JP4055482B2 - RECORDING MEDIUM CONVEYING DEVICE AND RECORDING DEVICE - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording medium conveying apparatus that conveys a recording medium, and a recording apparatus including the recording medium conveying apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, an ink jet printer, which is one of recording apparatuses, has a configuration in which, for example, a sheet, which is one of recording media, is recorded while being sent to a recording unit by a paper transport device and is sent to the outside. FIG. 10A is a diagram showing only the main part of the paper transport device in such an ink jet printer. In such an ink jet printer, the paper 1 is recorded by the recording head 3 while being nipped and fed by the paper feed roller 2 and its driven roller 2a, and is nipped by the paper discharge roller 4 and the spur roller 4a as its driven roller. To be discharged.
[0003]
[Problems to be solved by the invention]
In an inkjet printer including the above-described conventional paper transport device, when an image on which a large number of ink droplets are ejected, such as a solid image, is recorded on the paper 1, the paper 1 absorbs a large amount of ink. Thus, as shown in FIG. 10B, so-called cockling that swells in a wavy shape toward the recording head 3 after recording may occur. When this cockling occurs and develops, the distance between the paper 1 and the recording head 3 becomes non-uniform, and the flying distance of the ink droplets varies, resulting in uneven recording, or the paper 1 becomes a recording head. There is a problem that it contacts 3 and gets dirty.
[0004]
If the span between the paper feed roller 2 and the paper discharge roller 4 is relatively short, these problems can be prevented as much as possible by suppressing the cockling described above within an allowable range. However, in an inkjet printer or the like, in the near future, it is necessary to increase the number of nozzles for each color nozzle row or to arrange a plurality of color nozzle rows in the conveyance direction of the paper 1 in order to further increase the recording speed. In these cases, the size of the recording head 3 becomes longer in the transport direction of the paper 1 as shown in FIG.
[0005]
As the recording head 3 becomes longer, the span between the paper feed roller 2 and the paper discharge roller 4 becomes longer. Therefore, the paper feed roller 2 and its driven roller 2a, the paper discharge roller 4 and a spur roller 4a as its driven roller. The cockling cannot be prevented at all in the structure in which the sheet is conveyed and discharged between the two. Then, the cockling exceeds an allowable range, and there may be a situation in which the structure itself that conveys and discharges between the two sets of rollers does not hold depending on such an ink jet printer having a large head length.
[0006]
In addition, such cockling is relatively small when a special paper of an ink jet printer is used as the paper 1, and becomes large when a plain paper is used. For this reason, normally, in designing an ink jet printer or the like, the paper gap (paper 1 and recording head 3 in FIG. 10A) is considered in consideration of the amount of paper floating due to cockling when plain paper is used. A) is increased. However, when the paper gap is large as described above, even when special paper that is not necessary is used, the ink particles ejected from the nozzles of the recording head 3 are bent and the deviation of the landing point is caused. It becomes larger by that amount and may hinder the improvement of recording quality.
[0007]
On the other hand, in recent years, various proposals have been made which mainly have a hollow box-like suction part on the paper transport surface and suck the paper with a suction pump or the like through a plurality of through-suction holes provided in the suction part. (Refer to Unexamined-Japanese-Patent No. 63-303781 and Unexamined-Japanese-Patent No. 3-270 etc.). Among these, as a means for eliminating the above-described cockling, there is proposed that a sheet is sucked or sucked on a platen or the like through the suction holes.
[0008]
However, in any case, only a through-hole is opened in the hollow box-like suction portion and suction is performed, and it is difficult to prevent the above-described cockling over the entire surface of the sheet in the recording portion. Further, in the conventional example described in the above publication, since the through hole is opened in the hollow box-like suction portion and suction is performed, if the suction force is too strong, the paper feeding accuracy may be reduced. For this reason, at present, the actual situation is that it has not been put into practical use except for some large format printers that feed paper in the direction of gravity (uses the weight of the paper for paper feed).
