkles on the medium.

  Furthermore, in the case of the configuration 5, it is possible to carry at a carrying speed determined according to the diameter of the take-up roller without performing speed measurement or the like. Therefore, unlike the case where the conveyance speed is directly measured and controlled by feedback control or the like, for example, tension on the medium and fluctuations in the conveyance speed are less likely to occur. Therefore, if the configuration 5 is adopted, it is unlikely that wrinkles or the like occur in the medium due to fluctuations in the conveyance speed or tension.

  Note that the printing apparatus may further include a biasing unit that biases the feeding roller in a direction opposite to the direction of feeding the medium. In this case, for example, the tension applied to the medium can be adjusted by controlling the rotational torque applied to the feeding roller by the urging unit.

  (Configuration 6) The output control unit controls the driving unit so that the conveyance and the stop of the medium are repeated by causing the winding roller to rotate and stop repeatedly, and the printing unit stops the conveyance of the medium. In this state, the roller diameter calculation unit calculates the winding roller diameter based on the conveyance amount of the medium in the first conveyance before printing on the medium. The output control unit determines the output of the driving unit to be used in the next conveyance based on the winding roller diameter calculated by the above.

  When the conveyance and stop of the medium are repeated, the control of the tension applied to the medium becomes more important in order to suppress the generation of wrinkles and the like. On the other hand, with the configuration 6, the medium can be transported with high accuracy by determining the output of the driving unit each time transport is performed. This also makes it possible to appropriately suppress wrinkling of the medium.

  (Configuration 7) When performing the first transport, the roller diameter calculation unit calculates the take-up roller diameter when the medium is transported by a preset transport amount of the entire transport amount of the first transport. The output control unit changes the output of the driving unit to an output corresponding to the winding roller diameter calculated by the roller diameter calculating unit during the first conveyance. If comprised in this way, the output of a drive part can be set appropriately from the first conveyance. The first transport is, for example, the first transport in a series of printing operations in which the transport and stop of the medium are repeated.

  (Configuration 8) A transport device that transports a medium in a printing apparatus that uses a medium roll in which the medium is wound into a roll, and the medium roll is configured so that the medium is sequentially fed out from the medium roll in accordance with a pulling force of the medium. A take-out roller that rotatably holds the print medium, a take-up roller that takes up the printed medium, a drive unit that rotates the take-up roller in the direction of taking up the medium, and a medium roll according to the rotation of the take-up roller. Based on the conveyance amount detected by the conveyance amount detection unit, the conveyance amount detection unit that detects the conveyance amount of the sequentially fed medium, and the winding roller diameter that is the diameter of the roll-shaped medium wound around the winding roller A roller diameter calculation unit to calculate, and an output control unit to control the output of the drive unit based on the winding roller diameter calculated by the roller diameter calculation unit. If comprised in this way, the effect similar to the structure 1 can be acquired.

  (Structure 9) A printing method using a medium roll in which the medium is wound in a roll shape, and the medium roll can be rotated to the feeding roller so that the medium is sequentially fed out from the medium roll in accordance with the pulling-out force of the medium. Hold, print on the medium fed from the medium roll, rotate the take-up roller by the drive device in the direction of winding the medium, take up the medium printed by the printing unit on the take-up roller, and take up Detects the transport amount of the medium that is sequentially fed from the medium roll according to the rotation of the roller, and calculates the take-up roller diameter, which is the diameter of the roll-shaped medium wound around the take-up roller, based on the detected transport amount Then, the output of the driving device is controlled based on the calculated winding roller diameter. In this way, the same effect as in Configuration 1 can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the printing apparatus which can control appropriately conveyance of the medium by winding can be provided.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. FIG. 1 shows an example of the configuration of a printing apparatus 10 according to an embodiment of the present invention. The printing apparatus 10 is an ink jet printing apparatus using a medium roll 20 in which a medium 30 such as a thin film or paper is wound into a roll shape, and includes a transport unit 100 and a printing unit 112. The conveyance unit 100 includes a feeding roller 102, a motor 120, driven rollers 104 and 106, a table 110, a take-up roller 108, a motor 122, a conveyance amount detection unit 114, a roller diameter calculation unit 116, an output control unit 118, and a motor 120. 122.

