Web printer

Abstract

A web printer is provided. The web printer includes a housing that is capable of housing a web wound in a manner that one side of a recording paper is on the outside; a feed roller that pulls out the recording paper from the web and feeds the recording paper in a feed direction; a guide portion that is capable of abutting against the other side of the recording paper at an upstream of the feed direction of the feed roller; and a protrusion that is capable of abutting against the one side of the recording paper at the upstream of the feed direction of the feed roller and is capable of moving toward the guide portion.

Description

Technical Field

[0001] This disclosure relates to a roll paper printer. Background Technology

[0002] As shown in Patent Document 1, a printer that adjusts the tension of paper pulled from a roll of paper has been known for a long time. Furthermore, as shown in Patent Document 2, a printer that corrects the curling (curling) of paper pulled from a roll of paper has been known.

[0003] In order to adjust the tension of the paper pulled from the roll and correct the curling, the above two printer structures are required, which makes the printer a complex structure and also increases its size.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2010-52405

[0005] Patent Document 2: Japanese Patent Application Publication No. 2010-99852 Summary of the Invention

[0006] The roll paper printer includes: a receiving section for receiving a roll of paper wound with one side of the recording paper facing outwards; a transport roller for pulling the recording paper out of the roll and transporting it in a transport direction; a guide section upstream of the transport roller in the transport direction, capable of abutting against the other side of the recording paper; and a protrusion upstream of the transport roller in the transport direction, capable of abutting against the one side of the recording paper and movable toward the guide section. Attached Figure Description

[0007] Figure 1 This is a cross-sectional view of a roll paper printer when the diameter of the roll paper is relatively large.

[0008] Figure 2 This is an enlarged view centered on the conveying path when the diameter of the paper roll is large.

[0009] Figure 3 This is a cross-sectional view of a roll paper printer with a small roll paper diameter.

[0010] Figure 4 This is an enlarged view centered on the conveying path for a small diameter roll of paper. Detailed Implementation

[0011] 1. First Implementation Method

[0012] 1-1. Structure of a roll paper printer

[0013] The following is for reference Figures 1 to 4The roll paper printer 1 according to the embodiment will be described. Furthermore, the directions in the figures will be explained using a three-dimensional coordinate system. For ease of explanation, the positive direction of the Z-axis will be referred to as "up" or simply "up," and the negative direction as "down" or simply "down." The positive direction of the X-axis will be referred to as "right" or simply "right," and the negative direction as "left" or simply "left." The positive direction of the Y-axis will be referred to as "front" or simply "front," and the negative direction as "rear" or simply "rear."

[0014] The roll-paper printer 1 described in this embodiment is used, for example, in a POS (Point of Sale) system. A POS system is used in retail businesses such as shopping malls, department stores, convenience stores, and mobile vending machines, or in food service businesses such as restaurants, tea houses, and izakayas. The roll-paper printer 1 used in the POS system prints receipts, coupons, tickets, etc., depending on the goods or services offered.

[0015] like Figure 1 As shown, the roll paper printer 1 is configured to include a protrusion 3, a guide 5, a conveyor roller 6, a head 7, and a cutter 8.

[0016] A hinge 11 is provided on the housing 14 at a position below and in front. The cover 10 is mounted so as to be able to rotate about the hinge 11.

[0017] The housing 14 is equipped with a protrusion 3, a head 7, a second blade 8b of the cutter 8, and a storage section 12 (described later). On the other hand, the cover 10 is equipped with a guide section 5, a conveying roller 6, and a first blade 8a of the cutter 8.

[0018] The recording paper 2 is, for example, a strip of thermal paper. A thermal material is coated on one surface 2a of the recording paper 2, allowing images to be printed via the head 7. The other surface 2b of the recording paper 2 is the surface that contacts the transport roller 6.

[0019] The roll of paper R is wound onto the core R0 with the surface 2a of the recording paper 2 facing outwards and the back surface 2b facing inwards. The closer the recording paper 2 is to the core R0 of the roll of paper R, that is, the smaller the outer diameter of the roll of paper R, the more curled it becomes. Furthermore, in the following text, the outer diameter will be referred to as the diameter.

[0020] The width of recording paper 2 is, for example, 80 mm. The width of recording paper 2 can also be 58 mm. The thickness of recording paper 2 is, for example, 0.06 mm to 0.08 mm. The diameter of the core R0 is, for example, 18 mm.

