JP6719238B2 - Printer - Google Patents

Description

The present invention relates to a printing device that prints on a web.

2. Description of the Related Art A printing apparatus is known that prints on a web by ejecting ink from an inkjet head while continuously transporting a long web as a print medium (for example, see Patent Document 1).

In such a printing apparatus, the web may vibrate due to eccentricity of the rollers that convey the web. When such a vibration of the web occurs, the distance between the inkjet head and the web may fluctuate, and the landing deviation of the ink may occur. The deviation of the landing of the ink causes the deterioration of the print quality.

On the other hand, if the parts such as the rollers are processed and assembled with high accuracy, it is possible to suppress the occurrence of the vibration of the web as described above.

JP, 2013-71323, A

However, it has been difficult to process and assemble high-precision parts because many man-hours and costs are required. For this reason, there has been a demand for a technique capable of reducing the deterioration in print image quality due to the above-described vibration of the web while suppressing the high precision in the processing and assembly of the parts.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a printing apparatus that can reduce deterioration in print image quality on a web while suppressing high precision in processing and assembling parts.

In order to achieve the above-mentioned object, the first feature of the printing apparatus according to the present invention is a printing apparatus which prints by ejecting ink from an inkjet head onto a web, and is based on a transport unit for transporting the web and vibration of the web. An amplitude detector for detecting the amplitude, a tension adjuster for adjusting the tension of the web, and a controller for controlling the tension adjuster to adjust the tension of the web based on the amplitude of the web detected by the amplitude detector. And to prepare.

A second feature of the printing apparatus according to the present invention further includes a conveyance speed detection unit that detects a conveyance speed of the web, and the control unit calculates the frequency of the vibration of the web based on the output signal of the amplitude detection unit. Along with, the frequency of the fluctuation of the transport speed of the web is calculated based on the output signal of the transport speed detection unit, the amplitude of the web detected by the amplitude detection unit exceeds the amplitude threshold, and the calculated frequency of the vibration of the web. And the difference between the frequency of the fluctuation of the transport speed is less than or equal to the frequency difference threshold, the tension adjusting unit is controlled to change the tension of the web, and the amplitude of the web detected by the amplitude detecting unit exceeds the amplitude threshold. In addition, when the difference between the calculated frequency of the vibration of the web and the frequency of the fluctuation of the transport speed exceeds the frequency difference threshold, the transport unit is controlled to perform the error handling operation.

A third feature of the printing apparatus according to the present invention is a printing apparatus that prints by ejecting ink from an inkjet head onto a web, and a conveyance unit that conveys the web and an amplitude detection unit that detects an amplitude due to vibration of the web. And a tension adjusting unit that adjusts the tension of the web, and calculates the frequency of the vibration of the web based on the output signal of the amplitude detecting unit, and the difference between the calculated frequency of the vibration of the web and the natural frequency of the web is less than or equal to a threshold value. In this case, a control unit that controls the tension adjusting unit to change the tension of the web is provided.

A fourth feature of the printing apparatus according to the present invention is a printing apparatus that prints by ejecting ink from an inkjet head onto a web, and a conveyance unit that conveys the web and an amplitude detection unit that detects an amplitude due to vibration of the web. And a tension adjusting unit that adjusts the tension of the web, and a control unit that controls the conveying unit and the tension adjusting unit, and the control unit controls the frequency of the vibration of the web based on the output signal of the amplitude detection unit. Calculated, the amplitude of the web detected by the amplitude detection unit exceeds the amplitude threshold, and, if the difference between the calculated vibration frequency of the web and the natural frequency of the web is less than or equal to the frequency difference threshold, the tension of the web is set. Control the tension adjusting unit to change, the amplitude of the web detected by the amplitude detection unit exceeds the amplitude threshold, and the difference between the calculated frequency of the vibration of the web and the natural frequency of the web is the frequency. When the difference threshold is exceeded, the conveyance unit is controlled to perform an error handling operation.

A fifth aspect of the printing apparatus according to the present invention is a printing apparatus that prints ink by ejecting ink from an inkjet head onto a web, wherein at least one rotating roller including a carrying roller that carries the web, and the carrying roller. A driving unit for driving the web, and a conveying unit configured to convey the web along the rollers, an eccentricity frequency of each of the rollers according to a conveyance speed of the web, and an eccentricity of a rotation shaft of the driving source. The conveyance speed of the web is set so that the difference between the rotation fluctuation frequency of the conveyance roller and the natural frequency according to the set tension of the web is larger than the threshold value, and the web is conveyed at the set conveyance speed. And a control unit that controls the transport unit.

A sixth aspect of the printing apparatus according to the present invention is a printing apparatus that prints by ejecting ink from an inkjet head onto a web, the at least one rotating roller including a transport roller that transports the web, and the transport roller. And a drive source for driving the web, and a transport unit that transports the web at a set transport speed along each of the rollers, a tension adjusting unit that adjusts the tension of the web, and each roller according to the set transport speed of the web. The eccentricity frequency of the drive source and the rotational fluctuation frequency of the transport roller due to the eccentricity of the rotation axis of the drive source, and the difference between the natural frequency corresponding to the tension of the web is greater than the threshold value. And a control unit for controlling the tension adjusting unit so that the tension of the web becomes the set tension.

According to the first aspect of the printing apparatus of the present invention, the control unit controls the tension adjusting unit to adjust the tension of the web based on the amplitude of the web detected by the amplitude detecting unit. As a result, the amplitude due to the vibration of the web can be reduced, so that the deterioration of the print image quality due to the deviation of landing of ink can be reduced. Further, since the amplitude of the web is reduced by detecting the amplitude of the web and adjusting the tension, it is possible to prevent the processing and assembling of the parts from being highly accurate in order to suppress the occurrence of the vibration of the web. Therefore, it is possible to reduce the deterioration of the print image quality on the web while suppressing the high precision of the processing and assembly of the parts.

According to the second aspect of the printing apparatus of the present invention, the control unit controls that the amplitude of the web detected by the amplitude detection unit exceeds the amplitude threshold, and the calculated frequency of the vibration of the web and the fluctuation of the transport speed are When the difference from the frequency is less than or equal to the frequency difference threshold, the tension adjusting unit is controlled to change the tension of the web. As a result, the amplitude due to the vibration of the web can be reduced, so that the deterioration of the print image quality due to the deviation of landing of ink can be reduced. Further, the control unit, if the amplitude of the web detected by the amplitude detection unit exceeds the amplitude threshold value, and the difference between the calculated frequency of the vibration of the web and the frequency of the fluctuation of the transport speed exceeds the frequency difference threshold value, an error occurs. Since the conveyance unit is controlled to perform the corresponding operation, it is possible to cope with the situation where the web vibrates due to a sudden factor.

According to the third aspect of the printing apparatus of the present invention, the control unit causes the tension adjusting unit to change the tension of the web when the difference between the frequency of the vibration of the web and the natural frequency of the web is less than or equal to the threshold value. Control. As a result, the amplitude of the web vibration can be reduced by preventing the frequency of the web vibration and the natural frequency from overlapping. Further, since the amplitude of the web is reduced by detecting the amplitude of the web and adjusting the tension, it is possible to prevent the processing and assembling of the parts from being highly accurate in order to suppress the occurrence of the vibration of the web. Therefore, it is possible to reduce the deterioration of the print image quality on the web while suppressing the high precision of the processing and assembly of the parts.

