JP4667840B2 - Thermal printing device - Google Patents

Description

  The present invention relates to a thermal printing apparatus that performs image recording control on a sheet using a thermal recording material.

  Many proposals have been made for thermal printers that record images by bringing a thermal head into contact with a thermal recording material. Also, a certain type of thermal printer, for example, a so-called rewritable printing apparatus that performs image recording using a color-forming reversible thermosensitive recording material (for example, see Patent Document 1) using a leuco dye and a reversible developer. In addition to performing image recording with a thermal head, the image can be erased using a heat roller (see, for example, Patent Document 2).

In such a so-called rewritable thermal printing apparatus, in order to erase an image on a thermal recording paper, the image is erased by passing the paper between a heat roller using a halogen lamp as a heat source and a platen facing the heat roller. Is going. FIG. 7 shows a configuration example of an image erasing unit using a heat roller according to the prior art. According to the prior art, a heater using a halogen lamp is provided inside a cylindrical heat roller 3, and the heat roller 3 is configured to be pressed by a compression coil spring in the direction of the platen roller 11 opposed thereto. By passing the paper 60 between the heat roller 3 and the platen roller 11, the recording surface of the paper is heated to a predetermined temperature.
JP 2004-106308 A JP 2002-331697 A

  However, it has been found that such a so-called heat roller system has the following problems and disadvantages.

  (1) Since the entire heat roller is heated by the halogen lamp, it takes a long time (normally about 2 minutes) until the heat roller reaches a predetermined start temperature at which an image can be erased.

  (2) Since the heat roller is basically in line contact with the paper, the nip (contact area) is small, and the temperature of the heat roller is increased in order to give the paper heat energy necessary for erasing in a short time (for example, 170 ° C) must be set. Therefore, thermal stress is easily applied to the paper, and the power consumption of the heater is increased.

  (3) In relation to (2), the contact time must be increased in order to give the thermal energy necessary for erasing to the paper. However, since the nip is small, the paper conveyance speed is set to 60 mm / It can only be raised to about s. That is, there is a trade-off relationship between the sheet conveyance speed and the thermal stress and power consumption.

  (4) Since the heat roller also serves as a conveying roller together with the platen roller facing the heat roller, tension must be applied to the heat roller or the platen roller facing the heat roller. Therefore, not only heat but also load stress is applied to the paper. As a result, the life of the thermal recording paper is adversely affected. In addition, when the resistance to heat and load stress is increased, the paper becomes thick, and when it is thick, the heat capacity of the heat roller has to be increased, so that the warm-up time is further increased.

  (5) In the heat roller method, the heat roller is pressed against the recording surface of the paper and heat is directly transferred to the recording surface of the paper, so if foreign matter such as dust adheres to the recording surface of the paper, Only the dust adhering portion does not perform normal heat transfer, resulting in poor image erasure (unerased image). As a result, a high-quality formed image cannot be obtained.

  (6) In the heat roller system, since the heat roller is pressed against the recording surface of the paper, there is a possibility that dust adhering to the surface of the heat roller is transferred to the recording surface of the paper. On the other hand, when an image is recorded by the thermal head, the thermal head contacts the paper and conducts the heat of the thermal head directly to the thermal recording surface of the paper, but foreign matters such as dust adhere to the recording surface of the paper. If this is the case, heat transfer to the recording surface of the paper is not normal only in that portion, and there is a problem that a normal image is not recorded (printing failure).

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thermal printing apparatus that solves the above-mentioned various problems without using a heat roller that directly contacts a sheet.

(1) A thermal printing apparatus according to the present invention includes a sheet conveyance path for conveying a reversible thermal recording sheet that enables recording and erasing of an image by a thermal action, and a thermal recording sheet that has been conveyed on the sheet conveyance path. An image erasing unit that erases an image by heating, an image recording unit that presses a thermal head against the recording surface of the thermal recording paper conveyed on the paper conveyance path and records an image by heating the thermal head; With
The image erasing unit has a cylindrical shape having a longitudinal direction parallel to the paper conveyance path and perpendicular to the conveyance direction of the thermal recording paper, and is disposed in close proximity without contacting the thermal recording paper. And a housing having a cylindrical shape coaxial with the halogen lamp and having slits extending in the longitudinal direction of the halogen lamp at substantially the same area on the paper conveyance path side and the opposite side of the paper conveyance path And a blower for sending air from the outside of the housing to the inside of the housing through the slit on the opposite side of the paper conveyance path .

