JP2007230691A - Medium carrying mechanism and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a medium carrying mechanism capable of excellently carrying a medium without causing looseness in paper. <P>SOLUTION: A pull-up roller mechanism 20 is arranged substantially above a platen 3, and the pull-up roller mechanism 20 has a frame 21, an ejecting roller 22 and an upper cover 23. An energizing member 29 is installed in the upper cover 23, and the energizing member 29 abuts on mold rollers 26a and 26b having the same axes and the same diameter with those of the ejecting roller 22. The energizing member 29 is installed at an angle almost in parallel in an ideal carrying passage of the paper. A ribbon protector 30 is arranged between the platen 3 and a printing head 2, and its tip 30a is extended, and formed so as to immediately introduce the printed part between the ejecting roller 22 and the energizing member 29. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a medium transport mechanism that transports a medium on which printing is performed, and an image forming apparatus having the medium transport mechanism.

  2. Description of the Related Art Conventionally, in a printer device as an image forming apparatus, printing is performed by providing a medium transport mechanism that transports a medium before and after a print unit including a print head and a platen. FIG. 9 is a schematic side view showing a conventional printer apparatus. In FIG. 9, the printer apparatus 1 is provided with a print head 2 and a platen 3 facing each other. The print head 2 is mounted on a carriage 4, the carriage 4 is slidably supported on a carriage shaft 5, and the rear end portion of the carriage 4 is slidably supported by a carriage guide 6. The carriage 4 is guided by a carriage guide 6 and moves along the carriage shaft 6 during printing.

  A pin tractor 7 is provided at the rear part (right side) of the platen 3, and a medium guide 8 and a conveying roller 9 are provided at the lower part of the platen 3. A ribbon protector 10 is provided between the print head 2 and the platen 3. The ribbon protector 10 is fixed to the carriage 4.

  A pull-up roller mechanism 11 is provided substantially above the platen 3. The pull-up roller mechanism 11 is for pulling up the printed medium above the platen 3, and includes a frame 12, a discharge roller 13 rotatably provided on the frame 12, and an upper disposed opposite to the discharge roller 13. And a cover 14. The upper cover 14 is disposed with a predetermined interval with respect to the discharge roller 13.

  Next, the operation for printing on the medium will be described. Here, a case where printing is performed on continuous paper as a medium will be described. The continuous paper 15 is conveyed in the direction of the medium guide 8 by the pin tractor 7, and the continuous paper 15 enters between the print head 2 and the platen 3 by the rotation of the platen 3 and the conveyance roller 9. Here, printing is performed by the print head 2, and then the continuous paper 15 is further conveyed upward.

  The continuous paper 15 after printing is guided by the ribbon protector 10 and enters the pull-up roller mechanism 11. When the continuous paper 15 enters between the discharge roller 13 and the upper cover 14, the continuous paper 15 is further conveyed upward by the rotation of the discharge roller 13 and discharged. This completes the printing operation.

  In order to press the continuous paper 15 against the discharge roller 13, the upper cover 14 is provided with a curved portion 14 a formed in accordance with the outer shape of the discharge roller 13 and protrusions 14 b and 14 c formed on both sides of the curved portion 14 a. ing. By forming these protrusions 14b and 14c, the continuous paper 15 is pressed against the discharge roller 13, the discharge roller 13 obtains a feed force by this pressing force, and the continuous paper 15 is conveyed in the forward direction. .

An example of this type of printer is disclosed in Japanese Patent Application Laid-Open No. 11-227291.
Japanese Patent Laid-Open No. 11-227291

  However, in the above-described conventional printer apparatus, a predetermined gap is provided between the discharge roller 13 of the pull-up roller mechanism 11 and the upper cover 14, so that the discharge roller 13 rubs the back surface of the medium and generates slack. It also plays a role in preventing this. In this case, in order to prevent slack appropriately, the interval between the discharge roller 13 and the upper cover 14 needs to be accurately maintained.