According to the fourth aspect of the printing apparatus of the present invention, the control unit controls the amplitude of the web detected by the amplitude detection unit to exceed the amplitude threshold, and calculates the frequency of the vibration of the web and the natural frequency of the web. If the difference between and is less than or equal to the frequency difference threshold value, the tension adjusting unit is controlled to change the tension of the web. As a result, the amplitude of the web vibration can be reduced by preventing the frequency of the web vibration and the natural frequency from overlapping. As a result, it is possible to reduce the deterioration of the print image quality due to the landing deviation of the ink. Further, since the amplitude of the web is reduced by detecting the amplitude of the web and adjusting the tension, it is possible to prevent the processing and assembling of the parts from being highly accurate in order to suppress the occurrence of the vibration of the web. Therefore, it is possible to reduce the deterioration of the print image quality on the web while suppressing the high precision of the processing and assembly of the parts. In addition, the control unit handles the error when the amplitude of the web detected by the amplitude detection unit exceeds the amplitude threshold and the difference between the calculated frequency of the vibration of the web and the natural frequency of the web exceeds the frequency difference threshold. Since the conveyance unit is controlled to perform the operation, it is possible to cope with a situation where the web vibrates due to a sudden factor.

According to the fifth aspect of the printing apparatus of the present invention, the controller controls the eccentricity frequency of each roller according to the web conveyance speed and the rotation fluctuation frequency of the conveyance roller due to the eccentricity of the rotation axis of the drive source. The conveyance speed of the web is set so that the difference between each of them and the natural frequency of the web becomes larger than the threshold value, and the conveyance unit is controlled to convey the web at the set conveyance speed. Accordingly, the eccentricity of the roller and the natural frequency of the web do not overlap with each other, so that the amplitude of the web vibration can be suppressed. As a result, it is possible to reduce the deterioration of the print image quality due to the landing deviation of the ink. Further, since the vibration of the web is suppressed by setting the conveying speed of the web, it is possible to prevent the processing and assembly of the parts from being highly accurate in order to suppress the occurrence of the vibration of the web. Therefore, it is possible to reduce the deterioration of the print image quality on the web while suppressing the high precision of the processing and assembly of the parts.

According to the sixth aspect of the printing apparatus of the present invention, the control unit controls the eccentricity frequency of each roller according to the set conveyance speed of the web and the rotation fluctuation frequency of the conveyance roller due to the eccentricity of the rotation axis of the drive source. And the natural frequency according to the tension of the web are larger than the threshold, the tension of the web is set, and the tension adjusting unit is controlled so that the tension of the web becomes the set tension. Accordingly, the eccentricity of the roller and the natural frequency of the web do not overlap with each other, so that the amplitude of the web vibration can be suppressed. As a result, it is possible to reduce the deterioration of the print image quality due to the landing deviation of the ink. Further, since the vibration of the web is suppressed by setting the tension of the web, it is possible to prevent the processing and assembling of the parts from being highly accurate in order to suppress the occurrence of the vibration of the web. Therefore, it is possible to reduce the deterioration of the print image quality on the web while suppressing the high precision of the processing and assembly of the parts.

1 is a schematic configuration diagram of a printing apparatus according to a first embodiment. 3 is a control block diagram of the printing apparatus shown in FIG. 1. FIG. FIG. 2 is an enlarged view of the vicinity of a displacement sensor of the printing apparatus shown in FIG. 1. 6 is a flowchart illustrating an operation of the printing apparatus according to the first exemplary embodiment. 6 is a flowchart for explaining the operation of the printing apparatus according to the second embodiment. It is a figure which shows an example of a variation of the detection distance of a displacement sensor, and a variation of the web conveyance speed. It is a figure which shows the result which each performed Fourier transformation with respect to the data of the detection distance of the displacement sensor shown in FIG. 6, and the data of the web conveyance speed. It is a figure which shows an example of the fluctuation|variation of the detection distance of the displacement sensor in the web after tension change, and the fluctuation|variation of conveyance speed. It is a figure which shows the result which each performed Fourier transformation with respect to the data of the detection distance of the displacement sensor and the data of the web conveyance speed which are shown in FIG. FIG. 6 is a perspective view of a web between two adjacent head lower support members. 9 is a flowchart for explaining the operation of the printing apparatus according to the third embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Throughout the drawings, the same or equivalent parts or components are designated with the same or equivalent reference numerals.

The embodiments shown below exemplify a device and the like for embodying the technical idea of the present invention, and the technical idea of the present invention is that the material, shape, structure, arrangement, etc. of each component are Is not specified below. The technical idea of the present invention can be modified in various ways within the scope of claims.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a printing apparatus according to the first embodiment of the present invention. FIG. 2 is a control block diagram of the printing apparatus shown in FIG. FIG. 3 is an enlarged view of the vicinity of the displacement sensor of the printing apparatus shown in FIG. In the following description, the direction orthogonal to the plane of FIG. Further, the up, down, left and right of the paper surface in FIG. 1 are defined as up, down, left and right directions.

As shown in FIGS. 1 and 2, the printing apparatus 1 according to the first embodiment includes an unwinding unit 2, a printer unit 3, a winding unit 4, and a control unit 5.

The unwinding unit 2 unwinds the web W, which is a long print medium made of paper, film, or the like, to the printer unit 3. The unwinding unit 2 rotates the web roll support shaft 12 that supports the web roll 11 in the clockwise direction in FIG. 1 and conveys the web W to the right while nipping the web W with the pair of outfeed rollers 13. W is unwound to the printer unit 3. The web roll 11 is a roll of the web W.

The printer unit 3 conveys the web W and prints an image on the web W. The printer unit 3 is arranged adjacent to the unwinding unit 2 on the downstream side (right side) in the transport direction of the web W. The printer unit 3 includes a transport unit 21, a brake 22, a tension sensor 23, a roller encoder 24, a motor encoder 25, a displacement sensor 26, and a printing unit 27.

The transport unit 21 includes a pair of brake rollers 31, a tension detection roller 32, tension detection auxiliary rollers 33 and 34, upstream guide rollers 35 to 37, nine head lower support members 38, and downstream guide rollers. 39, 40, a pair of transport rollers 41, and a transport motor 42. The transport unit 21 receives the web W unwound from the unwinding unit 2 from the brake roller 31, the tension detection roller 32, the tension detection auxiliary rollers 33 and 34, the upstream guide rollers 35 to 37, and the downstream guide rollers 39 and 40. , And the conveyance roller 41 and the head lower support member 38.

The pair of brake rollers 31 apply tension to the web W. The pair of brake rollers 31 are arranged in the most upstream part of the printer unit 3. The pair of brake rollers 31 nip the web W while being driven to rotate while being conveyed. When the brake 22 is applied to the one brake roller 31, a tension is applied to the web W between the transport roller 41 and the brake roller 31.

