JP2007160556A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder which makes sure highly precise sending of even a strongly curling sheet by a conveyance roller while the sheet is held flat on a platen surface by a negative pressure, avoids a decrease of the image quality although ink mist in the apparatus is discharged by a discharge duct to the outside of a machine, and moreover suppresses consumption of power by a suction fan. <P>SOLUTION: The strength of a machine interior mist fan and a suction platen fan are synchronously adjusted. (1) During printing, the mist fan is made weak and the suction platen fan is made strong. (2) During line feeding, the mist fan is made strong and the suction platen fan is made weak. (3) The negative pressure of the suction platen fan during line feeding is made strong and weak depending on a diameter of a roll sheet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus having a duct for performing recording while sucking and conveying a sheet, and collecting in-machine ink mist generated simultaneously with recording.

  In the past, silver salt photographic prints were superior to inkjet recording devices that printed digital images, firstly image quality and secondly borderless photos that could record an image on the entire photographic paper. However, in recent years, there are a number of ink jet recording apparatuses that are equivalent to silver salt photographs in that image quality is improved to the extent that it is comparable to silver salt photographs and borderless recording is possible.

  By the way, in the ink jet recording apparatus, it is desirable that the ink is ejected vertically from the ejection port surface of the recording head. However, when the ejection direction is inclined due to various factors, the ink landing position is displaced, and the image quality is deteriorated. There is. In this case, the smaller the distance (nozzle height) between the discharge port surface and the sheet, the smaller the displacement of the landing position. However, when the nozzle height is reduced, the sheet and the discharge port surface may come into contact with each other due to the curling (warping) or floating of the sheet, the waving due to the ink absorption of the sheet, and the like, and ink stains may adhere to the sheet.

  Therefore, as shown in Patent Document 1, a configuration has been proposed in which a platen is provided at a position facing the recording head to reduce the nozzle height while suppressing curling and undulation of the sheet. With the suction platen, a large number of suction ports are drilled on the sheet contact surface of the suction box formed in a box shape, and negative pressure is generated by exhausting from the inside by a fan, and the sheet is sucked to the contact surface of the sheet A platen that can be held.

  This suction platen is effective in curling, floating, and corrugating the sheet, and can be brought along the platen surface that holds and defines the position of the sheet by air suction. Also, in the case of a roll-shaped sheet, curl wrinkles are light when the roll winding diameter is large, but there are considerable curl wrinkles when the winding diameter close to the winding core is small, and generally it cannot be held flat. By strong suction with a suction platen, strong curls can be sucked to keep the sheet flat.

  On the other hand, in the case of performing borderless recording with an ink jet recording apparatus, Patent Document 2 discloses a configuration in which a roll-shaped sheet is used, the sheet conveyance direction is automatically cut by a cutter, and the width direction is recorded in an area wider than the sheet width. Proposed. In this case, the ink discharged to the outside of the sheet width is absorbed by the absorber provided immediately below the sheet.

In recent years, printers that achieve photographic image quality have reduced the amount of ink discharged to a minimum of several pl to achieve that image quality, and as described above, the sheet width for borderless recording. Printing in a wider area. It is known that considerably more ink mist than usual is scattered in the apparatus when such a small droplet ink is ejected to the outside of the paper surface. The large sized printers for business use that record on wide roll paper such as JIS A0 and B0 versions have a large printing width and printing volume, so the amount of mist scattered in the device is not half-finished. This is a serious problem due to fatal damage such as contamination by the sensor and false detection of the sensor. Therefore, in general, in a large format printer, an exhaust duct is provided in the apparatus, and it is installed near the platen that defines the position of the sheet, that is, near the ink mist generation source. Is discharged.
JP 06-064175 JP-A-11-321016

  However, in the above conventional example, since the sheet is conveyed along the platen surface by the negative pressure due to air suction, if the negative pressure is too large, the conveyance roller that conveys the sheet becomes a conveyance resistance, and the sheet can be fed with high accuracy. Disappear. On the other hand, if the negative pressure is too small, the sheet quality cannot be maintained when a strong curled portion having a small winding diameter close to the roll core of the roll paper is conveyed, so that the image quality is deteriorated.

