JP2001220040A - Printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve conveyance accuracy and printing and printing accuracy by offsetting changes of a tensile force on the downstream side of a sheetlike body conveyance means. SOLUTION: This printing device is provided with a sheetlike body sending means 20 sending out a sheetlike body, a sheetlike body conveyance means 30 conveying the sheetlike body, a sheetlike body support means 38 absorbing the conveyed shetlike body by an absorbing means, a printing means 46 printing on the sheetlike body, and a sheetlike body winding means 25 winding the sheetlike body again after processing it by the printing means. Moreover, it is provided with a detection means 60 detecting a characteristic value causing changes of a tensile force of the sheetlike body on the downstream side in the direction of conveyance more than the sheetlike body conveyance means and an absorbing means control means increasing, decreasing, and controlling a suction force by the absorbing means to offset changes of the tensile force on the downstream side of the sheetlike body conveyance means based on characteristic values detected by the detection means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus for feeding and transporting a sheet-like material wound in a roll shape and performing printing or printing on the surface thereof. The present invention relates to a printing apparatus provided with a conveyance sheet supporting means for holding a sheet.

[0002]

2. Description of the Related Art As a conventional printing apparatus, a sheet-like material (for example, a PVC sheet or paper) is conveyed by a conveying device, and printing and printing are performed on the surface of the sheet-like material by a reciprocating print head. There is.

As shown in FIG. 11, such a printing apparatus has a configuration in which a platen 1 holding a sheet A during printing or printing is conveyed so that the platen 1 faces a print head 2. Is provided on the back side. The platen 2 includes a support plate 3 having a width slightly larger than the width of the sheet-like body. A substantially closed box 4 is mounted on the back side of the support plate 3. Many small holes are provided so as to communicate with the space inside the box 4. And
A suction blower 5 is attached to the back surface of the box 4 so as to communicate with the inside of the box. The air inside the box 4 is sucked from the small holes provided in the support plate 3 so that the suction blower 5 moves on the support plate 3. The conveyed sheet A is sucked so as to be substantially in close contact with the support plate 3. In this state, the printing process is performed on the sheet A by the print head 2.

In FIG. 1, a sheet A is fed from a paper feed roller 6 wound in a roll, and is sandwiched between a transport roller 7 and a pressing roller 10 to drive the transport roller 7. Transported by Further, the sheet-like body A is given tension by the tension rods 8 and 9. Furthermore,
The sheet A after printing / printing is wound by the winding roller 11.

[0005] A conventional printing apparatus is configured so that the suction force of a suction blower can be variably controlled, and the diameter of a rolled sheet-like material before printing held by a holding device is determined by a transport roller or the like. In the case of a gradual decrease as a result of sending out by driving of a conveying device comprising a suction device, a suction force of a suction blower is controlled to increase or decrease according to the size of the winding diameter (see Japanese Patent No. 2773051).

In this device, the back tension is applied to the sheet by a torque brake attached to the holding device. Therefore, the diameter of the roll decreases as the roll of the sheet is consumed. Then, it is made to solve a technical problem that the back tension increases, the transport accuracy decreases, and the printing / printing accuracy decreases.

[0007]

In the conventional printing apparatus shown in FIG. 11, the tension rods 8 and 9 are provided so as to be movable so as to apply tension to the sheet A. The angle of intersection (tangential direction) between the sheet-shaped member A and the take-up roller depends on when the take-up roller 11 is started and the take-up roller 11 has a small take-up diameter and when the take-up progresses and the take-up roller 11 has a large take-up diameter. Is changed, the tension on the downstream side of the conveyance roller 7 changes. When the difference in tension between the upstream side and the downstream side in the transport direction with respect to the transport roller 7 is increased, the transport of the sheet-shaped body A is not smoothed by the transport roller 7, which affects the transport accuracy and causes a decrease in printing accuracy. There is a risk.

Similarly, when the line feed amount for one pass of the print head 2 increases, the tension rods 8, 9
Is changed, the change in the intersection angle (tangential angle) between the take-up roller and the sheet-like body A becomes large, and the difference in tension between the upstream side and the downstream side of the transport roller 7 becomes large. There is a possibility that the transport accuracy and the printing accuracy may be reduced due to this.