[0021] The roll of paper R can be stored in the storage section 12 located at the bottom inside the housing 14. The cover 10 can open and close the storage section 12. When the user opens the cover 10 forward, they can enter the storage section 12.

[0022] The user can place the recording paper 2 in the roll paper printer 1 by simply opening the cover 10, storing the roll paper R in the storage section 12, pulling out the recording paper 2 from the roll paper R, and closing the cover 10.

[0023] When the cover 10 is closed, the guide portion 5 mounted on the cover 10 is positioned opposite the protrusion 3 mounted on the housing 14, with the recording paper 2 spaced apart. As a result, the transport path 9 of the recording paper 2 is formed to bend between the opposing guide portions 5 and the protrusion 3, as will be described later.

[0024] Furthermore, when the cover 10 is closed, a rectangular outlet 13 is formed at the boundary between the cover 10 and the housing 14.

[0025] Furthermore, when the cover 10 is closed, the conveyor roller 6 mounted on the cover 10 is positioned opposite the head 7 mounted on the housing 14, which holds the recording paper 2. As a result, the conveyor roller 6 abuts against the back side 2b of the recording paper 2 to perform conveying, and the head 7 abuts against the surface 2a of the recording paper 2 to perform printing.

[0026] The conveyor roller 6, which is positioned opposite the head 7 via the recording paper 2, is also called the impression roller.

[0027] Furthermore, the first blade 8a of the cutter 8 mounted on the cover 10 is positioned opposite the second blade 8b mounted on the housing 14, separated by a space from the recording paper 2. The first blade 8a can move toward the second blade 8b and cut the recording paper 2 located between them.

[0028] The head 7 is, for example, a row-type thermal head with multiple heating elements arranged side by side. The multiple heating elements of the head 7 are selected and heated based on the printing data, and an image is printed on the recording paper 2, which is thermal paper.

[0029] The conveyor roller 6 is rotated counterclockwise in the direction indicated by the arrow by a motor for the conveyor roller (not shown).

[0030] The conveyor roller 6 pulls the recording paper 2 out of the roll paper R in the receiving section 12 and conveys it via the conveyor path 9 in the conveying direction indicated by the arrows from the conveyor roller 6 and the head 7 to the discharge port 13 and the cutter 8. At this time, the roll paper R also rotates counterclockwise as the recording paper 2 is pulled out.

[0031] From upstream to downstream in the conveying direction, the following components are arranged in sequence: a receiving section 12, a conveying path 9 formed by a guide section 5 and a protrusion 3, a conveying roller 6 and a head 7, a cutter 8, and a discharge outlet 13.

[0032] The protrusion 3 can move in either direction A (a first direction) or direction B (a second direction). Specifically, the protrusion 3 can move forward in direction A toward the guide portion 5, and can also retreat in direction B away from the guide portion 5. Direction B is the opposite direction to direction A.

[0033] The protrusion 3 is mounted on the elastic member 4. The protrusion 3 is pushed in the direction A by the thrust S of the elastic member 4. The elastic member 4 is telescopic and is made of spring or rubber, etc. The elastic member 4 is, for example, a compression coil spring. Regarding the elastic member 4, one end is fixed to the housing 14, and the other end can push the protrusion 3 in the direction A.

[0034] The protrusion 3 is configured to move a distance of 6.0 mm in the direction B, based on the position where the recording paper 2 is not on the transport path 9 and is not in contact with the recording paper 2. This distance is also the length that the elastic member 4 can compress.

[0035] Furthermore, the protrusion 3 is configured to extend in the width direction of the recording paper 2, which is the left-right direction. For example, the protrusion 3 extends in the width direction, for example, 80 mm, in accordance with the width of the recording paper 2. The elastic member 4 may also be provided at least on the left and right sides of the protrusion 3. When the elastic member 4 is configured in this way, the protrusion 3 can apply the thrust S of the elastic member 4 evenly to the recording paper 2 in the width direction. The guide portion 5 is also configured to extend in the width direction of the recording paper 2 in the same way as the protrusion 3.

[0036] On the other hand, for the recording paper 2 pulled from the roll paper R and tightened by the conveyor roller 6, tension T1 is applied in the direction marked by the arrow, which is the same as the conveying direction. As a result, under the action of tension T1, the protrusion 3 abuts against the recording paper 2 and is pushed in the B direction.

[0037] 1-2. Regarding the case of larger diameter rolls of paper.

[0038] Figure 1 as well as Figure 2 This illustrates the case where the diameter of the roll of paper R is a larger diameter D1. Figure 3 as well as Figure 4 This illustrates the case where the diameter of the roll paper R is the smaller diameter D2. The two will be compared below for illustration.

