JP4534872B2 - Sheet transport device - Google Patents

Description

The present invention relates to a sheet conveying apparatus for accurately conveying sheets having different sizes.

  2. Description of the Related Art Conventionally, a printer is formed so as to be compatible with a plurality of sizes of sheets (printing sheets). In general, a pair of conveying rollers is used for conveying the sheet, and a plurality of pairs of conveying rollers are arranged at each location. The pitch of the conveying roller pair is generally set in accordance with the smallest size sheet and is generally the simplest method.

  However, when a large sheet is transported in the above configuration, a transport roller other than the transport roller dedicated to the printing operation prints even though the sheet is transported by the transport roller dedicated to the printing operation during the printing operation. There is a drawback that it is involved in transport during operation. Due to this defect, there is a disadvantage that the printing is adversely affected by the difference in the conveyance speed between the two roller pairs, or the impact when the sheet comes out of one of the conveyance roller pairs becomes an instantaneous conveyance unevenness and streaks are generated. .

Therefore, for example, a technique described in Patent Document 1 is known as a technique for compensating for such a defect.
JP, 7-271126, A The technique of the above-mentioned patent documents 1 forms the conveyance guide board which curved so that a sheet may form a loose loop between upstream and downstream conveyance roller pairs, and also in the middle of a conveyance guide board Auxiliary conveyance rollers that move up and down according to the sagging and tension of the sheet are installed. As a result, a sheet having a size smaller than the distance between the upstream conveyance roller pair and the downstream conveyance roller pair can be conveyed, and the speed difference between the upstream and downstream conveyance roller pairs and the shock at the time of entry are absorbed. Therefore, uneven conveyance can be eliminated.

However, even with the above-described conventional technology, large-sized sheets can be conveyed by a single conveyance by an upstream or downstream conveyance roller pair, an upstream conveyance roller pair, a downstream conveyance roller pair, and an auxiliary roller pair. However, since conveyance by any two combinations or all three combinations is mixed, there is a risk of being affected by the mutual roller pair, which is insufficient depending on the technical field in which more accurate sheet conveyance is required. There is a problem that.
Therefore, the problem to be solved by the present invention is to realize accurate conveyance when conveying sheets of different sizes.

The present invention solves the above-described problems by the following means.
Note that, in the following means for solving, what is shown in parentheses corresponds to that in the present embodiment.
The present invention includes a pair of first conveying rollers (conveying roller 5 and auxiliary roller 6) and a pair of second conveying rollers (a pinch roller 9A and a cap) positioned on the downstream side of the sheet conveying path from the first conveying roller. A stun 10A, or a pinch roller 9B and a capstan 10B), a position where the sheet is sandwiched and a retracted position where the sheet is not sandwiched, provided near the transport path between the first transport roller and the second transport roller. A pair of intermediate rollers (roller 7 and pickup roller 8) that can be positioned at a distance between the first conveying roller and the second conveying roller are longer than the length of the conveyed sheet. A first size (14 × 17 inches), or a second size (1 that is shorter than the length between the conveyance paths of the first conveyance roller and the second conveyance roller) Size reading means (IC tag reading device 23) for reading whether the sheet is the first size by the size reading means. The first conveying roller is controlled so as to move to a position where the sheet is not sandwiched, and when the sheet is read as the second size by the size reading unit, the sheet is sandwiched by the intermediate roller. A positioning unit for positioning the sheet is provided between the conveyance path between the second conveyance roller and the second conveyance roller. When the sheet is positioned by the positioning unit, the intermediate roller is disposed at the retracted position. In addition, when the size reading unit reads the sheet size as the second size, When the positioning by the positioning unit has ended is a sheet conveying apparatus which controls so as to place the said intermediate roller nip position of the seat.

(Function)
In the above invention, whether the size of the sheet is the first size or the second size is read. In the case of the large first size, the intermediate roller is opened and the sheet is conveyed by the first conveying roller and the second conveying roller. On the other hand, in the case of the small second size, the sheet is conveyed by the first conveying roller, the intermediate roller, and the second conveying roller.

In the following embodiments, the second conveying roller corresponds to the pinch roller 9A and the capstan 10A, or the pinch roller 9B and the capstan 10B.
In addition, the positioning unit corresponds to the positioning unit 30 in the embodiment.

