JP2008062432A - Recording medium carrying apparatus, and recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that in an inkjet recording apparatus, the range of the carrying direction of each head becomes wider accompanying the nozzle resolution increase for a highly minute printing, and there is an inclination that a spur space becomes longer, and at the time of the printing start, when a rolled paper is carried to a position directly under each head in order, the lifting of the paper occurs by the effect of the curled shape of the rolled paper, and as long as the rolled paper is carried at an equal speed by each roller, a state in which the lifting is always generated is presented. <P>SOLUTION: In a constitution in which a spur is installed among a plurality of printing heads, when the carrying speeds of a carrying means which is installed among printing heads are taken as a first carrying means, an (n)th carrying means speed, an n+1 carrying means and an (m)th carrying means from the upstream side, the first carrying means speed V<the (n)th carrying means speed vn≤the n+1 carrying means speed vn+1≤the (m)th carrying means speed vm is satisfied. After the carrying of the distal end of the rolled paper is started by the (n)th carrying means, and a period of time by which the slack of the rolled paper is eliminated directly under the recording head (n) has passed, the printing by the recording head (n) is started, and the control is performed in order from the upstream side of the rolled paper. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording medium transport apparatus that performs printing by controlling the floating state of a roll paper and printing start timing in an ink jet recording apparatus that performs printing by ejecting ink onto continuous paper such as roll paper.

  A line printer using a long head having a nozzle row having a print width has already been put into practical use. Advantages of general inkjet printing include excellent quietness due to non-contact with print media, high printing speed, high density printing, easy colorization, and equipment Is small.

  On the other hand, as a printer that performs borderless printing on glossy paper in order to perform photo printing, which is the greatest advantage of an inkjet printer, there is a printer that transports glossy roll paper formed in a roll shape, for example. When the ink jet printing method is applied to a printer, it is necessary to devise measures such as preventing paper floating and skewing at the print head portion. Furthermore, in order to perform high-quality printing of photographs and the like, it must be a precondition that the distance between the discharge surface of the print head and the surface of the print medium is kept narrow and constant.

  If such conditions are not maintained, there is a disadvantage that the print quality is lowered. As one method for solving this inconvenience, there is a method of suppressing the floating of the print medium by providing a plurality of spurs that are in direct contact with the roll paper surface upstream of the print position of the print head. Certainly, if the above method is used, the floating of the roll paper can be suppressed.

For example, Patent Literature 1 can be cited as a conventional example.
Japanese Patent Laid-Open No. 08-091651

  However, in recent years, with the improvement in nozzle resolution in order to enable high-definition printing in one pass, the width of each head in the transport direction tends to increase and the spur interval tends to increase. In such a configuration, when the roll paper is sequentially transported directly under each head at the start of printing, the paper floats due to the curl shape of the roll paper, so that it always floats as long as it is transported at a constant speed by each roller. Will occur.

  FIG. 7 is a diagram illustrating a print medium conveyance state in a conventional configuration. In the upper diagram of FIG. 7, the leading edge of the fed roll paper passes through the first head upstream spur and is positioned in front of the second head upstream spur. In the case of roll paper, since the curl shape remains, the float is suppressed where it is suppressed by the spur, but the curl shape remains just below the head and the float occurs. However, as can be seen from FIG. 7, the width of the conventional head is narrow and the spur-spur interval (about 35 mm) is close, so even if the curl is the tightest near the roll paper core, it is about 1.4 mm. Since only floating occurred, setting the distance between the head and the paper to about 1.7 mm did not cause any particular problem.

  FIG. 8 is a diagram illustrating a print medium conveyance state in a configuration (76.2 mm) in which a spur interval is increased with an increase in the size of the head. As the spur interval increases, a large curl shape remains until the leading edge of the roll paper passes the spur and reaches the next spur, and paper float occurs. When measured, the height is about 5.6 mm, which is a level where image formation by ink jet printing is impossible. In the worst case, the roll paper may come into contact with the head surface and induce breakage.