  If the distance between the discharge roller 13 and the upper cover 14 is not maintained at a predetermined value due to the quality of the parts at the time of manufacture, the feed force changes, which causes slack in the medium. For example, if the interval is wider than a predetermined value, a sufficient feed force cannot be obtained, and the medium becomes slack. On the other hand, if the interval is narrower than the predetermined value, the feed force becomes too large, and there is a problem that a gap is generated particularly in continuous paper. Referring to FIG. 9, the hole galling is a phenomenon in which when the continuous paper 15 is strongly pulled by the discharge roller 13, the upstream side of the feed hole of the continuous paper 15 engaged with the pin of the pin tractor 7 rises.

  SUMMARY An advantage of some aspects of the invention is that it provides a medium transport mechanism that can satisfactorily transport without causing slack in the medium.

  In order to solve the above-described problems, the present invention provides a medium transport mechanism that includes a roller and a guide member that is positioned downstream of a printing unit that performs printing on a medium and is opposed to the roller at a predetermined interval. An urging member for urging the medium in the direction of the roller and a positioning member for positioning the urging member so as to be substantially in the tangential direction of the roller are provided.

  The present invention also provides a first guide member that is disposed along the outer periphery of the platen in the printing unit and guides the medium in the downstream direction, a roller that is provided downstream of the printing unit and that conveys the medium, and the roller. In the medium transport mechanism having the second guide member disposed opposite to the medium at a predetermined interval, the leading end of the first guide member is extended so that the medium can be guided to the vicinity of the roller. It is what.

  According to the present invention, the biasing member for biasing the medium in the direction of the roller and the positioning member for positioning the biasing member so as to be substantially in the tangential direction of the roller are provided. It can be transported well.

  In addition, since the tip of the first guide member that guides the medium in the downstream direction from the printing unit is extended to the vicinity of the roller, it is possible to prevent the medium from being slackened between the printing unit and the roller. Become.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Elements common to the drawings are denoted by the same reference numerals. FIG. 1 is a side view showing a medium transport mechanism according to a first embodiment of the present invention. In each embodiment described below, a pull-up roller mechanism will be described as an example of the medium transport mechanism.

  In FIG. 1, the pull-up roller mechanism 20 according to the first embodiment includes a frame 21, a discharge roller 22 rotatably provided on the frame 21, and an upper cover 23 disposed to face the discharge roller 22. Have. The frame 21 is provided on the upper part of the platen, and a plurality of discharge rollers 22 are provided on the frame 21 so as to be rotatable, as shown in FIG. FIG. 2 is a perspective view showing the frame.

  In FIG. 2, the shafts 24 of the discharge rollers 22 a, 22 b, and 22 c are rotatably supported by the support portion 25 of the frame 21. Mold rollers 26a and 26b are provided adjacent to the discharge roller 22b and the discharge roller 22c. The mold rollers 26a, 26b are attached to the shaft 24, are formed of plastic, and have the same diameter as the discharge rollers 22a, 22b, 22c.

  In FIG. 1, a plurality of ribs 27 are formed on the upper cover 23. A curved portion 28a formed on the rib 27 in a portion facing the discharge roller 22 in accordance with the outer shape of the discharge roller 22, and a curved portion 28a. Protrusions 28b and 28c formed on both sides are provided. The upper cover 23 is provided with a biasing member 29 that presses the printed paper against the discharge roller 22. FIG. 3 shows the biasing member.

  The urging member 29 is formed of a Mylar film having a thickness of about 0.3 mm, and includes a mounting portion 30 and a guide portion 31 as shown in FIG. 3, and the guide portion 31 has a trapezoidal shape with a thin tip portion. Yes. The attachment portion 30 is fixed to the upper cover 23, and the back surface 31a of the guide portion 31 is in contact with the above-described mold rollers 26a and 26b. That is, the urging member 29 is provided at two locations facing the mold rollers 26a and 26b, and the back surfaces 31a of the respective guide portions 31 are in contact with the mold rollers 26a and 26b. At this time, the urging member 29 is in contact with the mold rollers 26a and 26b with a preset appropriate urging force.