  According to the above invention, by providing the case where the sheet is sandwiched by the intermediate roller according to the size and the case where the sheet is not sandwiched, it is possible to carry the sheet with an appropriate roller pair according to the size of the sheet. Thereby, accurate conveyance can be performed.

Embodiments of the present invention will be described below with reference to the drawings. The sheet conveying apparatus in the present invention is applied to a thermal printer.
FIG. 1 is a diagram illustrating an outline of a printer 1 according to the present embodiment. The printer 1 is, for example, a type in which image data used in a hospital and imaged by computed tomography (CT) is printed on a sheet (film-like cut paper) by thermal transfer using a printing head 11. is there.

Further, the printer 1 can be used for both horizontal and vertical placement. For example, in FIG. 1, it can be installed both horizontally with the paper feed tray 2 on the bottom surface side and vertically with the surface side shown in FIG. 1 on the top surface side.
In the following description, the horizontal type, that is, the paper feed tray 2 side is defined as the bottom surface side of the printer 1, and the left side (folding roller 14 side) in FIG. 1 is defined as the front surface side of the printer 1.

In FIG. 1, a paper feed tray 2 storing unprinted sheet bundles is provided on the bottom surface side of the printer 1, and a paper feed roller 3 is provided so as to contact the uppermost sheet. Yes.
Moreover, in this embodiment, the sheet | seat at the time of mounting | wearing is 1 pack which bundles 125 sheets, Comprising: As shown in FIG. 1, it wraps with the protection sheet. The uppermost sheet is in contact with the paper feed roller 3. Furthermore, an IC tag is provided on the lower surface side of the protective sheet in FIG. Information on at least the sheet size (in this embodiment, either 11 × 14 inches (small size) or 14 × 17 inches (large size)) is recorded on the IC tag.

Further, an IC tag reading device 23 is provided at a position facing the IC tag, which is a housing portion of the printer 1. The IC tag reader 23 reads the IC tag of the protective sheet when a pack of sheets is loaded.
The sheet carried out by the paper feed roller 3 is nipped and conveyed by the pair of conveyance rollers 4. In addition, on the back side of the printer 1, conveyance rollers 5 provided in two upper and lower stages are provided. Further, an auxiliary roller 6 is provided on these conveying rollers 5 in order to sandwich the sheet together with the conveying rollers 5.

A roller 7 and a pickup roller 8 are provided at a position where the sheet after passing through the conveying roller 5 and the auxiliary roller 6 passes. Here, although the rotation shaft of the roller 7 is fixed, the pickup roller 8 is fixed to the frame 31 so as to be rotatable, and the frame 31 is provided so as to be rotatable in both directions around the frame shaft 31a. It has been.
Then, the frame 31 is rotated clockwise or counterclockwise in FIG. 1 with the frame shaft 31a as a fulcrum, and the conveyed sheet is nipped between the roller 7 and the pickup roller 8 or not nipped. 7 and the pickup roller 8 are opened.

  The pickup roller 8 is driven based on the reading result of the IC tag reader 23. When the reading result of the IC tag reader 23 is 11 × 14 inches (small size), the frame 31 is rotated clockwise in FIG. 1 with the frame shaft 31a as a fulcrum, and the roller 7 and the pickup roller 8 is set so that the sheet is nipped and conveyed. On the other hand, when the read result is 14 × 17 inches (large size), the frame 31 is rotated counterclockwise in FIG. 1 with the frame shaft 31a as a fulcrum, and the roller 7 and the pickup roller 8 The sheet is set open so that the sheet passes through the gap between the two.

  A positioning portion 30 is provided at a position where the roller 7 and the pickup roller 8 are provided. The positioning unit 30 positions the sheet so that the orientation of the image is not shifted and the image is not lost.

  In the position where the sheet after passing through the roller 7 and the pickup roller 8 passes, a printing head 11 is attached to the upper surface side of the sheet in FIG. The printing head 11 is attached to a head support 12 and is formed so as to be rotatable about its fulcrum. A platen roller 13 is disposed at a position facing the printing head 11 (in FIG. 1, the lower surface side of the sheet). When printing is performed, the print head 11 is pressed against the platen roller 13 with the sheet interposed therebetween by rotating the head support 12 counterclockwise in FIG.