The tension detection roller 32 is wound around the web W so that the tension sensor 23 detects the tension of the web W. The web W is wound around the tension detection roller 32 from above. The tension detection roller 32 is rotated by the conveyed web W.

The tension detection assisting rollers 33 and 34 assist in winding the web W around the tension detection roller 32. The tension detection auxiliary rollers 33 and 34 are disposed below the tension detection roller 32, with the tension detection roller 32 being sandwiched therebetween and being separated from each other in the left-right direction. The tension detection auxiliary rollers 33 and 34 press the web W from above on the upstream side (left side) and the downstream side (right side) of the tension detection roller 32, respectively. The tension detection auxiliary rollers 33 and 34 are driven to rotate by the conveyed web W.

The upstream guide rollers 35 to 37 guide the web W between the tension detection auxiliary roller 34 and the head lower support member 38. The upstream guide rollers 35 to 37 are driven to rotate by the conveyed web W.

The lower head support member 38 supports the web W below the printing unit 27. The nine head lower support members 38 are arranged at equal intervals so as to draw a convex arch upward. The lower head support member 38 is a columnar member elongated in the front-rear direction. The lower head support member 38 is fixed in the printing apparatus 1 so as not to rotate following the web W.

The downstream guide rollers 39 and 40 guide the web W between the lower head support member 38 and the transport roller 41. The downstream guide rollers 39 and 40 are driven to rotate by the conveyed web W.

The pair of transport rollers 41 transport the web W to the winding unit 4 while nipping the web W. The pair of transport rollers 41 is arranged at the most downstream portion of the printer unit 3. One conveyance roller 41 is rotationally driven by the conveyance motor 42, and the other conveyance roller 41 is driven and rotated by the one conveyance roller 41 via the web W.

The carry motor 42 rotationally drives one of the carry rollers 41. An annular belt (not shown) is stretched between a rotary shaft of the carry motor 42 and a pulley (not shown) connected to one of the carry rollers 41, and this belt causes a rotational driving force of the carry motor 42. Is transmitted to one of the transport rollers 41.

The brake 22 applies a brake to one brake roller 31. The tension of the web W is adjusted according to the braking force of the brake 22. The brake 22 is, for example, a powder brake. The brake 22 corresponds to the tension adjusting unit in the claims.

The tension sensor 23 detects the tension of the web W by receiving a load corresponding to the tension of the web W from the tension detection roller 32 and detecting the load.

The roller encoder 24 outputs a pulse signal for each predetermined rotation angle of the upstream guide roller 36. The output pulse signal of the roller encoder 24 is used for controlling the ink ejection timing by the inkjet head 47 of the printing unit 27, which will be described later.

The motor encoder 25 outputs a pulse signal for each rotation angle of the rotation shaft of the carry motor 42. The output pulse signal of the motor encoder 25 is used for drive control of the carry motor 42.

The displacement sensor 26 is disposed below the web W between any two adjacent head lower support members 38, detects the distance from that position to the web W in the Z direction, and indicates the detection result. Is output. As shown in FIG. 3, the Z direction is a direction orthogonal to the plane formed by the web W stretched between two adjacent head lower support members 38 that sandwich the displacement sensor 26. The displacement sensor 26 is an optical distance measuring sensor. The displacement sensor 26 corresponds to the amplitude detection unit in the claims.

The X direction shown in FIG. 3 is a direction parallel to the front-back direction which is a direction orthogonal to the paper surface of FIG. The Y direction is a direction parallel to the plane formed by the web W stretched between two adjacent head lower support members 38 that sandwich the displacement sensor 26 and orthogonal to the X direction. The Z direction is a direction orthogonal to both the X direction and the Y direction.

The printing unit 27 ejects ink onto the web W transported by the transport unit 21 to print an image. The printing unit 27 includes four head units 46.

The four head units 46 eject ink of different colors (for example, black, cyan, magenta, and yellow). Each of the four head units 46 has a plurality of inkjet heads 47. In each head unit 46, two head rows each including a plurality of inkjet heads 47 arranged in the front-rear direction are formed.

The inkjet head 47 has a plurality of nozzles (not shown), and ejects ink from the nozzles. The inkjet head 47 is arranged to face the web W between the adjacent lower head supporting members 38.

The winding unit 4 is for winding the web W printed by the printer unit 3. The winding unit 4 is arranged adjacent to the downstream side (right side) of the printer unit 3. The winding unit 4 conveys the web W to the right while nipping the web W by the pair of infeed rollers 51, and rotates the winding shaft 52 in the clockwise direction in FIG. Take up and hold.

The control unit 5 controls the overall operation of the printing apparatus 1. The control unit 5 includes a CPU, a RAM, a ROM, a hard disk, and the like.

When performing printing, the control unit 5 conveys the web W through the unwinding unit 2, the printer unit 3, and the winding unit 4, while ejecting ink from the inkjet head 47 to print on the web W. During printing, the control unit 5 controls the brake 22 to adjust the tension of the web W based on the amplitude of the web W in the Z direction detected by the displacement sensor 26.

Next, the operation of the printing apparatus 1 will be described.

FIG. 4 is a flowchart for explaining the operation of the printing apparatus 1 according to the first embodiment. The process of the flowchart of FIG. 4 starts when a print job is input to the printing apparatus 1.

In step S1 of FIG. 4, the control unit 5 starts the conveyance of the web W. Specifically, the control unit 5 starts the rotational driving of the web roll support shaft 12 and the outfeed roller 13 of the unwinding unit 2. Further, the control unit 5 activates the carry motor 42 of the printer unit 3 to start the rotational drive of the carry roller 41 and also activates the brake 22. Here, when the conveyance of the web W is started, a default value is set as a set value of the tension of the web W. The control unit 5 sets the braking force of the brake 22 to a value according to the default value of the tension of the web W. Further, the control unit 5 starts the rotational driving of the infeed roller 51 and the winding shaft 52 of the winding unit 4.

As a result, the web W starts to be conveyed from the unwinding section 2 to the winding section 4. After the conveyance is started, the control unit 5 controls the unwinding unit 2, the printer unit 3, and the winding unit 4 so as to accelerate the conveyance speed of the web W.

Next, in step S2, the control unit 5 determines, based on the output pulse signal of the motor encoder 25, whether the transport speed of the web W has reached a predetermined print transport speed. When determining that the transport speed of the web W has not reached the print transport speed (step S2: NO), the controller 5 repeats step S2.

When it is determined that the transport speed of the web W has reached the print transport speed (step S2: YES), the control unit 5 causes the printing unit 27 to start printing in step S3. Specifically, the control unit 5 drives and controls the inkjet head 47 to eject ink based on the image data to be printed and the output pulse signal of the roller encoder 24.

Here, after the conveyance speed of the web W reaches the print conveyance speed, the control unit 5 controls the conveyance motor based on the output pulse signal of the motor encoder 25 so as to maintain the conveyance speed of the web W at the print conveyance speed. The rotation speed of 42 is controlled.