(2) The thermal printing apparatus of the present invention also has a sheet conveyance path for conveying a reversible thermosensitive recording sheet that enables recording and erasing of an image by thermal action, and thermal recording that has been conveyed on the sheet conveyance path. An image erasing unit that heats the paper to erase an image, and an image recording unit that presses the thermal head against the recording surface of the thermal recording paper conveyed on the paper conveyance path and records the image by heating the thermal head And comprising
The image erasing unit has a cylindrical shape having a longitudinal direction parallel to the paper conveyance path and perpendicular to the conveyance direction of the thermal recording paper, and is disposed in close proximity without contacting the thermal recording paper. A halogen lamp having a focal point, a parabolic mirror having a cross section centered on a plane orthogonal to the transport direction and having an opening on the paper transport path side formed on an inner surface, the longitudinal direction of the halogen lamp being A housing having a longitudinal slit at a position on the central axis of the parabolic mirror, and a blower for sending air from the outside of the housing to the inside of the housing through the slit. The opening on the paper conveyance path side in the object mirror is formed by arranging a plurality of slits in parallel with the direction perpendicular to the conveyance direction as a longitudinal direction .

  (1) According to the thermal printing apparatus of the present invention, the heating means of the image erasing unit is not in contact with the thermal recording paper, and is along the transport direction of the thermal recording paper and is a predetermined distance from the thermal recording paper. Since the recording surface of the heat-sensitive recording paper being conveyed is heated to a predetermined temperature by bringing the heat radiating member close in parallel, various problems due to the use of the conventional heat roller are solved. That is, since a heat roller having a large heat capacity is not used, the warm-up time can be shortened. In addition, since the area corresponding to the nip in the case of the heat roller is widened, thermal stress on the paper can be reduced, power consumption can be suppressed, and the paper conveyance speed can be increased. Further, load stress due to the heat roller or the platen roller can be avoided. Further, the image erasing unit hardly adheres dust to the recording surface of the paper, and the problem due to the dust in the image recording unit is solved and high-quality image formation is possible.

  (2) Further, according to the thermal printing apparatus of the present invention, the heating means of the image erasing unit heats the recording surface of the paper to a predetermined temperature by blowing hot air without contacting the paper. Similar to 1), various problems are caused by using a conventional heat roller. Moreover, foreign matter such as dust adhered to the recording surface of the paper is blown away by hot air in the image erasing unit, so that the problem caused by dust in the image recording unit is further effectively eliminated, and high-quality image formation is achieved. It becomes possible.

  (3) Further, according to the thermal printing apparatus of the present invention, the heating means of the image erasing section opens a heater on the thermal recording paper side surrounding the heater and a heater whose longitudinal direction is perpendicular to the paper transport direction. The temperature rise efficiency of the air as hot air can be increased and the hot air can be efficiently blown only to the required range on the paper. be able to. Therefore, the warm-up time, power consumption, and paper conveyance speed can be further increased.

  (4) Further, according to the thermal printing apparatus of the present invention, the inner surface of the housing that houses the heater is a discharge centered on a straight line that is parallel to the thermal recording paper and that extends in a direction perpendicular to the conveyance direction of the thermal recording paper. By configuring the object mirror and placing the heater at the focal point, the heat radiated from the heater can evenly heat a predetermined range that spreads in the paper transport direction, making the paper most efficient Can be heated.

  FIG. 1 is a sectional view showing an internal configuration of a printing apparatus 100 according to an embodiment of the present invention. On the right side of the printing apparatus 100 in FIG. 1, an elevating table 14 on which a large amount of paper is placed, and a separate paper feed tray 16 are provided. The sheet placed on the lifting table 14 is brought into contact with the pickup roller 9 at the left end of the uppermost sheet in the drawing when the lifting table 14 is raised. A clutch is provided on the drive shaft of the pickup roller 9, and the pickup roller 9 rotates rightward in FIG. Thus, the paper is conveyed in the left direction in the figure. Since the paper feed roller 6 rotates in the right direction in the figure, the fed paper is conveyed as it is in the left direction.

