JP2007290310A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that backfeeding such a medium as a thin rolled sheet causes an oblique direction force generated at an end of the sheet to exceed the stiffness of the medium to make the medium start folding from its end, and the medium run on a width regulating guide, or the medium itself be folded or bent. <P>SOLUTION: A loop shape which is made of a sheet temporarily raised by a sticky cleaning roller arranged on a peripheral surface of either of a pair of rollers, is abutted on the right and left width regulating guide. Thus, the stiffness of the sheet at its end is utilized in the loop shape, and thereby a repulsive force stronger than that of stiffness of the ordinary sheet, and the oblique direction force remaining at a sticky part is also modified by abutting the loop shape on a protrusion to separate it from the sticky roller. The problem is then solved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using a strip-like sheet, a roll-like sheet, or a hard plate that requires back-feeding of a recording medium and that removes skew during back-feeding.

  Conventionally, in a printer that uses a thin roll sheet or strip-shaped sheet as a recording medium, when the recording medium is transported in the normal printing direction, the speed of the roller pair on the downstream side is rotated faster to pull the recording medium in the transport direction. The method of stabilizing the conveyance behavior during printing on the recording medium was used.

  Also, when it is necessary to back-feed the medium during multi-color printing, the roll sheet or strip sheet is sent in the direction in which the sheet is pushed in contrary to the time of feeding. Begin skewing in either direction.

  At this time, a method is used in which the sheet is guided by the left / right width regulation guide used in the image forming apparatus of the present invention to prevent skewing.

As for the roll-shaped sheet, as described in JP-A-7-47670 (FIGS. 2 to 5), the roll is set on a shaft portion installed outside the main body, and conveyed when backfeeding. By releasing the pressure of the system roller pair and applying a winding drive to this shaft, the apparatus main body configuration is such that the influence of skewing due to the pushing-in at the time of back feed does not occur.
JP 7-47670 A

  However, for a thin medium with a recording medium thickness of about 100μ, the oblique force generated at the end of the recording medium starts to bend from the end of the recording medium, and runs over the width regulation guide. There is a problem that the medium itself is bent or bent.

  Further, in the apparatus using the configuration described in the prior art and Japanese Patent Application Laid-Open No. 7-47670, the roll is arranged outside the apparatus, so that the size of the main body is inevitably increased, and the roll shaft must be directly rotated. In other words, the diameter of the paper tube of the roll paper was determined, and the medium to be used was limited, or there was a problem that a mechanism that could be adjusted to any shaft diameter had to be added. .

  According to the first aspect of the present invention, a print head for forming an image on a recording medium, means for forming an image on the recording medium, conveying means for conveying the recording medium by a pair of rollers, and conveying the recording medium in forward and reverse directions A control unit, a configuration in which a recording medium is pressed and separated by a pair of rollers in a conveying unit, a cleaning roller having an adhesive on the outer peripheral surface of one of the rollers, and the vicinity of the roller pair In the image forming apparatus provided with a regulation guide capable of moving the recording medium in the width direction parallel to the conveyance direction, the recording medium is contacted and separated multiple times so as to form a loop shape due to the adhesiveness of the roller, Further, an image forming apparatus characterized in that a protrusion member is provided in the width regulating guide or in the vicinity of the guide toward the inside in the width direction of the recording medium.

  According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the protrusion provided on the width regulating guide itself or in the vicinity of the guide contacts the movement locus when the cleaning roller is in contact with or separated from the moving roller. It is characterized by being arranged on the upstream side or the downstream side in the vicinity.

  According to a third aspect of the present invention, in the image forming apparatus of the first aspect, when the cleaning roller releases the pressure on the recording medium, the amount of movement of the cleaning roller is lower than the protrusion on the outer peripheral surface of the cleaning roller. It is characterized by moving to a high position.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the image forming means is a thermal transfer type head.

  According to the above-described configuration, it is possible to maintain straightness by inserting the operation of moving the roller up to the upper side of the projection part a plurality of times even in the case of backfeeding a thin sheet of the recording medium.

  This is because the loop shape formed by the sheet temporarily lifted by the adhesiveness of the roller can use the left and right width regulation guide and the edge of the sheet edge in a loop shape, so that a repulsive force exceeding that of a normal sheet can be obtained. In addition, the force in the skew direction remaining on the adhesive portion by being applied to the protrusion and separated from the adhesive roller can be corrected using the force of returning the loop. Thereby, it is possible to provide an image forming apparatus that is small in size and low in cost.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of an image forming apparatus according to the present invention. FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus main body using a thermal method.

Hereinafter, the configuration of the apparatus main body and the arrangement positions of the width regulating guide, the guide protrusion, the cleaning roller, etc. according to the present invention will be described in detail with reference to the drawings.
1-1 in FIG. 1 is the arrangement of the apparatus main body 1, the ribbon cassette 10, and the print medium P in the main body, and the arrangement of the width regulating guide 8, the conveyance roller pair (upstream side) 5, and the conveyance roller pair (downstream side) 7. It is a block diagram.