  When the sheet passes between the print head 11 and the platen roller 13, the print head 11 prints the sheet. Although not shown in FIG. 1, an ink ribbon is disposed between the sheet and the print head 11, and the print head 11 prints on the sheet via the ink ribbon. When printing is not performed, the head support 12 is rotated clockwise in FIG. 1 to stand by at a position where the print head 11 is separated from the platen roller 13.

  Furthermore, pinch rollers 9A and 9B and capstans 10A and 10B are arranged on the upstream side and the downstream side of the printing head 11 and the platen roller 13, respectively, and the sheet is conveyed by these. As shown in FIG. 1, those provided on the upstream side of the printing head 11 are referred to as a pinch roller 9A and a capstan 10A, respectively, and those provided on the downstream side of the printing head 11 are respectively pinch rollers 9B. And the capstan 10B. When the pinch roller 9 and the capstan 10 are simply referred to, both or any one of the pinch roller 9 and the capstan 10 are indicated.

  Further, the sheet printed by the print head 11 is sent to the folding roller 14, and the folding roller 14 reverses the sheet conveyance direction by 180 degrees, and the conveyance direction is switched from the left direction to the right direction in FIG. It is done. When the sheet is further conveyed, it passes between the pinch roller 32 and the roller 34.

  Here, the rotating shaft of the roller 34 is fixed. The pinch roller 32 is rotatably attached to the frame 33. The frame 33 is provided so as to be rotatable about a fulcrum 33a. The pinch roller 32 and the roller 34 are for feeding the sheet to the density measuring unit 16 further downstream.

  When the result of reading the sheet size by the IC tag reader 23 is 11 × 14 inches (small size), the frame 33 is rotated counterclockwise in FIG. 1 about the fulcrum 33a, It is set so that the sheet is nipped and conveyed by the pinch roller 32 and the roller 34. On the other hand, when the reading result is 14 × 17 inches, the frame 33 is rotated clockwise in FIG. 1 around the fulcrum 33a to open the space between the pinch roller 32 and the roller 34. It is set so that the sheet passes through the gap between them.

  A density measuring unit 16 is provided further downstream of the pinch roller 32 and the roller 34. The density measuring unit 16 checks the print density with a density measuring device and monitors the state of image quality. The density measurement unit 16 includes a conveyance roller 16 similar to the conveyance roller 5 and two auxiliary rollers 17 (two locations above and below the conveyance roller 16 in FIG. 1) in contact with the conveyance roller 16. The conveying roller 16 and the two auxiliary rollers 17 are configured so that the sheet is reversed 180 degrees again.

  A pair of upper and lower conveying rollers 18 are provided on the downstream side after the sheet passes through the density measuring unit 16. A sheet discharge tray 19 is provided for storing the sheet that has passed through the conveying roller 18. The paper discharge tray 19 is located above the paper feed tray 2 described above.

Next, driving of the pickup roller 8 and the pinch roller 32 will be described.
FIG. 2 is a perspective view showing a mechanism unit including the pickup roller 8 and the pinch roller 32. 3 and 4 are side views thereof. In FIGS. 3 and 4, in order to facilitate understanding of the drawings, some gears, rollers, and the like are illustrated by solid lines even if they are invisible.

  In FIG. 2, the motor 40 is a motor that is a drive source for the pickup roller 8 and the pinch roller 32. A belt wheel 41 is fixed to the rotation shaft of the motor 40. On the other hand, a belt wheel 43 is provided in the vicinity thereof, and the belt 42 is hung between the belt wheels 41 and 43. A belt wheel 44 is provided coaxially with the belt wheel 43. Further, a belt wheel 46 is provided in the vicinity of the belt wheel 44. A belt 45 is put between the belt wheels 44 and 46.