  A clutch is provided on the drive shaft of the registration roller 21, and the leading end (left end in FIG. 1) of the fed paper comes into contact with the registration roller 21 when the clutch is off. Thereafter, when the clutch is turned on, the registration roller 21 rotates in the left direction and the sheet is conveyed in the left direction in the drawing.

  Similarly, the leading end (left end in the figure) of the uppermost sheet of the sheets placed on the sheet feeding tray 16 contacts the pickup roller 8. The drive shaft of the pickup roller 8 is provided with a clutch. When the clutch is in an on state, the pickup roller 8 rotates in the right direction in FIG. 1, and the sheet is conveyed in the left direction in the drawing. Since the paper feed roller 7 rotates in the right direction in the figure, the fed paper is conveyed in the left direction. A clutch is provided on the drive shaft of the registration roller 20, and the leading edge of the fed paper comes into contact with the registration roller 20 when the clutch is off. Thereafter, when the clutch is turned on, the registration roller 20 rotates in the left direction, and the sheet is conveyed in the left direction in the drawing.

  On the paper transport path, an R / W unit 5 that reads and writes a non-contact IC tag is disposed between the transport roller 13 and the transport roller 22. The drive shaft of the transport roller 13 is provided with a clutch, and when the R / W unit 5 reaches a position where the R / W unit 5 can read and write with respect to the non-contact IC tag built in the paper being transported, the clutch of the transport roller 13 is By turning it off, the paper is stopped in that state. When the sheet is stopped, the R / W unit 5 reads / writes data from / to the non-contact IC tag. Thereafter, the sheet is conveyed by turning on the clutch of the conveying roller 13. The transport roller 22 transports the paper forward (leftward in the figure).

  A cleaning roller 4 and a platen roller 12 as a driving roller facing the cleaning roller 4 are arranged in front of the conveying roller 22 to constitute a cleaning unit. When the paper passes between the cleaning roller 4 and the platen roller 12, the cleaning roller 4 removes the adhering matter adhering to the upper surface (recording surface) of the paper.

  An image erasing unit 95 is formed in front of the cleaning roller 4. The image erasing unit 95 raises the paper passing therethrough to a predetermined temperature.

  In front of the image erasing unit 95, cooling fans 2 and 2 for blowing air to the front and back surfaces of the paper are arranged above and below the paper transport path to constitute a cooling unit. The upper and lower cooling fans 2 and 2 gradually lower the temperature of the paper conveyed between them. This erases the image recorded on the paper.

  Further downstream of the cooling unit by the cooling fans 2 and 2, a platen roller 10 that sandwiches the paper between the thermal head 1 and the thermal head 1 is arranged to constitute an image recording unit. When the leading edge of the paper reaches the lower part of the thermal head 1, the thermal head 1 descends, contacts the recording surface of the paper, and records an image by driving the thermal head as the paper is transported.

  Conveying rollers 24 and 25 and a normal paper discharge unit 40 are provided further downstream from the position of the thermal head 1, and the image-recorded paper is conveyed and discharged to the normal paper discharge unit 40.

  Further, an abnormal paper discharge unit 50 is provided between the conveying roller 22 and the platen roller 12 to drop the abnormal paper downward by the flapper and discharge it.

  FIG. 2 is a diagram showing the configuration of the image erasing unit 95. FIG. 2 is a cross-sectional view in the direction perpendicular to the sheet surface along the sheet conveyance direction. Inside the cylindrical metal housing 92, a heater 91 made of a halogen lamp having a longitudinal direction perpendicular to the conveyance direction of the paper 60 and parallel to the paper 60 is disposed coaxially with the housing 92. Yes. A slit-like opening 93 extending in a direction perpendicular to the conveyance direction of the paper 60 is formed in the lower portion of the housing 92. In addition, a slit having substantially the same cross-sectional area as the opening 93 is provided on the upper portion of the housing 92 facing the opening 93, and an air passage from the blower 94 is connected to the slit. The air passage extends in the axial direction of the housing 92 so that the air from the blower 94 is blown into the housing over substantially the entire axial width of the housing 92. The housing 92 is provided with a temperature sensor 80s using a thermistor or the like for detecting the ambient temperature inside the housing 92.

  The paper 60 is transported along the transport path by the platen roller 12 and the transport roller 23 facing the cleaning roller 4.