[0009]
The present invention has been made in view of the various problems as described above, and an object of the present invention is to provide a recording medium transport apparatus capable of stabilizing the recording medium when recording on the recording medium, and the recording medium transport. It is to provide a recording apparatus provided with the apparatus.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the recording medium conveying apparatus of the present invention is a recording medium conveying apparatus that conveys a recording medium supplied onto a recording medium conveying surface while adsorbing the recording medium by an adsorption unit, and the adsorption unit includes a recording head It is characterized in that it is formed so that the negative pressure at the part opposite to is higher than the negative pressure at the other part. Thereby, since the negative pressure of the specific suction portion can be increased and the portion of the recording medium corresponding to the suction portion can be stably sucked, even if cockling extending in the transport direction occurs in the recording medium after recording, It is possible to prevent the influence from affecting the part of the recording medium. In particular, since the recording medium can be stably adsorbed in the recording unit, the distance between the recording medium and the recording head becomes uniform, high-precision recording can be maintained, and the contact between the recording medium and the recording head is This eliminates contamination of the recording medium.
[0011]
Further, the adsorbing portion is formed so that the negative pressure of the portion that first adsorbs the end portion of the recording medium is higher than the negative pressure of other portions. As a result, the end of the recording medium that is particularly easily curled can be stably adsorbed, so that the distance between the end of the recording medium and the recording head is uniform, and high-precision recording can be maintained. Contact between the end portion and the recording head is eliminated, and contamination of the end portion of the recording medium can be prevented.
[0012]
A plurality of suction holes provided in the recording medium conveying surface; a negative pressure adjusting hole that communicates with the plurality of suction holes to adjust a negative pressure; a decompression chamber that communicates with the negative pressure adjustment hole; A suction means for sucking air, wherein the suction hole communicates with the negative pressure adjusting hole; and a suction chamber in which an area of a suction surface facing the recording medium is larger than a cross-sectional area of the suction hole; It is characterized by having a suction unit including
[0013]
A plurality of suction holes provided in the recording medium conveyance surface; first and second decompression chambers communicating with a part for increasing the negative pressure and the other part among the plurality of suction holes; First and second suction means for sucking air in the second decompression chamber, respectively, wherein the suction hole has a suction hole communicating with the decompression chamber and an area of the suction surface facing the recording medium A suction unit including a suction chamber larger than the cross-sectional area of the suction hole is provided. In addition, the first suction means includes a plurality of fans arranged in series.
[0014]
Thereby, the suction hole desired to have a high suction force and the suction hole having the normal suction force can be partitioned by the partition wall, so that the negative pressure of the suction hole desired to have a high suction force can be reliably increased.
[0015]
In order to achieve the above object, the recording apparatus of the present invention is characterized by including the recording medium conveying apparatuses described above. Thereby, it is possible to provide a recording apparatus that exhibits the above-described effects.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0017]
FIG. 1 is a side view showing a recording medium conveying apparatus according to the first embodiment of the present invention. The recording medium transport apparatus 100 includes a suction unit 110 that sucks and holds a recording medium during recording, and a recording medium transport unit 150 that transports the recording medium from the upstream side to the downstream side of the suction unit 110. The suction unit 110 is disposed on the lower side of the recording head 231 for recording on a recording medium with the recording medium conveyance path L interposed therebetween. The upper suction part 120 and the lower suction force generation part 130 are formed in a hollow box shape having two upper and lower stages.
[0018]
The suction unit 120 includes a decompression chamber 121 formed therein, a negative pressure adjustment hole 125 communicating with the decompression chamber 121, and a plurality of substantially rectangular recesses formed in the recording medium conveyance surface 122 as shown in FIG. And a plurality of suction holes 124 having a smaller cross-sectional area than the suction chamber 123 extending in the vertical direction so that the suction chambers 123 communicate with the negative pressure adjusting holes 125, respectively.