  Furthermore, the suction port of the exhaust duct provided near the platen has the beauty that it can be exhausted in the vicinity of the ink mist generation source, but if you try to suck as much ink mist as possible, a high voltage is applied to the suction fan. Therefore, it is necessary to increase the rotation speed to generate a high wind speed and air volume. As a result, the high air speed and air volume also pulls ink droplets ejected from the print head, thereby degrading the image quality. In addition, in order to generate strong suction, the suction fan is always fully rotated during printing, and the limited power capacity is tightened by the suction fan other than the original purpose of recording on the sheet of the inkjet recording apparatus. Result.

  The present invention has been made in view of the problems of the conventional techniques as described above, and is capable of feeding a highly curled sheet with high accuracy by a conveying roller while keeping the platen surface flat by negative pressure. An object of the present invention is to provide an ink jet recording apparatus which ensures reliability and also does not cause deterioration of image quality while exhausting the ink mist in the apparatus to the outside by an exhaust duct and further suppresses power consumption by a suction fan. Yes.

  The present invention has been proposed in order to achieve the above-described object, and includes a recording unit that ejects ink onto a sheet to record an image, a platen that supports the sheet opposite to the recording unit, and a platen provided on the platen. A plurality of suction ports, a suction platen duct provided in the lower part of the platen, an in-machine clean suction duct different from the suction platen duct provided in the recording apparatus, and suction means for setting the inside of the two suction ducts to a negative pressure state And a control unit that adjusts the suction state of the two suction units, and a transport unit that transports the sheet, and is synchronized by the control unit during recording in which the recording unit ejects ink. The suction platen duct is adjusted so that a large negative pressure is generated, and at the same time, the suction duct plate duct is adjusted to a certain level or less. When the sheet is conveyed by the conveying unit, the control unit synchronizes with the suction platen duct and the control unit causes the suction platen duct to have a small negative pressure below a certain level. The pressure is adjusted so as to be generated, and at the same time, the pressure is adjusted so that a large negative pressure is generated in the in-flight clean duct.

  Further, in the ink jet recording apparatus that records an image by ejecting ink onto roll paper, the control means is adjusted so that a minimum negative pressure is generated at the time of initial setting when the roll diameter of the roll paper to be recorded is large. Further, the negative pressure is gradually increased as the winding diameter becomes smaller.

  According to the present invention, while ensuring that the sheet is kept flat on the platen surface by negative pressure, it is ensured that the sheet is fed with high accuracy by the conveying roller, and also the ink mist in the apparatus is exhausted to the outside by the exhaust duct. Therefore, it is possible to provide an ink jet recording apparatus that does not cause deterioration in image quality and further suppresses power consumption by a suction fan.

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

  FIG. 1 is a schematic explanatory diagram of an ink jet recording apparatus.

(Overall configuration of recording device)
The ink jet recording apparatus shown in FIG. 1 includes a sheet 1 that is a roll-shaped medium. The sheet 1 is fed by a pair of feeding rollers 2 and further conveyed by applying tension to the pair of feeding rollers 2 by a discharge roller 4. However, the recording unit 3 discharges ink to record an image. The sheet 1 on which an image is recorded is cut into a predetermined length by a cutter 5 and discharged and stacked on a discharge tray 8 disposed outside the apparatus by a discharge roller pair 7. Sheet chips from the cutter 5 are dropped and stored in the waste box 6.

  A platen 9 that supports the sheet 1 is disposed at a position facing the recording unit 3, and is configured to keep the sheet 1 flat even when ink is ejected from the recording unit 3. The platen 9 is provided with a plurality of suction ports 10 (see FIG. 2), and air is sucked through a suction duct 12 by a fan 11 which is a suction means disposed below the platen 9, thereby allowing the sheet 1 to be removed. The sheet 1 is conveyed while adsorbed to the platen 9 so as to maintain the flatness of the sheet 1.

  FIG. 2 illustrates a cross section XX in FIG. 1, and is a cross sectional view viewed from a direction orthogonal to the conveyance direction of the sheet 1. In the figure, the minimum width of the sheet width 1 that can be conveyed by the recording apparatus is indicated by w1, and the maximum width is indicated by w2. Since the recording apparatus according to the present embodiment conveys the sheet 1 on one side reference and the right side is the reference side in the figure, the maximum width w2 extends to the left side from w1. The recording unit 3 reciprocates in a direction (main scanning direction) orthogonal to the conveyance direction in order to record an image on the sheet 1.