[0039] Furthermore, in the following text, the diameter D1 of the roll paper R will be simply referred to as diameter D1, and an example of a case where the diameter of the roll paper R is larger will be shown. The diameter D2 of the roll paper R will be simply referred to as diameter D2, and an example of a case where the diameter of the roll paper R is smaller will be shown. Diameter D1 is, for example, 80 mm, and diameter D2 is, for example, 30 mm.

[0040] because Figure 1 The diameter D1 shown is... Figure 3 The diameter D2 shown is large, therefore the roll of paper R is larger and heavier, and the load on the conveyor roller 6 when conveying the recording paper 2 is also greater. The result is that... Figure 1 as well as Figure 2 The tension T1 of the recording paper 2 shown is also greater than Figure 3 as well as Figure 4 The tension T2 shown.

[0041] When the diameter is large, especially when the conveyor roller 6 starts conveying the recording paper 2, the load will increase sharply due to the inertia of the roll paper R, and the tension T1 of the recording paper 2 will also increase sharply.

[0042] In this situation, when the conveyor roller 6 starts conveying the recording paper 2, the load of the roll paper R will be affected by inertia, which may sometimes cause the conveyor roller 6 to fail to convey the recording paper 2.

[0043] The protrusion 3 abuts against the surface 2a of the recording paper 2 and moves in the B direction due to the tension T1 of the recording paper 2. At the same time, it causes the pushing force S of the elastic member 4 to act in the A direction, thus buffering the tension T1. In other words, while resisting the tension T1 that pushes the recording paper 2 in the B direction, the protrusion 3 uses the pushing force S of the elastic member 4 to push the recording paper 2 in the opposite direction of the B direction, thus acting in a way that cancels out the mutual forces.

[0044] As the protrusion 3 moves towards direction B, the elastic member 4 is compressed, thus increasing the thrust S of the elastic member 4. Therefore, as the tension T1 of the recording paper 2 increases, pushing the protrusion 3 towards direction B, the thrust S of the elastic member 4 pushing it back towards direction A also increases.

[0045] Thus, the protrusion 3 can buffer the tension of the recording paper 2 according to the tension of the recording paper 2, or in other words, according to the diameter of the roll paper R.

[0046] As a result, even with a large diameter such as D1, the conveyor roller 6 can stably convey the recording paper 2. In particular, even when the inertial effect is large at the beginning of conveying and the tension T1 of the recording paper 2 increases sharply, the conveyor roller 6 can still stably convey the recording paper 2 because the protrusion 3 buffers the tension T1.

[0047] However, as described above, when the conveyor roller 6 conveys the recording paper 2, the roll of paper R also unwinds from the recording paper 2 and rolls counterclockwise within the storage section 12. As the roll of paper R rolls, the load on the conveyor roller 6 when conveying the recording paper 2 changes due to variations in friction between the roll of paper R and the storage section 12. As a result, the tension T1 of the recording paper 2 also changes.

[0048] In particular, when the diameter D1 is large, the variation in tension T1 also increases. With a large variation in tension T1, the conveyor roller 6 may sometimes become unable to convey the recording paper 2 at a constant speed, leading to a deterioration in print quality. The constant speed at which the conveyor roller 6 conveys the recording paper 2 is, for example, 500 mm / s.

[0049] Even under these conditions, the protrusion 3 can move in direction A or B according to the change in tension T1 of the recording paper 2, while the thrust S of the elastic member 4 buffers the change in tension T1 of the recording paper 2. As a result, the conveyor roller 6 can convey the recording paper 2 at a fixed speed.

[0050] Next, using Figure 2 For the case of diameter D1, the explanation will focus on the conveying path 9 formed by the guide 5 and the protrusion 3.

[0051] The guide portion 5 has a recess 5a and a protrusion 5b connected upstream of the recess 5a in the conveying direction. The recess 5a of the guide portion 5 is positioned opposite the tip 3a of the protrusion 3. The recess 5a of the guide portion 5 is also called a recess, and the protrusion 5b is also called a convex portion.

[0052] like Figure 2 As shown, after the recording paper 2 pulled from the roll paper R by the conveyor roller 6 comes into contact with the protrusion 5b of the guide portion 5 on the back side 2b, the surface 2a comes into contact with the top end 3a of the protrusion 3 downstream in the conveying direction and is conveyed.