  The feeding roller 102 is a roller that holds the medium roll 20, and rotatably holds the medium roll 20 so that the medium 30 is sequentially fed out from the medium roll 20 according to the force with which the medium 30 is pulled out. The motor 120 is an example of an urging unit, and urges the feeding roller 102 in a direction opposite to the direction in which the medium 30 is fed in accordance with the output of the output control unit 118. Thereby, the motor 120 adjusts the tension applied to the medium 30.

  The driven rollers 104 and 106 are rollers for guiding the conveyance of the medium 30. The driven rollers 104 and 106 are respectively provided downstream of the feeding roller 102 in the transport direction of the medium 30 and rotate according to the movement of the transported medium 30. In this example, the driven roller 104 closer to the feeding roller 102 is a roller with an encoder and outputs a pulse signal having a pulse number proportional to the rotation amount. Note that a roller with a feed motor may be used instead of the driven roller 106 as long as it has an encoding function.

  The table 110 is a table that supports the lower surface of the medium 30 to be transported, and is provided between the driven roller 104 and the driven roller 106. Further, the table 110 holds the medium 30 by suction at a timing when the conveyance is temporarily stopped. Thereby, the medium 30 can be stopped at the time of printing. The printing unit 112 is an inkjet head, and is provided at a position facing the table 110 with the medium 30 interposed therebetween. The printing unit 112 performs printing on the medium 30 while the table 110 sucks and fixes the medium 30.

  The take-up roller 108 is a roller that takes up the medium 30 printed by the printing unit 112, and is provided downstream in the transport direction with respect to the driven roller 106. The motor 122 is an example of a drive unit, and rotates the take-up roller 108 in the direction of taking up the medium 30 according to the output of the output control unit 118. Accordingly, the take-up roller 108 sequentially feeds the medium 30 from the medium roll 20 held by the feed roller 102 and transports the medium 30 in the transport direction.

  In this example, the motor 122 is a stepping motor. The motor 122 receives the pulse signal from the output control unit 118 and rotates the winding roller 108 at a rotation speed proportional to the frequency of the pulse signal. In addition, the motor 122 applies a rotational torque corresponding to the electric power received from the output control unit 118 to the winding roller 108 to rotate the winding roller 108.

The carry amount detection unit 114 detects the carry amount of the medium 30 that is sequentially fed from the medium roll 20 in accordance with the rotation of the take-up roller 108. In this example, the conveyance amount detection unit 114 detects the rotation amount of the driven roller 104 as the conveyance amount of the medium 30 by measuring a pulse signal received from the driven roller 104. The conveyance amount detection unit 114 may detect the conveyance speed by measuring the frequency of the pulse signal.
The roller diameter calculation unit 116 calculates the winding roller diameter of the winding roller 108 based on the conveyance amount detected by the conveyance amount detection unit. In this example, the roller diameter calculation unit 116 further receives a pulse signal given to the motor 122 by the output control unit 118, and measures the pulse signal to calculate the amount of rotation of the winding roller 108. Based on the ratio of the rotation amount of the driven roller 104 and the rotation amount of the take-up roller 108 to the same conveyance amount, and the diameter of the driven roller 104, the roller diameter calculation unit 116 calculates the take-up roller diameter. The winding roller diameter is the diameter of the roll-shaped medium 30 wound around the winding roller 108.

  The output control unit 118 controls the output of the motor 120 and the motor 122 based on the winding roller diameter calculated by the roller diameter calculation unit 116. The output control unit 118 adjusts the rotational torque of the motor 120 and the motor 122 by adjusting the electric power applied to the motor 120 and the motor 122, for example. Thereby, the rotational torque received by the feeding roller 102 and the take-up roller 108 can be adjusted. Further, the tension applied to the medium 30 can be adjusted by adjusting the rotational torque for pulling both ends of the medium 30 being conveyed.

  In this example, the output control unit 118 controls the motor 122 so as to give the winding roller 108 a rotational torque proportional to the winding roller diameter. Thereby, the tension applied to the medium 30 can be kept constant. The output control unit 118 controls the rotation speed of the motor 122 by adjusting the frequency of the pulse signal applied to the motor 122. For example, the output control unit 118 controls the motor 122 so as to rotate the winding roller 108 at an angular velocity inversely proportional to the winding roller diameter. Thereby, the conveyance speed of the medium 30 can be kept constant.