  An angle formed between a tangent L (shown in FIG. 4) formed when the biasing member 29 contacts the mold rollers 26 a and 26 b and a direction in which the medium 15 enters between the discharge roller 22 and the biasing member 29. θ is set to a predetermined angle (for example, 10 °) or less. That is, the approach direction of the guide portion 31 of the urging member 29 and the medium 15 is set to be substantially parallel. FIG. 4 is a schematic side view showing the main part of the first embodiment.

  Below the pull-up roller mechanism 20, the print head 2 and the platen 3 are provided to face each other. The print head 2 is mounted on a carriage 4, the carriage 4 is slidably supported on a carriage shaft 5, and the rear end portion of the carriage 4 is supported by a carriage guide 6. The carriage 4 is guided by a carriage guide 6 and moves along the carriage shaft 6 during printing.

  A pin tractor 7 is provided at the rear part (right side) of the platen 3, and a medium guide 8 and a conveying roller 9 are provided at the lower part of the platen 3. A ribbon protector 32 is provided between the print head 2 and the platen 3. The ribbon protector 32 prevents the contact between the medium 15 and an ink ribbon (not shown) and guides the medium 15 toward the discharge roller 22 of the pull-up roller mechanism 20 and is fixed to the carriage 4.

  The tip 32a of the ribbon protector 32 extends in the direction of the discharge roller 22 of the pull-up roller mechanism 20 as compared with the conventional ribbon protector 10 shown in FIG. That is, after the medium 15 passes through the leading end portion 32 a of the ribbon protector 32, the leading end portion 32 a is extended to a position where the medium 15 enters between the discharge roller 22 and the urging member 29.

  Next, the operation of the first embodiment will be described. Here, a case where printing is performed on continuous paper as a medium will be described. In FIG. 1, the continuous paper 15 is conveyed in the direction of the medium guide 8 by the pin tractor 7, and the continuous paper 15 enters between the print head 2 and the platen 3 by the rotation of the platen 3 and the conveyance roller 9. Here, printing is performed by the print head 2, and then the continuous paper 15 is further conveyed upward.

  The continuous paper 15 after printing is guided by the ribbon protector 32 and enters the upper pull-up roller mechanism 20. At this time, as shown in FIG. 4, the continuous paper 15 is guided by the leading end 32 a of the ribbon protector 32 and enters between the discharge roller 22 of the pull-up roller mechanism 20 and the urging member 29 provided on the upper cover 23. To do. Since the urging member 29 is in contact with the mold rollers 26a and 26b having the same diameter as the discharge roller 22, the continuous paper 15 that has entered the pull-up roller mechanism 20 does not loosen, Directly enters between the discharge rollers 22, and after contacting the discharge rollers 22, the continuous paper 15 is further conveyed upward by the rotation of the discharge rollers 22.

  Here, a conventional paper conveyance path will be described. FIG. 5 is an operation explanatory view showing a conventional paper conveyance path. In FIG. 5, the ribbon protector 10 has a tip portion 10a shorter than the ribbon protector 32 of the present embodiment. After the continuous paper 15 passes through the leading end 10 a of the ribbon protector 10, it proceeds upward, hits the lower end 14 a of the upper cover 14, and then proceeds in the direction of the discharge roller 13.

  That is, after passing through the ribbon protector 10, the continuous paper 15 is slack because it does not go straight to the discharge roller 13. Further, when the continuous paper 15 hits the lower end portion 14 a of the upper cover 14, the conveying operation of the continuous paper 15 is stopped, and this also causes the continuous paper 15 to be slack.