During the conveyance of the web W, in the printer unit 3, the brake W is braked by the brake 22 to apply tension to the web W, and the conveyance roller 41 conveys the web W.

Returning to the description of FIG. 4, in step S4, the control unit 5 determines whether or not the calculation timing has come. This calculation timing is a timing for calculating the amplitude of the web W, and is set at every predetermined time from the time when the transport speed of the web W reaches the print transport speed. The amplitude of the web W calculated at this calculation timing is the amplitude due to the vibration of the web W in the head height direction, which is the direction orthogonal to the plane formed by the web W, at the position facing the inkjet head 47. In other words, the amplitude calculated at the calculation timing is the amplitude due to the vibration of the web W in the head height direction between two adjacent lower head supporting members 38.

Here, the vibration of the web W is caused by the rotating rollers (the brake rollers 31, the tension detecting rollers 32, the tension detecting auxiliary rollers 33 and 34, the upstream guide rollers 35 to 37, the downstream guide rollers 39, and 39) in the conveying unit 21. 40, the eccentricity of each of the transport rollers 41) and the eccentricity of the rotation shaft of the transport motor 42. The amplitude due to this vibration becomes approximately the same at the position facing each inkjet head 47. Therefore, in the present embodiment, the displacement sensor 26 is used to detect the amplitude of the web W at a position facing one inkjet head 47 as a representative.

When it is determined that the calculation timing has come (step S4: YES), the control unit 5 calculates the amplitude Zpp of the web W in the current detection period in step S5. The current detection period is a period from the previous calculation timing (when the conveyance speed of the web W reaches the print conveyance speed in the case of the first calculation timing this time) to the present calculation timing.

Specifically, the control unit 5 acquires the output signal of the displacement sensor 26 at every predetermined sampling timing. The output signal of the displacement sensor 26 indicates the detected value (detection distance) of the distance from the displacement sensor 26 to the web W in the Z direction (head height direction). The control unit 5 calculates the difference between the maximum value and the minimum value of the detection distance of the displacement sensor 26 at each sampling timing in the current detection period as the amplitude Zpp of the web W in the current detection period.

Next, in step S6, the control unit 5 determines whether or not the amplitude Zpp of the web W calculated in step S5 exceeds a predetermined threshold value (amplitude threshold value) Zt. When it is determined that the amplitude Zpp is less than or equal to the threshold value Zt (step S6: NO), the control unit 5 returns to step S4.

When it is determined that the amplitude Zpp exceeds the threshold value Zt (step S6: YES), in step S7, the tension is set in advance even if the tension of the web W is increased by one step from the current tension. Judge whether the upper limit is not exceeded.

When it is determined that the tension does not exceed the upper limit value even if the tension of the web W is increased by one step (step S7: YES), the control unit 5 controls the brake 22 to increase the tension of the web W by one step in step S8. Control. As a result, the tension of the web W increases and the amplitude is reduced. Then, the control unit 5 returns to step S4.

When it is determined that the tension exceeds the upper limit when the tension of the web W is increased by one step (step S7: NO), the control unit 5 controls each unit to perform the error handling operation in step S9. Specifically, the control unit 5 controls the unwinding unit 2, the printer unit 3, and the winding unit 4 so as to stop the printing by the printing unit 27 and stop the conveyance of the web W.

Next, in step S10, the control unit 5 sets a default value as the set value of the tension of the web W. This completes a series of operations. By setting the default value as the tension setting value of the web W in step S10, the tension setting value at the start of conveyance of the web W in the next printing operation becomes the default value.

When it is determined in step S4 that the calculation timing has not come (step S4: NO), in step S11, the control unit 5 determines whether or not the printing based on the print job is completed. When it is determined that the printing is not completed (step S11: NO), the control unit 5 returns to step S4.

When it is determined that the printing is finished (step S11: YES), the control unit 5 controls the unwinding unit 2, the printer unit 3, and the winding unit 4 in step S12 so as to finish the conveyance of the web W. After that, the control unit 5 performs the process of step S10 described above. This completes a series of operations.

As described above, in the printing apparatus 1, the control unit 5 controls the brake 22 to adjust the tension of the web W based on the amplitude Zpp of the web W detected by the displacement sensor 26. Specifically, when the detected amplitude Zpp of the web W exceeds the threshold value Zt, the control unit 5 controls the brake 22 to increase the tension of the web W. As a result, the vibration amplitude of the web W can be reduced. As a result, it is possible to reduce the deterioration of the print image quality due to the landing deviation of the ink.

Further, in the printing apparatus 1, the amplitude of the web W is reduced by detecting the amplitude of the web W and adjusting the tension. Therefore, in order to suppress the occurrence of vibration of the web W, it is possible to accurately process or assemble parts such as rollers. Can be suppressed.

Therefore, according to the printing apparatus 1, it is possible to reduce the deterioration of the print image quality on the web W while suppressing the high precision of the processing and assembly of the parts.

(Second embodiment)
Next, a second embodiment in which a part of the first embodiment described above is modified will be described.

In the second embodiment, the control unit 5 calculates the frequency fz of the vibration of the web W based on the output signal of the displacement sensor 26, and outputs the output pulse signal of the roller encoder 24 (corresponding to the carrying speed detection unit in the claims). Based on this, the frequency fs of fluctuations in the conveyance speed of the web W (speed fluctuations) is calculated. Then, the control unit 5 determines that the amplitude Zpp of the web W detected by the displacement sensor 26 exceeds the threshold value Zt, and the calculated frequency fz of the vibration of the web W and the frequency fs of the speed fluctuation of the web W are in the same frequency band. , The brake 22 is controlled to change the tension of the web W. Further, the control unit 5 determines that the amplitude Zpp of the web W detected by the displacement sensor 26 exceeds the threshold value Zt, and the calculated frequency fz of the vibration of the web W and the frequency fs of the speed fluctuation of the web W are in the same frequency band. If it does not belong to the above, each unit is controlled to perform an error handling operation.

The operation of the printing device 1 according to the second embodiment will be described with reference to the flowchart of FIG.

The processing of steps S21 to S24 in FIG. 5 is the same as the processing of steps S1 to S4 in FIG. 4 described above.

When it is determined in step S24 that the calculation timing has come (step S24: YES), in step S25, the control unit 5 determines the amplitude Zpp of the web W, the frequency fz of the vibration of the web W, and the web W in the current detection period. The frequency fs of the speed fluctuation is calculated.

Specifically, the control unit 5 calculates the amplitude Zpp of the web W by the same calculation method as in step S5 described above. Further, the control unit 5 calculates the frequency fz of the vibration of the web W by performing the Fourier transform on the data of the detection distance of the displacement sensor 26 at each sampling timing in the current detection period. In addition, the control unit 5 obtains the transport speed of the web W from the output pulse signal of the roller encoder 24 in the current detection period, and performs the Fourier transform on the data of the transport speed to obtain the frequency of the speed fluctuation of the web W. Calculate fs.