The present invention has been made in view of the above circumstances, and a printing apparatus capable of canceling a change in tension on the downstream side of a sheet-shaped body conveying means, improving conveyance accuracy, and further improving printing / printing accuracy. The purpose is to provide.

[0010]

According to a first aspect of the present invention, there is provided a printing apparatus which feeds a sheet-like body wound in a roll, and feeds the sheet-like body from the sheet-like body sending means. Sheet-like body conveying means for drawing in and conveying,
A plurality of small holes are provided in a support plate that supports the back surface of the sheet to be conveyed, and a sheet-like body supporting unit that sucks the small-sized holes from the small holes and makes the sheet-like body substantially in close contact with the support plate. A printing device for performing a printing process on a sheet material on the support plate, and a sheet material winding device for rewinding the sheet material after the printing device performs the process. Detecting means for detecting a characteristic value that causes a change in the tension of the sheet-like body downstream of the sheet-like body conveying means in the conveying direction; and conveying the sheet-like body based on the characteristic value detected by the detecting means. Suction means control means for controlling the suction force by the suction means to increase or decrease the tension change on the downstream side of the means.

According to the present invention, suction by suction means is performed so as to detect a characteristic value which causes a change in tension on the downstream side of the sheet conveying means in the conveying direction and cancel the tension on the downstream side of the sheet conveying means. Since the force is controlled to increase or decrease, it is possible to prevent a decrease in transport accuracy and printing accuracy due to a change in the tension on the downstream side.

In a printing apparatus according to a second aspect of the present invention, in the printing apparatus according to the first aspect, the suction unit control unit controls a tension of the sheet at a downstream side in a conveying direction of the sheet conveying unit. The suction force is controlled so that the difference between the two becomes small.

According to the present invention, the change in tension between the upstream side and the downstream side in the conveying direction of the sheet is reduced, and the conveying accuracy and the printing accuracy are improved.

According to a third aspect of the present invention, in the printing apparatus according to the first or second aspect, the detecting means comprises:
The sheet-shaped body winding means comprises a roll-diameter measuring means for measuring the diameter of the sheet-shaped body wound in a roll shape.

According to the present invention, the change in the tension is detected by detecting the winding diameter of the sheet wound by the sheet winding means, which influences the change in the tension on the downstream side in the transport direction of the sheet. Since the suction force of the suction means is controlled to increase or decrease in order to kill, the change in the tension is reduced, and the conveyance accuracy and printing accuracy are improved.

In a printing apparatus according to a fourth aspect of the present invention, in the printing apparatus according to the third aspect, the sheet-like body transporting means is provided upstream of the support plate in the direction of transport of the sheet-like body. The suction means control means controls the suction force to gradually increase as the roll diameter after winding measured by the roll diameter measurement means increases.

According to the present invention, since the winding diameter of the sheet is detected and the suction force of the suction means is controlled to increase or decrease in order to offset the change in the tension, the change in the tension is reduced, and the conveyance accuracy and printing accuracy are reduced. Is improved.

In a printing apparatus according to a fifth aspect of the present invention, in the printing apparatus according to the first or second aspect, the sheet-like body transport means is provided upstream of the support plate in the transport direction of the sheet-like body. And a conveyance amount control unit for controlling a conveyance amount by the sheet-shaped body conveyance unit, wherein the suction unit control unit gradually increases the suction force as the conveyance amount controlled by the conveyance amount control unit increases. Control.

According to the present invention, the conveying amount of the sheet-like body which affects the change in tension on the downstream side in the conveying direction of the sheet-like body is calculated from the conveying amount control means, and the suction force of the suction means is used to cancel the tension change. , The change in the tension is reduced, and the conveyance accuracy and the printing accuracy are improved.

In a printing apparatus according to a sixth aspect of the present invention, in the printing apparatus according to the third aspect, the sheet-like body transporting means is provided downstream of the support plate in the transport direction of the sheet-like body. The suction means control means controls the suction force to gradually decrease as the roll diameter after winding measured by the roll diameter measurement means increases.

According to the present invention, the change in the tension is detected by detecting the diameter of the sheet wound by the sheet winding means which affects the change in the tension on the downstream side in the transport direction of the sheet. Therefore, since the suction force of the suction means is controlled to increase or decrease, the change in the tension is reduced, and the conveyance accuracy and printing accuracy are improved.