  Actually, in order to form a high-quality image such as a photograph, it is desirable to maintain a distance of about 1 mm between the head and the paper.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a plurality of long recording heads having a plurality of nozzles arranged in the roll paper width direction orthogonal to the conveyance in the conveyance direction. In a recording apparatus that forms an image by causing ink to fly while synchronizing each recording head on roll paper conveyed directly under the head,
A first conveying means for sending the fed roll paper upstream of the plurality of arranged long recording heads to the recording head;
In each of the m rows of recording head 1 to recording head n to recording head m arranged side by side from the upstream side, they are arranged upstream of recording head n (1 ≦ n ≦ m) and downstream of recording head n−1. An n-th transport unit that transports the roll paper; a second transport unit that discharges the roll paper that has been transported from the (m + 1) -th transport unit downstream of the plurality of long recording heads; Control means for controlling the conveying speed of the conveying means, the nth conveying means and the second conveying means,
By the above control means,
First transport means speed V <nth transport means speed vn ≦ n + 1th transport means speed vn + 1
Then, after the leading end of the roll paper is started to be conveyed by the nth conveying means, the printing of the recording head n is started after a lapse of time when the looseness of the roll paper immediately below the recording head n is eliminated. The control is performed sequentially from the upstream side of the roll paper.

  The recording apparatus may further include a conveyance force reducing unit that reduces the conveyance force of the n-th conveyance unit after the roll paper is not loosened by the recording head n.

In the recording apparatus, the conveying force F of each conveying means is
First conveying means conveying force F1> Σnth conveying means conveying force Fn + second conveying means conveying force F2
The conveyance is always controlled by the conveyance force of the first conveyance means.

  By doing so, it is possible to quickly eliminate the paper floating that occurs between the spurs at the time of paper feeding, to narrow the head-paper spacing, and it is possible to print high-quality images such as result photographs. In addition, by quickly eliminating the paper floating due to curling and starting printing, it is possible to reduce the margin at the end of paper feeding.

  As described above, according to the present invention, in a configuration in which a spur is provided between a plurality of print heads, even if a print medium is floated when paper is fed, the float can be suppressed immediately. Contact between the discharge surface of the print head and the surface of the print medium can be prevented. Further, if the print head is an ink jet printing system, it is expected that the ink landing position accuracy can be improved, and a high-quality print can be formed on the print medium.

  In addition, according to the present invention, after the roll paper is no longer loosened, the transporting force of the transporting unit can be reduced to maintain a non-floating state, so the head-print medium distance is maintained constant. Printing conveyance is possible.

  Furthermore, according to the present invention, the conveyance accuracy is always controlled by the conveyance force of the first conveyance means, and the conveyance accuracy for determining the image quality can be improved in the ink jet recording method in which a print image is formed in a non-contact manner.

(Example 1)
The first embodiment of the present invention will be described below.

  In the embodiments described below, a printer is taken as an example of a recording apparatus using an inkjet recording method.

  In this specification, “recording” (sometimes referred to as “printing”) is not only for forming significant information such as characters and figures, but also for human beings, regardless of whether it is significant or not. Regardless of whether or not it has been manifested, it also represents a case where an image, a pattern, a pattern or the like is widely formed on a recording medium or the medium is processed.

  “Recording medium” means not only paper used in general recording apparatuses but also a wide range of materials that can accept ink, such as cloth, plastic, metal plate, glass, ceramics, wood, leather, etc. To do.

  Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used to form a pattern or the like, process a recording medium, or process an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).

  Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used for forming a pattern or the like, processing a recording medium, or processing an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).

  An embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic cross-sectional view showing the configuration of a print transport unit according to the present invention, FIG. 2 is a line of force / velocity diagram when transporting a print medium according to the present invention, and FIG. 3 is a print transport unit according to the present invention. FIG. 6 is a diagram illustrating a print medium conveyance state.