  FIG. 2B shows an example of a heating region by the opening 93 provided in the housing 92 shown in FIG. FIG. 7B shows an example of the heating width and its temperature distribution when a conventional heat roller is used. In both cases, the lower part of (B) shows the temperature distribution with the horizontal axis as the paper transport direction and the vertical axis as the temperature, and the upper part of (B) shows the planar distribution of the temperature.

  Thus, according to the conventional heat roller system, the heating width (nip) for the paper 60 is substantially linear, and the temperature distribution at the nip has a sharp mountain shape with a high peak temperature. On the other hand, according to the first embodiment, the heating width for the paper 60 can be secured larger than that in the heat roller system, and the peak temperature can be lowered accordingly.

  Thus, since a heat roller having a large heat capacity is not used, the warm-up time can be shortened. In addition, since the peak temperature can be lowered, thermal stress on the paper can be reduced, power consumption can be suppressed, and the paper conveyance speed can be increased. Further, load stress due to the heat roller or the platen roller can be avoided. Further, the image erasing unit hardly adheres dust to the recording surface of the paper, and the problem due to the dust in the image recording unit is solved and high-quality image formation is possible. In addition, since the platen roller facing the heat roller is unnecessary, the arrangement of the conveyance rollers for sequentially conveying the paper along the paper conveyance path can be eliminated by one roller pitch, and the size of the entire thermal printing apparatus can be reduced. .

Table 1 shows specific examples of the various effects in the first embodiment.
[Table 1]
__________________________________
Roller tension Erase speed Erase temperature Warm-up time Down size amount ______________________________
(A) 4.2kg 60mm / s 165 ℃ 120s −
(B) 0kg 60-100mm / s 120-165 ° C 30s 50-80mm
__________________________________
In Table 1, (A) is an example of a conventional heat roller system, and (B) is an example according to this embodiment. “Roller tension” is a mechanical load by the heat roller and the platen roller, and “erasing temperature” is the temperature of the heat roller or hot air. The “downsize amount” represents the amount of reduction in the length in the sheet conveyance direction due to the elimination of one sheet conveyance roller.

FIG. 3 is a block diagram of the control unit of the printing apparatus 100. The control circuit 70 performs the following controls.
A drive signal is output to the motor 17 of the lifting table 14 via the drive unit 75.
A driving signal is output to the clutches 18 and 19 of the pickup roller via driving units 77 and 78, respectively.
A drive signal is output via the drive unit 76 to the flapper 52 that drops and discharges abnormal paper in the direction of the abnormal paper discharge unit 50.
A drive signal is output via the drive unit 74 to the clutch 15 of the R / W unit.
The R / W unit 5 (not shown in FIG. 3) reads / writes data with respect to the non-contact IC tag built in the paper.
Control of the heater 91 of the image erasing unit 95 is performed via the driving unit 73.
Control of the blower 94 of the image erasing unit 95 is performed via the driving unit 86.
A drive signal is output to the thermal head elevating motor 26 via the drive unit 72.
A drive signal is output to the thermal head 1 via the drive unit 71.
Read the operation content of the operation unit 79 such as a key switch.
The detection signals of various sensors 80 are read, such as a sensor that detects the presence or absence of paper at a plurality of positions on the paper conveyance path and a sensor 80 s that detects the temperature of the image erasing unit 95.
Data is input / output to / from the host computer 101 via the interface 90.
Next, the processing procedure of the control circuit 70 shown in FIG. 3 will be described with reference to FIGS.
FIG. 4 is a flowchart relating to the control of the image erasing unit. First, the energization of the heater 91 is started, the ambient temperature inside the housing 92 is measured using the temperature sensor 80s, and the temperature T is waited for reaching a predetermined preheating temperature To (S1->S2->S3->S2->). ...). Thereafter, the blower 94 is turned on (S4). Subsequently, the temperature sensor 80s is used again to wait for the ambient temperature T to reach a predetermined specified value T1 (S5 → S6 → S5 →...). When the specified temperature is reached, an erasure unit flag indicating that the image erasing unit is functioning normally is set, and temperature control is started so that the ambient temperature T maintains the predetermined value T1 (S7 → S8). . This temperature control is performed by controlling the energization power to the heater 91 using a triac or the like.