  As described above, according to this example, it is possible to appropriately control the conveyance of the medium 30 by winding while keeping the tension and the conveyance speed applied to the medium 30 constant. Therefore, even when a thin medium such as a film is used, the generation of wrinkles or the like caused by winding can be appropriately suppressed. Thereby, an accurate printing result can be obtained.

  The output control unit 118 may further control the motor 122 for points other than those described above. For example, the output control unit 118 may control the motor 122 so that the medium 30 is conveyed by a specified amount by controlling the rotation amount of the take-up roller 108. In this case, the output control unit 118 controls the motor 122 by calculating the amount of rotation necessary for winding based on the diameter of the winding roller, for example.

  Hereinafter, operations of the roller diameter calculation unit 116 and the output control unit 118 will be described in more detail. First, the calculation performed by the roller diameter calculation unit 116 will be described. In this example, the roller diameter calculation unit 116 receives a pulse signal from the driven roller 104 that indicates the amount of rotation of the driven roller 104 and a pulse signal from the output control unit 118 that indicates the amount of rotation of the take-up roller 108. Based on this, a ratio between the rotation amount of the driven roller 104 and the rotation amount of the winding roller 108 with respect to the same conveyance amount is calculated. Based on this ratio and the diameter of the driven roller 104, the winding roller diameter is calculated.

For example, the outer diameter (diameter) of the driven roller 104 is d, the number of pulses of the pulse signal output from the output control unit 118 to the motor 122 to rotate the winding roller 108 once, A, and the driven roller 104 rotates once. If the number of pulses generated by the encoder is B, the number of pulses output by the encoder of the driven roller 104 corresponding to a predetermined conveyance amount is P _e , and the number of pulses received by the motor 122 is P _s. The take-up roller diameter (diameter) is D,
dπ × P _e / B = Dπ × P _s / A
Holds. Than this,
D = d × (A / B) × (P _e / P _s )
It becomes. Since A, d, and B are constants, if the constant q = d × (A / B) is set,
D = q × (P _e / P _s )
It becomes. Thus, a known d, using A, and B, and P _e and P _s, the take-up roller diameter D is can be calculated.

Here, when the conveyance amount used for calculating the take-up roller diameter D to a certain amount, P _s becomes constant. For example, when a fixed amount of pulses P ₀ set in advance as the number of pulses P _s is given to the motor 122 to carry a certain amount of conveyance, a constant k = (A × d) / (B × P ₀ ) can be set. In this case, D = k × P _e . In this way, the method of calculating the take-up roller diameter D with a constant carry amount starts the carry-out with the take-up roller diameter D unknown, for example, when the first (first) transfer of the medium 30 is performed. It is especially effective in cases.

  The roller diameter calculation unit 116 may calculate the winding roller diameter by a method other than the above. For example, the roller diameter calculation unit 116 may calculate the winding roller diameter after the conveyance is performed by using the winding roller diameter before the medium 30 is conveyed and the thickness of the medium 30. . In this case, for example, the roller diameter calculation unit 116 calculates the winding roller diameter after the conveyance is performed based on the change in the area before and after the conveyance of the circle having the diameter of the winding roller.

For example, when the medium 30 is sent by a certain transport amount, the transport amount is L, the thickness of the medium 30 is t, the radius corresponding to the winding roller diameter before transport is R, and the winding roller diameter after transport is If the radius corresponding to is R ′,
π × ^{R 2} tens of L × t = π × R ' 2
Holds. Than this,
R ′ = (R ² + Lt / π) ^1/2
Even in this method, the winding roller diameter D (= 2R ′) after conveyance can be calculated. Note that the thickness of the medium 30 is set in advance by, for example, a user's numerical input. For example, the thickness of the medium 30 may be set by measurement using a sensor or the like.