  In FIG. 1, reference numeral 1 denotes an apparatus main body, and a roll paper 21 as a print medium is fixed to a roll paper rotating body 22, and is sent out to a print transport unit by rotating. In FIG. 1, the tension is in a tensioned state, but the back tension is controlled by a loop detection sensor (not shown) so as to always form a loop of a certain level or more with a registration roller described later. Therefore, the conveyance accuracy is not deteriorated.

  The roll paper is a recording paper dedicated to inkjet, and uses coated paper provided with a receiving layer on the surface for increasing ink absorbability, and is wound so that the coated layer is on the outer side. The roll paper 21 fed from the roll paper rotating body 22 is detected by a registration sensor 23 and abutted against a nip portion between a registration roller 31 and a registration upper roller 32 serving as a first conveyance means, and is conveyed while correcting skew. Is done.

  The recording roller 7 is provided on the downstream side of the registration roller 31 in a non-contact manner on the side facing the roll paper. In FIG. 1, the number is 7n-1, 7n, 7n + 1, and 7n + 2, but the number and color arrangement order vary depending on image formation, image quality, and the like. In this recording head, nozzle rows are arranged in a direction perpendicular to the transport direction so as to be longer than the width of the roll paper 21 and are arranged so that borderless printing is possible. The roll paper is once under each head. A full color image is formed by passing (one-pass image recording). On the upstream side of each head 7n, a spur 42n is disposed on the upper side of the recording paper, and a spur driving roller 41n is disposed on the lower side to suppress the floating of the recording paper sent. In FIG. 1, the spur 42n-1 and the spur driving roller 42n-1 are provided between the registration roller and the first head. However, the first head and the registration roller are brought close to each other at the same distance as the other spurs. If it can be arranged, the spur 42n-1 and the spur drive roller 42n-1 may be omitted.

  During each spur, a platen 29 is disposed at an opposite position across the head and the roll paper, and ribs are formed on the side in contact with the roll paper to serve as a backup to prevent downward displacement of the recording paper. In FIG. 1, four recording heads are arranged, and five sets of spurs and spur driving rollers are arranged on the four recording heads, and n + 1 sets of spurs are arranged on n heads. It is configured to prevent floating underneath.

  Downstream of the spur m + 1, a driving roller 33 that is driven by the driving roller 33 serving as the second conveying means and a driving upper roller 34 are disposed, and the paper discharge guide guides the roll paper to a post-processing step (not shown) such as a cutter. 36 is arranged.

  Reference numerals 44 and 45 denote driving units that convey the printing unit, which are a driving roller driving source 44 and a registration roller driving source 45, respectively. The drive roller drive source is required to transmit the drive via a spur drive roller clutch 43n to a spur drive roller 41n that conveys the roll paper facing the spur 42n. In this embodiment, transmission is performed from a driving roller driving source, but each spur driving roller may have a driving source and control each of them. These drive sources are controlled by the operation control unit 46, carry the image in synchronization with the head, and drive the head while taking the conveyance timing by an encoder (illustrated) provided on the registration roller to form an image. It is configured to do.

  Next, FIG. 2 is a force line / velocity diagram when transported by the print transport unit print medium, and the main method of the present invention will be described using this.

The roll paper rotating body 22 rotates, and the supplied roll paper is held in the nip between the registration roller 31 and the registration upper roller 32 and conveyed to the print conveyance unit. The conveyed roll paper is conveyed downstream one after another by a spur 42n and a spur drive roller 41n arranged between the heads. At this time, as shown in FIG. A state where the leading edge of the roll paper passes through the spur 421 through the registration roller and is in front of the spur 422 is shown. When the leading edge of the roll paper passes through the spur 421, the roll paper that has been rolled up as a roll paper forms a curled shape and generates floating. As the conveyance proceeds, the float increases, but also proceeds in the conveyance direction at the same time. Therefore, the tip reaches the nip of the next spur 422, and the conveyance force is generated and proceeds. However, when the speed V1 and the speed V2 of the spur 421 and the spur 422 are constant, the loop formed until nipping remains as it is, and as a result, the state in which the paper float is generated is maintained, and realization of high image quality between narrow papers is realized. It becomes impossible. Or, it was unstable and image quality deteriorated. Therefore, the first transport means speed V <the nth transport means speed vn ≦ the (n + 1) th transport means speed vn + 1 ≦ the mth transport means speed vm.
Since the spurs on the downstream side are faster when they are controlled so as to be transported at the respective speeds, the loop formed so far is stretched and lifted up when held by the nip of the downstream transport means.