[0019]
The negative pressure adjusting hole 125 has a function of adjusting the negative pressure of the plurality of suction chambers 123. That is, the cross-sectional area of the negative pressure adjusting hole 125 communicating with the suction hole 124 extending from the suction chamber 123 to increase the negative pressure is larger than the cross-sectional area of the negative pressure adjusting hole 125 communicating with the suction hole 124 extending from the other suction chamber 123. Is formed to be smaller. The negative pressure adjusting hole 125 in this example is a suction chamber 123 that faces the recording head 231 and a suction chamber 123 that first sucks the end of the recording medium, that is, a suction located on the most upstream side of the suction unit 110. Each negative pressure in the chamber 123 is formed to be higher than the negative pressures in the other suction chambers 123.
[0020]
Here, the reason why the negative pressure of the suction chamber 123 can be adjusted by changing the cross-sectional area of the negative pressure adjusting hole 125 will be described with reference to FIG. As shown in FIG. 4, in the negative pressure adjusting hole 125, the cross-sectional area at the location {circle around (1)} is smaller than the cross-sectional area at the location {circle around (2)}. Then, assuming that the cross-sectional area of the location of ( ₁₎ is S ₁ , the flow velocity is U ₁ , the static pressure is P ₁ , the cross-sectional area of the location of ( ₂₎ is S ₂ , the flow velocity is U ₂ , and the static pressure is P ₂ , The following equation (1) holds.
^{_{P 2 + ρU 2 2/2}} = P 1 + ρU 1 2/2 ... (1)
Therefore, the amount of pressure reduction ΔP when shifting from the position (1) to the position (2) is expressed by the following equation (2).
ΔP = P ₂ −P ₁ = ρ (U ₁ ² −U ₂ ² ) / 2 (2)
Here, when the total flow rate is Q, the flow velocity U ₁ and the flow velocity U ₂ are expressed by the following equation (3).
U ₁ = Q / S ₁ , U ₂ = Q / S ₂ (3)
Therefore, the pressure reduction amount ΔP is expressed by the following equation (4) from the above equations (2) and (3).
ΔP = P ₂ −P ₁ = ρ ((Q / S ₁ ) ² − (Q / S ₂ ) ² ) / 2 (4)
In the above equation (4), since Q / S ₁ is a value larger than Q / S ₂ , the pressure reduction amount ΔP is always positive, and the negative pressure at point (1) is higher than the negative pressure at point (2). Become.
[0021]
The suction force generation unit 130 is communicated with the decompression chamber 121 of the suction unit 120 via the communication hole 131 and includes a pump 132 having a centrifugal fan therein. The pump 132 is attached to a predetermined position below the decompression chamber 121 so as to communicate with the decompression chamber 121 via the communication hole 131, and the centrifugal fan rotates during recording.
[0022]
The recording medium conveying means 150 includes a feeding roller 151 that feeds the recording medium between the recording head 231 and the suction unit 110, a driven roller 152 that is pressed against the feeding roller 151 from above, and the recording medium to the outside. A discharge roller 153 for discharging, and a spur roller 154 that comes into contact with the discharge roller 153 from above are provided. In addition, it is also possible not to provide the discharge roller 153 and the spur roller 154 by making the suction unit 110 movable in the discharge direction.
[0023]
As described above, the suction hole is constituted by the suction hole 124 and the suction chamber 123, and the suction hole 124 is formed by a small-diameter through hole, thereby increasing the utilization rate of the negative pressure that can be used for the characteristics of the pump 132. At the same time, by forming the suction chamber 123 as a substantially rectangular recess having a larger area than the suction hole 124, a large suction force can be generated with respect to the recording medium.
[0024]
Further, since the suction chamber 123 facing the recording head 231 is set to be higher than the negative pressure of the other suction chambers 123, the portion of the recording medium facing the recording head 231 can be stably adsorbed. In addition, even if cockling extending in the transport direction occurs in the recording medium after recording, it is possible to prevent the influence from reaching the portion of the recording medium. The distance between the recording medium and the recording head 231 is uniform, so that high-precision recording can be maintained, and contact between the recording medium and the recording head 231 is eliminated, and contamination of the recording medium can be prevented. .