In a printing apparatus according to a seventh aspect of the present invention, in the printing apparatus according to the first or second aspect, the sheet conveying means is provided downstream of the support plate in the conveying direction of the sheet. And a conveyance amount control unit for controlling a conveyance amount by the sheet-shaped body conveyance unit, wherein the suction unit control unit gradually reduces the suction force as the conveyance amount controlled by the conveyance amount control unit increases. Control.

According to the present invention, the conveyance amount of the sheet-like body which affects the change in the tension of the sheet-like body on the downstream side in the conveyance direction is calculated by the conveyance amount control means, and the suction force of the suction means is used to cancel the tension change. , The change in the tension is reduced, and the conveyance accuracy and the printing accuracy are improved.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a printing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration of a printing apparatus according to an embodiment of the present invention. As shown in FIG. 1, a sheet A (for example, a PVC sheet or paper) is wound in a roll shape around a paper feed roller 20, and the sheet A pulled out from the paper feed roller 20 is It passes between the two gripping rollers 21 arranged in parallel, is passed over the transport device 22, passes through the upper surface of the platen 38, and passes through the tension rod 24.
Is taken up by the take-up roller 25. Here, the sheet feeding roller 20 is a sheet-like body sending means of the present invention, the conveying device 22 is a sheet-like body conveying means, and the platen 3
Reference numeral 8 denotes a sheet-like body supporting means, and the winding roller 25 constitutes a sheet-like body winding means.

The paper feed roller 20 can be driven to rotate by a motor 18, and the sheet material A supplied to the paper feed roller 20 is fed before the sheet is conveyed so that a predetermined slack occurs. A is to be paid out.
Below the sheet feed roller 20, for example, an optical non-contact type sensor 19 for detecting the slack of the sheet A is disposed.

The gripping rollers 21 are mounted so as to be freely rotatable around a central axis. These gripping rollers 21 are brought into pressure contact with each other by a proximity pressure contact means (not shown), and press the sheet-like material A between each other at a predetermined pressure. To be gripped.

The tension rod 24 is rotatably attached to the opposite end of a link bar 27 that rotates about a support shaft 26 on the opposite side of the support shaft, and the link bar 27 is moved in one direction by a spring 28 attached thereto. Is urged to rotate. Thereby, the tension rod 24 is connected to the support shaft 2.
The sheet A is conveyed through the tension rod 24 by swinging about the center 6 to apply tension. A sensor 29 composed of, for example, a proximity switch is provided so as to sandwich each of the link bars 27. The link bar 27 is provided by these sensors 29.
Is detected at a predetermined position.

The transport device 22 is urged to swing toward the transport roller 30, which is rotationally driven by a motor 35, and sandwiches the sheet A between the transport roller 30 and the transport roller 30. Roller 34 to be pressed
And the sheet-shaped material A is sent to the downstream side in the conveyance direction by the conveyance roller 30 which is driven to rotate by the motor 35. The pressing roller 34 is rotatably attached to a tip of a pair of link bars 31 arranged on both sides, and the link bar 31 is swingably provided about a support shaft 32 as a fulcrum. Is mounted with a spring 33 for biasing the swing.

A printing mechanism for performing printing and printing processing on the surface of the sheet A is provided downstream of the conveying roller 30 in the conveying direction. The printing mechanism includes a printing unit 39 for actually printing or printing on the surface of the sheet A, and a platen 38 for holding the sheet A when printing or printing.

The printing means 39 includes a guide bar 40 extending in the width direction of the sheet A to be conveyed, a print head holder 44 movably provided along the guide bar 40, a driven roller 42, An endless belt 41 rotatably supported at both ends by rollers 45 and a print head 46 attached to the print head holder 44 are provided. Then, the print head holder 44 is reciprocated in the width direction of the sheet A by driving the motor 43,
Printing or printing processing is performed by a print head 46 attached to one end of the print head holder 44.