  FIG. 3 is a view showing a curled state of the roll paper. In FIG. 3a, the curl remains immediately below the head 1 and the float is generated. When the paper is further conveyed, the downstream spur is so fast that curling is no longer stretched, and printing is started as shown in FIG. 3C. It is possible to obtain a simple image.

Further, the transport force generated by the nip force in each roller is expressed as follows. First transport means transport force F> Σnth transport means transport force Fn + second transport means transport force F2
With this relationship, it is possible to perform printing while ensuring stable conveyance accuracy. As described above, the curl is extended by the downstream side spur, and is provided at the moment when the float stops and tension is generated in the spurs on both sides. At this time, a slip is generated by a roller having a weak nip force (conveying force), and the roll paper is conveyed while being controlled to a side having a strong conveying force. In this configuration, the ink jet method is used, and the recording paper surface is painted with ink immediately after head printing. If the surface is rubbed before the ink is fixed, the image quality deteriorates. A spur is used on the contact side. In the case of a spur, there is a limit to increasing the conveying force, and if it is increased too much, the spur may be attached to the surface of the recording paper. Also, the downstream transport means is accelerated to remove the curl, and if it is used as the downstream reference, the speed is increased step by step for each spur.If the upstream side is still printing, it is impossible to control printing. Is possible.

  In this configuration, the conveyance accuracy is controlled by the registration roller, and the conveyance force of the registration roller is superior to the total conveyance force of all the subsequent conveyance means, so that after the float is suppressed, the downstream roller always slips, Further, after the lift under the next head is eliminated, the drive transmission is cut by the clutch. By doing so, it is possible to realize a gap between narrow sheets and to perform high-quality recording by conveying at a constant speed.

  Next, an actual control method will be described with reference to FIGS. FIG. 4 is a graph of the speed increase rate of each conveying means and the decrease time of the slack due to curling, and FIG. 5 is a graph of the maximum curl height and the amount of slack of the paper.

  In FIG. 4, the vertical axis represents the speed increase rate of the downstream roller relative to the upstream roller in the time (seconds) until the sag disappears, and the reference printing speed is 100 mm / sec in this apparatus. FIG. 5 shows the amount of paper sag (mm) on the vertical axis and the maximum curl height (mm) on the horizontal axis. It can be seen that the amount of paper slack increases as the curl size increases. In this apparatus, the spur interval is 3 inches (76.2 mm) with an increase in the size of the head, and the maximum curl height measured at that time is 5.6 mm described in FIG. In order to eliminate the sagging before the tip is nipped by the next spur in order to eliminate the sagging of the paper at 1.1 mm at that time, it is necessary to eliminate the sagging in 0.762 sec or less. In that case, the acceleration rate must be 1.434% or more.

  FIG. 6 is a graph showing a print control timing table according to the present invention, in which the vertical axis indicates the elapsed time, and the horizontal axis indicates the location (absolute position) of the leading edge of the roll paper. If the roll paper is transported at a constant speed without being lifted even when it is transported by one roller, it will be transported on the dotted line extending diagonally downward to the right as shown in the graph (ideal straight line). ). However, in reality, curl occurs up to the first spur (76.2mm), so a time delay occurs and the position of the first spur is reached while drawing a curve. Since the roll is nipped by the first spur and transported at an increased speed, the leading edge of the roll paper moves on a straight line with an inclination from the ideal straight line, and the curl generated in the first spur disappears at the time it intersects the ideal straight line. . As indicated by the black arrows on the graph, the curl at each head decreases at the time, and the floating does not occur. Therefore, printing at each head is sequentially started after the black arrow.