  The recording medium P described in 1-1 of FIG. 1 is conveyed in the direction of the recording head 2 (downstream side of the apparatus) by the conveying roller pair 5. At this time, the presence / absence of the recording medium P and the leading edge of the recording medium P are detected by the recording medium presence / absence sensor 3 and the leading edge detection sensor 4.

  The recording head 2 is brought into contact with the recording medium P in order to start printing after the leading edge of the recording medium P passes immediately below the recording head 2. At this time, as shown in FIG. The ribbon 11 is sandwiched between the recording head 2 and the recording medium P. After printing, the ribbon 11 is forcibly separated from the recording medium P, and the printed ink ribbon is wound around the winding core 12 of the ribbon cassette 10. The color image is completed.

  Thereafter, the recording medium P is back-fed and returned to the printing start position, and printing of the second color is started. By repeating this as necessary, printing is completed.

  Among the operations described above, during the back feed operation of the recording medium P, the operation of temporarily releasing the pressure of the conveying roller pair (upstream side) 5 and the conveying roller pair (downstream side) 7 is added a plurality of times. In particular, the conveying roller 5 arranged on the upstream side of the print head 2 is provided with an adhesive cleaner roller 6 for cleaning the surface of the recording medium P before printing (FIG. 3). The width restricting guide 8 disposed in the left and right has protrusions 9 on the left and right sides, and the recording medium P is lifted up by the adhesive cleaner roller 6 when the pressure is released.

  Here, since the recording medium P forms a loop inside the width regulating guide 8 as described in 4-1 of FIG. 4, the force in the oblique direction is described as shown in 4-2 of FIG. The left and right end loops of the recording medium P act in a three-dimensional manner on the width regulating guide 8 with respect to the recording medium P that has been back-fed with D added thereto. A force greater than the repulsive force at the end of the seat can be obtained, and it is re-regulated in the straight direction.

  Further, as shown in FIG. 5, the force D in the oblique direction of the recording medium P remains as it is at the portion attached to the adhesive portion of the cleaner roller 6, so that the protruding portion 9 installed on the width regulating guide 8. Is forced to peel off from the cleaner roller 6 and return to the conveying path.

  As a result, even if the recording medium P is thin and weak, it is possible to cancel all the forces in the skew direction remaining between the adhesive portion of the cleaner roller 6 and the recording medium P, thereby reducing the size of the apparatus. In addition, cost reduction can be promoted.

  Another embodiment is shown in FIG. In FIG. 6, the protrusions 9 described in the first embodiment are arranged on both the upstream and downstream sides of the conveying roller pair (upstream side) 5.

1-1 External view showing the main body 1-2 Cross-sectional view showing the main body configuration (when the cover is open) Enlarged sectional view of the head during printing Diagram explaining the cross section of the transport path 4-1 A diagram explaining a medium loop when releasing pressure 4-2 A cross-sectional view explaining a skew state of a recording medium Detailed view of pressure-sensitive adhesive roller release of the present invention The figure which showed Example 2 about this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body 2 ... Recording head 3 ... Recording medium presence sensor 4 ... Top sensor 5 ... Conveying roller pair (upstream side)
6 ... Cleaner roller 7 ... Conveying roller pair (downstream)
8 Width control guide 9 Projection 10 Ribbon cassette 11 Ink ribbon 12 Winding core P Recording medium
D: Skew force to the recording medium

Claims (4)

Means for forming an image on a recording medium; conveying means for conveying the recording medium by a pair of rollers; control means for conveying the recording medium in a forward and reverse direction; and pressurizing the recording medium to the conveying means by a pair of rollers; A structure that makes contact with and separates under reduced pressure, a cleaning roller in which the outer peripheral surface of one of the roller pairs has adhesiveness, and a restriction that allows the recording medium to move in the left-right width direction parallel to the transport direction in the vicinity of the roller pair In an image forming apparatus provided with a guide, the recording medium is contacted and separated multiple times so as to form a loop shape due to the adhesiveness of the roller, and further directed toward the inside in the width direction of the recording medium in the vicinity of the width regulating guide or the guide. An image forming apparatus comprising a protruding member. The protrusion provided on the width regulation guide itself or in the vicinity of the guide is disposed on the upstream side or the downstream side in the vicinity of the cleaning roller that does not come into contact with the movement trajectory when the contact or separation of the cleaning roller is performed. The image forming apparatus according to claim 1. 2. The method according to claim 1, wherein when the pressure of the cleaning roller is released from the recording medium, a movement amount of the cleaning roller moves to a position where a lower part of the outer peripheral surface of the cleaning roller is higher than the protrusion. Image forming apparatus. The image forming apparatus according to claim 1, wherein the image forming unit is a thermal transfer type head.

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