The platen 38 is, as shown in FIG.
Support plate 48 having a width slightly larger than the width of sheet A
A rectangular frame 49 having a shape corresponding to the dimensions of the support plate 48 is mounted on the back side of the support plate 48, and a bottom plate 50 is provided on the opposite side of the support plate 48. And the frame body 49 so as to form a substantially closed space. A through hole 50a is formed in the bottom plate 50, and a suction blower 51 is attached to the through hole 50a.

The support plate 48 has a number of small holes 48a,
48b is provided in communication with the space formed by the bottom plate 50 and the frame. Small holes 14a provided in the support plate 48,
By suctioning the air in the internal space from the suction plate 14b by the suction blower 51, the sheet-like material A conveyed on the support plate 48 is sucked and brought into a substantially close contact state with the support plate 48. A is printed by the print head 46.

The take-up roller 25 can be driven to rotate by a motor 55. The take-up roller 25 is driven to rotate so that the sheet A is not excessively slacked by the signal of the sensor 29, and the sheet A is wound. To take.

In the vicinity of the winding roller 25, a roll diameter measuring means 60 for measuring the winding diameter of the wound sheet A is arranged. The roll diameter measuring means 60 has a link arm 63 swingably mounted around a support shaft 61, and a potentiometer 62 is connected to the support shaft 61 provided at the base end of the link arm 63. A disk plate 65 is attached to the tip of the link arm 63 so as to be rotatable about a support shaft 64. The disk plate 65 is in contact with the outer peripheral surface of the sheet A wound by the winding roller 25, and the increase in the winding diameter can be detected by the potentiometer 62 as the swing angle of the link arm 63. .

Next, the operation of the printing apparatus according to this embodiment will be described.

First, the print head holder 44 is
Is moved along the guide rod 40 by driving the print head 46 fixed to the print head holder 44.
Printing or printing is performed on the surface of the sheet-shaped body A which is ejected and conveyed by the ink. Next, with the printing, when the transport roller 30 is driven to rotate by the motor 35 for a predetermined period, the sheet A is transported to the platen 38 and the winding roller 25 side.

At this time, the conveyed sheet A slides on the support plate 48 against the platen 38 and is driven by the suction blower 51 to be sucked from the many small holes 48a and 48b formed in the support plate 48. Thus, close contact with the platen 38 is achieved. Since the gap between the small holes 48a is narrow, the edge of the sheet A is prevented from floating.

When the conveying roller 30 is driven for a predetermined period and the sheet A on the paper feed roller 20 side is sent out, the sheet A is loosened as shown by a two-dot chain line in FIG. 3 or FIG. Is reduced. When looseness is reduced, the output of the sheet product A is eliminated sensor 19 that was blocking the optical axis of the sensor 19 is turned off until then (t ₁ point in FIG. 5). Then, the sheet feeding roller 20 is rotated by the motor 18, and the sheet A is fed out by an appropriate length and supplied. As a result, looseness occurs again sheet product A, the output is turned on to block the optical axis of the sensor 19 (t ₂ time in FIG. 5).

Further, the conveying roller 30 is driven for a predetermined period to feed the sheet A to the platen 38 side, and as shown in FIG.
4 moves to the left side in the figure, and the link bar 27
The output of the sensor 29 is turned off deviate from 9 (t ₁ point in FIG. 5). Then, the winding roller 25 is driven by the motor 5.
5, the sheet A is wound up by an appropriate length. As a result, the output of the sensor 29 returns the tension rod 24 to its original position is turned on (t ₂ time in FIG. 5), the drive by the motor 55 is stopped.

In the state shown in FIG. 3, a sufficient amount of sheet A is still wound around the sheet feeding roller 20 because the sheet is not fed much, and a large amount of sheet A is still wound around the winding roller 25. Indicates a state that has not been taken. The state shown in FIG. 4 shows a state in which the sheet-shaped material A that has been fed for a predetermined time and wound on the sheet feeding roller 20 has decreased, and a large number of sheet-shaped materials A have been wound on the winding roller 25.

Here, regardless of whether or not the sheet is fed (the diameter of the winding roller 25 is large or small), the tension acting on the sheet A at the upstream side of the conveying roller 30 in the conveying direction does not change much. . This is because, as described above, the sheet 19 is controlled by the sensor 19 in the paper feed roller 20 so that the sheet A is always loosened. This is because a large slack or a positional relationship between the gripping roller 21 and the transport roller 30 is not largely changed.