Further, the belt wheel 45 is provided with a gear 47 coaxially. A gear 48 that meshes with the gear 47 is also provided. Furthermore, a gear 49 is provided coaxially with the gear 48 (see FIGS. 3 and 4).
Further, the gear 50 and the gear 51 are provided coaxially, and the gear 49 and the gear 50 are engaged with each other. Further, a gear 52 that meshes with the gear 50 is provided, and a gear 53 is provided coaxially with the gear 52. The gear 53 and the gear 54 are engaged with each other.

Furthermore, as shown in FIG. 2, the gear 54 is provided coaxially with the pickup roller 8. The gear 54 and the pickup roller 8 are rotatably attached to the frame 31. Further, as described above, the frame 31 is attached so as to be rotatable about the frame shaft 31a.
Further, as described above, in FIG. 2, the frame 33 is provided so as to be rotatable about the fulcrum 33a. Further, a pinch roller 32 is rotatably attached to one end side of the frame 33.
Further, a spring 56 is attached to the frame 33, and the frame 33 is urged counterclockwise in FIGS. 2 to 4 about the fulcrum 33a.

  On the other hand, rollers 57 are rotatably attached to the left and right ends of the frame 31. Then, when the frame 31 rotates counterclockwise in FIGS. 2 to 4, the roller 57 attached to the frame 31 comes into contact with the frame 33. When the frame 31 further rotates counterclockwise, the roller 57 pushes the frame 33 and rotates the frame 33 clockwise in FIGS. 2 to 4 against the urging force of the spring 56.

  When the frame 31 is rotated clockwise in FIGS. 2 to 4, the pickup roller 8 rotates to a position where it contacts the roller 7 (position shown in FIG. 4). Furthermore, at this time, as shown in FIG. 4, the contact between the frame 33 and the roller 57 is released, and the frame 33 is urged counterclockwise in FIG. The roller 32 stops at a position where it contacts the roller 34.

  That is, when the frame 31 is rotated to a position where the pickup roller 8 contacts the roller 7, the frame 33 is rotated to a position where the pinch roller 32 contacts the roller 34. Therefore, on the contrary, when the pickup roller 8 moves to a position away from the roller 7, the pinch roller 32 also moves to a position away from the roller 34 (FIG. 3).

As described above, the operations of the pickup roller 8 and the pinch roller 32 can be provided at a low cost with a simple structure, and the operation is a series of flows. Therefore, a mechanical control sensor is not required, and a malfunction or device due to erroneous detection can be obtained. Can prevent damage.
In addition, since the pickup roller 8 and the pinch roller 32 share power, not only the parts cost and manufacturing cost are reduced, but also the mechanism is simplified, so that stable quality with few malfunctions and failures can be achieved. Can be provided.

  Furthermore, as shown in FIG. 2, a torque limiter 55 is provided coaxially with the pickup roller 8. The torque limiter 55 rotates the frame 31 without rotating the gear 54 when a rotational force equal to or less than a predetermined force is transmitted to the gear 54 and transmits a rotational force exceeding the predetermined force to the gear 54. When rotating, the gear 54 is rotated.

That is, when the rotational force acting on the gear 54 is below a certain force, the gear 54 does not rotate and the frame 31 is rotated clockwise in FIGS. 2 to 4 about the frame shaft 31a. As a result, the frame 31 is moved to a position where the pickup roller 8 and the roller 7 come into contact (position shown in FIG. 4).
When the rotational force is further transmitted to the gear 54 after the pickup roller 8 and the roller 7 are brought into contact with each other, the rotational force exceeds the predetermined force, and the gear 54 and the pickup roller 8 are connected via the torque limiter 55. Rotate.

In the above configuration, the operation when the IC tag reader 23 reads a small size sheet (11 × 14 inches) will be described.
In FIG. 1, the printer 1 rotates the paper feed roller 3 counterclockwise to carry out one sheet from the paper feed tray 2. When the sheet continues to be conveyed, the sheet is nipped and conveyed by the conveying roller 5 and the auxiliary roller 6. At this time, the pickup roller 8 is separated from the roller 7 and stands by at a position where the space between the pickup roller 8 and the roller 7 is opened. Then, the conveyance of the sheet is stopped when the leading edge of the sheet passes the pickup roller 8. Note that whether or not the sheet has reached this position can be detected by, for example, a sheet detection sensor (not shown). The positioning unit 30 positions the sheet. As described above, since the positioning is performed by opening the pickup roller 8 and the roller 7, the positioning operation can be performed accurately without obstructing.