  On the other hand, in the present embodiment, as shown in FIG. 4, the continuous paper 15 directly enters between the biasing member 29 and the discharge roller 22, so that slack is generated until the continuous paper 15 contacts the discharge roller 22. There is nothing to do. Also, if the continuous paper 15 hits the back surface of the guide portion 31 of the biasing member 29 before entering the space between the biasing member 29 and the discharge roller 22, the guide portion 31 of the biasing member 29 as described above. And the angle θ formed by the straight line between the tip 32a of the ribbon protector 32, the urging member 29 and the contact portion between the mold rollers 26a and 26b is set to a predetermined angle or less, that is, the urging member 29, and the straight line between the tip portion 30a of the ribbon protector 30, the urging member 29 and the contact portion of the mold rollers 26a and 26b is almost parallel, so the continuous paper 15 is a guide for the urging member 29. There is almost no loosening until the continuous paper 15 reaches the discharge roller 22 in contact with the portion 31 so as to slide, and the conveyance of the continuous paper 15 is not stopped.

  Further, since the urging member 29 is in contact with the outer peripheral surfaces of the mold rollers 26 a and 26 b having the same diameter as the discharge roller 22, the urging member 29 does not push the continuous paper 15 from the discharge roller 22 toward the axis 24. Therefore, no slack is caused by pulling up the pushed up continuous paper 15 to the outer periphery of the discharge roller 22.

  As described above, in the first embodiment, the urging member 29 is brought into contact with the outer peripheral surfaces of the mold rollers 26 a and 26 b having the same diameter as the discharge roller 22, and the leading end portion 32 a of the ribbon protector 32 is extended. Therefore, it is possible to prevent the medium from slacking until the medium reaches the discharge roller 22, and it is possible to prevent printing deviation and perform good printing.

  Next, a second embodiment will be described. FIG. 6 is a perspective view showing a main part of the pull-up roller mechanism of the second embodiment. In FIG. 6, the pull-up roller mechanism 40 of the second embodiment has a frame 21 as in the first embodiment, and discharge rollers 22a, 22b, and 22c are rotatably provided on the frame 21. It has been. In the vicinity of the discharge roller 22b and the discharge roller 22c, a pair of columnar ribs 41 and 42 are provided with the shaft 24 therebetween.

  FIG. 7 is a side view showing the rib and the discharge roller. As shown in FIG. 7, the ribs 41 and 42 are provided on both sides of the shaft 24 of the discharge roller 22 on the upstream side and the downstream side in the paper transport direction. The upper ends 41a and 42b of the ribs 41 and 42 are respectively formed on inclined surfaces, and the guide portion 31 of the biasing member 29 is in contact with the inclined surfaces. And the inclination angle of the guide part 31 at the time of contact | abutting and the inclination angle of rib upper end part 41a, 42b correspond. When the guide portion 31 comes into contact, the back surface 31a of the guide portion 31 is in the tangential direction of the discharge roller 22 (as viewed from the side surface).

  That is, in the state where the urging member 29 is disposed, the guide portion 31 of the urging member 29 is in contact with the upper end portions 41a and 42b of the ribs 41 and 42 as shown in FIG. There is no contact. However, when viewed from the side, the back surface 31 a of the guide portion 31 of the biasing member 29 is disposed in the tangential direction of the discharge roller 22. The urging member 29 is in contact with the upper end portions 41a and 42b of the ribs 41 and 42 with a predetermined urging force, as in the first embodiment. Other configurations are the same as those of the first embodiment. The mounting angle of the urging member 29, that is, the angle when contacting the upper end portions 41a and 42b of the ribs 41 and 42 is the same as that in the first embodiment.

  Next, the operation of the second embodiment will be described. FIG. 8 is a side view showing the conveying operation of the second embodiment. In FIG. 8, the continuous paper 15 after printing is guided by the ribbon protector 32 and enters the upper pull-up roller mechanism 40. At this time, the continuous paper 15 is guided by the leading end portion 32 a of the ribbon protector 32, enters between the leading end portion 41 a of the rib 41 of the pull-up roller mechanism 40 and the urging member 29 provided on the upper cover 23, and further discharged. It enters between the roller 22 and the biasing member 29.