  The roller diameter calculation unit 116 may calculate the diameter of the medium roll 20 held by the feeding roller 102 by, for example, the same or similar method as the calculation of the take-up roller diameter D. For example, the roller diameter calculation unit 116 further detects the rotation amount of the feeding roller 102 and determines the diameter of the medium roll 20 based on the rotation amount of the driven roller 104, the rotation amount of the feeding roller 102, and the diameter of the driven roller 104. calculate. The roller diameter calculation unit 116 may calculate the diameter of the medium roll 20 after the conveyance is performed using the diameter of the medium roll 20 before the medium 30 is conveyed and the thickness of the medium 30. .

  Next, control performed by the output control unit 118 will be described. First, the control of the rotational torque of the motor 122 will be described. If the rotational torque applied to the winding roller 108 by the motor 122 is N and the tension applied to the medium 30 wound around the outermost periphery of the winding roller diameter D is F, N = D / 2 × F, and therefore F = 2 ×. N / D. Therefore, the tension applied to the medium 30 can be controlled by controlling the rotational torque of the motor 122. For example, the tension F applied to the medium 30 can be kept constant by controlling the motor 122 so that a rotational torque N proportional to the winding roller diameter D is applied to the winding roller 108.

  Here, when the inertia moment of the winding roller 108 in the state where the medium 30 is wound is I and the angular acceleration is a, I × a = N is established with respect to the rotational torque N (force moment). Therefore, if F = 2 × I × a / D and the winding roller diameter D can be calculated, the angular acceleration a can be controlled to keep the tension F constant. In this case, the output control unit 118 controls the output of the motor 122 so that the angular acceleration a is proportional to the winding roller diameter D.

Next, control of the rotation speed of the motor 122 will be described. As in the calculation of the winding roller diameter D, the outer diameter of the driven roller 104 is d, the number of pulses per rotation of the winding roller 108 is A, and the number of pulses per rotation of the driven roller 104 is B. Further, the frequency of the pulse signal output from the encoder of the driven roller 104 is f _e , and the frequency of the pulse signal given to the motor 122 is f _s . In this case, paying attention to the rotation amount of the driven roller 104,
Conveying speed = dπ / B × _fe
It is. From this equation, the frequency _fe corresponding to the desired conveyance speed can be calculated.

If attention is paid to the rotation amount of the take-up roller 108,
Transport speed = Dπ / A × _{f s}
But because
dπ / B × f _e = Dπ / A × f _s
Holds. Than this,
f _s = (d / D) × (A / B) × f _e
It is. Since A, d, and B are constants, if the constant q = d × (A / B) is set as in the calculation of the winding roller diameter D,
f _s = q × f _e / D
It becomes. Thus, the frequency f _{s of the} pulse signal to be output by the output control unit 118 is obtained from the frequency _fe corresponding to the desired conveying speed and the winding roller diameter D.

Here, in order to keep the conveyance speed constant, it is necessary to keep the frequency _fe of the pulse signal generated by the rotation of the driven roller 104 constant. Also, from the above equation, it can be seen that in order to keep f _e constant, a pulse signal having a frequency f _s inversely proportional to the winding roller diameter D may be given to the motor 122. In this case, the take-up roller 108 rotates at an angular velocity that is inversely proportional to the take-up roller diameter D. Therefore, by controlling the motor 122 so that the take-up roller 108 rotates at an angular velocity inversely proportional to the take-up roller diameter D, the conveyance speed of the medium 30 can be kept constant regardless of the size of the take-up roller diameter D. Can do.

  In this example, the output control unit 118 further controls the rotational torque that the motor 120 applies to the feeding roller 102. For example, the output control unit 118 controls the rotational torque of the motor 120 by the same or similar method as the rotational torque of the motor 122 based on the diameter of the medium roll 20 calculated by the roller diameter calculation unit 116. For example, the output control unit 118 controls the motor 120 so as to give the feeding roller 102 a rotational torque proportional to the calculated diameter of the medium roll 20. With this configuration, the tension applied to the medium 30 can be appropriately controlled. The output control unit 118 may control the output (biasing force) of the motor 120 so that the conveyance speed of the medium 30 is constant. If comprised in this way, the conveyance speed of the medium 30 can be controlled further appropriately.