[0053] Thus, the transport path 9 formed by the guide section 5 and the protrusion 3 meanders and bends with a variable curvature, as will be described later.

[0054] Furthermore, the protrusion 3 is made of resin such as plastic. Additionally, at least the portion of the protrusion 3 that contacts the surface 2a of the recording paper 2, i.e., the tip 3a, is covered by a sheet containing ultra-high molecular weight polyethylene (UHMWPE). While conventional polyethylene has a molecular weight of 2 to 3 million, UHMWPE increases the molecular weight to 1 to 7 million.

[0055] As a result, the friction between the tip 3a of the protrusion 3 and the recording paper 2 can be reduced, thereby reducing the load on the conveyor roller 6 when conveying the recording paper 2.

[0056] exist Figure 2 In the middle, because the diameter D1 is relatively large, the tension T1 of the recording paper 2 is also relatively large, which in turn pushes the protrusion 3 more strongly in the B direction. Therefore, Figure 2 The position of the protrusion 3 shown is... Figure 4 Compared to the position of the protrusion 3 with diameter D2 shown, it has become a position that has receded in the direction of B.

[0057] The result is, such as Figure 2 As shown, with Figure 4 Compared to the previous case, the protrusion 3 is located further away from the guide portion 5, thus forming a wider conveying path 9 between the guide portion 5 and the protrusion 3.

[0058] Furthermore, the angle of the recording paper 2 surrounding the top 3a of the protrusion 3, that is, the angle formed by the recording paper 2 from the protrusion 5b of the guide portion 5 toward the top 3a of the protrusion 3 and the angle formed by the recording paper 2 from the top 3a of the protrusion 3 toward the conveyor roller 6, is... Figure 2 The diameter D1 shown is greater than Figure 4 The case shown is for diameter D2.

[0059] The angle of the recording paper 2 at the top 3a of the surrounding protrusion 3 represents the curvature of the conveyor path 9. In the case of diameter D1, the curvature of the conveyor path 9 is also greater and the bend is gentler compared to the case of diameter D2.

[0060] Thus, in the case of diameter D1, the curvature of the transport path 9 is gentler compared to the case of diameter D2. Therefore, the area of ​​the portion of the recording paper 2 that abuts against the protrusion 5b of the guide portion 5 and the area of ​​the portion that abuts against the top 3a of the protrusion 3 are smaller.

[0061] As described above, the further protrusion 3 moves towards direction B, the more compressed the elastic component 4 becomes, and the greater the thrust S of the elastic component 4 becomes. Because Figure 2 The position of the protrusion 3 shown is... Figure 4 In comparison, it becomes a position that retreats further in the direction of B, therefore, the thrust S of the elastic component 4 is greater.

[0062] With a diameter of D1, even if the tension T1 of the recording paper 2 increases sharply at the start of transport, the tension T1 can be buffered immediately because the protrusion 3 is in a position that allows the thrust S of the elastic member 4 to exert a stronger effect.

[0063] 1-3. Regarding the case of smaller diameter rolls of paper.

[0064] use Figure 3 as well as Figure 4 For diameter D2 less than Figure 1 as well as Figure 2 The case of diameter D1 shown will be explained.

[0065] As described above, the curling of the recording paper 2, which is located near the core R0 of the roll paper R and has a smaller diameter such as D2, becomes stronger. Receipts, coupons, tickets, etc., printed on such recording paper 2 will also curl inwards as they are wound, thus degrading the quality of the printed matter. Furthermore, since there are no components to restrain the recording paper 2 downstream of the conveying roller 6 and the head 7 in the conveying direction, the curled recording paper 2 may also get caught on the cutter 8 and the discharge port 13.

[0066] The protrusion 3 enables the thrust S of the elastic member 4 to act in the direction of A and to abut against the surface 2a of the conveyed recording paper 2 to flatten it, thereby correcting the curl of the recording paper 2.

[0067] like Figure 3 As shown, because the diameter D2 is smaller than the diameter D1, the roll of paper R is lighter, resulting in a smaller load on the conveyor roller 6 when conveying the recording paper 2. The result is that... Figure 3 as well as Figure 4 The tension T2 of the recording paper 2 shown is also less than Figure 1 as well as Figure 2 The tension T1 is shown.

[0068] use Figure 4 The conveying path 9 formed by the guide part 5 and the protrusion 3 when the diameter D2 is smaller than the diameter D1 will be explained in detail.