  When the positioning is completed, the motor 40 is driven, and the motor 40 is controlled to rotate counterclockwise in FIGS. Thereby, the rotational force is transmitted to the gears 52 and 53, and the gears 52 and 53 rotate clockwise in FIG. The rotational force of the gear 52 and the gear 53 is a force that rotates the frame 31 clockwise. When the frame 31 is rotated clockwise, the pickup roller 8 comes into contact with the roller 7 (position shown in FIG. 4). Although the rotation of the frame 31 stops at this position, when the gears 52 and 53 are further rotated, the force exceeds the holding force of the torque limiter 55, and the gear 54 and the pickup roller 8 are rotated counterclockwise. Thus, the sheet is conveyed by the pickup roller 8 and the roller 7.

  When the leading edge of the sheet approaches the pinch roller 9A and the capstan 10A, the pinch roller 9A is separated from the capstan 10A and opens between both rollers. As a result, the sheet passes over the capstan 10A. Immediately after the leading edge of the sheet passes over the capstan 10A, the pinch roller 9A moves to the capstan 10A side, pinches the sheet, and the pickup roller 8 retracts from the roller 7, and the pickup roller 8 and the roller 7 Avoid pinching the sheet. Whether or not the leading edge of the sheet has passed over the capstan 10A is determined using, for example, a sheet detection sensor (not shown).

  Further, the sheet is conveyed further downstream by the pinch roller 9A and the capstan 10A. At this time, the head support 12 stands by at a position rotated clockwise in FIG. 1, and the printing head 11 is at a position away from the platen roller 13. Accordingly, the conveyed sheet passes over the platen roller 13. When the sheet is further conveyed, the sheet is sandwiched between the pinch roller 9B and the capstan 10B. Thereafter, the pinch roller 9A is separated from the capstan 10A and opens between both rollers. That is, as a result, the sheet is sandwiched only by the pinch roller 9B and the capstan 10B. Note that whether or not the sheet is sandwiched between the pinch roller 9B and the capstan 10B is determined by, for example, a sheet detection sensor as described above.

  Then, cueing of the sheet is performed. When the cueing is finished, the signal is sent to a drive unit (not shown) of the head support 12. The head support 12 is rotated counterclockwise in FIG. 1 to bring the printing head 11 into contact with the sheet. Then, the printing is performed by the printing head 11 and the sheet is controlled to be conveyed by the pinch roller 9B and the capstan 10B.

Further, when the sheet is conveyed, the conveying direction is changed to the right in FIG. When the sheet is further conveyed, the positions of the pinch roller 32 and the roller 34 are reached.
As described above, at the time of printing, the pick-up roller 8 is disposed at the retracted position with respect to the roller 7, and in conjunction with the operation, the pinch roller 32 is at the retracted position with respect to the roller 34 (pinch roller). 32 and the roller 34).

  When printing is completed, the signal is sent to the drive unit of the motor 40, and the frame 33 is rotated in the direction in which the pinch roller 32 contacts the roller. Then, the sheet is sandwiched between the pinch roller 32 and the roller 34 and conveyed. That is, the pinch roller 32 is controlled to stand by at the retracted position until the end of printing, and pinch the sheet when the printing ends. Then, as shown in FIGS. 3 and 4, the sheet is conveyed to the density measuring unit 16 by the pinch roller 32 and the roller 34 and the conveying belt 60.

Then, the density of the image printed by the density measuring unit 16 is measured, and the sheet is nipped and conveyed by the conveyance roller 16 and the auxiliary roller 17.
Further, the sheet that has passed through the conveyance roller 16 and the auxiliary roller 17 is nipped and conveyed by the conveyance roller 18 and is stored in the paper discharge tray 19.

  On the other hand, when the IC tag reading device 23 reads a large sheet (14 × 17 inches), the motor 40 is controlled to rotate clockwise in FIGS. 2 to 4. . As a result, the gears 52 and 53 rotate counterclockwise in FIG. When the rotational force is transmitted to the frame 31, the frame 31 is rotated counterclockwise in FIGS. When the frame 31 is rotated counterclockwise, the pickup roller 8 moves to the retracted position with respect to the roller 7 (position shown in FIG. 3).