  Since the urging member 29 is provided on the tangent line of the discharge roller 22, the continuous paper 15 having entered the pull-up roller mechanism 40 is conveyed along the arrangement direction of the guide portion 31 of the urging member 29, Therefore, it enters directly between the urging member 29 and the discharge roller 22 without causing slack. After contacting the discharge roller 22, the continuous paper 15 is conveyed further upward along the arrangement direction of the guide portion 31 of the urging member 29 by the rotation of the discharge roller 22.

  As described above, according to the second embodiment, the urging member 29 is disposed in contact with the upper end portions 41 a and 42 b of the ribs 41 and 42 so as to be in the tangential direction of the discharge roller 22. Since the leading end portion 32a of the ribbon protector 32 is stretched, it is possible to prevent the medium from slacking until the medium reaches the discharge roller 22, and to prevent printing deviation. Printing can be performed.

  In the second embodiment, the ribs 41 and 42 are provided on both the upstream side and the downstream side in the transport direction of the discharge roller 22. However, even if the rib 41 is provided only on the upstream side, the slack of the medium is generated. Can be prevented. However, the urging member 29 can be stably disposed by providing it on both the upstream side and the downstream side as in the second embodiment.

  In each of the above-described embodiments, the impact type printer device has been described as an example. However, the present invention is not limited to this, and in another type of printer device, for example, an image forming apparatus such as a non-impact printer. The present invention can also be applied to a medium transport mechanism.

It is a schematic side view which shows the pull-up roller mechanism of 1st Embodiment. It is a perspective view which shows a flame | frame. It is a perspective view which shows a biasing member. It is a schematic side view which shows the principal part of 1st Embodiment. FIG. 10 is an operation explanatory diagram illustrating a conventional paper conveyance path. It is a perspective view which shows the principal part of the pull-up roller mechanism of 2nd Embodiment. It is a side view which shows a rib and a discharge roller. It is a side view which shows the conveyance operation of 2nd Embodiment. It is a schematic side view which shows the conventional printer apparatus.

Explanation of symbols

3 Platen 20, 40 Pull-up roller mechanism 22 Discharge roller 26a, 26b Mold roller 29 Energizing member 30 Ribbon protector 41, 42 Rib

Claims (8)

In a medium transport mechanism that is provided downstream of a printing unit that performs printing on a medium and includes a roller and a guide member that is disposed to face the roller at a predetermined interval.
A biasing member that biases the medium toward the roller;
And a positioning member for positioning the urging member so as to be substantially in a tangential direction of the roller.   The medium conveying mechanism according to claim 1, wherein the biasing member is disposed at an angle close to an angle at which the medium enters the roller.   The medium conveying mechanism according to claim 1, wherein the positioning member is a roller-shaped member that is provided coaxially with the roller and has a diameter approximately equal to that of the roller.   The medium conveying mechanism according to claim 1, wherein the positioning member is a columnar member erected at a predetermined height.   The medium conveying mechanism according to claim 4, wherein the columnar member has an inclined surface at an upper end, and an inclination angle of the inclined surface coincides with an arrangement angle of the urging member. A first guide member disposed along the outer periphery of the platen in the printing unit and guiding the medium in the downstream direction; a roller provided downstream of the printing unit for conveying the medium; and a predetermined distance from the roller In the medium transport mechanism having the second guide member disposed opposite to
A medium transport mechanism, wherein a tip end portion of the first guide member is extended so that the medium can be guided to the vicinity of the roller. A biasing member that biases the medium toward the roller;
The medium conveying mechanism according to claim 6, further comprising a positioning member that positions the urging member so as to be substantially in a tangential direction of the roller.   An image forming apparatus comprising the medium transport mechanism according to claim 1.

Images