  FIG. 5 is a flowchart showing a series of flows under the control of the control circuit 70 from when a sheet is fed to when it is discharged. First, it waits for the eraser flag to be set (S11). If the eraser flag is set, the cooling fan 2 starts to be driven (S12).

  Thereafter, one of the clutches 18 or 19 of the pickup roller 8 or 9 is turned on to feed the paper and start conveying (S13). If it is detected that the sheet has reached the R / W unit 5 according to the reading result of the sensor for detecting the position of the sheet on the sheet conveyance path, the clutch 15 of the conveyance roller 13 of the R / W unit 5 is turned off ( S14 → S15).

  In this state, the non-contact IC tag in the sheet is close to the R / W unit 5, and the R / W unit 5 reads data from the non-contact IC tag (S16).

  The state (read status) of whether or not the data has been read correctly from the non-contact IC tag is checked (S17). If normal, the data is written in the non-contact IC tag or from the host computer 101. In response to the instruction, bitmap data to be recorded on the paper is generated (S18).

  Thereafter, the sheet is conveyed again by turning on the clutch 15 (S19). As a result, the sheet passes between the cleaning roller 4 and the platen roller 12, and the recording surface of the sheet is cleaned (S20).

  Thereafter, the sheet passes through the image erasing unit 95, whereby the recording surface of the sheet is heated to a predetermined temperature, and the previously recorded image is erased by subsequent cooling (S21). In addition, by driving the cooling fan 2, heat storage of the paper transport path and the paper is suppressed, and the recording surface of the paper is kept in a predetermined temperature range at the time of image recording by the subsequent thermal head.

Subsequently, when the leading edge of the paper reaches just before the head position of the thermal head 1, the thermal head lifting motor 26 is driven to bring the head portion of the thermal head 1 into contact with the paper, and then the thermal head 1 is driven to newly A simple image is recorded (S22).
Further, the sheet is conveyed as it is and discharged to the normal sheet discharge unit 40 (S23).

  If the data cannot be read from the non-contact IC tag, or the read data is abnormal, the flapper 52 is started up and the clutch 15 of the R / W unit is turned on to feed the paper to the abnormal paper discharge unit 50. It discharges (S17-> S24-> S25-> S26).

Next, a thermal printing apparatus according to the second embodiment will be described with reference to FIG.
FIG. 6 is a diagram showing a configuration of an image erasing unit similar to the part shown in FIG. In the example shown in FIG. 2, the slit-shaped opening 93 is provided in the portion of the housing 92 that faces the paper 60. However, in the image erasing unit according to the second embodiment, A heat dissipating part 96 is provided that is close to the sheet in parallel by a predetermined distance along the transport direction. Inside the housing 92, there is provided a heater 91 using a halogen lamp whose longitudinal direction is a direction perpendicular to the conveyance direction of the paper 60 and parallel to the paper 60. Similar to the structure shown in FIG. 2, a blower 94 is connected to the housing 92 so that air from the blower 94 flows into the housing 92 from the top.

  In this example, the heat dissipating part 96 is provided with a slit-like opening 93 extending in a direction perpendicular to the paper transport direction and parallel to the paper, and hot air is blown from the opening 93 to the paper 60. . However, unlike the structure shown in FIG. 2, a plurality of slit-like openings 93 are provided.

  The inner surface of the housing 92 has a cross section in a plane perpendicular to the paper 60 and along the conveyance direction of the paper 60, forming a parabola or an approximate parabola, parallel to the paper 60 and perpendicular to the conveyance direction of the paper 60. It constitutes an extended parabolic mirror. A heater 91 by a halogen lamp is arranged at the focal position of the parabolic mirror. With this structure, the heat radiated from the heater 91 can heat the heat radiating portion 96 spreading in the paper transport direction and the recording surface of the paper 60 most efficiently and evenly.

  FIG. 6B shows an example of the heating region by the heat radiation part 96 provided in the housing 92 shown in FIG. The lower part of (B) shows the temperature distribution with the horizontal axis as the paper conveyance direction and the vertical axis as the temperature, and the upper part of (B) shows the planar distribution of the temperature. The thermal printing apparatus according to the second embodiment has the following effects in addition to the effects described in the first embodiment. That is, the heating width can be made wider than that shown in FIG. 2, and even if the peak temperature is lowered by that amount, the recording surface of the paper 60 can be passed after being raised to a predetermined temperature. Further, if a plurality of slit-like openings 93 are provided, the radiation efficiency from the heater 91 is directly applied to the paper 60, so that the heating efficiency can be increased. Therefore, thermal stress and power consumption on the paper can be further suppressed, and the paper conveyance speed can be increased.