[0069] exist Figure 4 In, with Figure 2 Compared to the previous case, since the tension T2 of the recording paper 2 is less than the tension T1, the thrust S of the elastic member 4 will further push the protrusion 3 that is in contact with the recording paper 2 towards direction A. Therefore, Figure 4 The position of the protrusion 3 shown is, with Figure 2 Compared to the position of protrusion 3 shown, this is a position that moves further forward in the direction of A.

[0070] The result is, such as Figure 4 As shown, with Figure 2 Compared to the previous case, the protrusion 3 is positioned further forward towards the guide portion 5, resulting in a narrower conveying path 9 between the guide portion 5 and the protrusion 3.

[0071] Therefore, as Figure 4As shown, the angle of the recording paper 2 surrounding the top 3a of the protrusion 3, that is, the angle between the recording paper 2 from the protrusion 5b of the guide portion 5 toward the top 3a of the protrusion 3 and the recording paper 2 from the top 3a toward the conveyor roller 6, is... Figure 2 The situation is even smaller in comparison. Thus, Figure 4 The curvature of the conveyor path 9 shown is smaller and the bend is sharper.

[0072] Because the conveying path 9 has a more abrupt bend, the area of ​​the portion of the recording paper 2 that abuts against the protrusion 5b of the guide portion 5, and the area of ​​the portion that abuts against the tip 3a of the protrusion 3, are larger.

[0073] Thus, as the diameter decreases from D1 to D2, the protrusion 3 moves in the A direction, the curvature of the conveying path 9 becomes more abrupt, and it further bends in the direction that corrects the curling of the recording paper 2.

[0074] In other words, the protrusion 3 moves in response to changes in the diameter R of the paper roll, such as from D1 to D2. Furthermore, the curvature of the transport path 9 formed between the opposing guides 5 and the protrusion 3 changes according to the movement of the protrusion 3.

[0075] As a result, corresponding to the case where the diameter D2 becomes smaller and the curling of the recording paper 2 becomes stronger, the curvature of the transport path 9 becomes sharper, thereby enabling more effective correction of the curling.

[0076] Furthermore, to cope with situations where the effects of inertia are particularly significant, the thrust S of the elastic component 4 is sometimes set to be stronger. Specifically, compared to the initial thrust at the start of the conveying process... Figure 1 as well as Figure 2 Compared to the force of the tension T1 pushing the recording paper 2, the thrust S of the elastic member 4 is set to be stronger. Under such circumstances, even with a diameter D1, the protrusion 3 moves in the A direction and becomes approximately... Figure 3 as well as Figure 4 The case where the positions shown are the same.

[0077] As a result, even when the diameter D1 is larger than the diameter D2, it is possible to form a more sharply curved transport path 9 in the same way as when the diameter is D2, and to correct the curling of the recording paper 2.

[0078] Furthermore, the curvature of the tip 3a of the protrusion 3 that corrects curling is preferably 0.5 mm or more and 2.2 mm or less. For further effective correction of curling, the curvature of the tip 3a is preferably 0.8 mm or more and 1.0 mm or less.

[0079] By specifying the curvature of the tip 3a of the protrusion 3, the curling of the recording paper 2 can be corrected. As a result, the deterioration of the printed material quality can be suppressed. In addition, it can also prevent the curled recording paper 2 from getting caught on the cutter 8 and the discharge port 13.

[0080] As described above, the roll paper printer 1 of this embodiment has a protrusion 3 that can abut against the surface 2a of the recording paper 2 and can move toward the guide portion 5.

[0081] As a result, the protrusion 3 can move according to the diameter of the paper roll R and buffer the tension of the recording paper 2. In addition, the protrusion 3 can also move according to the situation where the diameter of the paper roll R becomes smaller and the curling of the recording paper 2 becomes stronger, so as to correct the curling.

[0082] Thus, the roll paper printer 1 of the above embodiment has a simple structure with a guide portion 5 and a protrusion 3, and can buffer the tension of the recording paper 2, thereby correcting curling. In addition, it can also control the size of the roll paper printer 1.

[0083] The embodiments described above have been described in detail with reference to the accompanying drawings. However, the specific structure is not limited to these embodiments. As long as it does not depart from the spirit of this disclosure, changes, substitutions, deletions, etc., can be made.

[0084] Although the example of a thermal printhead 7 has been described above, the printing method is not limited. For example, the printhead 7 can also be an inkjet printhead. In this case, since the inkjet printhead cannot contact the transport roller 6 and hold the recording paper 2, the driven roller that is opposite to the transport roller 6 and holds the recording paper 2 can be mounted on the housing 14.