  The borderless printing ports 100, 101, 102 are holes provided in the platen 9 that are widened outward in the width direction from the sheet edge position. For example, in FIG. 2, the sheet 1 having a width w1 is conveyed along the platen 9, and the recording unit 3 ejects ink from the end of the sheet 1 to the outside, and the ink ejected outside the sheet 1 is borderless printing. Discarded in the mouths 100 and 101 realizes image recording without borders on paper, such as silver halide photographic prints.

  The suction duct 12 divides a first chamber 12a continuous with the suction port 10 of the platen 9 into a second chamber 12b on the fan 11 side, and both chambers are connected by a first opening 12c. The first opening 12c is disposed directly below the conveyance path having the minimum sheet width w1.

  In the first chamber 12a, first ink absorbers 15 and 16 are provided on both sides of the first opening 12c. The first ink absorber 15 is arranged on the reference side (right side in the figure) of the sheet conveyance from the first opening 12c, and the first ink absorber 16 is arranged on the non-reference side (left side in the figure). . In the figure, the width of the first ink absorbers 15 and 16 is shown so that the end thereof coincides with the end of the sheet 1, but it is also possible to arrange the first ink absorbers 15 and 16 to the inside of the sheet 1.

  A second ink absorber 17 is provided in the second chamber 12b below the first opening 12c. In the figure, the dimension in the width direction of the second ink absorber 17 is shorter than the width of the first opening 12c, but it may be arranged longer than this. Further, a second opening 12d is provided between the first opening 12c of the second chamber 12b and the second ink absorber 17, and the fan 11 is connected to suck the air in the suction duct 12 to make it negative. It is comprised so that it may be set as a pressure state.

(Suction fan drive)
Next, generation and collection of ink mist will be described.

  Ink mist is an unnecessary ink droplet generated due to various factors, and is largely generated by the following three factors.

  (1) When ink droplets are ejected from the nozzle (not shown) of the recording means 3, ink droplets that are ejected simultaneously with the main ink droplets are inevitably generated.

  (2) Splashes that blew off when the main ink droplets landed on the sheet.

  (3) Ink droplets that do not land on the sheet and flutter inside the machine.

  1 and 2, the recording means 3 prints a borderless image on the sheet 1. The recording unit 3 ejects ink onto the sheet 1 while moving in the main scanning direction. At the time of this discharge, first, ink mist is generated (according to the above (1)). Further, the main ink droplets ejected from the recording means 3 land on the sheet 1 to form an image. At the time of collision with this sheet, some of the ink droplets of each one droplet are the sheet 1. It is not absorbed by the water and is generated as ink mist by flying off (according to (2) above). Further, in order to realize a borderless image, the recording unit 3 prints outside the width of the sheet 1 (w1 in FIG. 2). That is, ink is ejected toward the borderless printing ports 100 and 101 that are outside the sheet 1. Some of the ink droplets ejected toward the borderless printing port 100 or 101 are landed and absorbed by the absorber 15 or 16 directly below, but the distance from the nozzle surface to the absorber 15 or 16 is too long. For this reason, ink droplets, which are extremely small droplets, float on the various airflows existing in the apparatus (according to (3) above).

  Ink mist generated for various reasons as described above eventually adheres to various places in the machine, and the inside of the machine is contaminated with ink, causing various troubles. For example, the recording device does not adhere to some of the light-shielded sensors in the machine and the sensor flag is not light-shielded, but it is shielded by ink stains and erroneously detected. It may become impossible to operate.

  In order to maintain the normal operation of the recording apparatus, it is necessary to reduce mist as much as possible. In this proposal, in the vicinity of the ink mist generation source, that is, in the longitudinal direction (main scanning direction) of the platen 1, upward so as not to interfere with the conveyed sheet 1, and in the sub-scanning direction of the carriage so as not to interfere with the carriage 3. The suction port 110a extends to the rear position. The suction port 110a protrudes from the suction duct 110, and a suction fan 111 is provided in the suction duct 110a. The ink mist generated by the printing is sucked from the suction port 110a through the suction duct 110 by the negative pressure generated by the suction fan 111, and is discharged outside the apparatus after removing ink droplets through a filter (not shown). Therefore, the inside of the machine is not stained with ink mist.