Here, FIG. 6 shows an example of fluctuations in the detection distance of the displacement sensor 26 and fluctuations in the transport speed of the web W in one detection period. In FIG. 6, the vertical axis represents the difference between the detection distance of the displacement sensor 26 and the average distance during the detection period, and the difference between the transport speed of the web W and the average speed during the detection period. In the example of FIG. 6, the amplitude Zpp exceeds the threshold value Zt.

FIG. 7 shows the results of Fourier transform of the data of the detection distance of the displacement sensor 26 and the data of the transport speed of the web W shown in FIG. In FIG. 7, the horizontal axis represents frequency, and the vertical axis represents the speed fluctuation width and amplitude of the web W. The frequency corresponding to the maximum amplitude in the result of the Fourier transform for the data of the distance detected by the displacement sensor 26 is the frequency fz of the vibration of the web W. Further, the frequency corresponding to the maximum speed fluctuation width in the result of the Fourier transform for the web W conveyance speed data is the frequency fluctuation frequency fs of the web W.

Returning to FIG. 5, in step S26 following step S25, the control unit 5 determines whether or not the amplitude Zpp of the web W calculated in step S25 exceeds the threshold value Zt. When it is determined that the amplitude Zpp is less than or equal to the threshold value Zt (step S26: NO), the control unit 5 returns to step S24.

When it is determined that the amplitude Zpp exceeds the threshold value Zt (step S26: YES), in step S27, the control unit 5 calculates the vibration frequency fz of the web W and the frequency fluctuation frequency fs of the web W calculated in step S25. It is determined whether and belong to the same frequency band. Specifically, the control unit 5 determines whether or not the difference between the vibration frequency fz of the web W and the frequency fluctuation frequency fs is less than or equal to a threshold (frequency difference threshold) ft. When the difference between the frequency fz of the vibration of the web W and the frequency fs of the speed fluctuation is less than or equal to the threshold ft, the control unit 5 determines that the frequency fz of the vibration of the web W and the frequency fs of the speed fluctuation belong to the same frequency band. to decide.

When it is determined that the vibration frequency fz of the web W and the frequency fluctuation frequency fs belong to the same frequency band (step S27: YES), the control unit 5 proceeds to step S28. The processing of steps S28 and S29 is the same as the processing of steps S7 and S8 of FIG. 4 described above. After step S29, the control unit 5 returns to step S24.

Here, the main factor common to the vibration and speed fluctuation of the web W is the eccentricity of the rotating shafts of the transporting unit 21 (the brake rollers 31 and the like) and the rotation shaft of the transport motor 42. Therefore, when the vibration frequency fz of the web W and the frequency fs of the speed fluctuation belong to the same frequency band, the main factors of the vibration of the web W in which the amplitude Zpp exceeding the threshold value Zt is detected are rotations. It is considered that the rotation axis of the roller or the conveyance motor 42 is eccentric. Vibration of the web W caused by such a configuration of the transport unit 21 can be reduced by increasing the tension of the web W.

Therefore, when the vibration frequency fz of the web W and the frequency fs of the speed fluctuation belong to the same frequency band (step S27: YES), the controller 5 sets the tension to 1 as long as the tension of the web W does not exceed the upper limit value. Step up (step S29).

When it is determined that the vibration frequency fz of the web W and the frequency fluctuation frequency fs do not belong to the same frequency band (step S27: NO), the control unit 5 proceeds to step S30. When it is determined in step S28 that the tension of the web W is increased by one step, the tension exceeds the upper limit value (step S28: NO), the control unit 5 proceeds to step S30. The processing of steps S30 and S31 is the same as the processing of steps S9 and S10 of FIG. 4 described above. When step S31 ends, the series of operations ends.

Here, when the frequency fz of the vibration of the web W and the frequency fs of the speed fluctuation do not belong to the same frequency band (step S27: NO), eccentricity of each rotating roller of the transport unit 21 and the rotation shaft of the transport motor 42. There is a possibility that vibration with an amplitude Zpp exceeding the threshold value Zt is occurring due to a sudden factor other than the above. In this case, it is unknown whether the amplitude can be reduced by increasing the tension of the web W. Therefore, when the vibration frequency fz of the web W and the frequency fluctuation frequency fs do not belong to the same frequency band (step S27: NO), the control unit 5 performs an error operation (step S30).

When it is determined in step S24 that the calculation timing has not come (step S24: NO), the control unit 5 proceeds to step S32. The processing of steps S32 and S33 is the same as the processing of steps S11 and S12 of FIG. 4 described above. When the process of step S31 is performed after step S33, the series of operations ends.

FIG. 8 shows an example of fluctuations in the detection distance of the displacement sensor 26 and fluctuations in the transport speed of the web W after the tension has been changed by the above-described operation. FIG. 8 shows the measurement results of the vibration and the conveyance speed after changing the tension of the web W in which the vibration and the speed fluctuation shown in FIG. 6 have occurred. Further, FIG. 9 shows the results of performing Fourier transform on the data of the detection distance of the displacement sensor 26 and the data of the transport speed of the web W shown in FIG. As shown in FIGS. 8 and 9, the effect of reducing the amplitude of the web W is obtained as compared with FIGS. 6 and 7.

As described above, in the second embodiment, the control unit 5 calculates the frequency fz of the vibration of the web W based on the output signal of the displacement sensor 26, and the speed of the web W based on the output pulse signal of the roller encoder 24. The fluctuation frequency fs is calculated. Then, the control unit 5 determines that the amplitude Zpp of the web W detected by the displacement sensor 26 exceeds the threshold value Zt, and the calculated frequency fz of the vibration of the web W and the frequency fs of the speed fluctuation of the web W are in the same frequency band. , The brake 22 is controlled to change the tension of the web W. Thereby, the amplitude due to the vibration of the web W caused by the configuration of the transport unit 21 can be reduced. As a result, it is possible to reduce the deterioration of the print image quality due to the landing deviation of the ink.

Further, the control unit 5 determines that the amplitude Zpp of the web W detected by the displacement sensor 26 exceeds the threshold value Zt, and the calculated frequency fz of the vibration of the web W and the frequency fs of the speed fluctuation of the web W are in the same frequency band. If it does not belong to the above, each unit is controlled to perform an error handling operation. As a result, it is possible to deal with the situation where the web W is vibrated due to a sudden factor.

(Third Embodiment)
Next, a third embodiment in which a part of the above-described second embodiment is modified will be described.

In the third embodiment, the control unit 5 calculates the frequency fz of the vibration of the web W based on the output signal of the displacement sensor 26. Then, the control unit 5 causes the amplitude Zpp of the web W detected by the displacement sensor 26 to exceed the threshold value Zt, and calculates the frequency fz of the vibration of the web W and the web between two adjacent head lower support members 38. When the natural frequency f of W belongs to the same frequency band, the brake 22 is controlled to change the tension of the web W. Further, the control unit 5 causes the amplitude Zpp of the web W detected by the displacement sensor 26 to exceed the threshold value Zt, and calculates the vibration frequency fz of the web W and the web between the two adjacent head lower support members 38. When the natural frequency f of W does not belong to the same frequency band, each unit is controlled to perform the error handling operation.

The natural frequency f of the web W between the two adjacent lower head support members 38 is a frequency at which the web W between the two adjacent lower head support members 38 easily vibrates. This natural frequency f is expressed by the following equation (1).