[0025]
Further, each negative pressure of the suction chamber 123 that first sucks the end of the recording medium, that is, the suction chamber 123 located on the most upstream side of the suction unit 110 is set to be higher than the negative pressures of the other suction chambers 123. Therefore, it is possible to stably adsorb the end of the recording medium that is particularly easily curled, the distance between the end of the recording medium and the recording head 231 is uniform, and high-precision recording can be maintained. Contact between the end portion and the recording head 231 is eliminated, and contamination of the end portion of the recording medium can be prevented.
[0026]
In the embodiment shown in FIG. 1, the suction chamber 123 facing the recording head 231 and the suction chamber 123 that first sucks the end of the recording medium, that is, the suction chamber located on the most upstream side of the suction unit 110. Each negative pressure of 123 is adjusted to be higher than the negative pressures of the other suction chambers 123, but the present invention is not limited to this, and it is possible to adjust the negative pressure of the suction chamber 123 at any location. is there.
[0027]
The recording medium transport apparatus 100 having such a configuration operates as follows. The feed roller 151 and the like are rotationally driven to feed the recording medium between the recording head 231 and the suction unit 110. On the other hand, the pump 132 is driven to apply a suction force to the suction hole 124 and the suction chamber 123 via the communication hole 131, the decompression chamber 121, and the negative pressure adjustment hole 125. As a result, the recording medium is first flattened by suction with a strong suction force at the suction chamber 123 located on the most upstream side of the suction unit 110, and then in the suction chamber 123 facing the recording head 231. Adsorbed and transported with strong suction.
[0028]
At the same time, the recording head 231 performs recording by ejecting ink particles onto the recording medium while moving in the main scanning direction above the recording medium. As a result, cockling may occur in the recording medium after recording. However, since the portion of the recording medium facing the recording head 231 is stably adsorbed, the influence of cockling affects the portion of the recording medium. Never reach. Then, the discharge roller 153 and the like are driven to rotate, and the recording medium on which recording is completed is discharged to the outside.
[0029]
FIG. 3 is a side view showing a recording medium conveying apparatus according to the second embodiment of the present invention corresponding to FIG. 1, and the same components as those of the recording medium conveying apparatus 100 shown in FIG. Therefore, the description is omitted. This recording medium transport device 160 is not formed with the negative pressure adjusting hole 125 shown in FIG. 1, but instead is divided into two through a partition wall, a first decompression chamber 121a, a second decompression chamber 121b, A first communication hole 131a and a second communication hole 131b communicating with the decompression chambers 121a and 121b are formed, and the decompression chambers 121a and 131b are connected to the decompression chambers 121a and 131b at predetermined positions below the decompression chambers 121a and 121b. 1 is different from the recording medium conveying apparatus 100 shown in FIG. 1 in that it includes a first pump 132a and a second pump 132b attached in communication with 121b.
[0030]
The first decompression chamber 121a first sucks the suction hole 124 extending from the suction chamber 123 where the negative pressure is to be increased, that is, the suction hole 124 extending from the suction chamber 123 facing the recording head 231 and the end of the recording medium. The suction chamber 123 is formed so as to communicate with the suction hole 124 extending from the suction chamber 123 located on the most upstream side of the suction unit 110, and the second decompression chamber 121 b communicates with the suction hole 124 extending from the other suction chambers 123. It is formed to do.
[0031]
The first pump 132a acting on the first decompression chamber 121a is arranged so that two fans are in series, and the second pump 132b acting on the second decompression chamber 121b is arranged with one fan. It is installed. Thus, by using the first pump 132a in which two fans are arranged in series, as shown in FIG. 5, compared to a pump in which two fans are arranged in parallel, as shown in FIG. Although the flow rate is reduced, a high negative pressure can be obtained, and the suction chamber 123 that faces the recording head 231 and the suction chamber 123 that first sucks the end of the recording medium, that is, the most upstream side of the suction unit 110. Each negative pressure with the suction chamber 123 positioned can be higher than the negative pressures of the other suction chambers 123.