  The mist generated by the printing is sucked by the suction duct 110 and at the same time from the suction port 10 on the suction platen 1. When the sheet 1 is sucked and supported by the suction platen 9, the suction from the suction port 10 can only suck the sheet 1 and cannot suck the ink mist. For example, as shown in FIG. When printing a sheet 1 having a shorter width w1 in the recording apparatus capable of conveying up to this sheet, the ink mist is sucked by the remaining suction ports 10 not covered by the sheet 1. The suction of the ink mist by the suction port 10 which is not blocked is a small amount of suction compared to the suction port 110a extending over the entire width of the platen 9, but in the suction of the ink mist that has fluttered in the machine. Is still useful.

  The suction by the suction fan 11 is preferably performed immediately before the sheet 1 is transported to the platen 9 in order to suck and support the sheet 1, and the end is performed by the recording means 3 after the printing is finished. It is desirable not to return to the home position (not shown) outside the platen 9 but to suck ink mist that has fluttered in the machine after printing, and after a while, it is desirable. The suction by the suction fan 111 is preferably started immediately before the sheet 1 is transported and supported on the platen 9 and sucked and supported by the recording unit 3, and the ink droplets are started to be ejected by the recording unit 3. In order to suck the ink mist floating in the apparatus after printing as well as the suction fan 11 instead of at the same time as the end of the discharge, it is desirable that the suction is continued and after a while. Further, referring to the suction start and end timings of the suction fans 11 and 111, since the suction is performed while consuming the limited power capacity of the recording apparatus, the suction is performed at the required start timing. Needless to say, it is desirable to stop the suction exactly at the end timing, and it is also desirable from the viewpoint of power saving.

  Considering only to suppress the ink mist as much as possible, if the suction fans 11 and 111 are rotated to the maximum and the maximum negative pressure is generated in the suction platen 9 and the suction duct 110, the ink mist can be further collected and discharged. But it is impossible for two reasons. For example, if the negative pressure generated by the suction fan 11 is too high, the sheet 1 is attracted to the suction platen 9 and sticks too much, which causes excessive conveyance resistance for the feed roller pair 2 and the discharge roller pair 7. Therefore, the conveyance accuracy is lowered and the image quality is lowered. The other is that if the negative pressure generated by the suction fan 111 is too high, ambient air will be sucked too much from the suction port 110a, and ink droplets ejected from the recording means 3 will be attracted to reduce the landing accuracy. The image quality will deteriorate. For this reason, in the suction fan 11, the feeding roller until the recording means 3 generates negative pressure to the maximum when printing ink droplets, and the recording means 3 stops discharging and reverses and starts discharging again. When the sheet 1 is conveyed by the pair 2 or the discharge roller pair 4, a lower negative pressure is generated so that the sheet 1 does not float and the wavy shape does not collapse. Further, in the suction fan 111, during printing in which the recording unit 3 ejects ink droplets, a low negative pressure is generated so as not to attract the ink droplets, and the recording unit 3 stops ejection and reverses to start ejection again. When the sheet 1 is conveyed by the feed roller pair 2 and the paper discharge roller pair 4, the maximum negative pressure is generated in order to suck the ink mist generated in the immediately preceding printing as much as possible. In other words, in the present proposal, the control means (not shown) synchronizes to generate the negative pressure to the maximum in the suction fan 11 and at the same time to generate a certain low negative pressure in the suction fan 111, and at the same timing. The suction fan 111 generates a negative pressure to the maximum, and at the same time, the suction fan 11 generates a certain low negative pressure.

  The suction fans 11 and 111 are PWM-controlled by a control means (not shown), and can generate a desired rotational speed at a desired timing, that is, the negative pressure is adjusted accordingly.

  Furthermore, the driving of the suction fan will be described from the viewpoint of the roll paper.

  As shown in FIG. 1, the roll paper is a sheet wound in a roll shape, and the roll paper roll diameter becomes smaller as the paper is sequentially fed by the feed roller pair 2 and the paper discharge roller pair 4. . Since roll paper has been wound for a long time, it is normal for the sheet to have a “roller”. When the roll diameter has just started using a new roll paper, the roll is loose. As the roll is used, the winding diameter becomes smaller. Finally, when the roll paper is used up, the winding diameter is the smallest and the winding curl is the strongest at the same time.