On the other hand, the tension acting on the sheet A on the downstream side in the transport direction of the transport roller 30 varies. As shown in FIGS. 3 and 4, the positional relationship of the sheet A from the platen 30 to the tension rod 24 on the downstream side in the transport direction does not change much during the sheet feeding process. The positional relationship between the take-up roller 25 and the take-up roller 25 varies considerably depending on the amount of take-up of the take-up roller 25.

That is, as shown in FIG. 3 and FIG. 4, the angle A in the figures does not change depending on the transport amount or the like, but when the winding diameter of the winding roller 25 is small, the angle B in the figures is the winding roller. Angle C in the figure when the winding diameter of No. 25 is large
And gradually become smaller. As a result, the tension rod 24
According to the force balance conditions in the above, the tension applied to the sheet A is smaller when the winding diameter is larger than when the winding diameter of the sheet A is small.

Accordingly, if the sheet is conveyed under the same conveying conditions regardless of whether the winding diameter is small or large, the difference in tension between the upstream side and the downstream side of the conveying roller 30 gradually increases, and the sheet A of the conveying roller 30 There is a possibility that problems such as a decrease in transport accuracy and an obstacle to the transport process may occur. If the transport conditions can be changed and controlled so that there is no difference in the tension between the upstream side and the downstream side of the transport roller 30, the above problem can be effectively prevented.

Therefore, in the printing apparatus according to the embodiment of the present invention, the roll diameter of the sheet A wound around the take-up roller 25 is measured by the roll diameter measuring means 60 provided near the take-up roller 25, Based on the measurement result, the suction amount per unit time by the suction blower 51 attached to the platen 38 is changed to increase or decrease the transport resistance on the downstream side of the transport roller 30, thereby reducing the tension on the downstream side of the transport roller 30. It is increased or decreased to offset the upstream tension.

More specifically, when the winding diameter of the sheet A wound around the winding roller 25 increases, the disk plate 65 in contact with the outer peripheral surface swings about the support shaft 61. This swing amount is detected by the potentiometer 62, and the suction force of the suction blower 51 is gradually reduced in a stepwise manner as shown in FIG. As described above, the tension on the downstream side of the transport roller 30 decreases as the winding diameter of the winding roller 25 increases, so that the load due to the suction force is increased to compensate for the decrease in the tension. The suction blower 51
If the suction amount can be changed continuously by, for example, an inverter or the like, the suction amount may be changed continuously as shown in FIG.

In addition to the winding diameter of the take-up roller 25, another characteristic value that causes a change in tension on the downstream side of the conveyance roller 30 is the conveyance amount of the sheet A.

That is, when considering the time from the start of the supply of one roll of the sheet-shaped material A to the end of the winding, the fact that the integrated transport amount is large means that the above-mentioned wound diameter is also large. The suction force of the suction blower may be gradually reduced in accordance with an increase in the integrated transport amount, in the same manner as that in which the suction force of the suction blower is increased or decreased according to the winding diameter.

From a short-term perspective, the print head 4
6, the crossing angle (angle in the tangential direction) between the take-up roller 25 and the sheet A also changes, and the tension on the downstream side of the conveyance roller 30 changes even when the line feed amount (conveyance amount) for one pass increases or decreases. I do. This will be described with reference to FIGS. 7 shows a case where the line feed amount (conveyance amount) is small, and FIG. 8 shows a case where the line feed amount (conveyance amount) is large.

When the line feed amount (conveyance amount) is small, the amount conveyed by the conveyance roller 30 is small, so that the movement amount of the tension rod 24 becomes small, and the tension rod 24 is centered on the tension rod 24 as shown in FIG. The angle of the sheet A is D. On the other hand, when the line feed amount (conveyance amount) is large, the amount conveyed by the conveyance roller 30 is large.
The movement amount of the tension rod 24 increases, and the angle of the sheet-like body A about the tension rod 24 becomes E as shown in FIG. Angle D is greater than angle E. When the line feed amount (conveyance amount) is large, the tension becomes small from the condition of force balance at the position of the tension rod 24. Therefore, control is performed to increase the suction force of the suction blower 51.