  As described above, in this example, a special detector or the like is added to the apparatus by attaching an encoder to the driven roller 104 used for conveyance and using the motor 122, which is a stepping motor, as winding power. Therefore, the tension can be accurately controlled and the conveyance speed can be kept constant. Therefore, according to this example, it is possible to perform conveyance control with high accuracy at low cost, and it is possible to suppress the occurrence of wrinkles and the like caused by winding. This also makes it possible to obtain accurate printing results when printing is performed by the printing unit 112 that is an inkjet head.

  FIG. 2 is a flowchart illustrating an example of the operation of the printing apparatus 10. In this example, the output control unit 118 controls the motor 120 so that the conveyance and stop of the medium 30 are repeated by causing the winding roller 108 to rotate and stop. The printing unit 112 performs printing on the medium 30 in a state where the conveyance of the medium 30 is stopped. Accordingly, the printing apparatus 10 sequentially feeds the medium 30 from the medium roll 20 and sequentially performs printing on the fed medium 30.

  In this flowchart, first, the output control unit 118 starts driving the motor 120 to rotate the winding roller 108. Thereby, the first conveyance of the medium 30 is started (S102). In this first transfer, the output control unit 118 first gives the motor 120 a pulse signal having a preset fixed number of pulses. As a result, the take-up roller 108 rotates by the rotation amount corresponding to the fixed number of pulses, and conveys the medium 30 by the conveyance amount corresponding to the rotation amount.

  Next, the conveyance amount detection unit 114 counts the pulse signal output from the encoder of the driven roller 104, and detects the rotation amount of the driven roller 104 as the conveyance amount by which the medium 30 is conveyed (S104). Based on the ratio between the rotation amount of the driven roller 104 and the rotation amount of the winding roller 108 and the diameter of the driven roller 104, the roller diameter calculation unit 116 calculates the winding roller diameter (S106). Thereby, in the first conveyance, the roller diameter calculation unit 116 calculates the take-up roller diameter when the preset amount of medium 30 is conveyed. In the first transport, the take-up roller 108 transports the medium 30 in addition to the transport amount corresponding to the fixed number of pulses. The take-up roller 108 continues to convey the medium 30 in parallel with the shortage of the carry amount while the roller diameter calculation unit 116 or the like is calculating, for example.

  Subsequently, during the conveyance, the output control unit 118 changes the output of the motor 122 to an output corresponding to the calculated winding roller diameter (S108). Thereby, in the first conveyance, the tension applied to the medium 30 and the conveyance speed can be appropriately set.

  Then, at the point in time when the entire conveyance amount for the first conveyance is carried out, the output control unit 118 adjusts the output of the motor 122 so that the rotation of the winding roller 108 is stopped. Thereby, the conveyance of the medium 30 is stopped (S110). Then, according to the stop of the conveyance of the medium 30, the table 110 holds the medium 30 by suction. Further, the printing unit 112 performs printing on the suctioned and held medium 30 (S112).

  After the printing on the medium 30 corresponding to the first conveyance, when the conveyance and the printing are further repeated (S114: No), the roller diameter calculation unit 116 is based on the conveyance amount in the entire previous conveyance. Then, the winding roller diameter is calculated again (S116). Then, based on the calculated winding roller diameter, the output control unit 118 determines the output of the motor 122 to be used in the next conveyance (S118).

  Subsequently, the output control unit 118 changes the output of the motor 122 to the determined value, thereby starting the rotation of the winding roller 108. Thereby, the next conveyance is started (S120). After the conveyance is started, the process returns to step S110 and the subsequent operations are repeated. Thereby, conveyance and stop of the medium 30 are repeated. In addition, when all the conveyance is completed (S114: Yes), this flowchart ends.

  According to this example, the diameter of the take-up roller can be calculated before each conveyance, and the output of the motor 122 corresponding to this can be determined. In addition, the output of the motor 122 can be appropriately set also in the first conveyance. Therefore, according to this example, the medium 30 can be transported with high accuracy. Thereby, generation | occurrence | production of the wrinkle etc. of the medium 30 can be suppressed appropriately.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The present invention can be suitably used for a printing apparatus, for example.