  If the sheet 1 has no flatness and is curled like roll paper, the sheet 1 floats from the platen 9 when it is conveyed to the platen 9. When the sheet 1 floats, the sheet 1 comes into contact with the ejection surface (not shown) of the recording unit 3 when printing is performed by the recording unit 3, which directly leads to an ink ejection failure.

  Therefore, a negative pressure is generated on the suction platen 9 by the suction fan 11 so that the sheet 1 is sucked and held on the suction platen 9, the curling of the sheet 1 is eliminated, the paper float is eliminated, and the flatness of the sheet 1 is maintained. This prevents the drop landing accuracy from deteriorating.

  A roll diameter detection sensor (not shown) for detecting the roll diameter is provided in the vicinity of the roll paper set in the recording apparatus. As described above, in the present proposal, the suction fan 11 generates the maximum negative pressure during printing by the recording means, but the feeding roller pair 2 and the paper discharge roller pair 4 during reversal of the recording means 3 do not load the sheet. When transporting, a low negative pressure that does not cause paper floating is generated.

  In the present proposal, the suction fan 11 is controlled by a control unit (not shown) during the sheet conveyance in accordance with the roll diameter of the roll paper detected by a roll diameter detection sensor (not shown). That is, as shown in FIG. 3, when using a new roll paper having a winding diameter Rmax, a negative pressure generated during sheet conveyance is generated as a weak negative pressure Pmin that does not cause paper floating, and as the winding system becomes smaller. The negative pressure to be generated is increased, and when the roll paper whose winding system is the minimum Rmin is used up, the strong curl is eliminated and the negative pressure Pmax is generated so that the paper does not float. Further, referring to the adjustment of the suction fan 11 by the roll diameter, in order to use up the roll paper so that the paper does not float, the feeding roller pair 2 and the paper discharge roller pair 4 during the reversal of the recording unit 3 remove the sheet. It is only necessary to always generate a negative pressure Pmax during the conveyance, so that the paper does not float, and the conveyance accuracy of the feed roller pair 2 and the discharge roller pair 4 is not adversely affected. However, as in the present proposal, it is considered that the suction of the negative pressure of the suction fan 11 by the control means (not shown) and the suction pressure is adjusted by the roll diameter consumes the limited power capacity of the recording apparatus. Then, it goes without saying that it is more desirable, and it is also desirable from the viewpoint of power saving.

1 is a schematic diagram of an overall configuration of an ink jet recording apparatus according to an embodiment of the present invention. It is sectional drawing explaining the platen of the inkjet recording device by embodiment of this invention. FIG. 4 is a relationship diagram between a negative pressure generated by a suction fan that generates a negative pressure of a suction platen of the inkjet recording apparatus according to the embodiment of the present invention and a diameter of a roll paper.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sheet 2 Feed roller pair 3 Recording means 4 Discharge roller pair 5 Cutter 6 Waste box 7 Discharge roller pair 8 Discharge tray 9 Suction platen 10 Suction port 11 Platen duct suction fan 12 Suction platen duct 12a First chamber 12b Second chamber 12c First opening 12d Second opening 15 First ink absorber 16 First ink absorber 17 Second ink absorber 110 Suction duct 110a Suction port 111 Duct suction fan

Claims (2)

  A recording unit that records an image by ejecting ink on the sheet; a platen that supports the sheet opposite to the recording unit; a plurality of suction ports provided in the platen; and a suction platen duct provided in the lower part of the platen; An in-machine clean suction duct different from the suction platen duct provided inside the recording apparatus, suction means for making the inside of the two suction ducts into a negative pressure state, and control means for adjusting the suction conditions of the two suction means, respectively In the ink jet recording apparatus having a conveying means for conveying the sheet, the recording means synchronizes with the control means during recording in which ink is ejected so that a large negative pressure is generated in the suction platen duct. Adjusted so that a small negative pressure below a certain level is generated in the in-flight clean duct at the same time. When the sheet is conveyed by the means, the control means synchronizes and the control means adjusts so that a small negative pressure below a certain level is generated in the suction platen duct. An ink jet recording apparatus that is adjusted so as to generate a large negative pressure.   2. The ink jet recording apparatus according to claim 1, wherein when the image is recorded by ejecting ink onto roll paper, the control means generates a minimum negative pressure at the first setting time when the roll paper to be recorded has a large winding diameter. An ink jet recording apparatus, characterized in that the negative pressure is gradually increased as the winding diameter is further reduced.

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