Further, when the frame 31 is rotated as shown in FIG. 3, the roller 57 attached to the frame 31 comes into contact with the frame 33. As a result, the frame 33 pivots clockwise around the fulcrum 33a to the position shown in FIG. With the rotation of the frame 33, the pinch roller 32 is moved away from the roller 34 and does not come into contact with the roller 34.
The above state is maintained throughout the conveyance of a large size sheet. That is, while the large size sheet is being conveyed, the pickup roller 8 and the roller 7 and the pinch roller 32 and the roller 34 are not involved in the conveyance.

  In FIG. 1, the printer 1 rotates the paper feed roller 3 counterclockwise to carry out one sheet from the paper feed tray 2. When the sheet continues to be conveyed, the sheet is nipped and conveyed by the conveying roller 5 and the auxiliary roller 6. Similarly to the above, when the leading edge of the sheet reaches the capstan 10A (the position where the trailing edge of the large size sheet has passed through the conveyance roller 5 and the auxiliary roller 6, in other words, the large size sheet is conveyed to the conveyance roller 5). The positioning unit 30 positions the sheet at a position where the sheet can be conveyed by the auxiliary roller 6.

  When the positioning is completed, the leading edge of the sheet approaches the capstan 10A. At this time, the pinch roller 9A is located away from the capstan 10A and opens between the two rollers. Thereafter, the pinch roller 9A is moved to the capstan 10A side, and the pinch roller 9A and the capstan 10A sandwich the sheet and convey it. The print head 11 and the platen roller 13 are also opened, and the sheet passes between them.

  When the leading edge of the sheet is conveyed to the position of the pinch roller 9B and the capstan 10B on the downstream side of the printing head 11, the sheet is pinched by the pinch roller 9B and the capstan 10B. Thereafter, the pinch roller 9A is again moved away from the capstan 10A, and the space between the pinch roller 9A and the capstan 10A is released. That is, as a result, the sheet is held only by the pinch roller 9B and the capstan 10B. In this state, the cueing of the sheet is performed.

  When the cueing is finished, the signal is sent to a drive unit (not shown) of the head support 12. The head support 12 is rotated counterclockwise in FIG. 1 to bring the printing head 11 into contact with the sheet. Then, the printing is performed by the printing head 11 and the sheet is controlled to be conveyed by the pinch roller 9B and the capstan 10B.

Further, when the sheet is conveyed, the conveying direction is changed to the right in FIG. When the sheet is further conveyed, the positions of the pinch roller 32 and the roller 34 are reached.
As described above, when printing a large sheet, since the space between the pinch roller 32 and the roller 34 is open, the sheet passes through this space.
When the sheet is further conveyed, the sheet is nipped and conveyed by the conveying roller 16 and the auxiliary roller 17. At the same time, the density of the image printed by the density measuring unit 16 is measured.
Further, the sheet that has passed through the conveyance roller 16 and the auxiliary roller 17 is nipped and conveyed by the conveyance roller 18 and is stored in the paper discharge tray 19.

  As described above, in the present embodiment, the position where the sheet is held and the position where the sheet is not held can be taken by moving the position of the pickup roller 8 or the pinch roller 32 according to the forward / reverse rotation of the motor 40. it can. During printing, since the sheet is conveyed only by the pinch roller 9B and the capstan 10B on the downstream side of the printing head 11, the conveyance speed can be kept constant. In addition, during sheet conveyance, the sheet is sandwiched between only the roller pairs necessary for conveyance, and unnecessary rollers are opened, preventing momentary conveyance irregularities when bridging between the rollers. can do. Furthermore, it is possible to prevent the impact when the sheet comes out between the rollers from adversely affecting the printing.

  Further, since the sheet is positioned with the pair of rollers open, accurate positioning can be performed. Furthermore, when the sheet is cued, the sheet is sandwiched only by the pinch roller 9B and the capstan 10B, so that accurate cuing can be performed.