Here, a is a distance between two adjacent lower head supporting members 38 in the transport direction of the web W, as shown in FIG. b is the width of the web W. m is the order of the web W in the transport direction. n is the order of the web W in the width direction. T is the tension of the web W. ρ is the areal density of the web W. k is a coefficient according to the type of the web W and the like. In the printing apparatus 1, since both ends of the web W in the width direction are free ends, the order n=0. Further, in this embodiment, the order m=1.

In the printing apparatus 1, the distance between the head lower support members 38 is equal. Therefore, the value of a is the same between any two adjacent head lower support members 38, and the natural frequency f of the web W is the same.

The width direction of the web W is a direction parallel to the front-rear direction which is a direction orthogonal to the paper surface of FIG. The conveyance direction of the web W between the two adjacent lower head supporting members 38 is parallel to the plane formed by the webs W stretched between the two adjacent lower head supporting members 38 and orthogonal to the width direction. is there.

The operation of the printing apparatus 1 according to the third embodiment will be described with reference to the flowchart of FIG.

The processing of steps S41 to S43 of FIG. 5 is the same as the processing of steps S1 to S3 of FIG. 4 described above.

In step S44 subsequent to step S43, the control unit 5 calculates the natural frequency f of the web W between the two adjacent lower head support members 38 according to the current tension of the web W.

Next, in step S45, the control unit 5 determines whether or not the calculation timing has come.

When it is determined that the calculation timing has come (step S45: YES), the control unit 5 calculates the amplitude Zpp and the vibration frequency fz of the web W in the current detection period in step S46.

Next, in step S47, the control unit 5 determines whether the amplitude Zpp of the web W calculated in step S46 exceeds the threshold value Zt. When it is determined that the amplitude Zpp is equal to or smaller than the threshold value Zt (step S47: NO), the control unit 5 returns to step S45.

When it is determined that the amplitude Zpp exceeds the threshold value Zt (step S47: YES), in step S48, the control unit 5 determines the frequency fz of the vibration of the web W calculated in step S46 and the natural vibration calculated in step S44. It is determined whether or not the number f belongs to the same frequency band. Specifically, the control unit 5 determines whether or not the difference between the vibration frequency fz of the web W and the natural frequency f is less than or equal to a threshold (frequency difference threshold) ft. When the difference between the vibration frequency fz of the web W and the natural frequency f is less than or equal to the threshold ft, the control unit 5 determines that the vibration frequency fz of the web W and the natural frequency f belong to the same frequency band. ..

When it is determined that the frequency fz of the vibration of the web W and the natural frequency f belong to the same frequency band (step S48: YES), the control unit 5 proceeds to step S49. The processing of steps S49 and S50 is the same as the processing of steps S7 and S8 of FIG. 4 described above. After step S50, the control unit 5 returns to step S44.

Here, when the frequency fz of the vibration of the web W and the natural frequency f belong to the same frequency band, the amplitude of the web W is amplified. Therefore, it is considered that the amplitude Zpp exceeding the threshold value Zt has occurred.

As can be seen from the equation (1), the natural frequency f can be changed by changing the tension of the web W. Therefore, when the frequency fz of the vibration of the web W and the natural frequency f belong to the same frequency band (step S48: YES), the controller 5 sets the tension to one level unless the tension of the web W exceeds the upper limit value. Raise (step S50). Thereby, the frequency fz of the vibration of the web W detected by the displacement sensor 26 and the natural frequency f can be prevented from belonging to the same frequency band.

Here, as described above, the vibration of the web W is caused by the eccentricity of the rotating rollers (the brake rollers 31 and the like) in the transport unit 21, the eccentricity of the rotation shaft of the transport motor 42, and the like. The frequency of this vibration is common to the respective head lower support members 38. Therefore, by preventing the frequency fz of the vibration of the web W detected by the displacement sensor 26 and the natural frequency f from belonging to the same frequency band, the vibration of the web W between the lower head support members 38 is reduced. It is possible to prevent the frequency and the natural frequency f from belonging to the same frequency band. As a result, the amplitude of the web W between the lower head support members 38 can be reduced.

When it is determined that the frequency fz of the vibration of the web W and the natural frequency f do not belong to the same frequency band (step S48: NO), the control unit 5 proceeds to step S51. When it is determined in step S49 that the tension of the web W is increased by one step, the tension exceeds the upper limit (step S49: NO), the control unit 5 proceeds to step S51. The processing of steps S51 and S52 is the same as the processing of steps S9 and S10 of FIG. 4 described above. When step S52 ends, the series of operations ends.

Here, when the frequency fz of vibration of the web W and the natural frequency f do not belong to the same frequency band, due to a sudden factor other than that the frequency fz of the vibration of the web W and the natural frequency f overlap, There is a possibility that vibration with an amplitude Zpp exceeding the threshold value Zt has occurred. In this case, it is unknown whether the amplitude of the web W can be reduced by changing the natural frequency f. Therefore, when the vibration frequency fz of the web W and the natural frequency f do not belong to the same frequency band (step S48: NO), the control unit 5 performs an error operation (step S51).

When it is determined in step S45 that the calculation timing has not come (step S45: NO), the control unit 5 proceeds to step S53. The processing of steps S53 and S54 is the same as the processing of steps S11 and S12 of FIG. 4 described above. When the process of step S52 is performed after step S54, a series of operations ends.

As described above, in the third embodiment, the control unit 5 calculates the frequency fz of the vibration of the web W based on the output signal of the displacement sensor 26. Then, the control unit 5 causes the amplitude Zpp of the web W detected by the displacement sensor 26 to exceed the threshold value Zt, and the calculated frequency fz of vibration of the web W and the natural frequency f of the web W are in the same frequency band. If so, the brake 22 is controlled to change the tension of the web W. As a result, the vibration frequency of the web W and the natural frequency do not overlap with each other, so that the amplitude of the vibration of the web W can be reduced. As a result, it is possible to reduce the deterioration of the print image quality due to the landing deviation of the ink.

Further, since the amplitude of the web W is reduced by detecting the amplitude of the web W and adjusting the tension, it is possible to prevent the processing and assembling of parts such as rollers for suppressing the occurrence of vibration of the web W from being highly accurate.

Therefore, also in the third embodiment, it is possible to reduce the deterioration of the print image quality on the web W while suppressing the precision of the processing and assembly of the parts.

Further, the control unit 5 causes the amplitude Zpp of the web W detected by the displacement sensor 26 to exceed the threshold value Zt, and the calculated frequency fz of vibration of the web W and the natural frequency f of the web W to be in the same frequency band. If it does not belong, each unit is controlled to perform an error handling operation. As a result, it is possible to deal with the situation where the web W is vibrated due to a sudden factor.

(Fourth Embodiment)
Next, a fourth embodiment in which a part of the first embodiment described above is modified will be described.