In the above embodiment, the transfer accuracy is increased,
Printing accuracy can be improved.

FIGS. 9 and 10 show a printing apparatus according to another embodiment of the present invention. This shows an embodiment in which a platen 38 is provided on the upstream side of the transport roller 30. The suction force of the suction blower is controlled in the same way as in the above embodiment.

That is, in the case where the transport roller 30 is provided on the upstream side of the platen 38 as in the above embodiment, the suction force of the suction blower 51 is changed so as to cancel the change in the tension on the downstream side of the transport roller 30. However, in the present embodiment, the change in the tension on the downstream side of the transport roller 30 is
The transport resistance of the upstream side of the transport roller 30 is adjusted by increasing or decreasing the suction force of the suction blower to offset the difference in tension between the upstream side and the downstream side of the transport roller 30.

Referring to FIGS. 9 and 10, FIG.
As shown in FIG. 9, when the winding diameter of the take-up roller 25 is small (FIG. 9), the tension on the downstream side of the transport roller 30 increases, so that the suction force of the suction blower 51 is increased and the transport on the upstream side is performed. While increasing the resistance, as shown in FIG.
When the winding diameter of the take-up roller 25 is large, the tension on the upstream side becomes small. Therefore, the suction force of the suction blower 51 is reduced to reduce the conveyance resistance.

[0056]

As described above, according to the first aspect of the present invention,
According to the printing apparatus described above, a detecting unit that detects a characteristic value that causes a change in the tension of the sheet-shaped body downstream of the sheet-shaped body conveying unit in the conveying direction, and a characteristic value detected by the detecting unit. And a suction means control means for controlling the suction force of the suction means to increase or decrease the tension change on the downstream side of the sheet-shaped material conveying means on the basis of the characteristic value. The suction force by the suction unit is controlled to increase or decrease so as to cancel the tension on the downstream side of the transport unit, so that it is possible to prevent a decrease in transport accuracy and printing accuracy due to a change in the tension on the downstream side.

According to the printing apparatus of the second aspect of the present invention,
Since the suction force is controlled so that the difference in the tension of the sheet-like body is reduced on the upstream and downstream sides in the transport direction of the sheet-like body transport unit, the tension change between the upstream side and the downstream side in the sheet-like body transport direction is reduced. And the accuracy of conveyance and the accuracy of printing can be improved.

According to the printing apparatus of the third aspect of the present invention,
Detecting the winding diameter of the sheet-like body wound by the sheet-like body winding unit, which affects the tension change on the downstream side in the conveyance direction of the sheet-like body, controls the suction force of the suction unit to increase or decrease. And the accuracy of conveyance and the accuracy of printing can be improved.

According to the printing apparatus of the fourth aspect of the present invention, in the case where the sheet-like body conveying means is provided upstream of the support plate in the sheet-like body conveying direction,
Detecting the winding diameter of the sheet-like body wound by the sheet-like body winding unit, which affects the tension change on the downstream side in the conveyance direction of the sheet-like body, controls the suction force of the suction unit to increase or decrease. And the accuracy of conveyance and the accuracy of printing can be improved.

According to the printing apparatus of the fifth aspect of the present invention, when the sheet conveying means is provided upstream of the support plate in the conveying direction of the sheet, the conveying of the sheet is performed. Since the conveyance amount of the sheet-like body which affects the tension change on the downstream side in the direction is detected and the suction force of the suction means is controlled to increase or decrease, the change in the tension is reduced, and the conveyance accuracy and printing accuracy are improved.

According to the printing apparatus of the sixth aspect of the present invention, in the case where the sheet-like body conveying means is provided downstream of the support plate in the sheet-like body conveying direction,
Detecting the winding diameter of the sheet-like body wound by the sheet-like body winding unit, which affects the tension change on the downstream side in the conveyance direction of the sheet-like body, controls the suction force of the suction unit to increase or decrease. And the accuracy of conveyance and the accuracy of printing can be improved.

According to the printing apparatus of the present invention, in the case where the sheet-like body conveying means is provided downstream of the support plate in the sheet-like body conveying direction,
Since the conveyance amount is calculated by the conveyance amount control unit and the suction force of the suction unit is controlled, it is possible to improve the conveyance accuracy and the printing accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a printing apparatus according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a platen used in the printing apparatus of FIG.