[0085] Although the protrusion 3 is described above as being made of resin such as plastic, it could also be constructed by making the top end 3a of the protrusion 3 a metal cylinder with the same curvature and diameter. The metal could be, for example, stainless steel. Additionally, a bearing could be provided that allows the metal cylinder to rotate and move in both directions A and B. Furthermore, the metal cylinder could be covered by a sheet containing ultra-high molecular weight polyethylene.

[0086] Alternatively, a guide portion, consisting of a wall or similar structure, can be provided around the protrusion 3 to allow the protrusion 3 to move smoothly in both directions A and B. The guide portion can be configured to extend in both directions A and B around the protrusion 3.

[0087] Alternatively, the protrusion 5b that contacts the recording paper in the guide section 5 can be covered with a sheet containing ultra-high molecular weight polyethylene. This reduces friction between the protrusion 5b and the recording paper 2, thereby reducing the load on the transport roller 6 when transporting the recording paper 2.

[0088] Although the elastic member 4 is fixed to the housing 14 as described above, it can also be fixed to the storage part 12 that stores the roll of paper R. In this case, as long as it is set to store... Figure 1 as well as Figure 3 The storage section 12 shown extends to the upper position and the elastic member 4 is fixed thereon. At this time, since the protrusion 3 is mounted on the elastic member 4, the protrusion 3 is also mounted on the storage section 12.

[0089] Alternatively, the shaft can be positioned below and behind the housing 14, with one end of the rod rotatably mounted on the shaft and the protrusion 3 mounted on the other end of the rod. The protrusion 3 mounted on the other end of the rod can move about the shaft. The elastic member 4 can be configured to directly push the protrusion 3 or to push the protrusion 3 via the rod.

[0090] Although the example above described using the roll paper printer 1 with the discharge outlet 13 facing forward, it can also be used with the discharge outlet 13 facing upward. In this case, Figure 1 as well as Figure 3 The storage section 12 shown extends upwards, so that even when the discharge outlet 13 is in an upward position, the roll of paper R can be stored in the storage section 12.

[0091] Furthermore, the side of the recording paper 2 that abuts against the protrusion 3 may not be the side to be printed on. The roll paper R is wound in such a way that the side of the recording paper 2 to be printed on is the inside. In this case, the positions of the head 7 and the conveyor roller 6 become relative to... Figure 1 as well as Figure 3 The position shown is the opposite.

Claims

1. A roll paper printer, comprising: The storage section is capable of storing rolls of paper that are wound with one side of the recording paper facing outwards. A conveyor roller that pulls the recording paper out of the paper roll and conveys it in the conveying direction; A guide portion having a protrusion that is located upstream of the conveying roller in the conveying direction and is capable of abutting against the other side of the recording paper; A protrusion, located upstream of the conveying roller in the conveying direction, is capable of abutting against one surface of the recording paper and moving toward the guide portion. The protrusion is positioned vertically above the storage portion. The protrusion is positioned vertically above the projection. The conveying roller is positioned vertically above the protrusion. The area at the tip of the protrusion that allows the recording paper to move toward a portion of the guide is positioned immediately adjacent to the conveyor roller.

2. The roll paper printer as described in claim 1, wherein, The protrusion moves according to the diameter of the roll of paper.

3. The roll paper printer as described in claim 1 or claim 2, wherein, A curved transport path is formed between the opposing guide portions and the protrusions, the curvature of which changes according to the movement of the protrusions.

4. The roll paper printer as described in claim 1, wherein, The guide portion has a recess at a position opposite to the protrusion.

5. The roll paper printer as described in claim 1, wherein, The curvature of the tip of the protrusion is greater than 0.5 mm and less than 2.2 mm.

6. The roll paper printer as described in claim 1, wherein, In the protrusion, at least the portion that abuts against one side of the recording paper is covered by a sheet comprising ultra-high molecular weight polyethylene.

7. The roll paper printer as described in claim 1, wherein, It includes an elastic member that pushes the protrusion toward the guide portion. The protrusion is pushed in a first direction by the elastic member and in a second direction opposite to the first direction by the tension of the recording paper.

8. The roll paper printer as described in claim 1, wherein, As the diameter of the roll of paper decreases, the area of ​​contact between the recording paper and the protrusion increases, or the area of ​​contact between the recording paper and the protrusion and the projection increases.

9. The roll paper printer as described in claim 1, wherein, It has a head that performs printing on one side of the recording paper.

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