In the fourth embodiment, the control unit 5 controls the rotating rollers (the brake rollers 31, the tension detection rollers 32, the tension detection auxiliary rollers 33 and 34, the upstream guide rollers 35 to 37, and the downstream guide rollers) in the transport unit 21. 39, 40, the eccentric frequency of each of the transport rollers 41) and the rotation variation frequency of the transport roller 41 due to the eccentricity of the rotation shaft of the transport motor 42 (corresponding to the drive source in the claims), and two adjacent frequencies. The transport speed (print transport speed) of the web W during printing in the printer unit 3 is set so that the natural frequency f corresponding to the set tension of the web W between the head lower support members 38 does not belong to the same frequency band. .. Then, the control unit 5 controls the carry motor 42 to carry the web W at the set print carrying speed.

Here, the diameter of each brake roller 31 and each transport roller 41 is Φ1, the diameter of the upstream guide roller 36 is Φ2, the tension detection roller 32, the tension detection auxiliary rollers 33 and 34, the upstream guide rollers 35 and 37, and the downstream. It is assumed that the side guide rollers 39, 40 have a diameter of Φ3.

When the conveyance speed of the web W is V, the eccentricity frequency fb of each brake roller 31 and each conveyance roller 41 is expressed by the following equation (2). The eccentricity frequency fg of the upstream guide roller 36 is expressed by the following equation (3). The eccentricity frequency fr of the tension detection roller 32, the tension detection auxiliary rollers 33 and 34, the upstream guide rollers 35 and 37, and the downstream guide rollers 39 and 40 is represented by the following formula (4).

fb=V/Φ1 (2)
fg=V/Φ2 (3)
fr=V/Φ3 (4)
When the reduction ratio between the rotation shaft of the conveyance motor 42 and the conveyance roller 41 is R, the rotation fluctuation frequency fm of the conveyance roller 41 due to the eccentricity of the rotation shaft of the conveyance motor 42 is expressed by the following formula (5). expressed.

fm=(V/Φ1)×R (5)
Next, the operation of the printing device 1 according to the fourth embodiment will be described.

When starting the operation of the printing apparatus 1, the control unit 5 controls the unwinding unit 2, the printer unit 3, and the winding unit 4 to start the conveyance of the web W. At this time, the control unit 5 sets the braking force of the brake 22 to a value corresponding to the default value (setting tension) of the tension of the web W. After the conveyance is started, the control unit 5 controls the unwinding unit 2, the printer unit 3, and the winding unit 4 so as to accelerate the conveyance speed of the web W.

When the transport speed of the web W reaches the print transport speed, the control unit 5 controls the rotation speed of the transport motor 42 based on the output pulse signal of the motor encoder 25 so as to maintain the print transport speed. In this print conveyance speed, the difference between each of the eccentric frequencies fb, fg, fr, and the rotation fluctuation frequency fm and the natural frequency f of the web W corresponding to the default value of the tension of the web W is larger than the threshold value ft. The speed is preset as follows. The natural frequency f of the web W is calculated by the above equation (1).

After the transportation speed of the web W reaches the printing transportation speed, the control unit 5 causes the printing unit 27 to perform printing. When the printing is completed, the control unit 5 controls the unwinding unit 2, the printer unit 3, and the winding unit 4 so that the conveyance of the web W is completed.

As described above, in the fourth embodiment, the control unit 5 controls the eccentric frequencies fb, fg, fr of the rotating rollers of the transport unit 21 and the eccentricity of the rotation axis of the transport motor 42 to cause the transport roller 41 to move. The conveyance speed of the web W is set such that each of the rotation fluctuation frequencies fm and the natural frequency f corresponding to the set tension of the web W do not belong to the same frequency band. As a result, the eccentricity frequency of the roller and the natural frequency f of the web W are prevented from overlapping, so that the amplitude of the web W due to the vibration can be suppressed. As a result, it is possible to reduce the deterioration of the print image quality due to the landing deviation of the ink.

Further, since the vibration of the web W is suppressed by setting the conveyance speed of the web W, it is possible to prevent the processing and assembling of parts such as the rollers in order to suppress the generation of the vibration of the web W from being highly accurate.

Therefore, also in the fourth embodiment, it is possible to reduce the deterioration of the print image quality on the web W while suppressing the precision of the processing and assembly of the parts.

(Fifth Embodiment)
Next, a fifth embodiment in which a part of the above-described fourth embodiment is modified will be described.

In the fifth embodiment, the control unit 5 controls the eccentric frequencies fb, fg, fr, and the rotation fluctuation frequency fm corresponding to a predetermined print transport speed (set transport speed), and two adjacent under head supports. The tension of the web W during printing in the printer unit 3 is set so that the natural frequency f of the web W between the members 38 does not belong to the same frequency band. Then, the control unit 5 controls the brake 22 so that the tension of the web W becomes the set tension.

The operation of the printing device 1 in the fifth embodiment will be described.

When the operation of the printing apparatus 1 is started, the control unit 5 starts the conveyance of the web W and controls the unwinding unit 2, the printer unit 3, and the winding unit 4 so as to accelerate the conveyance speed of the web W. ..

At this time, the control unit 5 sets the braking force of the brake 22 to a value according to the set tension of the web W. This tension is set so that the difference between each of the eccentric frequencies fb, fg, fr, and the rotation fluctuation frequency fm corresponding to a predetermined print conveyance speed and the natural frequency f of the web W is larger than a threshold value ft. It is the tension. This tension can be calculated using the above equations (1) to (5). This tension is calculated to be a value within the appropriate range of the tension of the web W in the printer unit 3.

When the transport speed of the web W reaches the print transport speed, the control unit 5 controls the rotation speed of the transport motor 42 based on the output pulse signal of the motor encoder 25 so as to maintain the print transport speed. After the transportation speed of the web W reaches the printing transportation speed, the control unit 5 causes the printing unit 27 to perform printing. When the printing is completed, the control unit 5 controls the unwinding unit 2, the printer unit 3, and the winding unit 4 so that the conveyance of the web W is completed.

As described above, in the fifth embodiment, the control unit 5 controls the eccentric frequencies fb, fg, fr, and the rotation fluctuation frequency fm according to the predetermined print transport speed, and the natural frequency f of the web W to be changed. The tension of the web W is set so that and do not belong to the same frequency band. Thus, as in the fourth embodiment, the eccentricity frequency of the roller and the natural frequency f of the web W are prevented from overlapping so that the amplitude of the web W due to the vibration can be suppressed. As a result, it is possible to reduce the deterioration of the print image quality due to the landing deviation of the ink.

Further, since the vibration of the web W is suppressed by setting the tension of the web W, it is possible to prevent the processing and assembling of parts such as the rollers in order to suppress the generation of the vibration of the web W from being highly accurate.

Therefore, also in the fifth embodiment, it is possible to reduce the deterioration of the print image quality on the web W while suppressing the high accuracy of processing and assembly of the parts.

(Other embodiments)
As described above, the present invention has been described by the first to fifth embodiments, but it should not be understood that the description and drawings forming a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

Although the optical displacement sensor 26 is used to detect the amplitude of the web W in the first to third embodiments, the amplitude of the web W is detected by detecting the sound pressure using a microphone. May be.