  All the operations are controlled by moving each drive source and clutch by the operation control unit. By controlling in this way, after roll paper is fed, curl generated directly under each head is reduced to eliminate floating, and printing is started immediately thereafter, thereby shortening the first print time and maximum roll paper. This makes it possible to reduce the leading edge margin and improve the leading edge conveyance accuracy, and to realize high-quality recording using roll paper.

  In the case of a high-speed line printer having a configuration in which the distance between the upstream drive roller and the downstream drive roller is wide (3 inches) compared to the prior art and a plurality of the rollers are continuously arranged, it is important to reduce the leading edge of the recording paper. Since the paper feed accuracy greatly affects image formation because 1-pass printing is performed, it is indispensable to eliminate floating immediately below each head and perform printing with stable conveyance accuracy.

FIG. 3 is a schematic cross-sectional view illustrating a configuration of a print transport unit according to the present invention. FIG. 3 is a line of force / velocity diagram when conveying a print medium according to the present invention. FIG. 6 is a transition diagram of print medium conveyance in a print conveyance unit according to the present invention. A graph of the speed increasing rate of each conveying means and the slack reduction time due to curling. Graph of maximum curl height and paper slack. The print control timing table in this invention. FIG. 7 is a schematic cross-sectional view of a print transport unit according to a conventional technique. The schematic sectional drawing which showed the subject of the printing conveyance part which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording device 7 Recording head 22 Roll paper rotary body 23 Registration sensor 29 Platen 31 Registration roller 32 Registration upper roller 33 Driving roller 34 Driving upper roller 35 Paper ejection sensor 36 Paper ejection guide 41n Spur driving roller 42n Spur 43n Spur driving roller clutch 44 Driving roller driving source 45 Registration roller driving source 46 Operation control unit

Claims (4)

A plurality of long recording heads having a plurality of nozzles arranged in the width direction of the roll paper that is perpendicular to the conveyance are arranged in the conveyance direction, and each recording head is allowed to fly while synchronizing with the roll paper that is conveyed directly under the head. In a recording apparatus for forming an image,
A first conveying means for sending the fed roll paper upstream of the plurality of arranged long recording heads to the recording head;
In each of the m heads of the recording head 1, the recording head n, and the recording head m arranged side by side from the upstream side, the head is upstream of the recording head n (1 ≦ n ≦ m) and downstream of the recording head n-1. An n-th transport unit that transports the roll paper; a second transport unit that discharges the roll paper that has been transported from the (m + 1) -th transport unit downstream of the plurality of long recording heads arranged;
Control means for controlling the conveying speed of the first conveying means, the nth conveying means and the second conveying means,
By the above control means,
First transport means speed V <nth transport means speed vn ≦ n + 1th transport means speed vn + 1 ≦ mth transport means speed vm
After the time when the leading edge of the roll paper is started to be conveyed by the nth conveying means and the roll paper is not loosened immediately below the recording head n, printing of the recording head n is started, and the above control is sequentially performed from the upstream side of the roll paper. A recording apparatus.   The recording apparatus according to claim 1, further comprising a conveyance force reducing unit that reduces a conveyance force of the nth conveyance unit after the looseness of the roll paper in the recording head n is eliminated. In the recording apparatus, the conveying force F of each conveying means is
First conveying means conveying force F> Σnth conveying means conveying force Fn + second conveying means conveying force F2
2. The recording apparatus according to claim 1, wherein the conveyance is always controlled by the conveyance force of the first conveyance means.   In the recording apparatus, a conveyance amount detection unit is provided in a first conveyance unit that is upstream of the plurality of long recording heads and sends the fed roll paper to the recording head to detect the conveyance amount. 4. The recording apparatus according to claim 1, wherein the printing timing is controlled.

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