  In this embodiment, the case where the sheet is clamped and the case where the sheet is not clamped by the protrusion and retraction of the pickup roller 8 is provided. However, the present invention is not limited to this, and it is conceivable to control the power of the pickup roller 8 by connecting / disconnecting the power with a clutch or the like. However, even if the influence due to the speed difference between the mutual rollers can be eliminated, since the influence on the impact when the sheet comes out remains as a problem, in this embodiment, the pickup roller 8 is projected and retracted. .

The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications such as the following can be made.
(1) In the present embodiment, gears and belts are used as means for transmitting the driving force of the driving source (motor 40). However, the present invention is not limited to this. For example, a rubber roller that transmits driving force by frictional force is used. May be.

  (2) Further, as shown in FIG. 2, one pickup roller 8 and two pinch rollers 32 are provided. However, the number is not limited to this, and any number may be used depending on the material and width of the sheet used. Can be set.

  (3) Furthermore, in this embodiment, an IC tag is provided on the sheet, and the IC tag reader 23 reads the size information of the sheet described in the IC tag. For example, a barcode is attached to the sheet, It is possible to use means other than the IC, such as reading the sheet size with a barcode reader.

  Further, for example, when an IC tag can be provided for each sheet, the IC tag reader 23 reads the size for each sheet, and positions the pickup roller 8 with respect to the roller 7 and the pinch roller 32 with respect to the roller 34. May be switched. Switching of the position of the pickup roller 8 relative to the roller 7 may be performed at any time as long as the leading edge of the sheet reaches the position of the roller 7 and the pickup roller 8.

  (4) In the present embodiment, the IC tag is read before the sheet is conveyed. However, the present invention is not limited to this, and it may be read until the leading edge of the sheet exceeds the pickup roller 8.

  (5) Furthermore, in the present embodiment, the paper discharge tray 19 is disposed on the upper surface side of the paper feed tray 2. However, the paper discharge tray 19 is not necessarily provided, and the upper surface space of the paper feed tray 2 may only be used as a sheet discharge position.

  (6) Furthermore, in the present embodiment, a thermal printer is taken as an example of a printer, but the present invention can be applied to various printers such as an electrophotographic printer and an inkjet printer.

1 is a diagram illustrating an outline of a printer according to an embodiment. It is a perspective view which shows the mechanism part containing a pick-up roller and a pinch roller. It is a side view which shows the mechanism part containing a pick-up roller and a pinch roller, and shows the state which the roller and the pick-up roller contacted. It is a side view which shows the mechanism part containing a pick-up roller and a pinch roller, and shows the state which the pick-up roller left | separated with respect to the roller.

Explanation of symbols

5 Transport roller (first transport roller)
6 Auxiliary roller (first transport roller)
7 Roller (intermediate roller)
8 Pickup roller (intermediate roller)
9A Pinch roller (second transport roller)
9B Pinch roller (third transport roller)
10A capstan (second transport roller)
10B Capstan (third transport roller)
11 Printing head 23 IC tag reader (size reading means)
30 Positioning unit 32 Pinch roller (other transport rollers)

Claims (1)

A pair of first transport rollers;
A pair of second conveying rollers located on the downstream side of the sheet conveying path from the first conveying rollers;
A pair of intermediate rollers provided in the vicinity of a conveyance path between the first conveyance roller and the second conveyance roller and capable of being positioned at a position where the sheet is nipped and a retreat position where the sheet is not nipped;
The size of the sheet to be conveyed is a first size having a length greater than or equal to the length between the conveyance paths of the first conveyance roller and the second conveyance roller, or the first conveyance roller and the second conveyance roller Size reading means for reading whether the second size is shorter than the length between the transport paths of
When the sheet is read as the first size by the size reading unit, the intermediate roller is controlled to move to a position where the sheet is not sandwiched, and
When the size reading unit reads the sheet as the second size, the sheet is controlled to be sandwiched by the intermediate roller ,
Between the conveyance path between the first conveyance roller and the second conveyance roller, a positioning unit for positioning the sheet is provided,
When the sheet is positioned by the positioning unit, the intermediate roller is arranged at the retracted position, and when the size reading unit reads the sheet size as the second size, the positioning unit When the positioning is completed, control is performed so that the intermediate roller is disposed at the sheet holding position.
Sheet conveying device .

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