In the first to third embodiments, as the error handling operation, the operation of stopping the printing by the printing unit 27 and the conveyance of the web W is performed, but the operation is continued until the end of the printing by the print job being executed. After that, the conveyance of the web W may be stopped.

In the first embodiment, when the detected amplitude Zpp of the web W exceeds the threshold value Zt, the tension of the web W is increased by one step, but the method of adjusting the tension is not limited to this. The tension value of the web W may be set according to the value of the detected amplitude Zpp of the web W.

In the second embodiment, the output pulse signal of the roller encoder 24 is used to calculate the transport speed of the web W. However, an ammeter for detecting the drive current of the transport motor 42 is provided and based on the detected value of the ammeter. The transport speed of the web W may be calculated. Further, the output pulse signal of the motor encoder 25 may be used to calculate the transport speed of the web W.

In the third embodiment, when the detected amplitude Zpp of the web W exceeds the threshold value Zt and the frequency fz of the vibration of the web W and the natural frequency f of the web W belong to the same frequency band, The tension was changed. However, the determination as to whether the amplitude Zpp of the web W exceeds the threshold value Zt is omitted, and when the frequency fz of the vibration of the web W and the natural frequency f of the web W belong to the same frequency band, the tension of the web W is changed. It may be changed. Even in this case, by preventing the frequency of the vibration of the web W and the natural frequency from overlapping, the amplitude of the vibration of the web W can be reduced.

In the fourth embodiment, the eccentricity frequency fb of each brake roller 31, the eccentricity frequency fg of the upstream guide roller 36, the eccentricity frequency fr of the tension detection roller 32, and the eccentricity of the rotation shaft of the carry motor 42 are used. The conveyance speed of the web W is set such that the rotation fluctuation frequency fm of the conveyance roller 41 and the natural frequency f of the web W according to the set tension do not belong to the same frequency band. In addition to this, the conveyance speed of the web W may be set so that the natural frequency f of the web W does not overlap with the pulsation frequency of the conveyance motor 42. Further, in the case of a configuration having a gear that transmits the driving force from the transport motor 42 to the transport roller 41, the natural frequency f of the web W is set so as not to overlap with the frequency of the fluctuation of the rotation of the transport roller 41 due to the meshing of the gears. You may set the conveyance speed of W.

In the fifth embodiment, the eccentricity frequency fb of each brake roller 31 and the like, the eccentricity frequency fg of the upstream guide roller 36, the eccentricity frequency fr of the tension detection roller 32, and the conveyance motor 42 according to the set conveyance speed. The tension of the web W was set so that the rotation fluctuation frequency fm of the transport roller 41 due to the eccentricity of the rotating shaft and the natural frequency f of the web W do not belong to the same frequency band. In addition to this, the tension of the web W may be set so that the natural frequency f of the web W does not overlap with the pulsation frequency of the transport motor 42. Further, in the case of a configuration having a gear that transmits the driving force from the transport motor 42 to the transport roller 41, the natural frequency f of the web W is set so as not to overlap with the frequency of the fluctuation of the rotation of the transport roller 41 due to the meshing of the gears. The tension of W may be set.

In the first to fifth embodiments, the printing apparatus 1 has the configuration including the unwinding unit 2, the printer unit 3, and the winding unit 4. However, the printing device corresponding to the printer unit 3 has an unwinding device as an external device. Also, a configuration in which a winding device is connected may be used. Further, the printing device corresponding to the printer unit 3 may be connected to an external device other than the unwinding device and the winding device. For example, the cutting device or the like for cutting the web W may be connected to the printing device as an external device.

As described above, needless to say, the present invention includes various embodiments and the like not described here. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 Printing device 2 Unwinding part 3 Printer part 4 Winding part 5 Control part 21 Conveying part 22 Brake 23 Tension sensor 24 Roller encoder 25 Motor encoder 26 Displacement sensor 27 Printing part 31 Brake roller 32 Tension detection roller 33, 34 Tension detection assistance Rollers 35 to 37 Upstream guide rollers 38 Head lower support members 39, 40 Downstream guide rollers 41 Conveying rollers 42 Conveying motors 46 Head units 47 Inkjet heads W web

Claims (4)

A printing apparatus that prints by ejecting ink from an inkjet head onto a web,
A transport unit for transporting the web,
An amplitude detection unit that detects the amplitude due to the vibration of the web,
A tension adjusting unit that adjusts the tension of the web,
When the amplitude of the web detected by the amplitude detector exceeds the amplitude threshold, the controller that controls the tension adjuster to adjust the tension of the web so that the amplitude of the web is equal to or less than the amplitude threshold. A printing apparatus comprising: Further comprising a conveyance speed detection unit for detecting the conveyance speed of the web,
The control unit is
While calculating the frequency of the vibration of the web based on the output signal of the amplitude detection unit, calculates the frequency of the fluctuation of the web transport speed based on the output signal of the transport speed detection unit,
The amplitude of the detected web exceeds the amplitude threshold by the amplitude detection unit, and, if the difference between the frequency of the variation of the calculated frequency of the vibration of the web transport speed is less than the frequency difference threshold, the amplitude of the web the The tension adjusting unit is controlled so as to change the tension of the web so as to be the amplitude threshold or less ,
If the amplitude of the web detected by the amplitude detection unit exceeds the amplitude threshold, and the difference between the calculated frequency of vibration of the web and the frequency of fluctuation of the transport speed exceeds the frequency difference threshold, an error handling operation is performed. The printing apparatus according to claim 1, wherein the transport unit is controlled to perform the printing. A printing apparatus that prints by ejecting ink from an inkjet head onto a web,
A transport unit for transporting the web,
An amplitude detection unit that detects the amplitude due to the vibration of the web,
A tension adjusting unit that adjusts the tension of the web,
The frequency of the vibration of the web is calculated based on the output signal of the amplitude detector, and the difference between the calculated frequency of the vibration of the web and the natural frequency of the web is less than or equal to a threshold value, the frequency of the vibration of the web and the natural vibration of the web. A control unit that controls the tension adjusting unit so as to change the tension of the web so that the difference from the number exceeds the threshold value . A printing apparatus that prints by ejecting ink from an inkjet head onto a web,
A transport unit for transporting the web,
An amplitude detection unit that detects the amplitude due to the vibration of the web,
A tension adjusting unit that adjusts the tension of the web,
A control unit that controls the transport unit and the tension adjusting unit,
The control unit is
Calculate the frequency of vibration of the web based on the output signal of the amplitude detection unit,
If the amplitude of the web detected by the amplitude detection unit exceeds the amplitude threshold, and the difference between the calculated vibration frequency of the web and the natural frequency of the web is less than or equal to the frequency difference threshold, the vibration frequency of the web and the web The tension adjustment unit is controlled to change the tension of the web so that the difference between the natural frequency and the natural frequency exceeds the frequency difference threshold value ,
If the amplitude of the web detected by the amplitude detector exceeds the amplitude threshold and the difference between the calculated vibration frequency of the web and the natural frequency of the web exceeds the frequency difference threshold, an error handling operation is performed. A printing apparatus, characterized in that the transport unit is controlled.