  In the example shown in FIG. 6, the opening 93 is provided in the housing 92 and the blower 94 is connected. However, the recording surface of the paper 60 is heated by the radiant heat from the heat radiating unit 96 without providing the blower 94 and the opening 93. It may be. Further, by providing the opening 93 without providing the blower 94, the sheet 60 may be heated by the direct radiant heat from the heater 91 together with the radiant heat from the heat radiating unit 96. In these configurations, the temperature of the recording surface of the paper 60 can be indirectly and accurately measured by providing the temperature sensor 80s by the thermistor at a position substantially the same distance as the distance from the heater 91 to the paper 60.

1 is a diagram illustrating an internal configuration of a printing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of an image erasing unit of the printing apparatus. FIG. 3 is a block diagram illustrating a configuration of a control unit of the printing apparatus. It is a flowchart which shows the process sequence regarding the image deletion part of the control part. 4 is a flowchart illustrating a processing procedure from paper feeding to paper ejection of the control unit. FIG. 10 is a diagram illustrating a configuration of an image erasing unit of a printing apparatus according to a second embodiment. It is a figure which shows the structure of the image erasing part of the printing apparatus by a prior art.

Explanation of symbols

1-thermal head 2-cooling fan 3-heat roller 4-cleaning roller 5-R / W unit (non-contact IC tag read / write unit)
6,7-Feeding roller 8,9-Pickup roller 10,11,12-Platen roller 13-Conveying roller 14-Elevating table 16-Feeding tray 20,21-Registration roller 22-25-Conveying roller 40-Normal paper Ejector 50-Abnormal paper ejector 60-Paper 80s-Temperature sensor 91-Heater 92-Housing 93-Opening 94-Blower 95-Image erasure unit 96-Heat radiation unit 100-Printing device 101-Host computer

Claims (2)

A paper conveyance path for conveying a reversible thermosensitive recording paper that enables recording and erasing of an image by a thermal action, and an image erasing section that erases an image by heating the thermal recording paper conveyed on the paper conveyance path A thermal printing apparatus comprising: an image recording unit that presses a thermal head against a recording surface of the thermal recording paper that has been conveyed on the paper conveyance path and records an image by heating the thermal head;
The image erasing unit,
A halogen lamp parallel to the paper transport path and having a longitudinal direction in a direction perpendicular to the transport direction of the thermal recording paper, and a halogen lamp disposed in close proximity without contacting the thermal recording paper;
A housing having a cylindrical shape coaxial with the halogen lamp, and a slit having a longitudinal direction as a longitudinal direction of the halogen lamp, provided in substantially the same area on the paper conveyance path side and the opposite side of the paper conveyance path;
And a blower for sending air from the outside of the housing to the inside of the housing through the slit on the opposite side of the paper conveyance path. A paper conveyance path for conveying a reversible thermosensitive recording paper that enables recording and erasing of an image by a thermal action, and an image erasing section that erases an image by heating the thermal recording paper conveyed on the paper conveyance path A thermal printing apparatus comprising: an image recording unit that presses a thermal head against a recording surface of the thermal recording paper that has been conveyed on the paper conveyance path and records an image by heating the thermal head;
The image erasing unit,
A halogen lamp parallel to the paper transport path and having a longitudinal direction in a direction perpendicular to the transport direction of the thermal recording paper, and a halogen lamp disposed in close proximity without contacting the thermal recording paper;
A cross-sectional paraboloidal mirror is formed on the inner surface with the halogen lamp as a focal point, centering on a plane orthogonal to the transport direction, and opening on the paper transport path side, and a slit having the longitudinal direction of the halogen lamp as a longitudinal direction. A housing provided at a position on the central axis of the parabolic mirror;
A blower for sending air from the outside of the housing to the inside of the housing through the slit,
A thermal printing apparatus in which the opening on the paper conveyance path side in the cross-sectional parabolic mirror is configured by arranging a plurality of slits having a longitudinal direction in a direction orthogonal to the conveyance direction.

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