1 is a diagram illustrating an example of a configuration of a printing apparatus 10 according to an embodiment of the present invention. 4 is a flowchart illustrating an example of the operation of the printing apparatus 10.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Printing apparatus, 20 ... Medium roll, 30 ... Medium, 100 ... Conveying part, 102 ... Feeding roller, 104 ... Driven roller, 106 ... Driven roller, 108. ..Take-up roller, 110... Table, 112... Printing unit, 114 .. transport amount detection unit, 116... Roller diameter calculation unit, 118. (Biasing part), 122 ... Motor (drive part)

Claims (9)

A printing apparatus using a medium roll in which a medium is wound into a roll,
A feeding roller that rotatably holds the medium roll so that the medium is sequentially fed out from the medium roll in accordance with a force for pulling out the medium;
A printing unit that performs printing on the medium fed from the medium roll;
A winding roller that winds up the medium printed by the printing unit;
A drive unit for rotating the take-up roller in the direction of taking up the medium;
A transport amount detection unit that detects a transport amount of the medium sequentially fed from the medium roll in accordance with the rotation of the winding roller;
A roller diameter calculation unit that calculates a winding roller diameter, which is a diameter of the roll-shaped medium wound around the winding roller, based on the conveyance amount detected by the conveyance amount detection unit;
A printing apparatus comprising: an output control unit configured to control an output of the driving unit based on the winding roller diameter calculated by the roller diameter calculating unit.   The printing apparatus according to claim 1, wherein the output control unit controls the driving unit so as to apply a rotational torque proportional to the winding roller diameter to the winding roller.   The output control unit controls the output of the drive unit so that the angular acceleration of the rotation of the winding roller is proportional to the diameter of the winding roller, thereby making the rotational torque proportional to the diameter of the winding roller. The printing apparatus according to claim 2. A biasing unit that biases the feeding roller in a direction opposite to the direction of feeding the medium;
The output control unit further controls the urging force of the urging unit based on the conveyance amount of the medium detected by the conveyance amount detection unit so that the conveyance speed of the medium becomes constant. The printing apparatus according to claim 2 or 3.   5. The printing apparatus according to claim 1, wherein the output control unit controls the driving unit to rotate the winding roller at an angular velocity inversely proportional to the diameter of the winding roller. . The output control unit controls the driving unit so that the conveyance and the stop of the medium are repeated by causing the winding roller to rotate and stop repeatedly.
The printing unit performs printing on the medium in a state where conveyance of the medium is stopped,
Based on the conveyance amount of the medium in the first conveyance before printing on the medium, the roller diameter calculation unit calculates the winding roller diameter,
6. The output control unit determines an output of the driving unit to be used in the next conveyance based on the winding roller diameter calculated by the roller diameter calculation unit. A printing apparatus according to claim 1. When performing the first transport, when the medium is transported by a predetermined transport amount of the entire first transport amount, the roller diameter calculation unit calculates the winding roller diameter,
The output control unit changes the output of the drive unit to an output corresponding to the winding roller diameter calculated by the roller diameter calculation unit during the first conveyance. The printing apparatus as described. A transport device for transporting the medium in a printing apparatus using a medium roll in which the medium is wound into a roll,
A feeding roller that rotatably holds the medium roll so that the medium is sequentially fed out from the medium roll in accordance with a force for pulling out the medium;
A take-up roller for taking up the printed medium;
A drive unit for rotating the take-up roller in the direction of taking up the medium;
A transport amount detection unit that detects a transport amount of the medium sequentially fed from the medium roll in accordance with the rotation of the winding roller;
A roller diameter calculation unit that calculates a winding roller diameter, which is a diameter of the roll-shaped medium wound around the winding roller, based on the conveyance amount detected by the conveyance amount detection unit;
And an output control unit that controls an output of the driving unit based on the winding roller diameter calculated by the roller diameter calculating unit. A printing method using a medium roll in which the medium is wound into a roll,
The medium roll is rotatably held on a feeding roller so that the medium is sequentially fed out from the medium roll according to a force for pulling out the medium,
Printing on the medium fed out from the medium roll,
A winding roller is rotated by a driving device in the direction of winding the medium, and the medium printed by the printing unit is wound on the winding roller.
Detecting the transport amount of the medium sequentially fed from the medium roll according to the rotation of the winding roller;
A winding roller diameter, which is the diameter of the roll-shaped medium wound around the winding roller, is calculated based on the detected conveyance amount;
A printing method comprising controlling the output of the driving device based on the calculated winding roller diameter.

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