[0032]
In the embodiment shown in FIG. 3, the suction chamber 123 facing the recording head 231 and the suction chamber 123 that first sucks the end of the recording medium, that is, the suction chamber located on the most upstream side of the suction unit 110. Each negative pressure of 123 is adjusted to be higher than the negative pressures of the other suction chambers 123, but the present invention is not limited to this, and it is possible to adjust the negative pressure of the suction chamber 123 at any location. is there. In addition, the first pump 132a in which two fans are arranged in series is used, but the present invention is not limited to this, and a pump in which a plurality of fans are arranged in series is used. Is also possible.
[0033]
FIG. 6 is a perspective view showing an ink jet printer as a recording apparatus provided with the recording medium conveying apparatus of the present invention, and FIGS. 7 to 9 are a plan view, a front view, and a side view showing the main part. The ink jet printer 200 includes an automatic paper feed (ASF) unit 220 that is obliquely attached to the rear upper part of the printer main body 210, a recording unit 230 and a recording medium transport device 100 built in the printer main body 210. As the recording medium, various kinds of paper such as OHP film, tracing paper, postcard, etc. can be used in addition to the dedicated paper and plain paper of the ink jet printer 200.
[0034]
In this embodiment, the discharge roller 153 and the spur roller 154 are not required, the suction unit 110 that is movable in the discharge direction is provided, and the recording medium conveyance device 100 having the negative pressure adjustment hole 125 shown in FIG. 1 is provided. The ink jet printer 200 has the first decompression chamber 121a, the second decompression chamber 121b, the communication holes 131a and 131b, and the pumps 132a and 132b shown in FIG. 3, and the discharge shown in FIGS. The recording medium conveyance devices 100 and 160 having the roller 153 and the spur roller 154 can be similarly applied.
[0035]
The ASF unit 220 includes a tray 221 that stores the paper 1, a paper feed roller 222 that pulls out and supplies the paper 1 from the tray 221, and the like. The recording unit 230 includes a carriage 233 on which the recording head 231 and the ink cartridge 232 are mounted, a DC motor 235 that moves the carriage 233 along a guide shaft 234 disposed in the main scanning direction, and the like. The recording head 231 has a nozzle row composed of a plurality of nozzles such as 96 for each color of cyan, magenta, yellow, light cyan, light magenta, light yellow, and black, for example.
[0036]
The ink jet printer 200 having such a configuration operates as follows. When a recording command for the paper 1 stored in the tray 221 is input by a host computer or the like (not shown), the paper feed roller 222 is rotated to pick up the paper 1 stored in the tray 221 one by one. Feed paper. Further, the feed roller 152 and the like are rotationally driven to feed the paper 1 between the recording head 231 and the suction unit 110.
[0037]
On the other hand, the pump 132 is driven to apply a suction force to the suction hole 124 and the suction chamber 123 via the communication hole 131, the decompression chamber 121, and the negative pressure adjustment hole 125. Then, the leading edge of the paper 1 is attracted and flattened with a strong suction force to the suction chamber 123 located on the uppermost stream side of the suction unit 110, and then the suction chamber 123 facing the recording head 231 with a strong suction force. Adsorb and transport. At the same time, the DC motor 235 is driven to move the carriage 233 along the guide shaft 234 via the timing belt.
[0038]
At this time, the recording head 231 records the ink supplied from the ink cartridge 232 for each color by ejecting the ink on the paper 1 as fine ink droplets from all or a part of the plurality of nozzles according to the recording data. . As a result, cockling may occur in the paper 1 after recording. However, since the part of the paper 1 facing the recording head 231 is stably adsorbed, the influence of the cockling affects the part of the paper 1. Never reach. Then, the suction unit 110 moves in the discharge direction, and the sheet 1 on which recording has been completed is discharged from the discharge port 201 to the outside.