FIG. 3 is a schematic view of the printing apparatus shown in FIG. 1, illustrating an operation when a winding diameter of a winding roller is small.

FIG. 4 is a schematic view of the printing apparatus shown in FIG. 1, illustrating an operation when a winding diameter of a winding roller is large;

FIG. 5 is a diagram (timing chart) illustrating a control method of the printing apparatus illustrated in FIG. 1;

FIG. 6 is a graph showing a control method of a suction blower of the printing apparatus shown in FIG.

FIG. 7 is a schematic view of the printing apparatus shown in FIG. 1 for explaining an operation when a line feed amount is small.

FIG. 8 is a schematic view of the printing apparatus shown in FIG. 1, illustrating an operation when a line feed amount is large;

FIG. 9 is a schematic diagram illustrating a printing apparatus according to another embodiment of the present invention, and illustrates a case where a winding diameter of a winding roller is small.

FIG. 10 is a schematic diagram illustrating a printing apparatus according to another embodiment of the present invention, and illustrates a case where a winding diameter of a winding roller is large.

FIG. 11 is a diagram illustrating a conventional printing apparatus.

[Explanation of symbols]

 Reference Signs List 20 paper feed roller (sheet-like body feeding means) 25 take-up roller (sheet-like body take-up means) 30 transport roller (sheet-like body transport means) 38 platen (sheet-like body support means) 46 print head (printing means) 51 Suction blower (suction means) 60 Roll diameter measurement means (detection means) A sheet

Claims (7)

[Claims] 1. A sheet feeding means for feeding a sheet wound in a roll form, a sheet feeding means for pulling in a sheet from the sheet feeding means and feeding the sheet, and a sheet fed A plurality of small holes provided in a support plate for supporting the back surface of the body, a sheet-like body supporting means for sucking the small-sized holes from the small holes to bring the sheet-like body into close contact with the support plate, and the support plate A printing apparatus comprising: printing means for performing a printing process on an upper sheet material; and sheet material winding means for rewinding the sheet material after processing by the printing means. A detection unit that detects a characteristic value that causes a change in the tension of the sheet-like body downstream of the conveyance unit in the conveyance direction, and a downstream side of the sheet-like body conveyance unit based on the characteristic value detected by the detection unit. Tension change To offset the printing apparatus characterized by comprising a suction means control means for increasing or decreasing control the suction force by the suction means. 2. The apparatus according to claim 1, wherein the suction unit control unit controls the suction force such that a difference in tension between the sheet-shaped members on the downstream side in the conveying direction of the sheet-shaped member conveying unit is reduced. Item 6. The printing device according to Item 1. 3. The apparatus according to claim 1, wherein said detecting means comprises a roll diameter measuring means for measuring a diameter of the sheet material wound in a roll shape by said sheet material winding means. Or the printing device according to 2. 4. The sheet-like body transporting means is provided upstream of the support plate in the direction of transporting the sheet-like body, and the suction means control means is configured to take up a roll measured by the roll diameter measuring means. 4. The printing apparatus according to claim 3, wherein the suction force is controlled so as to gradually increase as the diameter of the subsequent roll increases. 5. The sheet-like body transporting means is provided upstream of the support plate in the sheet-like body transporting direction, and has a transport amount control means for controlling a transport amount by the sheet-like body transporting means. The printing apparatus according to claim 1, wherein the suction unit control unit controls the suction force to gradually increase as the conveyance amount controlled by the conveyance amount control unit increases. 6. The sheet-like body transporting means is provided downstream of the support plate in the sheet-like body transporting direction, and the suction means control means is configured to take up a roll measured by the roll diameter measuring means. 4. The printing apparatus according to claim 3, wherein the suction force is controlled so as to gradually decrease as the diameter of the subsequent roll increases. 7. The sheet-like material transport means is provided downstream of the support plate in the direction of transport of the sheet-like material, and has a transport amount control means for controlling a transport amount by the sheet-like material transport means. The printing apparatus according to claim 1, wherein the suction unit control unit controls the suction force to gradually decrease as the conveyance amount controlled by the conveyance amount control unit increases.