[0039]
【The invention's effect】
As described above, according to the recording medium conveying apparatus and the recording apparatus according to the present invention, the negative pressure of a specific suction portion can be increased and the portion of the recording medium corresponding to the suction portion can be stably suctioned. Even when cockling extending in the transport direction occurs in the recording medium after recording, it is possible to prevent the influence from reaching the portion of the recording medium. Accordingly, the distance between the recording medium and the recording head can be minimized and uniform, and stable conveyance can be performed, so that the recording accuracy can be improved and contamination due to contact between the recording medium and the recording head can be achieved. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a side view showing a recording medium transport apparatus according to a first embodiment of the present invention.
2 is a plan view showing a recording medium conveyance surface of the recording medium conveyance apparatus in FIG. 1; FIG.
FIG. 3 is a side view showing a recording medium carrying device according to a second embodiment of the present invention.
FIG. 4 is a diagram for explaining negative pressure adjustment in the recording medium conveyance device of FIG. 1;
FIG. 5 is a diagram for explaining negative pressure adjustment in the recording medium conveyance device of FIG. 3;
FIG. 6 is a perspective view showing an ink jet printer as a recording apparatus including the recording medium conveying apparatus of the present invention.
7 is a plan view showing a main part of the ink jet printer shown in FIG. 6;
8 is a front view showing a main part of the ink jet printer shown in FIG. 6;
9 is a side view showing a main part of the ink jet printer shown in FIG. 6;
FIG. 10 is a diagram showing only a main part of a paper transport device in a conventional ink jet printer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Paper 100 Recording medium conveyance apparatus 110 Suction unit 120 Suction part 121 Decompression chamber 121a First decompression chamber 121b Second decompression chamber 122 Recording medium conveyance surface 123 Suction chamber 124 Suction hole 125 Negative pressure adjustment hole 130 Suction force generation unit 131 Communication hole 131a 1st communication hole 131b 2nd communication hole 132 Pump 132a 1st pump 132b 2nd pump 150 Recording medium conveyance means 151 Feed roller 152 Followed roller 153 Discharge roller 154 Spur roller 160 Recording medium conveyance apparatus 200 Inkjet printer 210 Printer main body 220 ASF unit 221 Tray 222 Paper feed roller 230 Recording unit 231 Recording head 232 Ink cartridge 233 Carriage 234 Guide shaft 235 DC motor

Claims (6)

A recording medium conveying apparatus that conveys a recording medium supplied on a recording medium conveying surface while adsorbing the recording medium by an adsorption unit,
The recording medium transporting apparatus according to claim 1, wherein the suction portion is formed such that a negative pressure at a portion facing the recording head is higher than a negative pressure at another portion. The recording medium conveyance according to claim 1 , wherein the suction portion is formed such that a negative pressure at a portion where the end portion of the recording medium is first sucked is higher than a negative pressure at another portion. apparatus.   A plurality of suction holes provided in the recording medium conveying surface, a negative pressure adjustment hole communicating with the plurality of suction holes to adjust a negative pressure, a decompression chamber communicating with the negative pressure adjustment hole, and air in the decompression chamber The suction hole includes a suction hole that communicates with the negative pressure adjusting hole, and a suction chamber in which an area of the suction surface facing the recording medium is larger than a cross-sectional area of the suction hole. The recording medium conveying apparatus according to claim 1, further comprising a suction unit.   A plurality of suction holes provided in the recording medium conveyance surface; first and second decompression chambers communicating with a portion for increasing negative pressure and other portions among the plurality of suction holes; Each of the first and second suction means for sucking air in the decompression chamber, wherein the suction hole communicates with the decompression chamber, and an area of the suction surface facing the recording medium is the suction hole. The recording medium conveying apparatus according to claim 1, further comprising a suction unit including a suction chamber larger than a cross-sectional area of the recording medium. The recording medium conveying apparatus according to claim 4 , wherein the first suction unit includes a plurality of fans arranged in series. Recording apparatus comprising the recording medium transportation apparatus according to any one of claims 1-5.

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